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Albertus-Cámara I, Paredes-Ruiz MJ, Martínez-González-Moro I. Analysis of Muscle Oxygenation after a Normobaric Hypoxia Tolerance Test. J Funct Morphol Kinesiol 2024; 9:86. [PMID: 38804452 PMCID: PMC11130857 DOI: 10.3390/jfmk9020086] [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: 03/26/2024] [Revised: 05/02/2024] [Accepted: 05/08/2024] [Indexed: 05/29/2024] Open
Abstract
The aim of this work was to analyze the influence of acute normobaric hypoxia on quadricep oxygenation. Muscle oxygen saturation (SmO2) was measured using near-infrared spectrometry (NIRS) technology during a normobaric hypoxia tolerance test (NHTT). SmO2 was measured with a Humon Hex® device. In total, 54 healthy subjects participated, 68.5 of which were males and 31.5% of which were females. They performed an NHTT with the IAltitude® simulator, breathing air with an FiO2 level of 11% (equivalent to 5050 m). The maximum duration of the NHTT was set at 10 min, stopping if it reached 83% SpO2. The initial values (PRE) were compared with those obtained at the end of the test (POST) and after 10 min of recovery. The participants were divided into two groups based on whether (G1) they completed the ten minutes or not (G2). In total, 35.1% of men and 41.2% of women completed the 10 min. In both groups, significant differences were observed in the decrease in SmO2 values (p < 0.0001) (G1: PRE = 59.5 ± 12.48%; POST = 55.95 ± 14.30%; G2: PRE = 60.06 ± 13.46%; POST = 57.2 ± 12.3%). There were no differences between groups in any of the three periods. Exposure to normobaric hypoxia produces a decrease in quadricep levels of SmO2 in both sexes, regardless of whether the test is completed. Two patterns appeared: A.-less time and more hypoxia; B. a longer duration and less hypoxia.
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Affiliation(s)
| | | | - Ignacio Martínez-González-Moro
- Physical Exercise and Human Performance Research Group, Mare Nostrum Campus, University of Murcia, 30001 Murcia, Spain; (I.A.-C.); (M.-J.P.-R.)
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Koutlas A, Smilios I, Kokkinou EM, Myrkos A, Kounoupis A, Dipla K, Zafeiridis A. NIRS-Derived Muscle-Deoxygenation and Microvascular Reactivity During Occlusion-Reperfusion at Rest Are Associated With Whole-Body Aerobic Fitness. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2024; 95:127-139. [PMID: 36689603 DOI: 10.1080/02701367.2022.2159309] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
Purpose: Near-infrared spectroscopy (NIRS) indices during arterial occlusion-reperfusion maneuver have been used to examine the muscle's oxidative metabolism and microvascular function-important determinants of whole-body aerobic-fitness. The association of NIRS-derived parameters with whole-body VO2max was previously examined using a method requiring exercise (or electrical stimulation) followed by multiple arterial occlusions. We examined whether NIRS-derived indices of muscle deoxygenation and microvascular reactivity assessed during a single occlusion-reperfusion at rest are (a) associated with maximal/submaximal indices of whole-body aerobic-fitness and (b) could discriminate individuals with different VO2max. We, also, investigated which NIRS-parameter during occlusion-reperfusion correlates best with whole-body aerobic-fitness. Methods: Twenty-five young individuals performed an arterial occlusion-reperfusion at rest. Changes in oxygenated- and deoxygenated-hemoglobin (O2Hb and HHb, respectively) in vastus-lateralis were monitored; adipose tissue thickness (ATT) at NIRS-application was assessed. Participants also underwent a maximal incremental exercise test for VO2max, maximal aerobic velocity (MAV), and ventilatory-thresholds (VTs) assessments. Results: The HHbslope and HHbmagnitude of increase (occlusion-phase) and O2Hbmagnitude of increase (reperfusion-phase) were strongly correlated with VO2max (r = .695-.763, p < .001) and moderately with MAV (r = .468-.530; p < .05). O2Hbmagnitude was moderately correlated with VTs (r = .399-.414; p < .05). After controlling for ATT, the correlations remained significant for VO2max (r = .672-.704; p < .001) and MAV (r = .407; p < .05). Individuals in the high percentiles after median and tritile splits for HHbslope and O2Hbmagnitude had significantly greater VO2max vs. those in low percentiles (p < .01-.05). The HHbslope during occlusion was the best predictor of VO2max. Conclusion: NIRS-derived muscle deoxygenation/reoxygenation indices during a single arterial occlusion-reperfusion maneuver are strongly associated with whole-body maximal indices of aerobic-fitness (VO2max, MAV) and may discriminate individuals with different VO2max.
