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Hovorka M, Prinz B, Simon D, Zöger M, Rumpl C, Nimmerichter A. Long-Term Alterations in Pulmonary V˙O2 and Muscle Deoxygenation On-Kinetics During Heavy-Intensity Exercise in Competitive Youth Cyclists: A Cohort Study. Pediatr Exerc Sci 2024:1-7. [PMID: 38714302 DOI: 10.1123/pes.2023-0110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 02/20/2024] [Accepted: 03/12/2024] [Indexed: 05/09/2024]
Abstract
PURPOSE The aim of this investigation was to assess alterations of pulmonary oxygen uptake (V˙O2) and muscle deoxygenation on-kinetics during heavy-intensity cycling in youth cyclists over a period of 15 months. METHODS Eleven cyclists (initial age, 14.3 [1.6] y; peak V˙O2, 62.2 [4.5] mL·min-1·kg-1) visited the laboratory twice on 3 occasions within 15 months. Participants performed an incremental ramp exercise test and a constant workrate test within the heavy-intensity domain during the first visit and second visit, respectively. Subsequently, parameter estimates of the V˙O2 and muscle deoxygenation on-kinetics were determined with mono-exponential models. RESULTS The V˙O2 phase II time constant decreased from occasion 1 (34 [4] s) to occasion 2 (30 [4] s, P = .005) and 3 (28 [4] s, P = .010). However, no significant alteration was observed between occasions 2 and 3 (P = .565). The V˙O2 slow component amplitude either expressed in absolute values (ie, L·min-1) or relative to end exercise V˙O2 (ie, %) showed no significant changes throughout the study (P = .972 and .996). Furthermore, the muscle deoxygenation on-kinetic mean response time showed no significant changes throughout the study (18 [8], 18 [3], and 16 [5] s for occasions 1, 2, and 3, respectively; P = .279). CONCLUSION These results indicate proportional enhancements of local muscle oxygen distribution and utilization, which both contributed to the speeding of the V˙O2 on-kinetics herein.
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Affiliation(s)
- Matthias Hovorka
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
- Centre for Sport Science and University Sports, University of Vienna, Vienna,Austria
- Doctoral School of Pharmaceutical, Nutritional and Sport Sciences, University of Vienna, Vienna,Austria
| | - Bernhard Prinz
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
| | - Dieter Simon
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
| | - Manfred Zöger
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
| | - Clemens Rumpl
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
| | - Alfred Nimmerichter
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt,Austria
- Centre for Sport Science and University Sports, University of Vienna, Vienna,Austria
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Liu Y, Zhou A, Li F, Yue T, Xia Y, Yao Y, Zhou X, Zhang Y, Wang Y. Aerobic capacity and [Formula: see text] kinetics adaptive responses to short-term high-intensity interval training and detraining in untrained females. Eur J Appl Physiol 2023; 123:1685-1699. [PMID: 36995431 DOI: 10.1007/s00421-023-05182-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 03/14/2023] [Indexed: 03/31/2023]
Abstract
PURPOSE This study investigated the physical fitness and oxygen uptake kinetics (τ[Formula: see text]) along with the O2 delivery and utilization (heart rate kinetics, τHR; deoxyhemoglobin/[Formula: see text] ratio, ∆[HHb]/[Formula: see text]) adaptations of untrained female participants responding to 4 weeks of high-intensity interval training (HIIT) and 2 weeks of detraining. METHODS Participants were randomly assigned to HIIT (n = 11, 4 × 4 protocol) or nonexercising control (n = 9) groups. Exercising group engaged 4 weeks of treadmill HIIT followed by 2 weeks of detraining while maintaining daily activity level. Ramp-incremental (RI) tests and step-transitions to moderate-intensity exercise were performed. Aerobic capacity and performance (maximal oxygen uptake, [Formula: see text]; gas-exchange threshold, GET; power output, PO), body composition (skeletal muscle mass, SMM; body fat percentage, BF%), muscle oxygenation status (∆[HHb]), [Formula: see text], and HR kinetics were assessed. RESULTS HIIT elicited improvements in aerobic capacity ([Formula: see text], + 0.17 ± 0.04 L/min; GET, + 0.18 ± 0.05 L/min, P < 0.01; PO-[Formula: see text], ± 23.36 ± 8.37 W; PO-GET, + 17.18 ± 3.07 W, P < 0.05), body composition (SMM, + 0.92 ± 0.17 kg; BF%, - 3.08% ± 0.58%, P < 0.001), and speed up the τ[Formula: see text] (- 8.04 ± 1.57 s, P < 0.001) significantly, extending to better ∆[HHb]/[Formula: see text] ratio (1.18 ± 0.08 to 1.05 ± 0.14). After a period of detraining, the adaptation in body composition and aerobic capacity, as well as the accelerated τ[Formula: see text] were maintained in the HIIT group, but the PO-[Formula: see text] and PO-GET declined below the post-training level (P < 0.05), whereas no changes were reported in controls (P > 0.05). Four weeks of HIIT induced widespread physiological adaptations in females, and the majority of improvements were preserved after 2 weeks of detraining except for power output corresponding to [Formula: see text] and GET.
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Affiliation(s)
- Yujie Liu
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Aiyi Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Fengya Li
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Tian Yue
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yuncan Xia
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yibing Yao
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Xiaoxiao Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yihong Zhang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yan Wang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China.
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Reinpõld K, Rannama I. Oxygen Uptake and Bilaterally Measured Vastus Lateralis Muscle Oxygen Desaturation Kinetics in Well-Trained Endurance Cyclists. J Funct Morphol Kinesiol 2023; 8:jfmk8020064. [PMID: 37218860 DOI: 10.3390/jfmk8020064] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/10/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023] Open
Abstract
The aim of the present study was to compare and analyse the relationships between pulmonary oxygen uptake and vastus lateralis (VL) muscle oxygen desaturation kinetics measured bilaterally with Moxy NIRS sensors in trained endurance athletes. To this end, 18 trained athletes (age: 42.4 ± 7.2 years, height: 1.837 ± 0.053 m, body mass: 82.4 ± 5.7 kg) visited the laboratory on two consecutive days. On the first day, an incremental test was performed to determine the power values for the gas exchange threshold, the ventilatory threshold (VT), and V̇O2max levels from pulmonary ventilation. On the second day, the athletes performed a constant work rate (CWR) test at the power corresponding to the VT. During the CWR test, the pulmonary ventilation characteristics, left and right VL muscle O2 desaturation (DeSmO2), and pedalling power were continuously recorded, and the average signal of both legs' DeSmO2 was computed. Statistical significance was set at p ≤ 0.05. The relative response amplitudes of the primary and slow components of VL desaturation and pulmonary oxygen uptake kinetics did not differ, and the primary amplitude of muscle desaturation kinetics was strongly associated with the initial response rate of oxygen uptake. Compared with pulmonary O2 kinetics, the primary response time of the muscle desaturation kinetics was shorter, and the slow component started earlier. There was good agreement between the time delays of the slow components describing global and local metabolic processes. Nevertheless, there was a low level of agreement between contralateral desaturation kinetic variables. The averaged DeSmO2 signal of the two sides of the body represented the oxygen kinetics more precisely than the right- or left-leg signals separately.
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Affiliation(s)
- Karmen Reinpõld
- School of Natural Sciences and Health, University of Tallinn, 10120 Tallinn, Estonia
| | - Indrek Rannama
- School of Natural Sciences and Health, University of Tallinn, 10120 Tallinn, Estonia
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Goulding RP, Burnley M, Wüst RCI. How Priming Exercise Affects Oxygen Uptake Kinetics: From Underpinning Mechanisms to Endurance Performance. Sports Med 2023; 53:959-976. [PMID: 37010782 PMCID: PMC10115720 DOI: 10.1007/s40279-023-01832-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/04/2023]
Abstract
The observation that prior heavy or severe-intensity exercise speeds overall oxygen uptake ([Formula: see text]O2) kinetics, termed the "priming effect", has garnered significant research attention and its underpinning mechanisms have been hotly debated. In the first part of this review, the evidence for and against (1) lactic acidosis, (2) increased muscle temperature, (3) O2 delivery, (4) altered motor unit recruitment patterns and (5) enhanced intracellular O2 utilisation in underpinning the priming effect is discussed. Lactic acidosis and increased muscle temperature are most likely not key determinants of the priming effect. Whilst priming increases muscle O2 delivery, many studies have demonstrated that an increased muscle O2 delivery is not a prerequisite for the priming effect. Motor unit recruitment patterns are altered by prior exercise, and these alterations are consistent with some of the observed changes in [Formula: see text]O2 kinetics in humans. Enhancements in intracellular O2 utilisation likely play a central role in mediating the priming effect, probably related to elevated mitochondrial calcium levels and parallel activation of mitochondrial enzymes at the onset of the second bout. In the latter portion of the review, the implications of priming on the parameters of the power-duration relationship are discussed. The effect of priming on subsequent endurance performance depends critically upon which phases of the [Formula: see text]O2 response are altered. A reduced [Formula: see text]O2 slow component or increased fundamental phase amplitude tend to increase the work performable above critical power (i.e. W´), whereas a reduction in the fundamental phase time constant following priming results in an increased critical power.
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Affiliation(s)
- Richie P Goulding
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands.
| | - Mark Burnley
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Rob C I Wüst
- Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Amsterdam Movement Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ, Amsterdam, The Netherlands
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Ramonas A, Laursen PB, Williden M, Chang WL, Kilding AE. Carbohydrate intake before and during high intensity exercise with reduced muscle glycogen availability affects the speed of muscle reoxygenation and performance. Eur J Appl Physiol 2023:10.1007/s00421-023-05162-y. [PMID: 36897400 DOI: 10.1007/s00421-023-05162-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Accepted: 02/16/2023] [Indexed: 03/11/2023]
Abstract
Muscle glycogen state and carbohydrate (CHO) supplementation before and during exercise may impact responses to high-intensity interval training (HIIT). This study determined cardiorespiratory, substrate metabolism, muscle oxygenation, and performance when completing HIIT with or without CHO supplementation in a muscle glycogen depleted state. On two occasions, in a cross-over design, eight male cyclists performed a glycogen depletion protocol prior to HIIT during which either a 6% CHO drink (60 g.hr-1) or placebo (%CHO, PLA) was consumed. HIIT consisted of 5 × 2 min at 80% peak power output (PPO), 3 × 10-min bouts of steady-state (SS) cycling (50, 55, 60% PPO), and a time-to-exhaustion (TTE) test. There was no difference in SS [Formula: see text], HR, substrate oxidation and gross efficiency (GE %) between CHO and PLA conditions. A faster rate of muscle reoxygenation (%. s-1) existed in PLA after the 1st (Δ - 0.23 ± 0.22, d = 0.58, P < 0.05) and 3rd HIIT intervals (Δ - 0.34 ± 0.25, d = 1.02, P < 0.05). TTE was greater in CHO (7.1 ± 5.4 min) than PLA (2.5 ± 2.3 min, d = 0.98, P < 0.05). CHO consumption before and during exercise under reduced muscle glycogen conditions did not suppress fat oxidation, suggesting a strong regulatory role of muscle glycogen on substrate metabolism. However, CHO ingestion provided a performance benefit under intense exercise conditions commenced with reduced muscle glycogen. More research is needed to understand the significance of altered muscle oxygenation patterns during exercise.
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Affiliation(s)
- Andrius Ramonas
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand.
| | - Paul B Laursen
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
| | - Micalla Williden
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
| | | | - Andrew E Kilding
- School of Sports and Recreation, Auckland University of Technology, Sports Performance Research Institute New Zealand (SPRINZ), AUT University, PO Box 92006, Auckland, 1142, New Zealand
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Liu Y, Xia Y, Yue T, Li F, Zhou A, Zhou X, Yao Y, Zhang Y, Wang Y. Adaptations to 4 weeks of high-intensity interval training in healthy adults with different training backgrounds. Eur J Appl Physiol 2023; 123:1283-1297. [PMID: 36795131 DOI: 10.1007/s00421-023-05152-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 02/03/2023] [Indexed: 02/17/2023]
Abstract
PURPOSE This study investigated the physical fitness and oxygen uptake kinetics ([Formula: see text]) along with the exercise-onset O2 delivery (heart rate kinetics, τHR; changes in normalized deoxyhemoglobin/[Formula: see text] ratio, Δ[HHb]/[Formula: see text]) adaptations of individuals with different physical activity (PA) backgrounds responding to 4 weeks of high-intensity interval training (HIIT), and the possible effects of skeletal muscle mass (SMM) on training-induced adaptations. METHODS Twenty subjects (10 high-PA level, HIIT-H; 10 moderate-PA level, HIIT-M) engaged in 4 weeks of treadmill HIIT. Ramp-incremental (RI) test and step-transitions to moderate-intensity exercise were performed. Cardiorespiratory fitness, body composition, muscle oxygenation status, VO2 and HR kinetics were assessed at baseline and post-training. RESULTS HIIT improved fitness status for HIIT-H ([Formula: see text], + 0.26 ± 0.07 L/min; SMM, + 0.66 ± 0.70 kg; body fat, - 1.52 ± 1.93 kg; [Formula: see text], - 7.11 ± 1.05 s, p < 0.05) and HIIT-M ([Formula: see text], 0.24 ± 0.07 L/min, SMM, + 0.58 ± 0.61 kg; body fat, - 1.64 ± 1.37 kg; [Formula: see text], - 5.48 ± 1.05 s, p < 0.05) except for visceral fat area (p = 0.293) without between-group differences (p > 0.05). Oxygenated and deoxygenated hemoglobin amplitude during the RI test increased for both groups (p < 0.05) except for total hemoglobin (p = 0.179). The Δ[HHb]/[Formula: see text] overshoot was attenuated for both groups (p < 0.05) but only eliminated in HIIT-H (1.05 ± 0.14 to 0.92 ± 0.11), and no change was observed in τHR (p = 0.144). Linear mixed-effect models presented positive effects of SMM on absolute [Formula: see text] (p < 0.001) and ΔHHb (p = 0.034). CONCLUSION Four weeks of HIIT promoted positive adaptations in physical fitness and [Formula: see text] kinetics, with the peripheral adaptations attributing to the observed improvements. The training effects are similar between groups suggesting that HIIT is effective for reaching higher physical fitness levels.
