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Caen K, Bourgois JG, Stassijns E, Boone J. A longitudinal study on the interchangeable use of whole-body and local exercise thresholds in cycling. Eur J Appl Physiol 2022; 122:1657-1670. [PMID: 35435465 PMCID: PMC9014408 DOI: 10.1007/s00421-022-04942-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 03/23/2022] [Indexed: 12/03/2022]
Abstract
Purpose This study longitudinally examined the interchangeable use of critical power (CP), the maximal lactate steady state (MLSS) and the respiratory compensation point (RCP) (i.e., whole-body thresholds), and breakpoints in muscle deoxygenation (m[HHb]BP) and muscle activity (iEMGBP) (i.e., local thresholds). Methods Twenty-one participants were tested on two timepoints (T1 and T2) with a 4-week period (study 1: 10 women, age = 27 ± 3 years, \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{{2{\text{peak}}}}$$\end{document}V˙O2peak = 43.2 ± 7.3 mL min−1kg−1) or a 12-week period (study 2: 11 men, age = 25 ± 4 years, \documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{{2{\text{peak}}}}$$\end{document}V˙O2peak = 47.7 ± 5.9 mL min−1 kg−1) in between. The test battery included one ramp incremental test (to determine RCP, m[HHb]BP and iEMGBP) and a series of (sub)maximal constant load tests (to determine CP and MLSS). All thresholds were expressed as oxygen uptake (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2) and equivalent power output (PO) for comparison. Results None of the thresholds were significantly different in study 1 (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2: P = 0.143, PO: P = 0.281), but differences between whole-body and local thresholds were observed in study 2 (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{V}{\text{O}}_{2}$$\end{document}V˙O2: P < 0.001, PO: P = 0.024). Whole-body thresholds showed better 4-week test–retest reliability (TEM = 88–125 mL min−1 or 6–10 W, ICC = 0.94–0.98) compared to local thresholds (TEM = 189–195 mL min−1 or 15–18 W, ICC = 0.58–0.89). All five thresholds were strongly associated at T1 and T2 (r = 0.75–0.99), but their changes from T1 to T2 were mostly uncorrelated (r = − 0.41–0.83). Conclusion Whole-body thresholds (CP/MLSS/RCP) showed a close and consistent coherence taking into account a 3–6%-bandwidth of typical variation. In contrast, local thresholds (m[HHb]BP/iEMGBP) were characterized by higher variability and did not consistently coincide with the whole-body thresholds. In addition, we found that most thresholds evolved independently of each other over time. Together, these results do not justify the interchangeable use of whole-body and local exercise thresholds in practice.
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Affiliation(s)
- Kevin Caen
- Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium.,Center of Sports Medicine, Ghent University Hospital, Ghent, Belgium
| | - Jan G Bourgois
- Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium.,Center of Sports Medicine, Ghent University Hospital, Ghent, Belgium
| | - Eva Stassijns
- Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium
| | - Jan Boone
- Department of Movement and Sports Sciences, Ghent University, Watersportlaan 2, 9000, Ghent, Belgium. .,Center of Sports Medicine, Ghent University Hospital, Ghent, Belgium.
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Electromyographic and Systemic Physiological Thresholds in Single-Joint Elbow Flexion Movements. Int J Sports Physiol Perform 2021; 17:241-248. [PMID: 34611058 DOI: 10.1123/ijspp.2021-0163] [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: 03/26/2021] [Revised: 05/25/2021] [Accepted: 06/05/2021] [Indexed: 11/18/2022]
Abstract
PURPOSE Reported relationships between electromyographic (EMG) thresholds and systemic thresholds based on lactate, ventilation, or heart rate are contradictory. This might be related to the complexity of the investigated whole-body movements involving many muscles with different activation patterns. Therefore, the aim of the study was to investigate these relationships during an incremental single-joint exercise. METHODS Eighteen male subjects (29.7 [4.4] y) performed single-arm elbow flexions on a biceps curl machine with loads increasing every minute until exhaustion. EMG signals of the main elbow flexors (short and long head of the biceps brachii, flexor carpi radialis, and brachioradialis) as well as gas exchange variables, blood lactate concentration, and heart rate were measured, and 2 turn points based on a 3-phase model of metabolism were determined for each variable. RESULTS The first and second turn points for EMG were determined at 32.0% to 33.1% and 64.4% to 66.5% of maximal achieved performance (maximum weight), respectively. Systemic turn points were determined at 33.3% to 34.4% and 65.9% to 66.7% of maximum weight and were not significantly different from EMG turn points. Furthermore, systemic and EMG turn points showed a strong or very strong relationship at the first (ρ = .54-.93, P < .05) and second turn point (ρ = .76-.93, P < .01). CONCLUSIONS A close relationship between EMG and systemic turn points could be confirmed for the applied movement of a small muscle group. The determination of local single muscle thresholds using EMG provides additional muscle-specific information about performance-limiting properties of muscles involved in endurance-type incremental exercise.
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Features of electromyography threshold of the respiratory muscles during incremental exercise test. Respir Physiol Neurobiol 2021; 295:103785. [PMID: 34508868 DOI: 10.1016/j.resp.2021.103785] [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: 06/22/2021] [Revised: 08/19/2021] [Accepted: 09/06/2021] [Indexed: 11/23/2022]
Abstract
In this study, we aimed to examine the electromyography threshold (EMGT) of the respiratory muscle and accessory respiratory muscles. Sixteen healthy men underwent an incremental exercise test at 15 W/minute to the end point. Expired gases and electromyograms of the respiratory and lower limb muscles were measured. The breakpoints for the EMG and expired gas data were analyzed using a segmented regression model. EMGT of the sternocleidomastoid and diaphragm was significantly more delayed than the ventilation threshold (VT) (287.94 s, 288.15 s vs. 185.5 s, p = 0.028 and 0.044, respectively). The EMGT of respiratory muscles and VT were not related, though EMGT of rectus femoris and vastus lateralis correlated with VT (r = 0.854, p < 0.001; r = 0.657, p = 0.011, respectively). EMGT of respiratory muscles may be influenced by multiple factors, such as central command and afferent input of mechanical stimulation from muscles, in addition to VT-induced changes in metabolic dynamics.
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Abstract
HIGHLIGHTS Trunk frontal plane kinematics is the most sensitive parameter to fatigue. Practitioners should consider this finding during endurance training.Kinetics exhibit a stable linear increase in mean values but a non-linear increase in variance during an exhaustive incremental treadmill run. This may affect training at a submaximal fatigued state.Specific areas in the joint distributions of kinetics and kinematics during treadmill running exhibit increased sensitivity in predicting fatigue state.
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Sasaki K, Kimura T, Kojima S, Higuchi H. The temporal relationship of thresholds between muscle activity and ventilation during bicycle ramp exercise in community dwelling elderly males. J Phys Ther Sci 2016; 28:3213-3219. [PMID: 27942152 PMCID: PMC5140832 DOI: 10.1589/jpts.28.3213] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 07/29/2016] [Indexed: 11/24/2022] Open
Abstract
[Purpose] To compare the appearance time of the ventilatory threshold point and the electromyographic threshold in the activity of the vastus lateralis, rectus femoris, biceps femoris long head and gastrocnemius lateral head muscles during ramp cycling exercise in elderly males. [Subjects and Methods] Eleven community dwelling elderly males participated in this study. Subjects performed exercise testing with an expiratory gas analyzer and surface electromyography to evaluate the tested muscle activities during ramp exercise. [Results] The electromyographic threshold for rectus femoris was not valid because the slope after electromyographic threshold was not significant as compared to that before electromyographic threshold. The slope of the regression line for vastus lateralis was significantly decreased after electromyographic threshold while biceps femoris and gastrocnemius were increased. The electromyographic threshold appearance times for vastus lateralis and gastrocnemius were significantly earlier than ventilatory threshold point. There were no difference in electromyographic threshold appearance times among three muscles. [Conclusion] These results suggest that the increase in the slope of the regression line after electromyographic threshold for vastus lateralis was decreased, possibly indicating to postpone muscular fatigue resulting from the activation of biceps femoris and gastrocnemius as biarticular antagonists. This recruitment pattern might be an elderly-specific strategy.