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Geng Z, Wang J, Cao G, Tan C, Li L, Qiu J. Differential impact of heat and hypoxia on dynamic oxygen uptake and deoxyhemoglobin parameters during incremental exhaustive exercise. Front Physiol 2024; 14:1247659. [PMID: 38260100 PMCID: PMC10801013 DOI: 10.3389/fphys.2023.1247659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 12/13/2023] [Indexed: 01/24/2024] Open
Abstract
Purpose: This study aims to explore the relationship between the dynamic changes in oxygen uptake (V ˙ O 2 ) and deoxyhemoglobin (HHb) and peripheral fatigue in athletes during incremental exhaustive exercise under different environmental conditions, including high temperature and humidity environment, hypoxic environment, and normal conditions. Methods: 12 male modern pentathlon athletes were recruited and performed incremental exhaustive exercise in three different environments: normal condition (23°C, 45%RH, FiO2 = 21.0%, CON), high temperature and humidity environment (35°C, 70%RH, FiO2 = 21.0%, HOT), and hypoxic environment (23°C, 45%RH, FiO2 = 15.6%, HYP). Gas metabolism data of the athletes were collected, and muscle oxygen saturation (SmO2) and total hemoglobin content in the vastus lateralis muscles (VL) were measured to calculate the deoxyhemoglobin content. Linear and nonlinear function models were used to fit the characteristic parameters of V ˙ O 2 and HHb changes. Results: The results showed that compared to the CON, V ˙ O 2 , V ˙ CO 2 , and exercise time were decreased in the HOT and HYP (p < 0.05). Δ E V ˙ O 2 and OUES were reduced in the HOT and HYP compared to the CON (p < 0.05). The Gas exchange threshold in the CON corresponded to higher V ˙ O 2 than in the HYP and HOT (p < 0.05). Δ E V ˙ O 2 - 1 was reduced in the HOT compared to the HYP (p < 0.05). ΔEHHb was higher in the HOT compared to the CON (p < 0.05). ΔEHHb-1 was increased in the HYP compared to the CON (p < 0.05). There was a negative correlation between ΔEHHb and corresponding V ˙ O 2 max in the HOT (r = -0.655, p < 0.05), and a negative correlation between ΔEHHb-1 and corresponding V ˙ O 2 max in the HYP (r = -0.606, p < 0.05). Conclusion: Incremental exhaustive exercise in hypoxic environment and high temperature and humidity environments inhibits gas exchange and oxygen supply to skeletal muscle tissue in athletes. For athletes, the accelerated deoxygenation response of skeletal muscles during incremental exhaustive exercise in high temperature and humidity environments, as well as the excessive deoxygenation response before BP of deoxyhemoglobin in hypoxic environment, may be contributing factors to peripheral fatigue under different environmental conditions.