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Affiliation(s)
- Yujie Liu
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yuncan Xia
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Tian Yue
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Fengya Li
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Aiyi Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Xiaoxiao Zhou
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yibing Yao
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yihong Zhang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China
| | - Yan Wang
- School of Sports Medicine and Rehabilitation, Beijing Sport University, Beijing, 100084, China.
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Hovorka M, Prinz B, Simon D, Zöger M, Rumpl C, Nimmerichter A. Longitudinal alterations of pulmonary V.O2 on-kinetics during moderate-intensity exercise in competitive youth cyclists are related to alterations in the balance between microvascular O2 distribution and muscular O2 utilization. Front Sports Act Living 2022; 4:982548. [DOI: 10.3389/fspor.2022.982548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 10/31/2022] [Indexed: 11/17/2022] Open
Abstract
PurposeThe main purpose of the current study was to investigate the dynamic adjustment of pulmonary oxygen uptake (V.O2) in response to moderate-intensity cycling on three occasions within 15 months in competitive youth cyclists. Furthermore, the muscle Δdeoxy[heme] on-kinetics and the Δdeoxy[heme]-to-V.O2 ratio were modeled to examine possible mechanistic basis regulating pulmonary V.O2 on-kinetics.MethodsEleven cyclists (initial age, 14.3 ± 1.6 y; peak V.O2, 62.2 ± 4.5 mL.min−1.kg−1) with a training history of 2–5 years and a training volume of ~10 h per week participated in this investigation. V.O2 and Δdeoxy[heme] responses during workrate-transitions to moderate-intensity cycling were measured with breath-by-breath spirometry and near-infrared spectroscopy, respectively, and subsequently modeled with mono-exponential models to derive parameter estimates. Additionally, a normalized Δdeoxy[heme]-to-V.O2 ratio was calculated for each participant. One-way repeated-measures ANOVA was used to assess effects of time on the dependent variables of the responses.ResultsThe V.O2 time constant remained unchanged between the first (~24 s) and second visit (~22 s, P > 0.05), whereas it was significantly improved through the third visit (~13 s, P = 0.006–0.013). No significant effects of time were revealed for the parameter estimates of the Δdeoxy[heme] response (P > 0.05). A significant Δdeoxy[heme]-to-V.O2 ratio “overshoot” was evident on the first (1.09 ± 0.10, P = 0.006) and second (1.05 ± 0.09, P = 0.047), though not the third (0.97 ± 0.10, P > 0.05), occasion. These “overshoots” showed strong positive relationships with the V.O2 time constant during the first (r = 0.66, P = 0.028) and second visit (r = 0.76, P = 0.007). Further, strong positive relationships have been observed between the individual changes of the fundamental phase τp and the Δdeoxy[heme]-to-V.O2 ratio “overshoot” from occasion one to two (r = 0.70, P = 0.017), and two to three (r = 0.74, P = 0.009).ConclusionThis suggests that improvements in muscle oxygen provision and utilization capacity both occurred, and each may have contributed to enhancing the dynamic adjustment of the oxidative “machinery” in competitive youth cyclists. Furthermore, it indicates a strong link between an oxygen maldistribution within the tissue of interrogation and the V.O2 time constant.
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Masuda T, Takeuchi S, Kubo Y, Nishida Y. Validity of anaerobic threshold measured in resistance exercise. J Phys Ther Sci 2022; 34:199-203. [PMID: 35291469 PMCID: PMC8918104 DOI: 10.1589/jpts.34.199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/02/2021] [Indexed: 11/24/2022] Open
Abstract
[Purpose] Intensity for resistance exercise is estimated based on the maximum muscle
strength. Exercise prescription without evaluating the biological response has a
challenge. This study aimed to confirm whether anaerobic threshold measured using
cardiopulmonary exercise test in resistance exercise is appropriate or not. [Participants
and Methods] Resistance exercise adopted for the study was right-leg knee extension. The
participants were 10 healthy young males. We investigated whether the oxygen uptake
kinetics achieved a steady state within 3 min during the constant-load test with knee
extension at 80% anaerobic threshold using cardiopulmonary exercise test with knee
extension. If oxygen uptake kinetics achieved a steady state within 3 min, the exercise
intensity measured using cardiopulmonary exercise test was considered appropriate.
[Results] Anaerobic threshold was measured using the conventional approach in all
participants. The steady state of oxygen uptake kinetics could be achieved within 3 min.
In the constant-load test with knee extension at 80% anaerobic threshold, the oxygen
uptake kinetics achieved a steady state within 3 min. [Conclusion] Based on the findings,
the anaerobic threshold obtained using cardiopulmonary exercise test with resistance
exercise was judged as appropriate. The results of this study contribute to the accurate
setting of exercise load for resistance exercise and condition setting for the evaluation
of skeletal muscle function.
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Affiliation(s)
- Takayuki Masuda
- Department of Rehabilitation, Hamamatsu University School of Medicine, University Hospital: 1-20-1 Handayama, Higashi-ku, Hamamatsu-shi, Shizuoka 431-3192, Japan
| | - Shinta Takeuchi
- Department of Physical Therapy, School of Health Sciences at Narita, International University of Health and Welfare, Japan
| | | | - Yusuke Nishida
- Department of Physical Therapy, School of Health Sciences at Narita, International University of Health and Welfare, Japan
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Chopra K, Jeffries O, Tallent J, Heffernan S, Kilduff L, Gray A, Waldron M. Repeated Ischemic Preconditioning Effects on Physiological Responses to Hypoxic Exercise. Aerosp Med Hum Perform 2022; 93:13-21. [PMID: 35063051 DOI: 10.3357/amhp.5919.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
INTRODUCTION: Repeated ischemic preconditioning (IPC) can improve muscle and pulmonary oxygen on-kinetics, blood flow, and exercise efficiency, but these effects have not been investigated in severe hypoxia. The aim of the current study was to evaluate the effects of 7 d of IPC on resting and exercising muscle and cardio-pulmonary responses to severe hypoxia.METHODS: A total of 14 subjects received either: 1) 7 d of repeated lower-limb occlusion (4 × 5 min, 217 ± 30 mmHg) at limb occlusive pressure (IPC) or SHAM (4 × 5 min, 20 mmHg). Subjects were tested for resting limb blood flow, relative microvascular deoxyhemoglobin concentration ([HHB]), and pulmonary oxygen (Vo2p) responses to steady state and incremental exercise to exhaustion in hypoxia (fractional inspired O₂ = 0.103), which was followed by 7 d of IPC or SHAM and retesting 72 h post-intervention.RESULTS: There were no effects of IPC on maximal oxygen consumption, time to exhaustion during the incremental test, or minute ventilation and arterial oxygen saturation. However, the IPC group had higher delta efficiency based on pooled results and lower steady state Δ[HHB] (IPC ∼24% vs. SHAM ∼6% pre to post), as well as slowing the [HHB] time constant (IPC ∼26% vs. SHAM ∼3% pre to post) and reducing the overshoot in [HHB]: Vo₂ ratio during exercise onset.CONCLUSIONS: Collectively, these results demonstrate that muscle O₂ efficiency and microvascular O₂ distribution can be improved by repeated IPC, but there are no effects on maximal exercise capacity in severe hypoxia.Chopra K, Jeffries O, Tallent J, Heffernan S, Kilduff L, Gray A, Waldron M. Repeated ischemic preconditioning effects on physiological responses to hypoxic exercise. Aerosp Med Hum Perform. 2022; 93(1):13-21.
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Kubo Y, Fujita D, Matsumoto N, Katsuda Y, Nishida Y. Association between pulmonary oxygen uptake on-kinetics and acute cardiovascular responses to resistance exercise in patients with coronary artery disease: a preliminary study. J Phys Ther Sci 2021; 33:606-611. [PMID: 34393372 PMCID: PMC8332648 DOI: 10.1589/jpts.33.606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 05/24/2021] [Indexed: 11/24/2022] Open
Abstract
[Purpose] This study aimed to examine whether pulmonary oxygen uptake on-kinetics at the
onset of moderate-intensity exercise can predict acute cardiovascular responses to
resistance exercise. [Participants and Methods] The association between pulmonary oxygen
uptake on-kinetics and acute cardiovascular responses to a single resistance exercise
session was investigated in seven patients with low-risk coronary artery disease who
underwent revascularization through percutaneous coronary intervention. The participants
performed a cardiopulmonary exercise test on a cycle ergometer and a single resistance
exercise session at 30% of maximum voluntary contraction on a bilateral leg-extension
machine 1 week after surgery. We measured the ventilatory anaerobic threshold and
pulmonary oxygen uptake on-kinetics during the cardiopulmonary exercise test; left
ventricular ejection fraction at rest; and heart rate, systolic blood pressure, and rate
pressure product during the single resistance exercise session. [Results] Pulmonary oxygen
uptake on-kinetics showed a positive association with the amount of increase in systolic
blood pressure and rate pressure product during the single resistance exercise session,
but had no association with the amount of increase in heart rate. Ventilatory anaerobic
threshold and left ventricular ejection fraction were not associated with these
parameters. [Conclusion] These data suggested that pulmonary oxygen uptake on-kinetics can
be a useful evaluation index for predicting acute systolic blood pressure and rate
pressure product responses to low-intensity resistance exercise 1 week after percutaneous
coronary intervention in patients with low-risk coronary artery disease.
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Affiliation(s)
- Yusuke Kubo
- Kobori Orthopedic Clinic: 548-2 Nearaichou, Kita-ku, Hamamatsu city, Shizuoka 433-8108, Japan
| | - Daisuke Fujita
- Department of Physical Therapy, Fukuoka International University of Health and Welfare, Japan
| | | | | | - Yusuke Nishida
- Department of Physical Therapy, International University of Health and Welfare, Japan
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Rokkedal-Lausch T, Franch J, Poulsen MK, Thomsen LP, Weitzberg E, Kamavuako EN, Karbing DS, Larsen RG. Multiple-day high-dose beetroot juice supplementation does not improve pulmonary or muscle deoxygenation kinetics of well-trained cyclists in normoxia and hypoxia. Nitric Oxide 2021; 111-112:37-44. [PMID: 33831566 DOI: 10.1016/j.niox.2021.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/24/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Dietary nitrate (NO3-) supplementation via beetroot juice (BR) has been reported to lower oxygen cost (i.e., increased exercise efficiency) and speed up oxygen uptake (VO2) kinetics in untrained and moderately trained individuals, particularly during conditions of low oxygen availability (i.e., hypoxia). However, the effects of multiple-day, high dose (12.4 mmol NO3- per day) BR supplementation on exercise efficiency and VO2 kinetics during normoxia and hypoxia in well-trained individuals are not resolved. In a double-blinded, randomized crossover study, 12 well-trained cyclists (66.4 ± 5.3 ml min-1∙kg-1) completed three transitions from rest to moderate-intensity (~70% of gas exchange threshold) cycling in hypoxia and normoxia with supplementation of BR or nitrate-depleted BR as placebo. Continuous measures of VO2 and muscle (vastus lateralis) deoxygenation (ΔHHb, using near-infrared spectroscopy) were acquired during all transitions. Kinetics of VO2 and deoxygenation (ΔHHb) were modeled using mono-exponential functions. Our results showed that BR supplementation did not alter the primary time constant for VO2 or ΔHHb during the transition from rest to moderate-intensity cycling. While BR supplementation lowered the amplitude of the VO2 response (2.1%, p = 0.038), BR did not alter steady state VO2 derived from the fit (p = 0.258), raw VO2 data (p = 0.231), moderate intensity exercise efficiency (p = 0.333) nor steady state ΔHHb (p = 0.224). Altogether, these results demonstrate that multiple-day, high-dose BR supplementation does not alter exercise efficiency or oxygen uptake kinetics during normoxia and hypoxia in well-trained athletes.