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Affiliation(s)
- Kentaro Sasaki
- Department of Physical Therapy, Kinjo University, Japan; Graduate School of Health Sciences (Division of Distance Education), Kyushu University of Health and Welfare, Japan
| | - Tsuyoshi Kimura
- Department of Social Welfare, Faculty of Social Welfare, Kinjo University, Japan
| | | | - Hiroyuki Higuchi
- Graduate School of Health Sciences (Division of Distance Education), Kyushu University of Health and Welfare, Japan
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Subbu R, Weiler R, Whyte G. The practical use of surface electromyography during running: does the evidence support the hype? A narrative review. BMJ Open Sport Exerc Med 2016; 1:e000026. [PMID: 27900124 PMCID: PMC5117013 DOI: 10.1136/bmjsem-2015-000026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/17/2015] [Indexed: 11/07/2022] Open
Abstract
Background/aims Surface electromyography (sEMG) is a commonly used technique to investigate muscle activation and fatigue, which is non-invasive and can allow for continuous measurement. Systematic research on the use of sEMG in the sporting environment has been on-going for many years and predominantly based on cycling and rowing activities. To date there have been no reviews assessing the validity and reliability in sEMG exclusively in running activities specifically during on-field testing. The purpose of this review is to evaluate the use of sEMG in the practical context and whether this be translated to on-field testing. Methods Electronic literature searches were performed using the Cochrane Library, PUBMED, CINAHL and PeDro without restrictions on the study date to identify the relevant current English language literature. Results 10 studies were relevant after title and content review. All the studies identified were all level three evidence based. The general trends of the sEMG activity appear to correlate with running velocity and muscle fatigue seems almost always the consequence of prolonged, dynamic activity. However, these changes are not consistently measured or statistically significant throughout the studies raising the question of the accuracy and reliability when analysing sEMG measurements and making assumptions about the cause of fatigue. Conclusions An agreed consensus when measuring and analysing sEMG data during running activities particularly in field testing with the most appropriate study design and reliable methodology is yet to be determined and further studies are required.
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Affiliation(s)
- R Subbu
- University College London , Institute Sport Exercise and Health , University College London Hospitals NHS Foundation Trust, London , UK
| | - R Weiler
- University College London , Institute Sport Exercise and Health , University College London Hospitals NHS Foundation Trust, London , UK
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Miramonti AA, Stout JR, Fukuda DH, Robinson EH, Wang R, La Monica MB, Hoffman JR. Effects of 4 Weeks of High-Intensity Interval Training and β-Hydroxy-β-Methylbutyric Free Acid Supplementation on the Onset of Neuromuscular Fatigue. J Strength Cond Res 2016; 30:626-34. [PMID: 26418369 DOI: 10.1519/jsc.0000000000001140] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This study investigated the effects of high-intensity interval training (HIIT) and β-hydroxy-β-methylbutyric free acid (HMB) supplementation on physical working capacity at the onset of neuromuscular fatigue threshold (PWC(FT)). Thirty-seven participants (22 men, 15 women; 22.8 ± 3.4 years) completed an incremental cycle ergometer test (graded exercise test [GXT]); electromyographic amplitude from the right vastus lateralis was recorded. Assessments occurred preceding (PRE) and after 4 weeks of supplementation (POST). Participants were randomly assigned to control (C, n = 9), placebo (P, n = 14), or supplementation (S, n = 14) groups. Both P and S completed 12 HIIT sessions, whereas C maintained normal diet and activity patterns. The PWC(FT) (W) was determined using the maximal perpendicular distance (D(MAX)) method. Electromyographic amplitude (μVrms) over time was used to generate a cubic regression. Onset of fatigue (TF) was the x-value of the point on the regression that was at D(MAX) from a line between the first and last data points. The PWC(FT) was estimated using TF and GXT power-output increments. The 2-way analysis of variance (ANOVA) (group × time) resulted in a significant interaction for PWC(FT) (F = 6.69, p = 0.004). Post hoc analysis with 1-way ANOVA resulted in no difference in PWC(FT) among groups at PRE (F = 0.87, p = 0.43); however, a difference in PWC(FT) was shown for POST (F = 5.46, p = 0.009). Post hoc analysis among POST values revealed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes after HIIT for S (p < 0.001) and P (p = 0.016), but no change in C (p = 0.473). High-intensity interval training increased PWC(FT), but HMB with HIIT was more effective than HIIT alone. Furthermore, it seems that adding HMB supplementation with HIIT in untrained men and women may further improve endurance performance measures.
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Affiliation(s)
- Amelia A Miramonti
- Institute of Exercise Physiology and Wellness, Educational and Human Sciences, University of Central Florida, Orlando, Florida
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Detecting fatigue thresholds from electromyographic signals: A systematic review on approaches and methodologies. J Electromyogr Kinesiol 2016; 30:216-30. [PMID: 27529668 DOI: 10.1016/j.jelekin.2016.08.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 07/26/2016] [Accepted: 08/01/2016] [Indexed: 11/23/2022] Open
Abstract
The aim of the current paper was to systematically review the relevant existing electromyographic threshold concepts within the literature. The electronic databases MEDLINE and SCOPUS were screened for papers published between January 1980 and April 2015 including the keywords: neuromuscular fatigue threshold, anaerobic threshold, electromyographic threshold, muscular fatigue, aerobic-anaerobictransition, ventilatory threshold, exercise testing, and cycle-ergometer. 32 articles were assessed with regard to their electromyographic methodologies, description of results, statistical analysis and test protocols. Only one article was of very good quality. 21 were of good quality and two articles were of very low quality. The review process revealed that: (i) there is consistent evidence of one or two non-linear increases of EMG that might reflect the additional recruitment of motor units (MU) or different fiber types during fatiguing cycle ergometer exercise, (ii) most studies reported no statistically significant difference between electromyographic and metabolic thresholds, (iii) one minute protocols with increments between 10 and 25W appear most appropriate to detect muscular threshold, (iv) threshold detection from the vastus medialis, vastus lateralis, and rectus femoris is recommended, and (v) there is a great variety in study protocols, measurement techniques, and data processing. Therefore, we recommend further research and standardization in the detection of EMGTs.
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Pitt B, Dotan R, Millar J, Long D, Tokuno C, O'Brien T, Falk B. The electromyographic threshold in boys and men. Eur J Appl Physiol 2015; 115:1273-81. [PMID: 25588894 DOI: 10.1007/s00421-015-3100-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 01/04/2015] [Indexed: 11/26/2022]
Abstract
BACKGROUND Children have been shown to have higher lactate (LaTh) and ventilatory (VeTh) thresholds than adults, which might be explained by lower levels of type-II motor-unit (MU) recruitment. However, the electromyographic threshold (EMGTh), regarded as indicating the onset of accelerated type-II MU recruitment, has been investigated only in adults. PURPOSE To compare the relative exercise intensity at which the EMGTh occurs in boys versus men. METHODS Participants were 21 men (23.4 ± 4.1 years) and 23 boys (11.1 ± 1.1 years), with similar habitual physical activity and peak oxygen consumption (VO2pk) (49.7 ± 5.5 vs. 50.1 ± 7.4 ml kg(-1) min(-1), respectively). Ramped cycle ergometry was conducted to volitional exhaustion with surface EMG recorded from the right and left vastus lateralis muscles throughout the test (~10 min). The composite right-left EMG root mean square (EMGRMS) was then calculated per pedal revolution. The EMGTh was then determined as the exercise intensity at the point of least residual sum of squares for any two regression line divisions of the EMGRMS plot. RESULTS EMGTh was detected in 20/21 of the men (95.2 %) and only in 18/23 of the boys (78.3 %). The boys' EMGTh was significantly higher than the men's (86.4 ± 9.6 vs. 79.7 ± 10.0 % of peak power output at exhaustion; p < 0.05). The pattern was similar when EMGTh was expressed as percentage of VO2pk. CONCLUSIONS The boys' higher EMGTh suggests delayed and hence lesser utilization of type-II MUs in progressive exercise, compared with men. The boys-men EMGTh differences were of similar magnitude as those shown for LaTh and VeTh, further suggesting a common underlying factor.
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Affiliation(s)
- Brynlynn Pitt
- Applied Physiology Laboratory, Faculty of Applied Health Sciences, Brock University, 500 Glenridge Ave, St. Catharines, ON, L2T 2Y1, Canada
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Tikkanen O, Hu M, Vilavuo T, Tolvanen P, Cheng S, Finni T. Ventilatory threshold during incremental running can be estimated using EMG shorts. Physiol Meas 2012; 33:603-14. [DOI: 10.1088/0967-3334/33/4/603] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Sakamaki-Sunaga M, Loenneke J, Thiebaud R, Abe T. Onset of blood lactate accumulation and peak oxygen uptake during graded walking test combined with and without restricted leg blood flow. COMPARATIVE EXERCISE PHYSIOLOGY 2012. [DOI: 10.3920/cep12007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to compare the peak oxygen uptake (VO2peak) and lactate threshold / onset of blood lactate accumulation (LT/OBLA) during an incremental exercise test with and without blood flow restriction (BFR). Six male subjects performed a graded walking test on a treadmill with and without BFR in random order, and oxygen uptake (VO2), minute ventilation (VE), and blood lactate concentration were measured during each test. During the BFR test, the subjects wore pressure cuff belts on the most proximal portion of each thigh. At a given workload (e.g. during walking at 100 m/min) VO2 was 17% higher in BFR than in free-flow. Exercise time to exhaustion during BFR was shorter compared with free-flow despite the ratings of perceived exertion being similar between both conditions. Peak heart rate did not reach same level in the BFR test as it did in free-flow, with the heart rate 5 beats lower with BFR. VO2peak and VE peak were also 17% and 9%, respectively, lower in BFR than in free-flow. Compared with the control, O2 pulse (an index of stroke volume) was 14% lower in BFR. During BFR, VO2 at LT and OBLA were lower compared with free-flow. However, percentages of VO2peak at LT and OBLA were similar between BFR and free-flow. Our results suggest that the BFR-induced decrease in VO2peak may be associated with reductions in venous return and stroke volume. Additionally, these results suggest that increased muscle fiber recruitment with BFR may relate to the earlier LT/OBLA observed at lower intensities.
