J Soo1, S Racinais2, T J Fairchild3, M Ihsan2,4, M Buchheit5,6, O Girard7,8. 1. Murdoch Applied Sport Science Laboratory, Murdoch University, Perth, Australia. 2. Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar. 3. The Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Perth, Australia. 4. Human Potential and Translational Research Program, Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Republic of Singapore. 5. Research Department, Laboratory Sport, Expertise and Performance, French Institute of Sport (INSEP), 7370, Paris, EA, France. 6. Institute for Health and Sport (iHeS), Victoria University, Melbourne, Australia. 7. Research and Scientific Support, Aspetar Orthopaedic and Sports Medicine Hospital, Doha, Qatar. oliv.girard@gmail.com. 8. School of Human Sciences (Exercise and Sport Science), The University of Western Australia, Crawley, WA, Australia. oliv.girard@gmail.com.
Abstract
PURPOSE: This study examined the effect of graded hypoxia during exhaustive intermittent cycling on subsequent exercise performance and neuromuscular fatigue characteristics in normoxia. METHODS: Fifteen well-trained cyclists performed an exhaustive intermittent cycling exercise (EICE 1; 15 s at 30% of anaerobic power reserve interspersed with 45 s of passive recovery) at sea level (SL; FiO2 ~ 0.21), moderate (MH; FiO2 ~ 0.16) and severe hypoxia (SH; FiO2 ~ 0.12). This was followed, after 30 min of passive recovery in normoxia, by an identical exercise bout in normoxia (EICE 2). Neuromuscular function of the knee extensors was assessed at baseline, after EICE 1 (post-EICE 1), and EICE 2 (post-EICE 2). RESULTS: The number of efforts completed decreased with increasing hypoxic severity during EICE 1 (SL: 39 ± 30, MH: 22 ± 13, SH: 13 ± 6; p ≤ 0.02), whereas there was no difference between conditions during EICE 2 (SL: 16 ± 9, MH: 20 ± 14, SH: 24 ± 17; p ≥ 0.09). Maximal torque (p = 0.007), peripheral (p = 0.02) and cortical voluntary activation (p < 0.001), and twitch torque (p < 0.001) decreased from baseline to post-EICE 1. Overall, there were no significant difference in any neuromuscular parameters from post-EICE 1 to post-EICE 2 (p ≥ 0.08). CONCLUSION: Increasing hypoxia severity during exhaustive intermittent cycling hampered exercise capacity, but did not influence performance and associated neuromuscular responses during a subsequent bout of exercise in normoxia performed after 30 min of rest.
PURPOSE: This study examined the effect of graded hypoxia during exhaustive intermittent cycling on subsequent exercise performance and neuromuscular fatigue characteristics in normoxia. METHODS: Fifteen well-trained cyclists performed an exhaustive intermittent cycling exercise (EICE 1; 15 s at 30% of anaerobic power reserve interspersed with 45 s of passive recovery) at sea level (SL; FiO2 ~ 0.21), moderate (MH; FiO2 ~ 0.16) and severe hypoxia (SH; FiO2 ~ 0.12). This was followed, after 30 min of passive recovery in normoxia, by an identical exercise bout in normoxia (EICE 2). Neuromuscular function of the knee extensors was assessed at baseline, after EICE 1 (post-EICE 1), and EICE 2 (post-EICE 2). RESULTS: The number of efforts completed decreased with increasing hypoxic severity during EICE 1 (SL: 39 ± 30, MH: 22 ± 13, SH: 13 ± 6; p ≤ 0.02), whereas there was no difference between conditions during EICE 2 (SL: 16 ± 9, MH: 20 ± 14, SH: 24 ± 17; p ≥ 0.09). Maximal torque (p = 0.007), peripheral (p = 0.02) and cortical voluntary activation (p < 0.001), and twitch torque (p < 0.001) decreased from baseline to post-EICE 1. Overall, there were no significant difference in any neuromuscular parameters from post-EICE 1 to post-EICE 2 (p ≥ 0.08). CONCLUSION: Increasing hypoxia severity during exhaustive intermittent cycling hampered exercise capacity, but did not influence performance and associated neuromuscular responses during a subsequent bout of exercise in normoxia performed after 30 min of rest.
Authors: Robert F Chapman; Joel M Stager; David A Tanner; James Stray-Gundersen; Benjamind D Levine Journal: Med Sci Sports Exerc Date: 2011-09 Impact factor: 5.411
Authors: Markus Amann; Massimo Venturelli; Stephen J Ives; John McDaniel; Gwenael Layec; Matthew J Rossman; Russell S Richardson Journal: J Appl Physiol (1985) Date: 2013-05-30