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Affiliation(s)
- Torben Rokkedal-Lausch
- Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark.
| | - Jesper Franch
- Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark
| | - Mathias K Poulsen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark
| | - Lars P Thomsen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark
| | - Eddie Weitzberg
- Department of Physiology and Pharmacology, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ernest N Kamavuako
- Center for Robotics Research, Department of Engineering, King's College London, London, United Kingdom
| | - Dan S Karbing
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark
| | - Ryan G Larsen
- Sport Sciences - Performance and Technology, Department of Health Science and Technology, Aalborg University, DK-9220, Aalborg, Denmark
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Inglis EC, Iannetta D, Murias JM. Association between [Formula: see text]O 2 kinetics and [Formula: see text]O 2max in groups differing in fitness status. Eur J Appl Physiol 2021; 121:1921-1931. [PMID: 33730210 DOI: 10.1007/s00421-021-04623-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/05/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE This study evaluated (i) the relationship between oxygen uptake ([Formula: see text]O2) kinetics and maximal [Formula: see text]O2 ([Formula: see text]O2max) within groups differing in fitness status, and (ii) the adjustment of [Formula: see text]O2 kinetics compared to that of central [cardiac output (Q̇), heart rate (HR)] and peripheral (deoxyhemoglobin over [Formula: see text]O2 ratio ([HHb]/[Formula: see text]O2)] O2 delivery, during step-transitions to moderate-intensity exercise. METHODS Thirty-six young healthy male participants (18 untrained; 18 trained) performed a ramp-incremental test to exhaustion and 3 step-transitions to moderate-intensity exercise. Q̇ and HR kinetics were measured in 18 participants (9 untrained; 9 trained). RESULTS No significant correlation between τ̇[Formula: see text]O2 and [Formula: see text]O2max was found in trained participants (r = 0.29; p > 0.05) whereas a significant negative correlation was found in untrained (r = - 0.58; p < 0.05) and all participants (r = - 0.82; p < 0.05). τQ̇ (18.8 ± 5.5 s) and τHR (20.1 ± 6.2 s) were significantly greater than τ[Formula: see text]O2 (13.9 ± 2.7 s) for trained (p < 0.05). No differences were found between τQ̇ (22.8 ± 8.45 s), τHR (21.2 ± 8.3 s) and τ[Formula: see text]O2 (28.9 ± 5.7 s) for untrained (p > 0.05). τQ̇ demonstrated a significant strong positive correlation with τHR in trained (r = 0.76; p < 0.05) but not untrained (r = 0.61; p > 0.05). A significant overshoot in the [HHb]/[Formula: see text]O2 ratio was found in the untrained groups (p < 0.05) but not in the trained groups (p > 0.05) CONCLUSION: The results indicated that when comparing participants of different fitness status (i) there is a point at which greater V̇O2max values are not accompanied by faster [Formula: see text]O2 kinetics; (ii) central delivery of O2 does not seem to limit the kinetics of [Formula: see text]O2; and (iii) O2 delivery within the active tissues might contribute to the slower [Formula: see text]O2 kinetics response in untrained participants.
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Affiliation(s)
- Erin Calaine Inglis
- Faculty of Kinesiology, University of Calgary, KNB 434, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, KNB 434, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, KNB 434, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
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13
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The effect of age and training status on oxygen uptake kinetics in women. Respir Physiol Neurobiol 2020; 278:103439. [PMID: 32360209 DOI: 10.1016/j.resp.2020.103439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 03/27/2020] [Accepted: 03/27/2020] [Indexed: 11/21/2022]
Abstract
We examined the effect of age and training status on the oxygen uptake (V˙ O2) kinetics of untrained and recreationally trained women. Young (20-35yr), middle-age (40-55yr) and older (58-71yr) recreationally trained (YTR, n = 10; MTR, n = 12; OTR, n = 9) and untrained (YUT, n = 12; MUT, n = 10; OUT, n = 9) women participated in this crossectional study. Breath-by-breath V˙ O2 and near-infrared-spectroscopy-derived (NIRS) muscle deoxygenation [HHb] were monitored continuously during increasing and constant walking exercises. On-transition V˙ O2 and [HHb] responses to moderate intensity walking were modeled as mono-exponential. The data were normalized for each subject (0%-100 %), and [HHb]/ V˙ O2 ratio was calculated as the average [HHb]/ V˙ O2 during the 20- to 120-s period after the onset of moderate intensity walking exercise. The time constant of V˙ O2 (τ V˙ O2) was longer in OUT(23.8 ± 2.4), MUT(25.4 ± 5.1), YUT(23.1 ± 3.4) than in YTR(16.2 ± 2.0), MTR(16.7 ± 3.9), OTR(16.3 ± 2.8) women (p < 0.05). The [HHb]/ V˙ O2 ratio in OUT (1.31 ± 0.18) was higher than in YTR(1.08 ± 0.05), MTR(1.13 ± 0.09), YUT(1.12 ± 0.09) (p < 0.05). It is concluded that recreationally trained women had faster V˙ O2 kinetics along with better matching of O2 delivery and utilization at the site of gas exchange in the exercising muscles.
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14
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Colosio AL, Teso M, Pogliaghi S. Prolonged static stretching causes acute, nonmetabolic fatigue and impairs exercise tolerance during severe-intensity cycling. Appl Physiol Nutr Metab 2020; 45:902-910. [PMID: 32176851 DOI: 10.1139/apnm-2019-0981] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested the hypothesis that static stretching, an acute, nonmetabolic fatiguing intervention, reduces exercise tolerance by increasing muscle activation and affecting muscle bioenergetics during cycling in the "severe" intensity domain. Ten active men (age, 24 ± 2 years; body mass, 74 ± 11 kg; height, 176 ± 8 cm) participated in identical constant-load cycling tests of equal intensity, of which 2 tests were carried out under control conditions and 2 were done after stretching. This resulted in a 5% reduction of maximal isokinetic sprinting power output. We measured (i) oxygen consumption, (ii) electromyography, (iii) deoxyhemoglobin, (iv) blood lactate concentration; (v) time to exhaustion, and (vi) perception of effort. Finally, oxygen consumption and deoxyhemoglobin kinetics were determined. Force reduction following stretching was accompanied by augmented muscle excitation at a given workload (p = 0.025) and a significant reduction in time to exhaustion (p = 0.002). The time to peak oxygen consumption was reduced by stretching (p = 0.034), suggesting an influence of the increased muscle excitation on the oxygen consumption kinetics. Moreover, stretching was associated with a mismatch between O2 delivery and utilization during the isokinetic exercise, increased perception of effort, and blood lactate concentration; these observations are all consistent with an increased contribution of the glycolytic energy system to sustain the same absolute intensity. These results suggest a link between exercise intolerance and the decreased ability to produce force. Novelty We provided the first characterization of the effects of prolonged stretching on the metabolic response during severe cycling. Stretching reduced maximal force and augmented muscle activation, which in turn increased the metabolic response to sustain exercise.
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Affiliation(s)
- Alessandro L Colosio
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
| | - Massimo Teso
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
| | - Silvia Pogliaghi
- Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Via Casorati 43, Verona 37131, Italy
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Mattu AT, Iannetta D, MacInnis MJ, Doyle‐Baker PK, Murias JM. Menstrual and oral contraceptive cycle phases do not affect submaximal and maximal exercise responses. Scand J Med Sci Sports 2019; 30:472-484. [DOI: 10.1111/sms.13590] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 10/09/2019] [Accepted: 10/28/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Anmol T. Mattu
- Faculty of Kinesiology University of Calgary Calgary AB Canada
| | - Danilo Iannetta
- Faculty of Kinesiology University of Calgary Calgary AB Canada
| | | | - Patricia K. Doyle‐Baker
- Faculty of Kinesiology University of Calgary Calgary AB Canada
- School of Architecture, Planning and Landscape University of Calgary Calgary AB Canada
| | - Juan M. Murias
- Faculty of Kinesiology University of Calgary Calgary AB Canada
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Breese BC, Saynor ZL, Barker AR, Armstrong N, Williams CA. Relationship between (non)linear phase II pulmonary oxygen uptake kinetics with skeletal muscle oxygenation and age in 11-15 year olds. Exp Physiol 2019; 104:1929-1941. [PMID: 31512297 DOI: 10.1113/ep087979] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/09/2019] [Indexed: 12/28/2022]
Abstract
NEW FINDINGS What is the central question of this study? Do the phase II parameters of pulmonary oxygen uptake ( V ̇ O 2 ) kinetics display linear, first-order behaviour in association with alterations in skeletal muscle oxygenation during step cycling of different intensities or when exercise is initiated from an elevated work rate in youths. What is the main finding and its importance? Both linear and non-linear features of phase II V ̇ O 2 kinetics may be determined by alterations in the dynamic balance between microvascular O2 delivery and utilization in 11-15 year olds. The recruitment of higher-order (i.e. type II) muscle fibres during 'work-to-work' cycling might be responsible for modulating V ̇ O 2 kinetics with chronological age. ABSTRACT This study investigated in 19 male youths (mean age: 13.6 ± 1.1 years, range: 11.7-15.7 years) the relationship between pulmonary oxygen uptake ( V ̇ O 2 ) and muscle deoxygenation kinetics during moderate- and very heavy-intensity 'step' cycling initiated from unloaded pedalling (i.e. U → M and U → VH) and moderate to very heavy-intensity step cycling (i.e. M → VH). Pulmonary V ̇ O 2 was measured breath-by-breath along with the tissue oxygenation index (TOI) of the vastus lateralis using near-infrared spectroscopy. There were no significant differences in the phase II time constant ( τ V ̇ O 2 p ) between U → M and U → VH (23 ± 6 vs. 25 ± 7 s; P = 0.36); however, the τ V ̇ O 2 p was slower during M → VH (42 ± 16 s) compared to other conditions (P < 0.001). Quadriceps TOI decreased with a faster (P < 0.01) mean response time (MRT; i.e. time delay + τ) during U → VH (14 ± 2 s) compared to U → M (22 ± 4 s) and M → VH (20 ± 6 s). The difference (Δ) between the τ V ̇ O 2 p and MRT-TOI was greater during U → VH compared to U → M (12 ± 7 vs. 2 ± 7 s, P < 0.001) and during M → VH (23 ± 15 s) compared to other conditions (P < 0.02), suggesting an increased proportional speeding of fractional O2 extraction. The slowing of the τ V ̇ O 2 p during M → VH relative to U → M and U → VH correlated positively with chronological age (r = 0.68 and 0.57, respectively, P < 0.01). In youths, 'work-to-work' transitions slowed microvascular O2 delivery-to-O2 utilization with alterations in phase II V ̇ O 2 dynamics accentuated between the ages of 11 and 15 years.
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Affiliation(s)
- Brynmor C Breese
- School of Biomedical Sciences, Faculty of Medicine and Dentistry, University of Plymouth, Plymouth, UK
| | - Zoe L Saynor
- Department of Sport and Exercise Science, Faculty of Science, University of Portsmouth, Portsmouth, UK
| | - Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Neil Armstrong
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Craig A Williams
- Children's Health and Exercise Research Centre, Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
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17
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Kubo Y, Fujita D, Sugiyama S, Hosokawa M, Nishida Y. Pulmonary oxygen uptake on-kinetics can predict acute physiological responses to resistance exercise training in healthy young men. Clin Physiol Funct Imaging 2019; 39:339-344. [PMID: 31087806 DOI: 10.1111/cpf.12583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 05/11/2019] [Indexed: 11/30/2022]
Abstract
PURPOSE To clarify whether pulmonary oxygen uptake kinetics ( τ V ˙ O 2 p ) at the onset of moderate-intensity exercise can predict acute physiological responses to resistance exercise training (RET). METHODS We investigated the relationship between τ V ˙ O 2 p and acute metabolic and hemodynamic responses to a single RET session in 27 healthy young adult men. Cardiopulmonary exercise was on a cycle ergometer, and a single RET at 30% or 60% of one-repetition maximum was on a bilateral leg-extension machine. We measured the anaerobic threshold, peak V ˙ O 2 and τ V ˙ O 2 p while cardiopulmonary exercising, and the rates of increase in blood lactate (Bla), heart rate (HR), systolic blood pressure (SBP) and rate pressure product (RPP) for a single RET. RESULTS There were significant positive associations between τ V ˙ O 2 p and the rates of increase in Bla, HR, SBP and RPP during a single RET session (P<0·05). However, the anaerobic threshold and peak V ˙ O 2 did not significantly affect these parameters. CONCLUSION The τ V ˙ O 2 p is a useful evaluation index for predicting acute physiological responses to RET.