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Affiliation(s)
- M. Sakamaki-Sunaga
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan
- Women's Junior College of Nippon Sports Science University, 7-1-1 Fukasawa, Setagaya-ku, Tokyo 158-8508, Japan
| | - J.P. Loenneke
- Department of Health and Exercise Science, University of Oklahoma, 1405 Asp Avenue, Norman OK 73019, USA
| | - R.S. Thiebaud
- Department of Health and Exercise Science, University of Oklahoma, 1405 Asp Avenue, Norman OK 73019, USA
| | - T. Abe
- Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan
- Department of Health and Exercise Science, University of Oklahoma, 1405 Asp Avenue, Norman OK 73019, USA
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DiMenna FJ, Bailey SJ, Jones AM. Influence of body position on muscle deoxy[Hb+Mb] during ramp cycle exercise. Respir Physiol Neurobiol 2010; 173:138-45. [PMID: 20654739 DOI: 10.1016/j.resp.2010.07.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 07/13/2010] [Accepted: 07/13/2010] [Indexed: 10/19/2022]
Abstract
We used near-infrared spectroscopy (NIRS) to test the hypothesis that body position alters the sigmoidal response profile of muscle fractional O(2) extraction (estimated using deoxy[Hb+Mb]) during incremental cycle exercise. Seven male subjects (mean±SD age 32±13 years) completed a ramp incremental cycling test to exhaustion (30W/min) in both the supine and upright body positions. The sigmoidal (as opposed to hyperbolic) model that provided the better fit to deoxy[Hb+Mb] data during upright cycling was also present for the supine response; however, the slope of the sigmoid was increased (upright: 0.052±0.012 vs. supine: 0.090±0.036%⋅%P(peak)(-1); P<0.05) and a plateau occurred at a lower work rate (upright: 83±8 vs. supine: 68±19%P(peak)(-1); P<0.05) during supine exercise. These changes occurred in the absence of a leftward shift of the sigmoid. We also found a significantly greater deltaV(O)₂/deltaW slope above compared to below gas exchange threshold (GET) for both conditions (upright: 9.8±0.5 vs. 8.2±0.9; supine: 10.7±0.9 vs. 8.0±0.8) and for supine compared to upright cycling above GET. These findings suggest that the supine posture affects O₂ extraction and V(O)₂ kinetics to a greater extent as work rate progresses during ramp incremental exercise.
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Affiliation(s)
- Fred J DiMenna
- School of Sport and Health Sciences, St. Luke's Campus, University of Exeter, Heavitree Road, Exeter, Devon EX1 2LU, UK
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Kendall KL, Smith AE, Graef JL, Walter AA, Moon JR, Lockwood CM, Beck TW, Cramer JT, Stout JR. Validity of Electromyographic Fatigue Threshold as a Noninvasive Method for Tracking Changes in Ventilatory Threshold in College-Aged Men. J Strength Cond Res 2010; 24:109-13. [DOI: 10.1519/jsc.0b013e31819b79bc] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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The influence of ambient temperature on power at anaerobic threshold determined based on blood lactate concentration and myoelectric signals. Int J Occup Med Environ Health 2009; 22:1-6. [DOI: 10.2478/v10001-009-0005-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Graef JL, Smith AE, Kendall KL, Walter AA, Moon JR, Lockwood CM, Beck TW, Cramer JT, Stout JR. The relationships among endurance performance measures as estimated from VO2PEAK, ventilatory threshold, and electromyographic fatigue threshold: a relationship design. DYNAMIC MEDICINE : DM 2008; 7:15. [PMID: 18783626 PMCID: PMC2542988 DOI: 10.1186/1476-5918-7-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Accepted: 09/10/2008] [Indexed: 11/21/2022]
Abstract
Background The use of surface electromyography has been accepted as a valid, non-invasive measure of neuromuscular fatigue. In particular, the electromyographic fatigue threshold test (EMGFT) is a reliable submaximal tool to identify the onset of fatigue. This study examined the metabolic relationship between VO2PEAK, ventilatory threshold (VT), and the EMGFT, as well as compared the power output at VO2PEAK, VT, and EMGFT. Methods Thirty-eight college-aged males (mean ± SD = 22.5 ± 3.5 yrs) performed an incremental test to exhaustion on an electronically-braked cycle ergometer for the determination of VO2PEAK and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMGFT value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2-minute work bouts (ranging from 75–325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10-second intervals and plotted over the 2-minute work bout. The resulting slopes from each successive work bout were used to calculate EMGFT. Results Power outputs and VO2 values from each subject's incremental test to exhaustion were regressed. The linear equations were used to compute the VO2 value that corresponded to each fatigue threshold. Two separate one-way repeated measure ANOVAs indicated significant differences (p < 0.05) among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 ± 0.50 l·min-1) and EMGFTVO2(1.84 ± 0.53 l·min-1) were not significantly different (p > 0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 ± 37.8 W compared with 134.1 ± 43.5 W at EMGFT (p > 0.05) with a strong correlation between the two variables (r = 0.766). Conclusion Metabolic measurements, as well as the power outputs at VT and EMGFT, were strongly correlated. The significant relationship between VT and EMGFT suggests that both procedures may reflect similar physiological factors associated with the onset of fatigue. As a result of these findings, the EMGFT test may provide an attractive alternative to estimating VT.
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Affiliation(s)
- Jennifer L Graef
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Abbie E Smith
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Kristina L Kendall
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Ashley A Walter
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Jordan R Moon
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Christopher M Lockwood
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Travis W Beck
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Joel T Cramer
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
| | - Jeffrey R Stout
- Department of Health and Exercise Science, University of Oklahoma, Huston Huffman Center, 1401 Asp Ave., Norman, OK 73019, USA
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Candotti CT, Loss JF, Melo MDO, La Torre M, Pasini M, Dutra LA, de Oliveira JLN, de Oliveira LP. Comparing the lactate and EMG thresholds of recreational cyclists during incremental pedaling exercise. Can J Physiol Pharmacol 2008; 86:272-8. [DOI: 10.1139/y08-020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to determine the validity of using the electromyography (EMG) signal as a noninvasive method of estimating the lactate threshold (LT) power output in recreational cyclists. Using an electromagnetic bicycle ergometer and constant pedaling cadence of 80 rpm, 24 recreational cyclists performed an incremental exercise protocol that consisted of stepwise increases in power output of 25 W every 3 min until exhaustion. The EMG signal was recorded from the right vastus lateralis (VL) and right rectus femoris (RF) throughout the test. Blood samples were taken from the fingertip every 3 min. The LT was determined by examining the relation between the lactate concentration and the power output using a log–log transformation model. The root mean square (RMS) value from the EMG signal was calculated for every 1-second non-superimposing window. Sets of pairs of straight regression lines were plotted and the corresponding determination coefficients (R2) were calculated. The intersection point of the pair of lines with the highest R2 product was chosen to represent the EMG threshold (EMGT). The results showed that the correlation coefficients (r) between EMGT and LT were significant (p < 0.01) and high for the VL (r = 0.826) and RF (r = 0.872). The RF and VL muscles showed similar behavior during the maximal incremental test and the EMGT and LT power output were equivalent for both muscles. The validity of using EMG to estimate the LT power output in recreational cyclists was confirmed.
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Affiliation(s)
- Cláudia Tarragô Candotti
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Jefferson Fagundes Loss
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Mônica de Oliveira Melo
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Marcelo La Torre
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Maicon Pasini
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Lucas Araújo Dutra
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - José Leandro Nunes de Oliveira
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
| | - Lino Pinto de Oliveira
- Universidade do Vale do Rio dos Sinos, Curso de Educação Física, São Leopoldo, Brazil
- Universidade Federal do Rio Grande do Sul, Rua Felizardo, 750, 90690-200 Porto Alegre, RS, Brazil
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17
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Hanon C, Thépaut-Mathieu C, Vandewalle H. Determination of muscular fatigue in elite runners. Eur J Appl Physiol 2005; 94:118-25. [PMID: 15696315 DOI: 10.1007/s00421-004-1276-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/02/2004] [Indexed: 10/25/2022]
Abstract
This study analyses the changes in the electromyographic activity (EMG) of six major muscles of the leg during an incremental running test carried out on a treadmill. These muscles, the gluteus maximus (GM), biceps femoris (BF), vastus lateralis (VL), rectus femoris (RF), tibialis anterior (TA) and gastrocnemius (Ga) are known to have quite different functions during running. The aim of this study was to develop a methodology adapted to the analysis of integrated EMG (iEMG) running results, and to test the chronology of the onset of fatigue of the major muscles involved in running. Nine well-trained subjects [VO(2max) 76 (2.9) ml.min(-1).kg(-1)] took part in this study. They completed a running protocol consisting of 4 min stages, incrementally increasing in speed until exhaustion. The EMG signal was recorded during ten bursts of activation analysed separately at 45 s and 3 min 40 s of each stage. During running, consideration of the alteration in stride frequency with either an increase in speed or the onset of fatigue appears to be an indispensable part of the assessment of muscular fatigue. This allows the comparison of muscular activation between the various stage speeds by the use of common working units. Distance seems to be the only working unit that allows this comparison and thus the determination of the appearance of fatigue during running. The biarticular hip-mobilising muscles (RF and BF), which present two different bursts of activation during one running cycle, are the muscles that show the earliest signs of fatigue.