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Affiliation(s)
- Zhizhong Geng
- School of Sports and Health, Shanghai University of Sport, Shanghai, China
| | - Jinhao Wang
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Guohuan Cao
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Chenhao Tan
- Shanghai Research Institute of Sports Science, Shanghai, China
| | - Longji Li
- School of Sports and Health, Shanghai University of Sport, Shanghai, China
| | - Jun Qiu
- Shanghai Research Institute of Sports Science, Shanghai, China
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Fleitas-Paniagua PR, de Almeida Azevedo R, Trpcic M, Murias JM, Rogers B. Combining Near-Infrared Spectroscopy and Heart Rate Variability Derived Thresholds to Estimate the Critical Intensity of Exercise. J Strength Cond Res 2024; 38:e16-e24. [PMID: 37815285 DOI: 10.1519/jsc.0000000000004597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/11/2023]
Abstract
ABSTRACT Fleitas-Paniagua, PR, de Almeida Azevedo, R, Trpcic, M, Murias, JM, and Rogers, B. Combining near-infrared spectroscopy and heart rate variability derived thresholds to estimate the critical intensity of exercise. J Strength Cond Res 38(1): e16-e24, 2024-Critical intensity determination often requires costly tools and several testing sessions. Alternative approaches display relatively large individual variation. Therefore, simpler estimations with improved precision are needed. This study evaluated whether averaging the heart rate (HR) and oxygen uptake (V̇O 2 ) responses associated with the muscle deoxyhemoglobin concentration breakpoint ([HHb] BP ) and the heart rate variability (HRV) given by the detrended fluctuation analysis second threshold (HRVT2) during ramp incremental (RI) test improved the accuracy of identifying the HR and V̇O 2 at the respiratory compensation point (RCP). Ten female and 11 male recreationally trained subjects performed a 15 W·minute -1 RI test. Gas exchange, near-infrared spectroscopy (NIRS), and RR interval were recorded to assess the RCP, [HHb] BP , and HRVT2. Heart rate (mean ± SD : 158 ± 14, 156 ± 13, 160 ± 14 and, 158 ± 12 bpm) and V̇O 2 (3.08 ± 0.69, 2.98 ± 0.58, 3.06 ± 0.65, and 3.02 ± 0.60 L·minute -1 ) at the RCP, [HHb] BP , HRVT2, and HRVT2&[HHb] BP average (H&H Av ), respectively, were not significantly different ( p > 0.05). The linear relationship between H&H Av and RCP was higher compared with the relationship between [HHb] BP vs RCP and HRVT2 vs RCP for both HR ( r = 0.85; r = 0.73; r = 0.79, p > 0.05) and V̇O 2 ( r = 0.94; r = 0.93; r = 0.91, p > 0.05). Intraclass correlation between RCP, [HHb] BP , HRVT2, and H&H AV was 0.93 for V̇O 2 and 0.79 for HR. The [HHb] BP and the HRVT2 independently provided V̇O 2 and HR responses that strongly agreed with those at the RCP. Combining [HHb] BP and the HRVT2 resulted in estimations of the V̇O 2 and HR at the RCP that displayed smaller variability compared with each modality alone.
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Affiliation(s)
| | | | | | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
- College of Health and Life Sciences, Hamad Bin Khalifa University, Doha, Qatar; and
| | - Bruce Rogers
- College of Medicine, University of Central Florida, Orlando, Florida
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Wang A, Brothers RM, Hurr C. Application of blood flow restriction in hypoxic environment augments muscle deoxygenation without compromising repeated sprint exercise performance. Exp Physiol 2023; 108:728-739. [PMID: 36934386 PMCID: PMC10988449 DOI: 10.1113/ep091032] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/01/2023] [Indexed: 03/20/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does applying blood flow restriction during the rest periods of repeated sprint exercise in a hypoxic environment lead to greater local hypoxia