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Affiliation(s)
- Yusuke Kubo
- Kobori Orthopedic Clinic, Hamamatsu City, Shizuoka, Japan
| | - Daisuke Fujita
- Department of Physical Therapy, Health Science University, Yamanashi, Japan
| | | | - Masato Hosokawa
- Department of Rehabilitation, Iwata City Hospital, Iwata City, Shizuoka, Japan
| | - Yusuke Nishida
- Department of Physical Therapy, International University in Health and Welfare, Narita City, Chiba, Japan
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18
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Barstow TJ. Understanding near infrared spectroscopy and its application to skeletal muscle research. J Appl Physiol (1985) 2019; 126:1360-1376. [PMID: 30844336 DOI: 10.1152/japplphysiol.00166.2018] [Citation(s) in RCA: 221] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Near infrared spectroscopy (NIRS) is a powerful noninvasive tool with which to study the matching of oxygen delivery to oxygen utilization and the number of new publications utilizing this technique has increased exponentially in the last 20 yr. By measuring the state of oxygenation of the primary heme compounds in skeletal muscle (hemoglobin and myoglobin), greater understanding of the underlying control mechanisms that couple perfusive and diffusive oxygen delivery to oxidative metabolism can be gained from the laboratory to the athletic field to the intensive care unit or emergency room. However, the field of NIRS has been complicated by the diversity of instrumentation, the inherent limitations of some of these technologies, the associated diversity of terminology, and a general lack of standardization of protocols. This Cores of Reproducibility in Physiology (CORP) will describe in basic but important detail the most common methodologies of NIRS, their strengths and limitations, and discuss some of the potential confounding factors that can affect the quality and reproducibility of NIRS data. Recommendations are provided to reduce the variability and errors in data collection, analysis, and interpretation. The goal of this CORP is to provide readers with a greater understanding of the methodology, limitations, and best practices so as to improve the reproducibility of NIRS research in skeletal muscle.
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Affiliation(s)
- Thomas J Barstow
- Department of Kinesiology, Kansas State University , Manhattan, Kansas
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19
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Francisco CDO, Beltrame T, Hughson RL, Milan-Mattos JC, Ferroli-Fabricio AM, Galvão Benze B, Ferraresi C, Parizotto NA, Bagnato VS, Borghi-Silva A, Porta A, Catai AM. Effects of light-emitting diode therapy (LEDT) on cardiopulmonary and hemodynamic adjustments during aerobic exercise and glucose levels in patients with diabetes mellitus: A randomized, crossover, double-blind and placebo-controlled clinical trial. Complement Ther Med 2019; 42:178-183. [DOI: 10.1016/j.ctim.2018.11.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 09/21/2018] [Accepted: 11/09/2018] [Indexed: 11/12/2022] Open
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20
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Hamasaki A, Arima S, Hirakoba K. Changes in pulmonary oxygen uptake and muscle deoxygenation kinetics during cycling exercise in older women performing walking training for 12 weeks. Eur J Appl Physiol 2018; 118:2179-2188. [PMID: 30046886 DOI: 10.1007/s00421-018-3946-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 07/17/2018] [Indexed: 11/25/2022]
Abstract
PURPOSE This study examined the hypothesis that walking training (WT) could accelerate the slowed time constant (τ) of phase II in pulmonary oxygen uptake ([Formula: see text]O2) on-kinetics in older women. Also, we aimed to demonstrate that O2 delivery and O2 utilization were better matched at the site of gas exchange in exercising muscles when τ[Formula: see text]O2 was shortened. METHODS 20 recreationally active older women underwent WT sessions of approximately 60 min, 3-4 times a week for 12 weeks. We assessed [Formula: see text]O2, heart rate (HR) and deoxygenated-hemoglobin concentration ([HHb]) kinetics during a constant-load exercise test before training (0 week-Pre), and at 6 and 12 weeks (6 weeks-Mid, 12 weeks-Post) throughout the training period. RESULTS Maximal oxygen uptake ([Formula: see text]O2max) was unchanged throughout the training program. τHR tended to decline at Mid (58.6 ± 22.0 s), and was significantly shorter at Post (51.7 ± 21.7 s, p = 0.01) compared to Pre (67.1 ± 23.8 s). τ[Formula: see text]O2 significantly decreased from 38.9 ± 8.6 s for Pre, to 31.5 ± 7.9 s for Mid (p = 0.02), and 32.3 ± 10.5 s for Post (p = 0.03). The normalized [HHb] to [Formula: see text]O2 ratio (Δ[HHb]/Δ[Formula: see text]O2) at Pre (1.32 ± 0.93) gradually approached the perfectly matched value (= 1.0) at Mid (1.15 ± 0.61) and Post (1.07 ± 0.52). CONCLUSIONS The restoration to baseline (≒ 30 s) of the slower τ[Formula: see text]O2 due to WT, which may reflect better matching of O2 delivery and O2 utilization at the site of gas exchange, suggests that a longer period of WT could be a useful tool for improving exercise tolerance in older individuals.
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Affiliation(s)
- Akiko Hamasaki
- Katsuura Orthopaedics Clinic, 485-252 Tona, Katsuura, Chiba, 299-5225, Japan.
| | - Saburo Arima
- Katsuura Orthopaedics Clinic, 485-252 Tona, Katsuura, Chiba, 299-5225, Japan
| | - Kohji Hirakoba
- Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, Japan
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Oxygen Uptake and Muscle Deoxygenation Kinetics During Skating: Comparison Between Slide-Board and Treadmill Skating. Int J Sports Physiol Perform 2018; 13:783-788. [PMID: 29140137 DOI: 10.1123/ijspp.2017-0440] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To compare the oxygen-uptake ([Formula: see text]) kinetics during skating on a treadmill and skating on a slide board and to discuss potential mechanisms that might control the [Formula: see text] kinetics responses during skating. METHODS Breath-by-breath pulmonary [Formula: see text] and near-infrared spectroscopy-derived muscle deoxygenated hemoglobin and myoglobin ([HHbMb]) were monitored continuously in 12 well-trained, young, long-track speed skaters. On-transient [Formula: see text] and [HHbMb] responses to skating on a treadmill and skating on a slide board at 80% of the estimated gas exchange threshold were fitted as monoexponential function. The signals were time-aligned, and the individual [HHbMb]-to-[Formula: see text] ratio was calculated as the average value from 20 to 120 s after exercise starts. RESULTS The time constants for the adjustment of phase II [Formula: see text] (τ [Formula: see text]) and [HHbMb] (τ [HHbMb]) were low and similar between slide board and treadmill skating (18.1 [3.4] vs 18.9 [3.6] for τ [Formula: see text] and 12.6 [4.0] vs 12.4 [4.0] s for τ [HHbMb]). The [Formula: see text] ratio was not different from 1.0 (P > .05) in both conditions. CONCLUSIONS The fast [Formula: see text] kinetics during skating suggest that chronic adaptation to skating might overcome any possible restriction in leg blood flow during low-intensity exercise. The [Formula: see text] ratio values also suggest a good matching of O2 delivery to O2 utilization in trained speed skaters. The similar τ [Formula: see text] and τ [HHbMb] values between slide board and treadmill further reinforce the validity of using a slide board for skating testing and training purposes.
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Goulding RP, Roche DM, Marwood S. Elevated baseline work rate slows pulmonary oxygen uptake kinetics and decreases critical power during upright cycle exercise. Physiol Rep 2018; 6:e13802. [PMID: 30039557 PMCID: PMC6056736 DOI: 10.14814/phy2.13802] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 06/26/2018] [Indexed: 01/08/2023] Open
Abstract
Critical power is a fundamental parameter defining high-intensity exercise tolerance, and is related to the phase II time constant of pulmonary oxygen uptake kinetics (τV˙O2). Whether this relationship is causative is presently unclear. This study determined the impact of raised baseline work rate, which increases τV˙O2, on critical power during upright cycle exercise. Critical power was determined via four constant-power exercise tests to exhaustion in two conditions: (1) with exercise initiated from an unloaded cycling baseline (U→S), and (2) with exercise initiated from a baseline work rate of 90% of the gas exchange threshold (M→S). During these exercise transitions, τV˙O2 and the time constant of muscle deoxyhemoglobin kinetics (τ[HHb + Mb] ) (the latter via near-infrared spectroscopy) were determined. In M→S, critical power was lower (M→S = 203 ± 44 W vs. U→S = 213 ± 45 W, P = 0.011) and τV˙O2 was greater (M→S = 51 ± 14 sec vs. U→S = 34 ± 16 sec, P = 0.002) when compared with U→S. Additionally, τ[HHb + Mb] was greater in M→S compared with U→S (M→S = 28 ± 7 sec vs. U→S = 14 ± 7 sec, P = 0.007). The increase in τV˙O2 and concomitant reduction in critical power in M→S compared with U→S suggests a causal relationship between these two parameters. However, that τ[HHb + Mb] was greater in M→S exculpates reduced oxygen availability as being a confounding factor. These data therefore provide the first experimental evidence that τV˙O2 is an independent determinant of critical power. Keywords critical power, exercise tolerance, oxygen uptake kinetics, power-duration relationship, muscle deoxyhemoglobin kinetics, work-to-work exercise.
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Affiliation(s)
- Richie P. Goulding
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Denise M. Roche
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
| | - Simon Marwood
- School of Health SciencesLiverpool Hope UniversityLiverpoolUnited Kingdom
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George MA, McLay KM, Doyle-Baker PK, Reimer RA, Murias JM. Fitness Level and Not Aging per se, Determines the Oxygen Uptake Kinetics Response. Front Physiol 2018; 9:277. [PMID: 29662455 PMCID: PMC5890239 DOI: 10.3389/fphys.2018.00277] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 03/08/2018] [Indexed: 11/16/2022] Open
Abstract
Although aging has been associated to slower V˙O2 kinetics, some evidence indicates that fitness status and not aging per se might modulate this response. The main goal of this study was to examine the V˙O2, deoxygenated hemoglobin+myoglobin (deoxy-[Hb+Mb]) kinetics, and the NIRS-derived vascular reperfusion responses in older compared to young men of different training levels (i.e., inactive, recreationally active, and endurance trained). Ten young inactive [YI; 26 ± 5 yrs.; peak V˙O2 (V˙O2peak), 2.96 ± 0.55 L·min−1], 10 young recreationally active (YR; 26 ± 6 yrs.; 3.92 ± 0.33 L·min−1), 10 young endurance trained (YT; 30 ± 4 yrs.; 4.42 ± 0.32 L·min−1), 7 older inactive (OI; 69 ± 4 yrs.; 2.50 ± 0.31 L·min−1), 10 older recreationally active (OR; 69 ± 5 yrs.; 2.71 ± 0.42 L·min−1), and 10 older endurance trained (OT; 66 ± 3 yrs.; 3.20 ± 0.35 L·min−1) men completed transitions of moderate intensity cycling exercise (MODS) to determine V˙O2 and deoxy-[Hb+Mb] kinetics, and the deoxy-[Hb+Mb]/V˙O2 ratio. The time constant of V˙O2 (τV˙O2) was greater in YI (38.8 ± 10.4 s) and OI (44.1 ± 10.8 s) compared with YR (26.8 ± 7.5 s) and OR (26.6 ± 6.5 s), as well as compared to YT (14.8 ± 3.4 s), and OT (17.7 ± 2.7 s) (p < 0.05). τV˙O2 was greater in YR and OR compared with YT and OT (p < 0.05). The deoxy-[Hb+Mb]/V˙O2 ratio was greater in YI (1.23 ± 0.05) and OI (1.29 ± 0.08) compared with YR (1.11 ± 0.03) and OR (1.13 ± 0.06), as well as compared to YT (1.01 ± 0.03), and OT (1.06 ± 0.03) (p < 0.05). Similarly, the deoxy-[Hb+Mb]/ V˙O2 ratio was greater in YR and OR compared with YT and OT (p < 0.05). There was a main effect of training (p = 0.033), whereby inactive (p = 0.018) and recreationally active men (p = 0.031) had significantly poorer vascular reperfusion than endurance trained men regardless of age. This study demonstrated not only that age-related slowing of V˙O2 kinetics can be eliminated in endurance trained individuals, but also that inactive lifestyle negatively impacts the V˙O2 kinetics response of young healthy individuals.
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Affiliation(s)
| | - Kaitlin M McLay
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Patricia K Doyle-Baker
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Faculty of Environmental Design, University of Calgary, Calgary, AB, Canada
| | - Raylene A Reimer
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
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Beltrame T, Villar R, Hughson RL. Sex differences in the oxygen delivery, extraction, and uptake during moderate-walking exercise transition. Appl Physiol Nutr Metab 2017; 42:994-1000. [DOI: 10.1139/apnm-2017-0097] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous studies in children and older adults demonstrated faster oxygen uptake (V̇O2) kinetics in males compared with females, but young healthy adults have not been studied. We hypothesized that young men would have faster aerobic system dynamics in response to the onset of exercise than women. Interactions between oxygen supply and utilization were characterized by the dynamics of V̇O2, deoxyhemoglobin (HHb), tissue saturation index (TSI), cardiac output (Q̇), and calculated arteriovenous O2 difference (a–vO2diff) in women and men. Eighteen healthy active young women and men (9 of each sex) with similar aerobic fitness levels volunteered for this study. Participants performed an incremental cardiopulmonary treadmill exercise test and 3 moderate-intensity treadmill exercise tests (at 80% V̇O2 of gas exchange threshold). Data related to the moderate exercise were submitted to exponential data modelling to obtain parameters related to the aerobic system dynamics. The time constants of V̇O2, a–vO2diff, HHb, and TSI (30 ± 6, 29 ± 1, 16 ± 1, and 15 ± 2 s, respectively) in women were statistically (p < 0.05) faster than the time constants in men (42 ± 10, 49 ± 21, 19 ± 3, and 20 ± 4 s, respectively). Although Q̇ dynamics were not statistically different (p = 0.06) between groups, there was a trend to slower Q̇ dynamics in men corresponding with the slower V̇O2 kinetics. These results indicated that the peripheral and pulmonary oxygen extraction dynamics were remarkably faster in women. Thus, contrary to the hypothesis, V̇O2 dynamics measured at the mouth at the onset of submaximal treadmill walking were faster in women compared with men.