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Affiliation(s)
- Christine Hanon
- Laboratoire de Biomécanique et de Physiologie, Institut National du Sport et de l'Education Physique, Paris, France.
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Ekkekakis P, Hall EE, Petruzzello SJ. Practical markers of the transition from aerobic to anaerobic metabolism during exercise: rationale and a case for affect-based exercise prescription. Prev Med 2004; 38:149-59. [PMID: 14715206 DOI: 10.1016/j.ypmed.2003.09.038] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND The high rates of dropout from exercise programs may be attributed in part to the poor ability of most individuals to accurately self-monitor and self-regulate their exercise intensity. The point of transition from aerobic to anaerobic metabolism may be an appropriate level of exercise training intensity as it appears to be effective and safe for a variety of populations. Possible practical markers of this event were compared. METHODS Two samples of 30 young and healthy volunteers each participated in incremental treadmill tests until volitional exhaustion. The ventilatory threshold, a noninvasive estimate of the aerobic-anaerobic transition, was identified from gas exchange data. Heart rate, self-ratings of affective valence (pleasure-displeasure), perceived activation, and perceived exertion were recorded every minute. RESULTS In both samples, heart rate, perceived activation, and perceived exertion rose continuously, whereas the ratings of affective valence showed a pattern of quadratic decline, initiated once the ventilatory threshold was exceeded. CONCLUSIONS Exercise intensity that exceeds the point of transition from aerobic to anaerobic metabolism is accompanied by a quadratic decline in affective valence. This marker may be useful in aiding exercisers to recognize the transition to anaerobic metabolism and, thus, more effectively self-monitor and self-regulate the intensity of their efforts.
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Affiliation(s)
- Panteleimon Ekkekakis
- Department of Health and Human Performance, Iowa State University, 235 Barbara E. Forker Building, Ames, IA 50011, USA.
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Hug F, Laplaud D, Savin B, Grélot L. Occurrence of electromyographic and ventilatory thresholds in professional road cyclists. Eur J Appl Physiol 2003; 90:643-6. [PMID: 14508692 DOI: 10.1007/s00421-003-0949-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2003] [Indexed: 10/26/2022]
Abstract
The temporal relationship between the electromyographic (EMG) and ventilatory thresholds was investigated during incremental exercise performed by eight professional road cyclists. The exercise, performed on a cycloergometer, started at 100 W with successive increments of 26 Wx min(-1) until exhaustion. Gas exchange and the root mean square value of EMG (RMS) from eight lower limb muscles were examined throughout the exercise period. Professional cyclists achieved a maximal oxygen consumption, i.e. VO(2max), of 5.4 (0.5) l x min(-1) [74.6 (2.5) ml x min(-1) x kg(-1), range: 67.8-82.4 ml x min(-1) x kg(-1)] and a maximum power ( W(max)) of 475 (30) W (range: 438-516 W). Our results showed at least the occurrence of a first EMG threshold (EMG(Th1)) in 50% (gastrocnemius lateralis) of the subjects and a second EMG threshold (EMG(Th2)) in 63% (gastrocnemius medialis). EMG(Th1) occurred significantly before the first ventilatory threshold (VT(1)), i.e. at 52 (2)% and 62 (9)% of W(max), respectively. Inversely, no significant difference was observed between the occurrence of EMG(Th2) and the second ventilatory threshold (VT(2)), i.e. at 86 (1)% and 89 (7)% of W(max), respectively. These results suggest that the use of EMG may be a useful non-invasive method for detecting the second ventilatory threshold in most of the muscles involved in cycling exercise.
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Affiliation(s)
- F Hug
- Déterminants Physiologiques de l'Activité Physique, Faculté des Sciences du Sport, Université de la Méditerranée (Aix-Marseille II), 163 avenue de Luminy, CC 910, 13288, Marseille, France.
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Hug F, Faucher M, Kipson N, Jammes Y. EMG signs of neuromuscular fatigue related to the ventilatory threshold during cycling exercise. Clin Physiol Funct Imaging 2003; 23:208-14. [PMID: 12914560 DOI: 10.1046/j.1475-097x.2003.00497.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We questioned whether electromyographic (EMG) signs of neuromuscular fatigue accompany the changes in respiratory variables measured at the ventilatory threshold (VTh) during exercise on a cycloergometer. This was based on the assumption that the activation of muscle afferents sensitive to accumulation of lactate and potassium is suspected to elicit both the EMG signs of fatigue and hyperventilation. In 39 subjects performing an incremental cycling, the EMG estimates of neuromuscular fatigue in vastus lateralis were a non-linear increase in root mean square (RMS), a decrease in median frequency (MF), a non-linear increase in low-frequency EMG energies (EL), and/or a decrease in high-frequency energies (EH). VTh was determined from a non-linear increase in VCO2 [VTh(VCO2 slope)] and an increased value of the respiratory equivalent for oxygen [VTh(VE/VO2)]. We measured a significant increase in venous blood concentration of lactate and potassium, and a significant pHv fall at VTh. One EMG estimate of fatigue was detected in 33/39 individuals and two EMG estimates in 17 subjects. Highly significant positive correlations were found between the oxygen uptakes corresponding to each EMG estimate and to each detection criterion of VTh. These observations suggest that the activation of muscle sensory pathways contribute to the mechanism of VTh.
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Affiliation(s)
- François Hug
- Laboratoire de Physiopathologie Respiratoire (UPRES EA 2201), Institut Jean Roche, Faculté de Médecine, Université de la Méditerranée, Hôpital Nord, Assistance Publique--Hôpitaux de Marseille, Marseille, France
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21
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Perry SR, Housh TJ, Weir JP, Johnson GO, Bull AJ, Ebersole KT. Mean power frequency and amplitude of the mechanomyographic and electromyographic signals during incremental cycle ergometry. J Electromyogr Kinesiol 2001; 11:299-305. [PMID: 11532601 DOI: 10.1016/s1050-6411(00)00057-2] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The purpose of this investigation was to determine the relationships for mechanomyographic (MMG) amplitude, MMG mean power frequency (MPF), electromyographic (EMG) amplitude, and EMG MPF versus power output during incremental cycle ergometry. Seventeen adults volunteered to perform an incremental test to exhaustion on a cycle ergometer. The test began at 50 W and the power output was increased by 30 W every 2 min until the subject could no longer maintain 70 rev min(-1). The MMG and EMG signals were recorded simultaneously from the vastus lateralis during the final 10 s of each power output and analyzed. MMG amplitude, MMG MPF, EMG amplitude, EMG MPF, and power output were normalized as a percentage of the maximal value from the cycle ergometer test. Polynomial regression analyses indicated that MMG amplitude increased (P<0.05) linearly across power output, but there was no change (P>0.05) in MMG MPF. EMG amplitude and MPF were fit best (P<0.05) with quadratic models. These results demonstrated dissociations among the time and frequency domains of MMG and EMG signals, which may provide information about motor control strategies during incremental cycle ergometry. The patterns for amplitude and frequency of the MMG signal may be useful for examining the relationship between motor-unit recruitment and firing rate during dynamic tasks.
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Affiliation(s)
- S R Perry
- University of Nebraska-Lincoln, P.O. Box 0229, Lincoln, NE 68588-0229, USA.
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22
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Saunders MJ, Evans EM, Arngrimsson SA, Allison JD, Warren GL, Cureton KJ. Muscle activation and the slow component rise in oxygen uptake during cycling. Med Sci Sports Exerc 2000; 32:2040-5. [PMID: 11128849 DOI: 10.1097/00005768-200012000-00012] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE During constant-rate high-intensity exercise, a steady state for oxygen uptake (VO2) is not achieved and, after the initial rapid increase, VO2 continues to increase slowly. The mechanism underlying the slow-component rise in VO2 during high-intensity exercise is unknown. It has been hypothesized that increased muscle use may be a contributing factor, but only limited electromyograph (EMG) data are available supporting this hypothesis. The purpose of this study was to determine whether there is an association between the VO2 slow component and muscle use assessed by contrast shifts in magnetic resonance images (magnetic resonance imaging (MRI)). METHODS The VO2 slow component was measured in 16 subjects during two 15-min bouts of cycling performed at high and low intensities. EMG and MRI transverse relaxation times (T2) were obtained after 3 and 15 min to determine muscle activity at each intensity. RESULTS Low-intensity cycling produced no VO2 slow component, and no increases in muscle activity, except for a small increase (P < 0.05) in the T2 of the vastus lateralis. During high-intensity cycling, VO2, T2 of the vastus lateralis, rectus femoris and whole leg, and EMG activity and median power frequency of the vastus lateralis rose significantly (P < 0.05) from 3 to 15 min. Percent increases in VO2 and muscle T2 were related during high-intensity cycling (r = 0.63), but not during low-intensity cycling (r = 0.00). CONCLUSION We conclude that increased muscle use is in part responsible for the slow component rise in oxygen uptake. The results support the hypothesis that during constant-rate exercise at intensities above lactate threshold, progressively greater use of fast-twitch motor units increases energy demand and causes concomitant progressive increases in VO2 and lactate.