within exercising muscles without compromising training workload? What is the main finding and its importance? Repeated sprint exercise with blood flow restriction administered during rest periods under systemic hypoxia led to severe local hypoxia within the exercised muscles without a reduction in power output. The maintained power output might be due to elevated neuromuscular activation. Accordingly, the proposed repeated sprint exercise in the current study may be an effective training modality. ABSTRACT Repeated sprint exercise (RSE) is a popular training modality for a wide variety of athletic activities. The purpose of this study was to assess the combined effects of systemic hypoxia and blood flow restriction (BFR) on muscle deoxygenation and RSE performance. Twelve healthy young men performed a standard RSE training modality (five sets of 10 s maximal sprint with a 60 s rest) under four different conditions: (1) normoxic control (NC), normoxia (N, 20.9%) + control BFR (C, 0 mmHg); (2) normoxic BFR (NB), normoxia (N, 20.9%) + BFR (B, 140 mmHg); (3) hypoxic control (HC), hypoxia (H, 13.7%) + control BFR (C, 0 mmHg); and (4) hypoxic BFR (HB): hypoxia (H, 13.7%) + BFR (B, 140 mmHg). BFR was only administered during the rest period of the respective RSE trials. In the local exercising muscles, muscle oxygen saturation (Sm O 2 $\textit{Sm}{O}_{2}$ ) and neuromuscular activity were measured using near-infrared spectroscopy and surface electromyography, respectively. SmO2 was lower in systemic hypoxia conditions relative to normoxia conditions (P < 0.05). A rther decrease in SmO2 was observed in HB relative to HC (Set 1: HC 70.0 ± 17.5 vs. HB 57.4 ± 11.3%, P = 0.001; Set 4: HC 67.5 ± 14.6 vs. HB 57.0 ± 12.0%, P = 0.013; Set 5: HC 61.0 ± 15.3 vs. HB 47.7 ± 11.9%, P < 0.001). No differences in RSE performance were observed between any of the conditions (P > 0.05). Interestingly, an elevated neuromuscular activity was seen in response to the BFR, particularly during conditions of systemic hypoxia (P < 0.05). Thus, RSE with BFR administered during rest periods under systemic hypoxia led to severe local hypoxia without compromising training workload.
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Affiliation(s)
- Anjie Wang
- Integrative Exercise Physiology Laboratory, Department of Physical Education, College of EducationJeonbuk National UniversityJeonjuSouth Korea
| | - R. Matthew Brothers
- Integrative Vascular Physiology Laboratory, Department of KinesiologyCollege of Nursing and Health InnovationUniversity of Texas at ArlingtonArlingtonTXUSA
| | - Chansol Hurr
- Integrative Exercise Physiology Laboratory, Department of Physical Education, College of EducationJeonbuk National UniversityJeonjuSouth Korea
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Hovorka M, Simon D, Leo P, Prinz B, Nimmerichter A. Alterations in aerobic fitness and muscle deoxygenation during ramp incremental exercise in trained youth cyclists: a ~3-year longitudinal study. J Sports Sci 2023; 41:121-131. [PMID: 37037676 DOI: 10.1080/02640414.2023.2200565] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Alterations of aerobic fitness and muscle deoxygenation during a ramp incremental exercise test (GXT) were assessed on two occasions within a time-frame of 2.9 ± 0.1y in competitive youth cyclists. Nine cyclists (age, 14.5 ± 1.1y; peak oxygen uptake (V˙O2peak), 62.6 ± 4.2 mL.min-1.kg-1) participated in this investigation. V˙O2peak, the gas exchange threshold (GET) and the respiratory compensation point (RCP), as well as the muscle deoxygenation response pattern were determined during a GXT using open circuit spirometry and near-infrared spectroscopy, respectively. T-tests and Pearson's correlations were used to assess effects of time on the dependent variables and relationships between changes of parameter estimates of aerobic