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Affiliation(s)
- Thomas Beltrame
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
- Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brasilia, Distrito Federal, CEP: 71605-001, Brazil
| | - Rodrigo Villar
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
- Faculty of Health Sciences, Division of Natural Sciences, Franklin Pierce University, Rindge, NH 03461, USA
| | - Richard L. Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, ON N2L 3G1, Canada
- Schlegel-University of Waterloo Research Institute for Aging, Waterloo, ON N2J 0E2, Canada
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Mattioni Maturana F, Peyrard A, Temesi J, Millet GY, Murias JM. Faster V̇O 2 kinetics after priming exercises of different duration but same fatigue. J Sports Sci 2017; 36:1095-1102. [PMID: 28721747 DOI: 10.1080/02640414.2017.1356543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
This study compared the responses of two priming exercises of similar fatigue on the adjustment of the oxygen uptake time constant (τV̇O2) in cycling. Ten healthy young adults (25 ± 3 yr) performed: three step transitions from a 20-W baseline to the power output (PO) below the gas exchange threshold (MOD, MODPRE); a 3-min bout (P3MIN) at 90% of peak PO (POpeak), followed by MOD (MOD3MIN); and a 6-min bout (P6MIN) at 80% of POpeak, followed by MOD (MOD6MIN). The O2 supply-to-O2 demand ([HHb]/V̇O2) ratio was calculated for MODPRE, MOD3MIN, and MOD6MIN. Neuromuscular fatigue was measured isometrically pre- and post-priming exercise. Reductions in maximal voluntary contraction (-29 ± 6 vs -34 ± 7%) and high-frequency doublet amplitude (-48 ± 13 vs -43 ± 11%) were not significantly different between P3MIN vs P6MIN, suggesting similar fatigue. τV̇O2 for MOD3MIN and MOD6MIN were similar, being ~25% smaller than MODPRE. The [HHb]/V̇O2 ratio was significantly greater in MODPRE (1.13 ± 0.12) compared to MOD3MIN (1.02 ± 0.04) and MOD6MIN (1.02 ± 0.04). This study showed that priming exercise of shorter duration and higher intensity, was sufficient to accelerate V̇O2 kinetics similarly to that observed subsequent to P6MIN when the muscle fatigue was similar.
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Affiliation(s)
- Felipe Mattioni Maturana
- a Human Performance Laboratory, Faculty of Kinesiology , University of Calgary , Calgary , Canada
| | - Arthur Peyrard
- a Human Performance Laboratory, Faculty of Kinesiology , University of Calgary , Calgary , Canada
| | - John Temesi
- a Human Performance Laboratory, Faculty of Kinesiology , University of Calgary , Calgary , Canada
| | - Guillaume Y Millet
- a Human Performance Laboratory, Faculty of Kinesiology , University of Calgary , Calgary , Canada
| | - Juan M Murias
- a Human Performance Laboratory, Faculty of Kinesiology , University of Calgary , Calgary , Canada
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26
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Beltrame T, Hughson RL. Linear and non-linear contributions to oxygen transport and utilization during moderate random exercise in humans. Exp Physiol 2017; 102:563-577. [PMID: 28240387 DOI: 10.1113/ep086145] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/23/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? The pulmonary oxygen uptake (pV̇O2) data used to study the muscle aerobic system dynamics during moderate-exercise transitions is classically described as a mono-exponential function controlled by a complex interaction of the oxygen delivery-utilization balance. This elevated complexity complicates the acquisition of relevant information regarding aerobic system dynamics based on pV̇O2 data during a varying exercise stimulus. What is the main finding and its importance? The elevated complexity of pV̇O2 dynamics is a consequence of a multiple-order interaction between muscle oxygen uptake and circulatory distortion. Our findings challenge the use of a first-order function to study the influences of the oxygen delivery-utilization balance over the pV̇O2 dynamics. The assumption of aerobic system linearity implies that the pulmonary oxygen uptake (pV̇O2) dynamics during exercise transitions present a first-order characteristic. The main objective of this study was to test the linearity of the oxygen delivery-utilization balance during random moderate exercise. The cardiac output (Q̇) and deoxygenated haemoglobin concentration ([HHb]) were measured to infer the central and local O2 availability, respectively. Thirteen healthy men performed two consecutive pseudorandom binary sequence cycling exercises followed by an incremental protocol. The system input and the outputs pV̇O2, [HHb] and Q̇ were submitted to frequency-domain analysis. The linearity of the variables was tested by computing the ability of the response at a specific frequency to predict the response at another frequency. The predictability levels were assessed by the coefficient of determination. In a first-order system, a participant who presents faster dynamics at a specific frequency should also present faster dynamics at any other frequency. All experimentally obtained variables (pV̇O2, [HHb] and Q̇) presented a certainly degree of non-linearity. The local O2 availability, evaluated by the ratio pV̇O2/[HHb], presented the most irregular behaviour. The overall [HHb] kinetics were faster than pV̇O2 and Q̇ kinetics. In conclusion, the oxygen delivery-utilization balance behaved as a non-linear phenomenon. Therefore, the elevated complexity of the pulmonary oxygen uptake dynamics is governed by a complex multiple-order interaction between the oxygen delivery and utilization systems.
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Affiliation(s)
- T Beltrame
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada.,Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brasília, Distrito Federal, Brazil
| | - R L Hughson
- Faculty of Applied Health Sciences, University of Waterloo, Waterloo, Ontario, Canada.,Schlegel-University of Waterloo Research Institute for Aging, Waterloo, Ontario, Canada
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McNarry MA, Harrison NK, Withers T, Chinnappa N, Lewis MJ. Pulmonary oxygen uptake and muscle deoxygenation kinetics during heavy intensity cycling exercise in patients with emphysema and idiopathic pulmonary fibrosis. BMC Pulm Med 2017; 17:26. [PMID: 28143453 PMCID: PMC5282850 DOI: 10.1186/s12890-017-0364-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 01/10/2017] [Indexed: 05/29/2023] Open
Abstract
BACKGROUND Little is known about the mechanistic basis for the exercise intolerance characteristic of patients with respiratory disease; a lack of clearly defined, distinct patient groups limits interpretation of many studies. The purpose of this pilot study was to investigate the pulmonary oxygen uptake ([Formula: see text] O2) response, and its potential determinants, in patients with emphysema and idiopathic pulmonary fibrosis (IPF). METHODS Following a ramp incremental test for the determination of peak [Formula: see text] O2 and the gas exchange threshold, six emphysema (66 ± 7 years; FEV1, 36 ± 16%), five IPF (65 ± 12 years; FEV1, 82 ± 11%) and ten healthy control participants (63 ± 6 years) completed three repeat, heavy-intensity exercise transitions on a cycle ergometer. Throughout each transition, pulmonary gas exchange, heart rate and muscle deoxygenation ([HHb], patients only) were assessed continuously and subsequently modelled using a mono-exponential with ([Formula: see text] O2, [HHb]) or without (HR) a time delay. RESULTS The [Formula: see text] O2 phase II time-constant (τ) did not differ between IPF and emphysema, with both groups significantly slower than healthy controls (Emphysema, 65 ± 11; IPF, 69 ± 7; Control, 31 ± 7 s; P < 0.05). The HR τ was slower in emphysema relative to IPF, with both groups significantly slower than controls (Emphysema, 87 ± 19; IPF, 119 ± 20; Control, 58 ± 11 s; P < 0.05). In contrast, neither the [HHb] τ nor [HHb]:O2 ratio differed between patient groups. CONCLUSIONS The slower [Formula: see text] O2 kinetics in emphysema and IPF may reflect poorer matching of O2 delivery-to-utilisation. Our findings extend our understanding of the exercise dysfunction in patients with respiratory disease and may help to inform the development of appropriately targeted rehabilitation strategies.
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Affiliation(s)
| | - Nicholas K Harrison
- College of Medicine, Swansea University, Swansea, UK.,Respiratory Unit, Morriston Hospital, Swansea, UK
| | - Tom Withers
- A-STEM, College of Engineering, Swansea University, Swansea, UK
| | | | - Michael J Lewis
- A-STEM, College of Engineering, Swansea University, Swansea, UK
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28
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McLay KM, Murias JM, Paterson DH. Similar pattern of change in V̇o 2 kinetics, vascular function, and tissue oxygen provision following an endurance training stimulus in older and young adults. Am J Physiol Regul Integr Comp Physiol 2017; 312:R467-R476. [PMID: 28122720 DOI: 10.1152/ajpregu.00399.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/23/2017] [Accepted: 01/23/2017] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to examine the time course of changes in the oxygen uptake (V̇o2) kinetics response subsequent to short-term exercise training (i.e., 24, 48, 72, and 120 h posttraining) and examine the relationship with the time course of changes in microvascular [deoxygenated hemoglobin concentration ([HHb])-to-V̇o2 ratio ([HHb])/V̇o2)] and macrovascular [flow-mediated dilation (FMD)] O2 delivery to the active tissues/limbs. Seven healthy older [OA; 74 ± 6 (SD) yr] and young men (YA; 25 ± 3 yr) completed three endurance cycling exercise training sessions at 70% V̇o2peak Moderate-intensity exercise on-transient V̇o2 (measured breath by breath) and [HHb] (measured by near-infrared spectroscopy) were modeled with a monoexponential and normalized (0-100% of response), and the [HHb])/V̇o2 was calculated. Ultrasound-derived FMD of the popliteal artery was assessed after 5 min of cuff occlusion. %FMD was calculated as the greatest percent change in diameter from baseline. Time constant of V̇o2 (τV̇o2) was significantly reduced in both OA (~18%) and YA (~23%) at 24 h (P < 0.001) posttraining and remained decreased at 48 h before returning toward pretraining (PRE) values. Both groups showed a significant decrease in the [HHb])/V̇o2 at 24, 48, and 72 h (P = 0.001, 0.01, and 0.03, respectively) posttraining before returning toward PRE values at 120 h. %FMD followed a similar time course to that of changes in the [HHb])/V̇o2, being significantly greater in both OA (by ~64%) and YA (by ~26%) at 24 h (P < 0.001), remaining increased at 48 and 72 h (P = 0.02 and 0.03, respectively), and returning toward PRE values at 120 h. These data suggest the rate of adjustment of V̇o2 may be constrained by O2 availability in the active tissues.
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Affiliation(s)
- Kaitlin M McLay
- Canadian Centre for Activity and Aging, London, Ontario, Canada.,School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and
| | - Juan M Murias
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and .,Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | - Donald H Paterson
- Canadian Centre for Activity and Aging, London, Ontario, Canada.,School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and
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29
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Affiliation(s)
- Juan M Murias
- Faculty of Kinesiology University of Calgary Calgary, AB CANADA Canadian Centre for Activity and Aging University of Western Ontario London, ON CANADA School of Kinesiology University of Western Ontario London, ON CANADA
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Cerebral and Muscle Tissue Oxygenation During Incremental Cycling in Male Adolescents Measured by Time-Resolved Near-Infrared Spectroscopy. Pediatr Exerc Sci 2016; 28:275-85. [PMID: 26451845 PMCID: PMC4826640 DOI: 10.1123/pes.2015-0037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Near-infrared spectroscopy has long been used to measure tissue-specific O2 dynamics in exercise, but most published data have used continuous wave devices incapable of quantifying absolute Hemoglobin (Hb) concentrations. We used time-resolved near-infrared spectroscopy to study exercising muscle (Vastus Lateralis, VL) and prefrontal cortex (PFC) Hb oxygenation in 11 young males (15.3 ± 2.1 yrs) performing incremental cycling until exhaustion (peak VO2 = 42.7 ± 6.1 ml/min/kg, mean peak power = 181 ± 38 W). Time-resolved near-infrared spectroscopy measurements of reduced scattering (μs´) and absorption (μa) at three wavelengths (759, 796, and 833 nm) were used to calculate concentrations of oxyHb ([HbO2]), deoxy Hb ([HbR]), total Hb ([THb]), and O2 saturation (stO2). In PFC, significant increases were observed in both [HbO2] and [HbR] during intense exercise. PFC stO2% remained stable until 80% of total exercise time, then dropped (-2.95%, p = .0064). In VL, stO2% decreased until peak time (-6.8%, p = .01). Segmented linear regression identified thresholds for PFC [HbO2], [HbR], VL [THb]. There was a strong correlation between timing of second ventilatory threshold and decline in PFC [HbO2] (r = .84). These findings show that time-resolved near-infrared spectroscopy can be used to study physiological threshold phenomena in children during maximal exercise, providing insight into tissue specific hemodynamics and metabolism.