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Affiliation(s)
- M J Saunders
- Department of Exercise Science, The University of Georgia, Athens, USA.
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23
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Abstract
OBJECTIVES To analyse the slow component of oxygen uptake (VO2) in professional cyclists and to determine whether this phenomenon is due to altered neuromuscular activity, as assessed by surface electromyography (EMG). METHODS The following variables were measured during 20 minute cycle ergometer tests performed at about 80% of VO2MAX in nine professional road cyclists (mean (SD) age 26 (2) years; VO2max 72.6 (2.2) ml/kg/min): heart rate (HR), gas exchange variables (VO2, ventilation (VE), tidal volume (VT), breathing frequency (fb), ventilatory equivalents for oxygen and carbon dioxide (VE/VO2 and VE/VCO2 respectively), respiratory exchange ratio (RER), and end tidal PO2 and PCO2 (PETO2 and PETCO2 respectively)), blood variables (lactate, pH, and [HCO3-]) and EMG data (root mean from square voltage (rms-EMG) and mean power frequency (MPF)) from the vastus lateralis muscle. RESULTS The mean magnitude of the slow component (from the end of the third minute to the end of exercise) was 130 (0.04) ml in 17 minutes or 7.6 ml/min. Significant increases from three minute to end of exercise values were found for the following variables: VO2 (p<0.01), HR (p<0.01), VE (p<0.05), fb (p<0.01), VE/VO2 (p<0.05), VE/VCO2 (p<0.01), PETO2 (p<0.05), and blood lactate (p<0.05). In contrast, rms-EMG and MPF showed no change (p>0.05) throughout the exercise tests. CONCLUSIONS A significant but small VO2 slow component was shown in professional cyclists during constant load heavy exercise. The results suggest that the primary origin of the slow component is not neuromuscular factors in these subjects, at least for exercise intensities up to 80% of VO2MAX.
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Affiliation(s)
- A Lucía
- Departamento de Ciencias Morfológicas y Fisiología, Universidad Europea de Madrid, Spain.
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Lucía A, Sánchez O, Carvajal A, Chicharro JL. Analysis of the aerobic-anaerobic transition in elite cyclists during incremental exercise with the use of electromyography. Br J Sports Med 1999; 33:178-85. [PMID: 10378070 PMCID: PMC1756168 DOI: 10.1136/bjsm.33.3.178] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVES To investigate the validity and reliability of surface electromyography (EMG) as a new non-invasive determinant of the metabolic response to incremental exercise in elite cyclists. The relation between EMG activity and other more conventional methods for analysing the aerobic-anaerobic transition such as blood lactate measurements (lactate threshold (LT) and onset of blood lactate accumulation (OBLA)) and ventilatory parameters (ventilatory thresholds 1 and 2 (VT1 and VT2)) was studied. METHODS Twenty eight elite road cyclists (age 24 (4) years; VO2MAX 69.9 (6.4) ml/kg/min; values mean (SD)) were selected as subjects. Each of them performed a ramp protocol (starting at 0 W, with increases of 5 W every 12 seconds) on a cycle ergometer (validity study). In addition, 15 of them performed the same test twice (reliability study). During the tests, data on gas exchange and blood lactate levels were collected to determine VT1, VT2, LT, and OBLA. The root mean squares of EMG signals (rms-EMG) were recorded from both the vastus lateralis and the rectus femoris at each intensity using surface electrodes. RESULTS A two threshold response was detected in the rms-EMG recordings from both muscles in 90% of subjects, with two breakpoints, EMGT1 and EMGT2, at around 60-70% and 80-90% of VO2MAX respectively. The results of the reliability study showed no significant differences (p > 0.05) between mean values of EMGT1 and EMGT2 obtained in both tests. Furthermore, no significant differences (p > 0.05) existed between mean values of EMGT1, in the vastus lateralis and rectus femoris, and VT1 and LT (62.8 (14.5) and 69.0 (6.2) and 64.6 (6.4) and 68.7 (8.2)% of VO2MAX respectively), or between mean values of EMGT2, in the vastus lateralis and rectus femoris, and VT2 and OBLA (86.9 (9.0) and 88.0 (6.2) and 84.6 (6.5) and 87.7 (6.4)% of VO2MAX respectively). CONCLUSION rms-EMG may be a useful complementary non-invasive method for analysing the aerobic-anaerobic transition (ventilatory and lactate thresholds) in elite cyclists.
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Affiliation(s)
- A Lucía
- Departamento de Ciencias Morfológicas y Fisiología, Universidad Europea de Madrid, Spain
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Moritani T, Yoshitake Y. 1998 ISEK Congress Keynote Lecture: The use of electromyography in applied physiology. International Society of Electrophysiology and Kinesiology. J Electromyogr Kinesiol 1998; 8:363-81. [PMID: 9840892 DOI: 10.1016/s1050-6411(98)00018-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Electromyogram (EMG) analyses (surface, intramuscular and evoked potentials) in studies of muscle function have attracted increasing attention during recent years and have been applied to assess muscle endurance capacity, anaerobic and lactate thresholds, muscle biomechanics, motor learning, neuromuscular relaxation, optimal walking and pedalling speeds, muscle soreness, neuromuscular diseases, motor unit (MU) activities (MU recruitment and rate coding), and skeletal muscle fatigue. This paper deals with the use of EMG analyses employed in the area of applied physiology and is divided into three sections: surface EMG analyses; intramuscular EMG analyses; and evoked potential analyses.
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Affiliation(s)
- T Moritani
- Laboratory of Applied Physiology, Graduate School of Human and Environmental Studies, Kyoto University, Japan.
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Lu SS, Lau CP, Tung YF, Huang SW, Chen YH, Shih HC, Tsai SC, Lu CC, Wang SW, Chen JJ, Chien EJ, Chien CH, Wang PS. Lactate and the effects of exercise on testosterone secretion: evidence for the involvement of a cAMP-mediated mechanism. Med Sci Sports Exerc 1997; 29:1048-54. [PMID: 9268962 DOI: 10.1097/00005768-199708000-00010] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of swimming and lactate on the release of testosterone were examined in male rats. During in vivo experiments, male rats were catheterized via the right jugular vein and blood was collected at 0, 10, 15, 30, and 60 min following the exercise, or they were catheterized via the right jugular vein and the left femoral vein and blood was collected at 0, 2, 5, 10, 15, 30, 60, and 120 min after a 10-min infusion at lactate (13 mg.kg-1.min-1). Trunk blood and blood from the testicular vein were also collected after 10 min of swimming or water immersion. In an in vitro experiment, testicular fragments were challenged with lactate (0.01-10 mM) and/or human chorionic gonadotropin (hCG; 0.5 IU.mL-1), and the mediobasal hypothalamus (MBH) was challenged with lactate (8 mM). The post-exercise levels of plasma lactate and testosterone at 10, 15, and 30 min were higher than resting levels. Plasma luteinizing hormone (LH) was increased following 30 min of swimming. Administration of lactate or hCG increased in a dose dependent manner testicular cyclic adenosine 3':5' monophosphate (cAMP) and testosterone release. Plasma testosterone increased after swimming and lactate infusion. Incubation of MBH with lactate increased the gonadotropin-releasing hormone (GnRH) level in the medium. These results suggest that the increased plasma testosterone levels in male rats during exercise is at least partially a result of a direct and LH-independent stimulatory effect of lactate on the secretion of testosterone by increasing testicular cAMP production. Swim-elevated plasma LH may be a result of a rise of GnRH caused by lactate.
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Affiliation(s)
- S S Lu
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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Lucía A, Vaquero AF, Pérez M, Sánchez O, Sánchez V, Gómez MA, Chicharro JL. Electromyographic response to exercise in cardiac transplant patients: a new method for anaerobic threshold determination? Chest 1997; 111:1571-6. [PMID: 9187176 DOI: 10.1378/chest.111.6.1571] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The purpose of this study was to investigate the possible use of integrated surface electromyography (iEMG) in cardiac transplant patients (CTPs) as a new noninvasive determinant of the metabolic response to exercise by studying the relationship between the iEMG threshold (iEMGT) and other more conventional methods for anaerobic threshold (AT) determination, such as the lactate threshold (LT) and the ventilatory threshold (VT). Thirteen patients (age: 57+/-7 years, mean+/-SD; height: 163+/-7 cm; body mass: 70.5+/-8.6 kg; posttransplant time: 87+/-49 weeks) were selected as subjects. Each of them performed a ramp protocol on a cycle ergometer (starting at 0 W, the workload was increased in 10 W/min). During the tests, gas exchange data, blood lactate levels, and iEMG of the vastus lateralis were collected to determine VT, LT, and iEMGT, respectively. The results evidenced no significant difference between mean values of VT, LT, or iEMGT, when expressed either as oxygen uptake (11.1+/-2.4, 11.7+/-2.3, and 11.0+/-2.8 mL/kg/min, respectively) or as percent maximum oxygen uptake (61.6+/-7.5, 62.2+/-7.7, and 59.6+/-8.2%, respectively). In conclusion, our findings suggest that iEMG might be used as a complementary, noninvasive method for AT determination in CTPs. In addition, since the aerobic impairment of these patients is largely due to peripheral limitation, determination of iEMGT could be used to assess the effectiveness of an exercise rehabilitation program to improve muscle aerobic capacity in CTPs.