fitness and the muscle deoxygenation response, respectively. Workrate and metabolic rate at GET (33 ± 20 and 42 ± 23%) and RCP (36 ± 20 and 40 ± 22%), and V˙O2peak (30 ± 18%) significantly increased throughout the study (P < 0.05). The muscle deoxygenation response showed a significant rightward shift from occasion one to two (P < 0.05). Alterations in the workrate/metabolic rate at RCP, and V˙O2peak, were correlated with alterations of the muscle deoxygenation response (R = 0.71-0.89, P < 0.05). Together, this is thought to indicate a superior muscle perfusion within the tissue of interrogation at the same metabolic rate on occasion two vs. one, which partially contributed to the improved aerobic fitness in the cyclists 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
| | - Dieter Simon
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt, Austria
| | - Peter Leo
- Training and Sports Sciences, University of Applied Sciences Wiener Neustadt, Wiener Neustadt, Austria
- Department of Sports Science, University of Innsbruck, Innsbruck, Austria
| | - Bernhard Prinz
- 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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Iannetta D, Inglis EC, Maturana FM, Spigolon G, Pogliaghi S, Murias JM. Transient speeding of V̇O2 kinetics following acute sessions of sprint interval training: Similar exercise dose but different outcomes in older and young adults. Exp Gerontol 2022; 164:111826. [DOI: 10.1016/j.exger.2022.111826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 04/10/2022] [Accepted: 04/26/2022] [Indexed: 11/30/2022]
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Wan X, Liu C, Olson TP, Chen X, Lu W, Jiang W. Differences in Peak Oxygen Uptake in Bicycle Exercise Test Caused by Body Positions: A Meta-Analysis. Front Cardiovasc Med 2021; 8:734687. [PMID: 34708089 PMCID: PMC8542763 DOI: 10.3389/fcvm.2021.734687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/13/2021] [Indexed: 11/13/2022] Open
Abstract
Background: As demand for cardiopulmonary exercise test using a supine position has increased, so have the testing options. However, it remains uncertain whether the existing evaluation criteria for the upright position are suitable for the supine position. The purpose of this meta-analysis is to compare the differences in peak oxygen uptake (VO2peak) between upright and supine lower extremity bicycle exercise. Methods: We searched PubMed, Web Of Science and Embase from inception to March 27, 2021. Self-control studies comparing VO2peak between upright and supine were included. The quality of the included studies was assessed using a checklist adapted from published papers in this field. The effect of posture on VO2peak was pooled using random/fixed effects model. Results: This meta-analysis included 32 self-control studies, involving 546 participants (63% were male). 21 studies included only healthy people, 9 studies included patients with cardiopulmonary disease, and 2 studies included both the healthy and cardiopulmonary patients. In terms of study quality, most of the studies (n = 21, 66%) describe the exercise protocol, and we judged theVO2peak to be valid in 26 (81%) studies. Meta-analysis showed that the upright VO2peak exceeded the supine VO2peak [relative VO2peak: mean difference (MD) 2.63 ml/kg/min, 95% confidence interval (CI) 1.66-3.59, I 2 = 56%, p < 0.05; absolute VO2peak: MD 0.18 L/min, 95% CI 0.10-0.26, I 2 = 63%, p < 0.05). Moreover, subgroup analysis showed there was more pooled difference in healthy people (4.04 ml/kg/min or 0.22 L/min) than in cardiopulmonary patients (1.03 ml/kg/min or 0.12 L/min). Conclusion: VO2peak in the upright position is higher than that in supine position. However, whether this difference has clinical significance needs further verification. Systematic Review Registration: identifier, CRD42021233468.