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31
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Grey TM, Spencer MD, Belfry GR, Kowalchuk JM, Paterson DH, Murias JM. Effects of age and long-term endurance training on VO2 kinetics. Med Sci Sports Exerc 2016; 47:289-98. [PMID: 24870579 DOI: 10.1249/mss.0000000000000398] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study examined the effects of age and training status on the pulmonary oxygen uptake (VO2p) kinetics of untrained and chronically trained young, middle-age, and older groups of men. METHODS Breath-by-breath VO2p and near-infrared spectroscopy-derived muscle deoxygenation ([HHb]) were monitored continuously in young (20-39 yr) trained (YT, n = 8) and untrained (YuT, n = 8), middle-age (40-59 yr) trained (MT, n = 9) and untrained (MuT, n = 9), and older (60-85 yr) trained (OT, n = 9) and untrained (OuT, n = 8) men. On-transient VO2p and [HHb] responses to cycling exercise at 80% of the estimated lactate threshold (three repeats) were modeled as monoexponential. Data were scaled to a relative percentage of the response (0%-100%), the signals time aligned, and the individual [HHb]-to-VO2p ratio was calculated as the average [HHb]/VO2 during the 20- to 120-s period after exercise onset. RESULTS The time constant for the adjustment of phase II pulmonary VO2 (τVO2p) was larger in OuT (42.0 ± 11.3 s) compared with that in YT (17.0 ± 7.5 s), MT (18.1 ± 5.3 s), OT (19.8 ± 5.4 s), YuT (25.7 ± 6.6 s), and MuT (24.4 ± 7.4 s) (P < 0.05). Similarly, the [HHb]/VO2 ratio was larger than 1.0 in OuT (1.30 ± 0.13, P < 0.05) and this value was larger than that observed in YT (1.01 ± 0.07), MT (1.04 ± 0.05), OT (1.04 ± 0.04), YuT (1.05 ± 0.03), and MuT (1.02 ± 0.09) (P < 0.05). CONCLUSIONS This study showed that the slower VO2kinetics typically observed in older individuals can be prevented by long-term endurance training interventions. Although the role of O2 delivery relative to peripheral use cannot be elucidated from the current measures, the absence of age-related slowing of VO2 kinetics seems to be partly related to a preservation of the matching of O2 delivery to O2 utilization in chronically trained older individuals, as suggested by the reduction in the [HHb]/VO2 ratio.
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Affiliation(s)
- Tyler M Grey
- 1Canadian Centre for Activity and Aging, University of Western Ontario, London, Ontario, CANADA; 2School of Kinesiology, University of Western Ontario, London, Ontario, CANADA; 3Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, CANADA; and 4Faculty of Kinesiology, University of Calgary, Calgary, Alberta, CANADA
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32
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Kiely C, Rocha J, O'Connor E, O'Shea D, Green S, Egaña M. Influence of menopause and Type 2 diabetes on pulmonary oxygen uptake kinetics and peak exercise performance during cycling. Am J Physiol Regul Integr Comp Physiol 2015; 309:R875-83. [PMID: 26269520 DOI: 10.1152/ajpregu.00258.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 08/11/2015] [Indexed: 02/02/2023]
Abstract
We investigated if the magnitude of the Type 2 diabetes (T2D)-induced impairments in peak oxygen uptake (V̇O2) and V̇O2 kinetics was affected by menopausal status. Twenty-two women with T2D (8 premenopausal, 14 postmenopausal), and 22 nondiabetic (ND) women (11 premenopausal, 11 postmenopausal) matched by age (range = 30-59 yr) were recruited. Participants completed four bouts of constant-load cycling at 80% of their ventilatory threshold for the determination of V̇O2 kinetics. Cardiac output (CO) (inert gas rebreathing) was recorded at rest and at 30 s and 240 s during two additional bouts. Peak V̇O2 was significantly (P < 0.05) reduced in both groups with T2D compared with ND counterparts (premenopausal, 1.79 ± 0.16 vs. 1.55 ± 0.32 l/min; postmenopausal, 1.60 ± 0.30 vs. 1.45 ± 0.24 l/min). The time constant of phase II of the V̇O2 response was slowed (P < 0.05) in both groups with T2D compared with healthy counterparts (premenopausal, 29.1 ± 11.2 vs. 43.0 ± 12.2 s; postmenopausal, 33.0 ± 9.1 vs. 41.8 ± 17.7 s). At rest and during submaximal exercise absolute CO responses were lower, but the "gains" in CO larger (both P < 0.05) in both groups with T2D. Our results suggest that the magnitude of T2D-induced impairments in peak V̇O2 and V̇O2 kinetics is not affected by menopausal status in participants younger than 60 yr of age.
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Affiliation(s)
- Catherine Kiely
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin, Ireland
| | - Joel Rocha
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin, Ireland
| | - Eamonn O'Connor
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin, Ireland
| | - Donal O'Shea
- Endocrinology, St. Columcille's and St. Vincent's Hospitals, Dublin, Ireland; and
| | - Simon Green
- School of Science and Health and School of Medicine, University of Western Sydney, Sydney, Australia
| | - Mikel Egaña
- School of Medicine, Department of Physiology, Trinity College Dublin, Dublin, Ireland;
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Murias JM, Edwards JA, Paterson DH. Effects of short-term training and detraining on VO2 kinetics: Faster VO2 kinetics response after one training session. Scand J Med Sci Sports 2015; 26:620-9. [PMID: 25946038 DOI: 10.1111/sms.12487] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/02/2015] [Indexed: 11/28/2022]
Abstract
This study examined the time course of short-term training and detraining-induced changes in oxygen uptake ( V ˙ O 2 ) kinetics. Twelve men (24 ± 3 years) were assigned to either a 50% or a 70% of V ˙ O 2 m a x training intensity (n = 6 per group). V ˙ O 2 was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration (Δ[HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient V ˙ O 2 and Δ[HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [ H H b ] / V ˙ O 2 ratio was calculated. Similar changes in time constant of V ˙ O 2 ( t V ˙ O 2 ) were observed in both groups. The combined group mean for t V ˙ O 2 decreased ∼14% (32.3 to 27.9 s, P < 0.05) after one training session with a further ∼11% decrease (27.9 to 24.8 s, P < 0.05) following two training sessions. The t V ˙ O 2 p remained unchanged throughout the remaining of training and detraining. A significant "overshoot" in the [ H H b ] / V ˙ O 2 ratio was decreased (albeit not significant) after one training session, and abolished (P < 0.05) after the second one, with no overshoot observed thereafter. Speeding of V ˙ O 2 kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O2 delivery to O2 utilization is a mechanism proposed to influence this response.
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Affiliation(s)
- J M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - J A Edwards
- Canadian Centre for Activity and Aging, Ontario, London, Canada.,School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - D H Paterson
- Canadian Centre for Activity and Aging, Ontario, London, Canada.,School of Kinesiology, University of Western Ontario, London, ON, Canada
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34
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Koga S, Rossiter HB, Heinonen I, Musch TI, Poole DC. Dynamic heterogeneity of exercising muscle blood flow and O2 utilization. Med Sci Sports Exerc 2014; 46:860-76. [PMID: 24091989 DOI: 10.1249/mss.0000000000000178] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resolving the bases for different physiological functioning or exercise performance within a population is dependent on our understanding of control mechanisms. For example, when most young healthy individuals run or cycle at moderate intensities, oxygen uptake (VO2) kinetics are rapid and the amplitude of the VO2 response is not constrained by O2 delivery. For this to occur, muscle O2 delivery (i.e., blood flow × arterial O2 concentration) must be coordinated superbly with muscle O2 requirements (VO2), the efficacy of which may differ among muscles and distinct fiber types. When the O2 transport system succumbs to the predations of aging or disease (emphysema, heart failure, and type 2 diabetes), muscle O2 delivery and O2 delivery-VO2 matching and, therefore, muscle contractile function become impaired. This forces greater influence of the upstream O2 transport pathway on muscle aerobic energy production, and the O2 delivery-VO2 relationship(s) assumes increased importance. This review is the first of its kind to bring a broad range of available techniques, mostly state of the art, including computer modeling, radiolabeled microspheres, positron emission tomography, magnetic resonance imaging, near-infrared spectroscopy, and phosphorescence quenching to resolve the O2 delivery-VO2 relationships and inherent heterogeneities at the whole body, interorgan, muscular, intramuscular, and microvascular/myocyte levels. Emphasis is placed on the following: 1) intact humans and animals as these provide the platform essential for framing and interpreting subsequent investigations, 2) contemporary findings using novel technological approaches to elucidate O2 delivery-VO2 heterogeneities in humans, and 3) future directions for investigating how normal physiological responses can be explained by O2 delivery-VO2 heterogeneities and the impact of aging/disease on these processes.
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Affiliation(s)
- Shunsaku Koga
- 1Applied Physiology Laboratory, Kobe Design University, JAPAN; 2Division of Respiratory and Critical Care Physiology and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, and School of Biomedical Sciences, University of Leeds, Leeds, UNITED KINGDOM; 3Turku PET Centre and Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku and Turku University Hospital, Turku, FINLAND; Division of Experimental Cardiology, Thoraxcenter, Erasmus MC, University Medical Center Rotterdam, Rotterdam, THE NETHERLANDS; and 4Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, KS
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Murias JM, Spencer MD, Paterson DH. The critical role of O2 provision in the dynamic adjustment of oxidative phosphorylation. Exerc Sport Sci Rev 2014; 42:4-11. [PMID: 24188979 DOI: 10.1249/jes.0000000000000005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
It has been proposed that the adjustment of oxygen uptake (V˙O2) during the exercise on-transient is controlled intracellularly in young healthy individuals and that insufficient local O2 delivery plays a rate-limiting role in aging and disease only. This review shows that adequate O2 provision to the active tissues is critical in the dynamic adjustment of oxidative phosphorylation even in young healthy individuals.
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Affiliation(s)
- Juan M Murias
- 1Canadian Centre for Activity and Aging; and 2School of Kinesiology, University of Western Ontario, London, Ontario, Canada
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36
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Faster $$\dot{V}{\text{O}}_{ 2}$$ V ˙ O 2 kinetics after eccentric contractions is explained by better matching of O2 delivery to O2 utilization. Eur J Appl Physiol 2014; 114:2169-81. [DOI: 10.1007/s00421-014-2937-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 06/10/2014] [Indexed: 10/25/2022]
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Kubo Y, Nishida Y. Relationships of pulmonary oxygen uptake kinetics with skeletal muscle fatigue resistance and peak oxygen uptake in healthy young adults. J Phys Ther Sci 2014; 25:1363-6. [PMID: 24396189 PMCID: PMC3881456 DOI: 10.1589/jpts.25.1363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 05/29/2013] [Indexed: 12/03/2022] Open
Abstract
[Purpose] The objective of this study was to determine the validity of pulmonary oxygen
uptake kinetics in assessment of the ability of skeletal muscles to utilize oxygen.
[Subjects] We evaluated 12 young, healthy males. [Methods] The subjects completed a series
of tests to determine their peak oxygen uptake, pulmonary oxygen uptake kinetics at the
onset of moderate-intensity treadmill exercise, and the rate of decline in
electromyographic (EMG) mean power frequency (MPF) (EMG MPFrate) during one
continuous, fatiguing, isometric muscle action of the plantar flexors until exhaustion at
approximately 60% maximum voluntary contraction. We discussed the relationships between
pulmonary oxygen uptake kinetics and EMG MPFrate reflecting the ability of
skeletal muscles to utilize oxygen and between pulmonary oxygen uptake kinetics and peak
oxygen uptake reflecting the ability to deliver oxygen to skeletal muscles. We
hypothesized that pulmonary oxygen uptake kinetics may be more highly correlated with EMG
MPFrate than peak oxygen uptake. [Results] Pulmonary oxygen uptake kinetics
(33.9 ± 5.9 s) were more significantly correlated with peak oxygen uptake (50.6 ±
5.5 mL/kg/min) than EMG MPFrate (−14.7 ± 8.7%/s). [Conclusion] Pulmonary oxygen
uptake kinetics is a noninvasive index that is mainly usable for evaluation of the ability
of cardiovascular system to deliver oxygen to skeletal muscles in healthy young adults
with slower pulmonary oxygen uptake kinetics (>20 s).