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Affiliation(s)
- A Lucía
- Unidad de Investigación, Escuela de Medicina de la Educación Física y el Deporte, Universidad Complutense de Madrid, Spain
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Lu SS, Lau CP, Tung YF, Huang SW, Chen YH, Shih HC, Tsai SC, Lu CC, Wang SW, Chen JJ, Chien EJ, Chien CH, Wang PS. Lactate stimulates progesterone secretion via an increase in cAMP production in exercised female rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:E910-5. [PMID: 8944680 DOI: 10.1152/ajpendo.1996.271.5.e910] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effect of exercise on the production of ovarian progesterone was examined in female rats. During in vivo experiments, diestrous rats were catheterized via the right jugular vein (RJV), and blood samples were collected before and after 10, 15, 30, and 60 min of swimming. In addition, blood samples were collected from the RJV before and 2, 5, 10, 15, 30, 60, and 120 min after 10 min of infusion of lactate (13 mg.kg-1.min-1) through the left femoral vein. To explore if lactate modulates progesterone secretion by acting directly on rat ovary or on anterior pituitary gland (AP), an in vitro experiment that mimicked the in vivo condition was performed. The ovarian tissue was challenged with lactate (0.01-10 mM) or porcine follicle-stimulating hormone (1 microgram/ml) and 3-isobutyl-1-methylxanthine (1 mM) for 60 min, and the AP was challenged with lactate ranging from 0.1 to 10 mM or 10 nM gonadotropin-releasing hormone for 30 min. The postexercise levels of plasma glucose, lactate, and progesterone at 10, 15, and 30 min were significantly higher than the corresponding basal levels. Plasma luteinizing hormone (LH) did not change after exercise. An elevation of plasma lactate and progesterone was found at 15 and 30 min subsequent to 10 min of infusion of lactate. Lactate ranging from 0.01 to 10 mM significantly increased ovarian adenosine 3',5'-cyclic monophosphate (cAMP) and progesterone production in a dose-dependent manner. LH concentration in plasma was not changed subsequent to lactate infusion. LH level in media samples was not altered after incubation of AP with lactate. These results suggest that the increase of plasma progesterone level in rats during exercise is independent of LH secretion and at least in part is due directly to a stimulatory effect of lactate on the production of ovarian cAMP.
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Affiliation(s)
- S S Lu
- Department of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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Vogiatzis I, Spurway NC, Jennett S, Wilson J, Sinclair J. Changes in ventilation related to changes in electromyograph activity during repetitive bouts of isometric exercise in simulated sailing. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1996; 72:195-203. [PMID: 8820885 DOI: 10.1007/bf00838638] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study examined the control of ventilation during repetitive bouts of isometric exercise in simulated sailing. Eight male sailors completed four successive 3-min bouts of similar isometric effort on a dinghy simulator; bouts were separated by 15-s rest intervals. Quadriceps muscle integrated electromyograph activity (iEMG) was recorded during each bout and expressed as a percentage of activity during maximal voluntary contraction (%iEMGmax). From the first to the fourth bout, the 3-min mean averages for ventilation and for %iEMGmax increased from 19.8 (SEM 1.1) to 37.5 (SEM 3.0) l.min-1 and from 31 (SEM 4) to 39 (SEM 4)% respectively; also, ventilation and %iEMGmax over each minute throughout the four bouts were significantly correlated (r = 0.85; P < 0.05). Progressive hyperventilation reduced the mean end-tidal partial pressure of carbon dioxide from 5.0 (SEM 0.3) kPa during bout 1 to 4.3 (SEM 0.4) kPa during bout 4 [37.7 (SEM 2.0) to 32.4 (SEM 3.0) mmHg]. From the first to the fourth bout the end-of-bout blood lactate concentration did not increase significantly although the concentration from the third bout onwards was significantly greater than at rest. The results suggested that the development of muscle fatigue, which was enhanced by the insufficiency of recovery during the 15-s intervals and mirrored in the progressive increase in iEMG, was linked with stimuli causing progressive hyperventilation. Though these changes in ventilation and iEMG could not be associated with changes in blood lactate concentration, they could both have been related to accumulating metabolites within the muscles themselves.
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Affiliation(s)
- I Vogiatzis
- Institute of Biomedical and Life Sciences, University of Glasgow, Scotland, UK
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Taylor AD, Bronks R. Reproducibility and validity of the quadriceps muscle integrated electromyogram threshold during incremental cycle ergometry. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1995; 70:252-7. [PMID: 7607201 DOI: 10.1007/bf00238572] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The principle aims of this research were, firstly, to determine if the relationship between integrated electromyography (iEMG) and exercise intensity was linear or threshold-like, and secondly, to determine if the relationship between iEMG and exercise intensity was repeatable on different test occasions. A group of 20 trained male subjects participated in the study. Each subject completed two incremental exercise tests on a Monark cycle ergometer. The tests were identical and separated from each other by a mean period of 42 (SD 12) h. The EMG signals were recorded from the vastus lateralis, rectus femoris and vastus medialis muscles at each intensity using surface electrodes. The relationship between iEMG and intensity was shown to be linear (r = 0.95 to r = 0.98) with no obvious iEMG thresholds present. The gradients of simple regression lines fitted to the iEMG compared to intensity were not significantly different on the retest occasion (CV 9%-12%). In summary, the findings of this study indicated that, during incremental exercise, the relationship between iEMG of the quadriceps musculature and exercise intensity was linear and not threshold-like. Furthermore, the linear relationship between iEMG and workload was repeatable on different test occasions.
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Affiliation(s)
- A D Taylor
- Centre for Human Movement Science and Sports Management, Southern Cross University, Lismore, NSW, Australia
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31
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Housh TJ, deVries HA, Johnson GO, Housh DJ, Evans SA, Stout JR, Evetovich TK, Bradway RM. Electromyographic fatigue thresholds of the superficial muscles of the quadriceps femoris. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1995; 71:131-6. [PMID: 7588679 DOI: 10.1007/bf00854969] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this investigation was to compare the thresholds of neuromuscular fatigue determined simultaneously from the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) muscles using the electromyographic fatigue threshold (EMGFT) test. Eight adult volunteers [mean (SD) age, 33 (10) years] served as subjects for this investigation. The results of a one-way repeated measured ANOVA indicated that there was a significant (P < 0.05) difference among the mean EMGFT values for the VL [248(31)W], VM [223(43)W] and RF [220(30)W] muscles. Tukey post-hoc comparisons indicated that the EMGFT for the RF was significantly (P < 0.05) lower than that of the VL. These findings suggested that during cycle ergometry there is a dissociation in neuromuscular fatigue characteristics of the superficial muscles of the quadriceps femoris group.
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Affiliation(s)
- T J Housh
- Human Performance Laboratory, University of Nebraska-Lincoln 68588-0229, USA
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32
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Mateika JH, Duffin J. A review of the control of breathing during exercise. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1995; 71:1-27. [PMID: 7556128 DOI: 10.1007/bf00511228] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
During the past 100 years many experimental investigations have been carried out in an attempt to determine the control mechanisms responsible for generating the respiratory responses observed during incremental and constant-load exercise tests. As a result of these investigations a number of different and contradictory control mechanisms have been proposed to be the sole mediators of exercise hyperpnea. However, it is now becoming evident that none of the proposed mechanisms are solely responsible for eliciting the exercise respiratory response. The present-day challenge appears to be one of synthesizing the proposed mechanisms, in order to determine the role that each mechanism has in controlling ventilation during exercise. This review, which has been divided into three primary sections, has been designed to meet this challenge. The aim of the first section is to describe the changes in respiration that occur during constant-load and incremental exercise. The second section briefly introduces the reader to traditional and contemporary control mechanisms that might be responsible for eliciting at least a portion of the exercise ventilatory response during these types of exercise. The third section describes how the traditional and contemporary control mechanisms may interact in a complex fashion to produce the changes in breathing associated with constant-load exercise, and incorporates recent experimental evidence from our laboratory.