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Affiliation(s)
- Xiaohua Wan
- Department of Cardiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Chang Liu
- Department of Cardiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Thomas P Olson
- Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic and Foundation, Rochester, MN, United States
| | - Xiankun Chen
- The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Healthy Systems and Policy, Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden.,Key Unit of Methodology in Clinical Research, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China
| | - Weihui Lu
- Department of Cardiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Wei Jiang
- Department of Cardiology, Guangdong Provincial Hospital of Chinese Medicine, Guangzhou, China.,The Second Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, China.,Guangdong Provincial Key Laboratory of Chinese Medicine for Prevention and Treatment of Refractory Chronic Diseases, Guangzhou, China
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Paredes-Ruiz MJ, Jódar-Reverte M, Ferrer-López V, González-Moro IM. MUSCLE OXYGENATION OF THE QUADRICEPS AND GASTROCNEMIUS DURING MAXIMAL AEROBIC EFFORT. REV BRAS MED ESPORTE 2021. [DOI: 10.1590/1517-8692202127022020_0076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
ABSTRACT Introduction: Near infrared spectroscopy (NIRS) is a non-invasive technique that is used in the assessment of tissue oxygenation and the monitoring of physical activity. Objective: To determine the influence of sexual, anthropometric and ergospirometric factors on muscle oxygenation of the quadriceps and gastrocnemius, obtained by NIRS during a stress test. Methods: Twenty healthy subjects participated in this study (10 women). Two Humon Hex® devices were placed on the dominant side of the quadriceps and gastrocnemius muscles to measure muscle oxygen saturation (SmO2). The stress test was performed on a treadmill with electrocardiographic control and measurement of oxygen consumption. SmO2 was obtained at rest and after maximum effort during the stress test. In addition, the height, weight, skinfold and waist contour were measured. Bioimpedance was used to obtain the percentages of fat mass and muscle mass, which were used to calculate the relative fat mass (RFM). Results: The SmO2 of both muscles at rest is higher in males than in females. At maximum effort, the SmO2 of the quadriceps is similar in both groups. The SmO2 of both muscles is positively related to height, body mass, percentage of mass muscle and waist contour, and negatively with percentage of mass fat, RFM and skinfold thickness. The negative correlation between fat percentage and oxygen saturation is more evident in females. It was observed that the variables that quantify maximum effort are not related to the SmO2 values, except for the correlation between HR max and SmO2 of the gastrocnemius muscle in males. Conclusion: The SmO2 of recreational athletes is influenced by the location of the device and the fat mass of the subjects. The biggest differences between the sexes are in the gastrocnemius muscle. Level of Evidence II; Diagnostic Studies - Investigating a Diagnostic Test .
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Azevedo RDA, Béjar Saona JE, Inglis EC, Iannetta D, Murias JM. The effect of the fraction of inspired oxygen on the NIRS-derived deoxygenated hemoglobin "breakpoint" during ramp-incremental test. Am J Physiol Regul Integr Comp Physiol 2019; 318:R399-R409. [PMID: 31850819 DOI: 10.1152/ajpregu.00291.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During ramp-incremental (RI) exercise to exhaustion, the near-infrared spectroscopy-derived deoxygenated hemoglobin ([HHb]) signal in the vastus lateralis muscle shows a linear increase up to a point at which a plateau-like response is manifested ([HHb]bp). This study investigated if 1) the [HHb]bp is affected by different fractions of inspired O2 (FIO2) [hypoxia (16%; HYPO); normoxia (21%; NORM); hyperoxia (30%; HYPER)]; and 2) an abrupt change to hyperoxic-inspired gas just before the occurrence of the [HHb]bp (HYPERSWITCH) would affect the [HHb] plateau-like response. Ten physically active male participants reported to the laboratory on four separate occasions to perform an RI test to exhaustion in NORM, HYPO, and HYPER and an RI test to exhaustion with an abrupt increase in FIO2 (30%; HYPERSWITCH) 15 W before the power output (PO) associated with [HHb]bp in normoxia. PO, [HHb], tissue O2 (StO2), and pulse O2 saturation (SpO2) were recorded continuously. Peak PO was significantly lower in HYPO (290 ± 21 W) and higher in HYPER (321 ± 22 W) and HYPERSWITCH (320 ± 19 W) compared with NORM (311 ± 18 W). The PO associated with [HHb]bp was not different between NORM and HYPER (246 ± 23 vs. 247 ± 24 W), but it was lower in HYPO (198 ± 31 W) than NORM and HYPER. The PO associated with the [HHb]bp in HYPERSWITCH (240 ± 23) was not different compared with NORM. HYPER and HYPERSWITCH resulted in greater StO2 and SpO2 compared with NORM. These results suggest that the [HHb]bp response is not dependent of O2 driving pressure and that other physiological mechanisms might determine its occurrence.
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Affiliation(s)
| | | | | | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Canada
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