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Affiliation(s)
- Yusuke Kubo
- Rehabilitation Sciences, Seirei Christopher University, Japan ; Kobori Orthopedic Clinic, Japan
| | - Yuusuke Nishida
- Rehabilitation Sciences, Seirei Christopher University, Japan
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Chin LMK, Heigenhauser GJF, Paterson DH, Kowalchuk JM. Effect of voluntary hyperventilation with supplemental CO2on pulmonary O2uptake and leg blood flow kinetics during moderate-intensity exercise. Exp Physiol 2013; 98:1668-82. [DOI: 10.1113/expphysiol.2013.074021] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Barker AR, Trebilcock E, Breese B, Jones AM, Armstrong N. The effect of priming exercise on O2 uptake kinetics, muscle O2 delivery and utilization, muscle activity, and exercise tolerance in boys. Appl Physiol Nutr Metab 2013; 39:308-17. [PMID: 24552371 DOI: 10.1139/apnm-2013-0174] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study used priming exercise in young boys to investigate (i) how muscle oxygen delivery and oxygen utilization, and muscle activity modulate oxygen uptake kinetics during exercise; and (ii) whether the accelerated oxygen uptake kinetics following priming exercise can improve exercise tolerance. Seven boys that were aged 11.3 ± 1.6 years completed either a single bout (bout 1) or repeated bouts with 6 min of recovery (bout 2) of very heavy-intensity cycling exercise. During the tests oxygen uptake, muscle oxygenation, muscle electrical activity and exercise tolerance were measured. Priming exercise most likely shortened the oxygen uptake mean response time (change, ±90% confidence limits; -8.0 s, ±3.0), possibly increased the phase II oxygen uptake amplitude (0.11 L·min(-1), ±0.09) and very likely reduced the oxygen uptake slow component amplitude (-0.08 L·min(-1), ±0.07). Priming resulted in a likely reduction in integrated electromyography (-24% baseline, ±21% and -25% baseline, ±19) and a very likely reduction in Δ deoxyhaemoglobin/Δoxygen uptake (-0.16, ±0.11 and -0.09, ±0.05) over the phase II and slow component portions of the oxygen uptake response, respectively. A correlation was present between the change in tissue oxygenation index during bout 2 and the change in the phase II (r = -0.72, likely negative) and slow component (r = 0.72, likely positive) oxygen uptake amplitudes following priming exercise, but not for muscle activity. Exercise tolerance was likely reduced (change -177 s, ±180) following priming exercise. The altered phase II and slow component oxygen uptake amplitudes in boys following priming exercise are linked to an improved localised matching of muscle oxygen delivery to oxygen uptake and not muscle electrical activity. Despite more rapid oxygen uptake kinetics following priming exercise, exercise tolerance was not enhanced.
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Affiliation(s)
- Alan R Barker
- Children's Health and Exercise Research Centre, Sport and Health Sciences, University of Exeter, Exeter EX1 2LU, UK
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40
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Spencer MD, Keir DA, Nederveen JP, Murias JM, Kowalchuk JM, Paterson DH. Prolonged moderate-intensity exercise oxygen uptake response following heavy-intensity priming exercise with short- and longer-term recovery. Appl Physiol Nutr Metab 2013; 38:566-73. [DOI: 10.1139/apnm-2012-0244] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study examines the effects of recovery duration following heavy-intensity “priming” exercise (Hvy) on pulmonary oxygen (O2) uptake (V̇O2p) during subsequent prolonged moderate-intensity exercise (Mod). Nine participants (6 men and 3 women) (27 ± 7 years) each completed 3 repetitions of 2 continuous Mod 1-Hvy-Mod 2 leg-cycling protocols in which Mod 2 lasted 30 min, but was preceded by a recovery duration of either 6 (R6) or 20 (R20) min at 20 W following Hvy; in each case, Mod 1 and Hvy lasted 6 min and were preceded by 6 min at 20 W. V̇O2p, heart rate (HR), and near-infrared spectroscopy (NIRS)–derived muscle deoxygenation ([HHb]) responses were modeled as a monoexponential; additionally, 60-s averages were computed every 6 min in Mod 1 and Mod 2. V̇O2p was elevated (p < 0.05) throughout Mod 2 compared with Mod 1 in both R6 and R20 (by −82 mL·min−1 or ∼5.0%); this occurred despite a complete recovery of baseline V̇O2p (V̇O2pBsln) following R20. HR and minute ventilation (V̇E), but not [HHb], were also elevated throughout Mod 2. The phase II time constant for V̇O2p (τV̇O2p) was reduced in Mod 2 (22 s (Mod 1), 19 s (Mod 2); p < 0.05), as was the “overshoot” in the normalized [HHb]/O2 uptake ratio (p < 0.05). This study shows that V̇O2p was elevated during Mod following Hvy, regardless of recovery duration; however, a determining role for V̇O2pBsln is precluded. Furthermore, neither V̇O2p, HR, nor V̇E showed any evidence of a readjustment back to no-Hvy conditions during prolonged Mod (p > 0.05). Lastly, regardless of recovery duration, τV̇O2p was reduced to a similar extent with Hvy, likely resulting from an improved matching of local muscle O2 delivery to O2 utilization.
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Affiliation(s)
- Matthew D. Spencer
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Daniel A. Keir
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Joshua P. Nederveen
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Juan M. Murias
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - John M. Kowalchuk
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
- Department of Physiology and Pharmacology, The University of Western Ontario, London, ON N6A 3K7, Canada
| | - Donald H. Paterson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON N6A 3K7, Canada
- School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada
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Williams AM, Paterson DH, Kowalchuk JM. High-intensity interval training speeds the adjustment of pulmonary O2 uptake, but not muscle deoxygenation, during moderate-intensity exercise transitions initiated from low and elevated baseline metabolic rates. J Appl Physiol (1985) 2013; 114:1550-62. [PMID: 23519229 DOI: 10.1152/japplphysiol.00575.2012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During step transitions in work rate (WR) within the moderate-intensity (MOD) exercise domain, pulmonary O2 uptake (Vo2p) kinetics are slowed, and Vo2p gain (ΔVo2p/ΔWR) is greater when exercise is initiated from an elevated metabolic rate. High-intensity interval training (HIT) has been shown to speed Vo2p kinetics when step transitions to MOD exercise are initiated from light-intensity baseline metabolic rates. The effects of HIT on step transitions initiated from elevated metabolic rates have not been established. Therefore, this study investigated the effects of HIT on Vo2p kinetics during transitions from low and elevated metabolic rates, within the MOD domain. Eight young, untrained men completed 12 sessions of HIT (spanning 4 wk). HIT consisted of 8-12 1-min intervals, cycling at a WR corresponding to 110% of pretraining maximal WR (WRmax). Pre-, mid- and posttraining, subjects completed a ramp-incremental test to determine maximum O2 uptake, WRmax, and estimated lactate threshold (θL). Participants additionally completed double-step constant-load tests, consisting of step transitions from 20 W → Δ45% θL [lower step (LS)] and Δ45 → 90% θL [upper step (US)]. HIT led to increases in maximum O2 uptake (P < 0.05) and WRmax (P < 0.01), and τVo2p of both lower and upper MOD step transitions were reduced by ∼40% (LS: 24 s → 15 s; US: 45 s → 25 s) (P < 0.01). However, the time course of adjustment of local muscle deoxygenation was unchanged in the LS and US. These results suggest that speeding of Vo2p kinetics in both the LS and US may be due, in part, to an improved matching of muscle O2 utilization to microvascular O2 delivery within the working muscle following 12 sessions of HIT, although muscle metabolic adaptations cannot be discounted.
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Affiliation(s)
- Alexandra M Williams
- Canadian Centre for Activity and Aging and School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
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Zerbini L, Spencer MD, Grey TM, Murias JM, Kowalchuk JM, Schena F, Paterson DH. Effect of acute hypoxia on muscle blood flow, VO2p, and [HHb] kinetics during leg extension exercise in older men. Eur J Appl Physiol 2013; 113:1685-94. [DOI: 10.1007/s00421-013-2599-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 01/22/2013] [Indexed: 11/30/2022]
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Dogra S, Spencer MD, Murias JM, Paterson DH. Oxygen uptake kinetics in endurance-trained and untrained postmenopausal women. Appl Physiol Nutr Metab 2013; 38:154-60. [DOI: 10.1139/apnm-2012-0173] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The rate of adjustment for pulmonary oxygen uptake (τV̇O2p) is slower in untrained and in older adults. Near-infrared spectroscopy (NIRS) has shed light on potential mechanisms underlying this in young men and women and in older men; however, there is no such data available in older women. The purpose of this study was to gain a better understanding of the mechanisms of slower τV̇O2p in older women who were either endurance-trained or untrained. Endurance-trained (n = 10; age, 62.6 ± 1.0 years) and untrained (n = 9; age, 69.1 ± 2.2 years) older women attended 2 maximal and 2 submaximal (90% of ventilatory threshold) exercise sessions. Oxygen uptake (V̇O2) was measured breath by breath, using a mass spectrometer, and changes in deoxygenated hemoglobin concentration of the vastus lateralis ([HHb]) were measured using NIRS. Heart rate was measured continuously with a 3-lead electrocardiogram. τV̇O2p was faster in trained (35.1 ± 5.5 s) than in untrained (57.0 ± 8.1 s) women. The normalized [HHb] to V̇O2 ratio, an indicator of muscle O2 delivery to O2 utilization, indicated a smaller overshoot in trained (1.09 ± 0.1) than in untrained (1.39 ± 0.1) women. Heart rate data indicated a faster adjustment of heart rate in trained (33.0 ± 13.0) than in untrained (68.7 ± 14.1) women. The pairing of V̇O2p data with NIRS-derived [HHb] data indicates that endurance-trained older women likely have better matching of O2 delivery to O2 utilization than older untrained women during moderate-intensity exercise, leading to a more rapid adjustment of V̇O2p.
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Affiliation(s)
- Shilpa Dogra
- School of Recreation Management and Kinesiology, Acadia University, 550 Main St, Wolfville, NS B4P 2R6, Canada
| | - Matthew D. Spencer
- Canadian Centre for Activity and Aging, School of Kinesiology, University of Western Ontario, London, ON N6A 3K7, Canada
| | - Juan M. Murias
- Canadian Centre for Activity and Aging, School of Kinesiology, University of Western Ontario, London, ON N6A 3K7, Canada
| | - Donald H. Paterson
- Canadian Centre for Activity and Aging, School of Kinesiology, University of Western Ontario, London, ON N6A 3K7, Canada
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Spencer MD, Gravelle BMR, Murias JM, Zerbini L, Pogliaghi S, Paterson DH. Duration of “Phase I” V̇o2p: a comparison of methods used in its estimation and the effects of varying moderate-intensity work rate. Am J Physiol Regul Integr Comp Physiol 2013; 304:R238-47. [DOI: 10.1152/ajpregu.00419.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was designed to investigate whether absolute work rate (WR) affects Phase I pulmonary oxygen uptake (V̇o2p) duration during moderate-intensity (Mod) exercise and to compare two methods for estimating Phase I V̇o2p duration (PI-Dur). Fourteen males (24 ± 5 yr) each completed 4–8 repetitions of Mod transitions from 20 W to 50, 70, 90, 110, and 130 W. PI-Dur was identified by 1) a marked decrease in both respiratory exchange ratio and end-tidal partial pressure of O2 following exercise onset [i.e., visual inspection of three independent reviewers, and the average (Avg) of the two most similar values]; or 2) the intersection (time delay, TD) of the first and second components in a biexponential nonlinear regression of the entire V̇o2p response from exercise onset. PI-Dur did not differ among WRs ( P > 0.05), regardless of the estimation method used. No differences were detected between Avg and TD (time in s) at any of the five WRs (50 W, 21 ± 6 vs. 23 ± 10 s; 70 W, 23 ± 9 vs. 23 ± 7 s; 90 W, 24 ± 3 vs. 22 ± 5 s; 110 W, 23 ± 6 vs. 22 ± 6 s; 130 W, 21 ± 6 vs. 21 ± 7 s; P > 0.05 for Avg and TD, respectively). Broad limits of agreement within Bland-Altman plots revealed relatively weak agreement among reviewers for individual estimation of PI-Dur. A nonsignificant correlation coefficient ( r = 0.13) and broad limits of agreement suggest disparity between individual Avg and TD estimates of PI-Dur. The present data do not support a role for Mod WR in determining PI-Dur per se. Furthermore, this study illustrated a poor agreement of PI-Dur estimates derived from two different, but accepted methods.
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Affiliation(s)
- Matthew D. Spencer
- Canadian Centre for Activity and Aging,
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Braden M. R. Gravelle
- Canadian Centre for Activity and Aging,
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Juan M. Murias
- Canadian Centre for Activity and Aging,
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Livio Zerbini
- CeRiSM, Centre of Sport Health and Mountain, Universiy of Verona, Italy; and
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e del Movimento, Universiy of Verona, Italy
| | - Silvia Pogliaghi
- Dipartimento di Scienze Neurologiche, Neuropsicologiche, Morfologiche e del Movimento, Universiy of Verona, Italy
| | - Donald H. Paterson
- Canadian Centre for Activity and Aging,
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
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Lanzi S, Borrani F, Wolf M, Gojanovic B, Malatesta D. Effects of prior short multiple-sprint exercises with different intersprint recoveries on the slow component of oxygen uptake during high-intensity exercise. Appl Physiol Nutr Metab 2012; 37:1080-90. [DOI: 10.1139/h2012-096] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study compares the effects of two short multiple-sprint exercise (MSE) (6 × 6 s) sessions with two different recovery durations (30 s or 180 s) on the slow component of oxygen uptake ([Formula: see text]O2) during subsequent high-intensity exercise. Ten male subjects performed a 6-min cycling test at 50% of the difference between the gas exchange threshold and [Formula: see text]O2peak (Δ50). Then, the subjects performed two MSEs of 6 × 6 s separated by two intersprint recoveries of 30 s (MSE30) and 180 s (MSE180), followed 10 min later by the Δ50 (Δ5030 and Δ50180, respectively). Electromyography (EMG) activities of the vastus medialis and lateralis were measured throughout each exercise bout. During MSE30, muscle activity (root mean square) increased significantly (p ≤ 0.04), with a significant leftward-shifted median frequency of the power density spectrum (MDF; p ≤ 0.01), whereas MDF was significantly rightward-shifted during MSE180 (p = 0.02). The mean [Formula: see text]O2 value was significantly higher in MSE30 than in MSE180 (p < 0.001). During Δ5030, [Formula: see text]O2 and the deoxygenated hemoglobin ([HHb]) slow components were significantly reduced (–27%, p = 0.02, and –34%, p = 0.003, respectively) compared with Δ50. There were no significant modifications of the [Formula: see text]O2 slow component in Δ50180 compared with Δ50 (p = 0.32). The neuromuscular and metabolic adaptations during MSE30 (preferential activation of type I muscle fibers evidenced by decreased MDF and a greater aerobic metabolism contribution to the required energy demands), but not during MSE180, may lead to reduced [Formula: see text]O2 and [HHb] slow components, suggesting an alteration in motor units recruitment profile (i.e., change in the type of muscle fibers recruited) and (or) an improved muscle O2 delivery during subsequent exercise.