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Affiliation(s)
- J H Mateika
- Department of Physiology, University of Toronto, Ontario, Canada
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33
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Taylor AD, Bronks R. Electromyographic correlates of the transition from aerobic to anaerobic metabolism in treadmill running. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1994; 69:508-15. [PMID: 7713071 DOI: 10.1007/bf00239868] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This study analysed the changes in electromyographic (EMG) activity of the vastus lateralis, biceps femoris and gastrocnemius muscles during incremental treadmill running. The changes in EMG were related to the lactate and ventilatory thresholds. Ten trained subjects participated in the study. Minute ventilation, oxygen consumption, carbon dioxide expired and the fraction of oxygen in the expired gas were recorded continuously. Venous blood samples were collected at each exercise intensity and analysed for lactate concentration. The EMG were recorded at the end of each exercise intensity using surface electrodes. The EMG were quantified through integration (iEMG) and by calculating the mean power frequency (MPF). The iEMG measurements were characterized by a breakpoint in the vastus lateralis and/or gastrocnemius muscles in eight of the subjects tested. However, the results indicated that blood lactate concentrations had already begun to increase in a nonlinear fashion before the iEMG breakpoint had been surpassed. Consequently, the occurence of the lactate threshold cannot be attributed solely to the change in motor unit recruitment or rate coding patterns demonstrated by the iEMG breakpoint. The ventilatory threshold was shown to be a far more reliable and convenient noninvasive predictor of the lactate threshold in comparison with EMG techniques. In conclusion, the EMG measurements used in this study (i.e. iEMG and MPF) were not considered to be viable noninvasive determinants of the aerobic-anaerobic transition phase in treadmill running.
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Affiliation(s)
- A D Taylor
- Centre for Human Movement and Sports Management, Southern Cross University, Lismore, NSW, Australia
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Mateika JH, Duffin J. The ventilation, lactate and electromyographic thresholds during incremental exercise tests in normoxia, hypoxia and hyperoxia. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1994; 69:110-8. [PMID: 7805664 DOI: 10.1007/bf00609402] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
These experiments examined the effect of hypoxia and hyperoxia on ventilation, lactate concentration and electromyographic activity during an incremental exercise test in order to determine if coincident chances in ventilation and electromyographic activity occur during an incremental exercise test, despite an enhancement or reduction of peripheral chemoreceptor activity. In addition, these experiments were completed to determine if electromyographic activity and ventilation are enhanced or reduced in response to the inspiration of oxygen-depleted and oxygen-enriched air, respectively. Seven subjects performed three incremental exercise tests, until volitional exhaustion was achieved, while inspiring air with a fractional concentration of oxygen of either 66%, 21% or 17%. In addition, another single subject completed two tests while inspiring air with a fractional concentration of either 17% or 21%. During the tests, ventilation, mixed expired oxygen and carbon dioxide, arterialized venous blood and the electromyographic activity from the vastus lateralis were sampled. From these values ventilation, electromyographic and lactate thresholds were detected during normoxia, hypoxia and hyperoxia. The results showed that although ventilation and lactate concentration were significantly less during hyperoxia as compared to normoxia or hypoxia, the carbon dioxide production values were not significantly different between the normoxic, hypoxic and hyperoxic conditions. For a particular condition, the time, carbon dioxide production and oxygen consumption values that corresponded to the ventilation and electromyographic thresholds were not significantly different, but the values corresponding to the lactate threshold were significantly less than those for the electromyographic and ventilation thresholds. Comparisons between the three conditions showed that the time, carbon dioxide production and oxygen consumption values corresponding to each of these thresholds were not significantly difficult.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J H Mateika
- Department of Anesthesia, University of Toronto, Ontario, Canada
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Mateika JH, Duffin J. Coincidental changes in ventilation and electromyographic activity during consecutive incremental exercise tests. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1994; 68:54-61. [PMID: 8162924 DOI: 10.1007/bf00599242] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
These experiments examined the effect of metabolic acidosis, induced as a result of dynamic exercise, on ventilation, lactate concentration and electromyographic activity. Seven subjects performed two consecutive incremental exercise tests until volitional exhaustion was achieved. The two tests were identical and were separated by a 7-min period of light exercise. During the tests, ventilation, mixed expired oxygen and carbon dioxide, arterialized venous blood and electromyographic activity from the vastus lateralis was sampled. The results showed that the ventilation and electromyographic measurements followed a similar time course during both tests, although ventilation during the initial 6 min of the second test was significantly greater than the values recorded during the first test. In addition, throughout the first test lactate concentration increased with time, and pH, bicarbonate concentration and partial pressure of carbon dioxide decreased. In contrast, during the second test, lactate concentration decreased, and pH and bicarbonate concentration increased; during a period of time when ventilation and electromyographic activity were increasing. These findings have led us to conclude that changes in ventilation and electromyographic activity observed during incremental exercise are not related to changes in blood lactate concentration. It is suggested that such a conclusion supports the hypothesis that the changes in ventilation are mediated by an increase in neural activity originating from the subthalamic motor region or exercising limbs, induced in response to the need to progressively recruit fast twitch muscle fibres as exercise work rate is increased and as individual muscle fibres begin to fatigue.
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Affiliation(s)
- J H Mateika
- Department of Anaesthesia, University of Toronto, Ontario, Canada
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36
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Takaishi T, Ono T, Yasuda Y. Relationship between muscle fatigue and oxygen uptake during cycle ergometer exercise with different ramp slope increments. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1992; 65:335-9. [PMID: 1425634 DOI: 10.1007/bf00868137] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The surface electromyogram (EMG) from active muscle and oxygen uptake (VO2) were studied simultaneously to examine changes of motor unit (MU) activity during exercise tests with different ramp increments. Six male subjects performed four exhausting cycle exercises with different ramp slopes of 10, 20, 30 and 40 W.min-1 on different days. The EMG signals taken from the vastus lateralis muscle were stored on a digital data recorder and converted to obtain the integrated EMG (iEMG). The VO2 was measured, with 20-s intervals, by the mixing chamber method. A non-linear increase in iEMG against work load was observed for each exercise in all subjects. The break point of the linear relationship of iEMG was determined by the crossing point of the two regression lines (iEMGbp). Significant differences were obtained in the exercise intensities corresponding to maximal oxygen uptake (VO2max) and the iEMGbp between 10 and 30, and 10 and 40 W.min-1 ramp exercises (P < 0.05). However, no significant differences were obtained in VO2max and VO2 corresponding to the iEMGbp during the four ramp exercises. With respect to the relationship between VO2 and exercise intensity during the ramp increments, the VO2-exercise intensity slope showed significant differences only for the upper half (i.e. above iEMGbp). These results demonstrated that the VO2max and VO2 at which a nonlinear increase in iEMG was observed were not varied by the change of ramp slopes but by the exercise intensity corresponding to VO2max and the iEMGbp was varied by the change of ramp slopes.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T Takaishi
- College of General Education, Nagoya City University, Japan
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37
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Fishman RS, Systrom DM. Preoperative cardiopulmonary exercise testing: determining the limit to exercise and predicting outcome after thoracotomy. J Cardiothorac Vasc Anesth 1991; 5:614-26. [PMID: 1768827 DOI: 10.1016/1053-0770(91)90019-p] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Over the past 15 years evaluation of the patient with exertional complaints has changed from a simple qualitative estimate of overall fitness to a detailed assessment of cardiovascular and pulmonary pathophysiology. By quantifying exercise impairment and identifying the physiological limit to exercise, CPEx can help direct and evaluate the efficacy of medical and surgical interventions. Although no clear consensus has emerged, an objective determination of the etiology of exercise intolerance may also help identify the patient at increased risk for postthoracotomy complications.
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Affiliation(s)
- R S Fishman
- Pulmonary and Critical Care Unit, Massachusetts General Hospital, Boston 02114
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38
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Matsumoto T, Ito K, Moritani T. The relationship between anaerobic threshold and electromyographic fatigue threshold in college women. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1991; 63:1-5. [PMID: 1915324 DOI: 10.1007/bf00760792] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The purpose of this study was to investigate the relationship between anaerobic threshold (Th(an)) and muscle fatigue threshold (EMGFT) as estimated from electromyographic (EMG) data taken from the quadriceps muscles (vastus lateralis) during exercise on a cycle ergometer. The subjects in this study were 20 female college students, including highly trained endurance athletes and untrained sedentary individuals, whose fitness levels derived from their maximal oxygen consumption ranged from 24.9 to 62.2 ml.kg-1.min-1. The rate of increase in integrated EMG (iEMG) activity as a function of time (iEMG slope) was calculated at each of four constant power outputs (350, 300, 250, 200 W), sufficiently high to bring about muscle fatigue. The iEMG slopes so obtained were plotted against the exercise intensities imposed, resulting in linear plots which were extrapolated to zero slope to give an intercept on the power axis which was in turn interpreted as the highest exercise intensity sustainable without electromyographic evidence of neuromuscular fatigue (EMGFT). The Th(an) was estimated from gas exchange parameters during an incremental exercise test on the same cycle ergometer. The mean results indicated that oxygen uptake (VO2) at Than was 1.39 l.min-1, SD 0.44 and VO2 at EMGFT was 1.33 l.min-1, SD 0.57. There was no significant difference between these mean values (P greater than 0.05) and there was a highly significant correlation between VO2 at Than and VO2 at EMGFT (r = 0.823, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T Matsumoto
- Laboratory of Applied Physiology, College of Liberal Arts and Sciences, Kyoto University, Japan
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Rodrigues EA, Maddahi J, Brown H, Pantaleo N, Freeman M, Koerner S, Waxman A, Berman DS. Responses of left and right ventricular ejection fractions to aerobic and anaerobic phases of upright and supine exercise in normal subjects. Am Heart J 1989; 118:319-24. [PMID: 2750653 DOI: 10.1016/0002-8703(89)90192-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The effects of aerobic and anaerobic exercise on ventricular performance were studied in 13 normal subjects who underwent simultaneous pulmonary gas exchange evaluation and exercise radionuclide ventriculography in the supine and upright postures. Right and left ventricular ejection fraction was measured serially at 2-minute intervals during exercise. The anaerobic threshold occurred at 74% and 80% of maximum heart rate, respectively, during upright and supine exercise. Left and right ventricular ejection fractions rose from rest to the anaerobic threshold (p less than 0.01, p less than 0.01, respectively) and there was a further increase between the anaerobic threshold and maximum exercise (p less than 0.01, p less than 0.01, respectively). The rate of rise of ejection fraction beyond the anaerobic threshold was slightly blunted compared with the rise prior to attaining the anaerobic threshold. There was no significant difference in ventricular performance between supine and upright exercise. The data demonstrate that ventricular performance increases steadily during exercise and is not limited by the conversion of aerobic to anaerobic metabolism.