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Affiliation(s)
- Stefano Lanzi
- Department of Physiology, Faculty of Biology and Medicine, Institute of Sport Sciences University of Lausanne (ISSUL), 1015 Lausanne, Switzerland
| | - Fabio Borrani
- Department of Physiology, Faculty of Biology and Medicine, Institute of Sport Sciences University of Lausanne (ISSUL), 1015 Lausanne, Switzerland
- Department of Sport and Exercise Science, University of Auckland, Auckland 1142, New Zealand
| | - Martin Wolf
- Division of Neonatology, University Hospital Zurich, Frauenklinikstr. 10, 8091 Zurich, Switzerland
| | - Boris Gojanovic
- Department of Locomotion, University Hospital (CHUV), 1005 Lausanne, Switzerland
| | - Davide Malatesta
- Department of Physiology, Faculty of Biology and Medicine, Institute of Sport Sciences University of Lausanne (ISSUL), 1015 Lausanne, Switzerland
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Murias JM, Spencer MD, Pogliaghi S, Paterson DH. Noninvasive estimation of microvascular O2 provision during exercise on-transients in healthy young males. Am J Physiol Regul Integr Comp Physiol 2012; 303:R815-23. [DOI: 10.1152/ajpregu.00306.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two methods for estimating changes in microvascular O2 delivery during the on-transient of exercise were evaluated. They were tested to assess the role of the adjustment of the estimated microvascular O2 delivery in the speeding of V̇o2 kinetics during a Mod1-Hvy-Mod2 protocol (Mod, moderate-intensity exercise; Hvy, heavy-intensity “priming” exercise), in which Mod2 is preceded by a bout of Hvy. Mod pulmonary V̇o2 (V̇o2p) and deoxy-hemoglobin [HHb] data were collected in 12 males (23 ± 3 yr); response profiles were fit with a monoexponential. Signals were also 1) scaled to a relative % of the response (0–100%) to calculate the [HHb]/V̇o2 ratio for each individual and 2) rearranged in the Fick equation for estimation of capillary blood flow (Qcap). A transient [HHb]/V̇o2 “overshoot” observed in Mod1 (1.06 ± 0.05; P < 0.05) was absent during Mod2 (1.01 ± 0.06; P > 0.05); reductions in the [HHb]/V̇o2 ratio (Mod1 − Mod2) were related to reductions in phase II τV̇o2p ( r = 0.82; P < 0.05). For Qcap, a near-exponential response was observed in 8/12 subjects in Mod1 and only in 4/12 subjects in Mod2. The Qcap profile was shown to be highly dependent on the [HHb] baseline-to-amplitude ratio. Thus, accurate and physiologically consistent estimations of Qcap were not possible in most cases. This study confirmed that priming exercise results in an improved O2 delivery as shown by the decreased [HHb]/V̇o2 ratio that was related to the smaller τV̇o2 in Mod2. Additionally, this study suggested that Qcap analysis may not be valid and should be interpreted with caution when assessing microvascular delivery of O2.
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Affiliation(s)
- Juan M. Murias
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and
| | - Matthew D. Spencer
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and
| | - Silvia Pogliaghi
- Laboratorio di Fisiologia dell'esercizio, Facoltà di Scienze motorie, Università degli Studi di Verona, Verona, Italy
| | - Donald H. Paterson
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and
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Gravelle BMR, Murias JM, Spencer MD, Paterson DH, Kowalchuk JM. Adjustments of pulmonary O2 uptake and muscle deoxygenation during ramp incremental exercise and constant-load moderate-intensity exercise in young and older adults. J Appl Physiol (1985) 2012; 113:1466-75. [PMID: 22961268 DOI: 10.1152/japplphysiol.00884.2011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The matching of muscle O(2) delivery to O(2) utilization can be inferred from the adjustments in muscle deoxygenation (Δ[HHb]) and pulmonary O(2) uptake (Vo(2p)). This study examined the adjustments of Vo(2p) and Δ[HHb] during ramp incremental (RI) and constant-load (CL) exercise in adult males. Ten young adults (YA; age: 25 ± 5 yr) and nine older adults (OA; age: 70 ± 3 yr) completed two RI tests and six CL step transitions to a work rate (WR) corresponding to 1) 80% of the estimated lactate threshold (same relative WR) and 2) 50 W (same absolute WR). Vo(2p) was measured breath by breath, and Δ[HHb] of the vastus lateralis was measured using near-infrared spectroscopy. Δ[HHb]-WR profiles were normalized from baseline (0%) to peak Δ[HHb] (100%) and fit using a sigmoid function. The sigmoid slope (d) was greater (P < 0.05) in OA (0.027 ± 0.01%/W) compared with YA (0.017 ± 0.01%/W), and the c/d value (a value corresponding to 50% of the amplitude) was smaller (P < 0.05) for OA (133 ± 40 W) than for YA (195 ± 51 W). No age-related differences in the sigmoid parameters were reported when WR was expressed as a percentage of peak WR. Vo(2p) kinetics compared with Δ[HHb] kinetics for the 50-W transition were similar between YA and OA; however, Δ[HHb] kinetics during the transition to 80% of the lactate threshold were faster than Vo(2p) kinetics in both groups. The greater reliance on O(2) extraction displayed in OA during RI exercise suggests a lower O(2) delivery-to-O(2) utilization relationship at a given absolute WR compared with YA.
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Affiliation(s)
- Braden M R Gravelle
- Canadian Centre for Activity and Aging, The University of Western Ontario, London, Ontario, Canada
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McNarry MA, Kingsley MIC, Lewis MJ. Influence of exercise intensity on pulmonary oxygen uptake kinetics in young and late middle-aged adults. Am J Physiol Regul Integr Comp Physiol 2012; 303:R791-8. [PMID: 22855280 DOI: 10.1152/ajpregu.00203.2012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is unclear whether pulmonary oxygen uptake (Vo2) kinetics demonstrate linear, first-order behavior during supra gas exchange threshold exercise. Resolution of this issue is pertinent to the elucidation of the factors regulating oxygen uptake (Vo2) kinetics, with oxygen availability and utilization proposed as putative mediators. To reexamine this issue with the advantage of a relatively large sample size, 50 young (24 ± 4 yr) and 15 late middle-aged (54 ± 3 yr) participants completed repeated bouts of moderate and heavy exercise. Pulmonary gas exchange, heart rate (HR), and cardiac output (Q) variables were measured throughout. The phase II τ was slower during heavy exercise in both young (moderate: 22 ± 9; heavy: 29 ± 9 s; P ≤ 0.001) and middle-aged (moderate: 22 ± 9; heavy: 30 ± 8 s; P ≤ 0.001) individuals. The HR τ was slower during heavy exercise in young (moderate: 33 ± 10; heavy: 44 ± 15 s; P ≤ 0.05) and middle-aged (moderate: 30 ± 12; heavy: 50 ± 20 s; P ≤ 0.05) participants, and the Q τ showed a similar trend (young moderate: 21 ± 13; heavy: 28 ± 16 s; middle-aged moderate: 32 ± 13; heavy: 40 ± 15 s; P ≥ 0.05). There were no differences in primary component Vo2 kinetics between age groups, but the middle-aged group had a significantly reduced Vo2 slow component amplitude in both absolute (young: 0.25 ± 0.09; middle-aged: 0.11 ± 0.06 l/min; P ≤ 0.05) and relative terms (young: 15 ± 10; middle-aged: 9 ± 4%; P ≤ 0.05). Thus Vo2 kinetics do not demonstrate dynamic linearity during heavy intensity exercise. Speculatively, the slower phase II τ during heavy exercise might be attributable to reduced oxygen availability. Finally, the primary and slow components of Vo2 kinetics appear to be differentially influenced by middle age.
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Affiliation(s)
- Melitta A McNarry
- College of Engineering, Swansea Univ., Singleton Park, Swansea, SA2 8PP, UK.
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Effect of moderate-intensity work rate increment on phase II τVO₂, functional gain and Δ[HHb]. Eur J Appl Physiol 2012; 113:545-57. [PMID: 22829340 DOI: 10.1007/s00421-012-2460-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 07/07/2012] [Indexed: 10/27/2022]
Abstract
This study systematically examined the role of work rate (WR) increment on the kinetics of pulmonary oxygen uptake (VO(2p)) and near-infrared spectroscopy (NIRS)-derived muscle deoxygenation (Δ[HHb]) during moderate-intensity (Mod) cycling. Fourteen males (24 ± 5 years) each completed four to eight repetitions of Mod transitions from 20 to 50, 70, 90, 110 and 130 W. VO(2p) and Δ[HHb] responses were modelled as a mono-exponential; responses were then scaled to a relative % of the respective response (0-100 %). The Δ[HHb]/VO(2) ratio was calculated as the average Δ[HHb]/VO(2) during the 20-120 s period of the on-transient. When considered as a single group, neither the phase II VO(2p) time constant (τVO(2p); 27 ± 9, 26 ± 11, 25 ± 10, 27 ± 14, 29 ± 13 s for 50-130 W transitions, respectively) nor the Δ[HHb]/VO(2) ratio (1.04 ± 0.13, 1.10 ± 0.13, 1.08 ± 0.07, 1.09 ± 0.11, 1.09 ± 0.09, respectively) was affected by WR (p > 0.05); yet, the VO(2) functional gain (G; ΔVO(2)/ΔWR) increased with increasing WR transitions (8.6 ± 1.3, 9.1 ± 1.2, 9.5 ± 1.0, 9.5 ± 1.0, 9.9 ± 1.0 mL min(-1) W(-1); p < 0.05). When subjects were stratified into two groups [Fast (n = 6), τVO(2p130W) < 25 s < τVO(2p130W), Slower (n = 8)], a group by WR interaction was observed for τVO(2p). The increasing functional G persisted (p < 0.05) and did not differ between groups (p > 0.05). The Δ[HHb]/VO(2) ratio was smaller (p < 0.05) in the Fast than Slower group, but was unaffected by WR. In conclusion, the present study demonstrated (1) a non-uniform effect of Mod WR increment on τVO(2p); (2) that τVO(2p) in the Slower group is likely determined by an O(2) delivery limitation; and (3) that increasing Mod WR increments elicits an increased functional G, regardless of the τVO(2p) response.
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De Roia G, Pogliaghi S, Adami A, Papadopoulou C, Capelli C. Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults. Am J Physiol Regul Integr Comp Physiol 2012; 302:R1158-66. [DOI: 10.1152/ajpregu.00269.2011] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging is associated with a functional decline of the oxidative metabolism due to progressive limitations of both O2 delivery and utilization. Priming exercise (PE) increases the speed of adjustment of oxidative metabolism during successive moderate-intensity transitions. We tested the hypothesis that such improvement is due to a better matching of O2 delivery to utilization within the working muscles. In 21 healthy older adults (65.7 ± 5 yr), we measured contemporaneously noninvasive indexes of the overall speed of adjustment of the oxidative metabolism (i.e., pulmonary V̇o2 kinetics), of the bulk O2 delivery (i.e., cardiac output), and of the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) during moderate-intensity step transitions, either with (ModB) or without (ModA) prior PE. The local matching of O2 delivery to utilization was evaluated by the ΔHHb/ΔV̇o2 ratio index. The overall speed of adjustment of the V̇o2 kinetics was significantly increased in ModB compared with ModA ( P < 0.05). On the contrary, the kinetics of cardiac output was unaffected by PE. At the muscle level, ModB was associated with a significant reduction of the “overshoot” in the ΔHHb/ΔV̇o2 ratio compared with ModA ( P < 0.05), suggesting an improved O2 delivery. Our data are compatible with the hypothesis that, in older adults, PE, prior to moderate-intensity exercise, beneficially affects the speed of adjustment of oxidative metabolism due to an acute improvement of the local matching of O2 delivery to utilization.
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Affiliation(s)
- Gabriela De Roia
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Silvia Pogliaghi
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Alessandra Adami
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
- Department of Basic Neurosciences, School of Medicine, Geneva, Switzerland
| | - Christina Papadopoulou
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
| | - Carlo Capelli
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, School of Human Movement Sciences, University of Verona, Italy; and
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