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Affiliation(s)
- E A Rodrigues
- Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048
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Abstract
The anaerobic threshold consists of a lactate threshold and a ventilatory threshold. In some conditions there may actually be 2 ventilatory thresholds. Much of the work detailing the lactate threshold is strongly based on blood lactate concentration. Since, in most cases, blood lactate concentration does not reflect production in active skeletal muscle, inferences about the metabolic state of contracting muscle will not be valid based only on blood lactate concentration measurements. Numerous possible mechanisms may be postulated as generating a lactate threshold. However, it is very difficult to design a study to influence only one variable. One may ask, does reducing F1O2 cause an earlier occurrence of a lactate threshold during progressive exercise by reducing oxygen availability at the mitochondria? By stimulating catecholamine production? By shifting more blood flow away from tissues which remove lactate from the blood? Or by some other mechanism? Processes considered essential to the generation of a lactate threshold include: (a) substrate utilisation in which the ability of contracting muscle cells to oxidise fats reaches maximal power at lactate threshold; and (b) catecholaminergic stimulation, for without the presence of catecholamines it appears a lactate threshold cannot be generated. Other mechanisms discussed which probably enhance the lactate threshold, but are not considered essential initiators are: (a) oxygen limitation; (b) motor unit recruitment order; (c) lactate removal; (d) muscle temperature receptors; (e) metabolic stimulation; and (f) a threshold of lactate efflux. Some mechanisms reviewed which may induce or contribute to a ventilatory threshold are the effects of: (a) the carotid bodies; (b) respiratory mechanics; (c) temperature; and (d) skeletal muscle receptors. It is not yet possible to determine the hierarchy of effects essential for generating a ventilatory threshold. This may indicate that the central nervous system integrates a broad range of input signals in order to generate a non-linear increase in ventilation. Evidence indicates that the occurrence of the lactate threshold and the ventilatory threshold may be dissociated; sometimes the occurrence of the lactate threshold significantly precedes the ventilatory threshold and at other times the ventilatory threshold significantly precedes the lactate threshold. It is concluded that the 2 thresholds are not subserved by the same mechanism.
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Affiliation(s)
- M L Walsh
- Kinesiology Department, Simon Fraser University, Burnaby
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Helal JN, Guezennec CY, Goubel F. The aerobic-anaerobic transition: re-examination of the threshold concept including an electromyographic approach. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1987; 56:643-9. [PMID: 3119335 DOI: 10.1007/bf00424804] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The surface electromyogram (EMG) from the vastus lateralis muscle and the metabolic and respiratory parameters were studied simultaneously during an incremental exercise in order to identify EMG signal modifications during the aerobic-anaerobic transition. Subjects performed an incremental test on the bicycle ergometer from an initial work load of 175 W to exhaustion by steps of 25 W. Ventilatory flow (VE), oxygen uptake (VO2) and carbon dioxide flow (VCO2) were recorded continuously. For lactate concentration determination, venous blood samples were collected during the final 30 s of each step. EMG signals were stored on magnetic tape. They were then converted into successive spectra to allow the study of EMG total power (PEMG) and mean power frequency (MPF) evolutions. A non linear increase in blood lactate reflected by a breaking point at 250 W was observed. A change in VE/VO2 ratio occurred at 275 W. PEMG value showed a non linear increase reflected by a breaking point at 275 W. MPF value increased from the first to the seventh step with a tendency to decrease at the last step. A great interindividual variance of EMG data was observed indicating the difficulty of correlating mean values of EMG parameters with mean values of blood lactate in order to explain sudden lactate increase by fast twitch fibre recruitment. However, comparison of individual EMG data suggests a progressive recruitment of fast twitch fibres as work load increases.
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Affiliation(s)
- J N Helal
- Département de Génie Biologique, UA CNRS 858, Université de Technologie, Paris, France
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Moritani T, Berry MJ, Bacharach DW, Nakamura E. Gas exchange parameters, muscle blood flow and electromechanical properties of the plantar flexors. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1987; 56:30-7. [PMID: 3830139 DOI: 10.1007/bf00696372] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Sixteen men were tested to determine VO2max (ml X kg-1 X min-1), anaerobic threshold VO2 (ATVO2) and oxygen kinetics (time constant, T.C.) during running on a treadmill. For measuring maximal calf blood flow (maxBF, ml X 100 ml-1 X min-1), venous occlusion plethysmography was employed immediately following a combination of arterial occlusion and toe raising exercise to exhaustion. In addition, supramaximal electrical stimulations were given to determine maximal calf twitch force (Fmax, N), maximal rate of twitch force development (dF/dt) and relaxation (R X dF/dt, N X ms-1) and electro-mechanical delay time (EMD, ms). Results demonstrated that VO2max, ATVO2 and maxBF were all inversely related to T.C. (p less than 0.05). MaxBF and ATVO2 showed the highest correlation (r = 0.89, p less than 0.01). Stepwise multiple linear regression analyses revealed that variance in VO2max (60%) and ATVO2 (84%) could be accounted for by the combined effects of the following peripheral factors: VO2max = 51,25-3.24(dF/dt) + 0.14(maxBF), and ATVO2 = 11.68 + 0.42(maxBF) - 0.2(Fmax). These findings, together with the results of cluster analysis, suggest a tight link between ATVO2 and peripheral blood flow capacity. On the other hand, a moderate correlation (r = 0.64, p less than 0.01) between VO2max and maxBF might be due in part to individual differences in oxygen extraction-utilization capacity during heavy exercise above anaerobic threshold.
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Eldridge JE, Giansiracusa RF, Jones RH, Hossack KF. Computerized detection of the lactate threshold in coronary artery disease. Am J Cardiol 1986; 57:1088-91. [PMID: 3085465 DOI: 10.1016/0002-9149(86)90679-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A computer program for identifying oxygen consumption at the lactate threshold was evaluated by expired gas analysis during treadmill exercise testing in 15 patients with prior myocardial infarction. There was a strong correlation (r = 0.85, p less than 0.001) between computer-identified oxygen consumption (14.1 +/- 4.6 ml/kg/min) and the oxygen consumption (14.6 +/- 4.8 ml/kg/min) corresponding to an increase of arterial lactate level to above the normal value at rest (1.3 mM). The computer program was superior to previously described visual methods for identifying the ventilatory threshold.
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Viitasalo JT, Luhtanen P, Rahkila P, Rusko H. Electromyographic activity related to aerobic and anaerobic threshold in ergometer bicycling. ACTA PHYSIOLOGICA SCANDINAVICA 1985; 124:287-93. [PMID: 4013794 DOI: 10.1111/j.1748-1716.1985.tb07663.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Electromyographic activity (EMG) of the knee extensor musculature (m. vastus lateralis, m. vastus medialis, m. rectus femoris), triceps surae (m. gastrocnemius, m. soleus) and m. tibialis anterior was studied in ergometer bicycling at five different power outputs around aerobic (AerT) and anaerobic (AnT) thresholds. EMGs were sampled with surface electrodes for ten revolutions at the beginning, in the middle and at the end of each work load and integrated (IEMG) separately for each of the muscles and for the descending (work) and ascending (rest) phase of the revolution. The mean power frequency (MPF) of the power spectral density function for the descending periods was also calculated. The first work load was 50% of the maximal load, the second at the level of AerT, the third at the AnT, the fourth between the AnT and the maximal load and the fifth load was maximal. The AerT and AnT were determined using blood lactate, ventilation volume and oxygen consumption. Five males from 21 to 38 years of age volunteered as subjects. When the IEMGs of the knee extensor and triceps surae musculature were related to the work load a nonlinearity was found at the aerobic threshold while no further change in the linearity was found at the AnT. The non-linear increase of the IEMG at the AerT was found both for the working (descending) and resting (ascending) phases of the cycling. In the MPF no difference below and above the AnT was found. It was thought that the integral of EMG activity could serve as an indicator of the aerobic threshold of an individual muscle.
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