Peltonen J E, Rusko H K, Rantamäki J, Sweins K, Niittymäki S, Viitasalo J T
Unit for Sports and Exercise Medicine, Institute of Biomedicine, University of Helsinki, Finland.
Eur J Appl Physiol Occup Physiol. 1997;76(6):495-503. doi: 10.1007/s004210050281.
Six male rowers rowed maximally for 2500 m in ergometer tests during normoxia (fractional concentration of oxygen in inspired air, F(I)O2 0.209), in hyperoxia (F(I)O2 0.622) and in hypoxia (F(I)O2 0.158) in a randomized single-blind fashion. Oxygen consumption (VO2), force production of strokes as well as integrated electromyographs (iEMG) and mean power frequency (MPF) from seven muscles were measured in 500-m intervals. The iEMG signals from individual muscles were summed to represent overall electrical activity of these muscles (sum-iEMG). Maximal force of a stroke (Fmax) decreased from the 100% pre-exercise maximal value to 67 (SD 12)%, 63 (SD 15)% and 76 (SD 13)% (P < 0.05 to normoxia, ANOVA) and impulse to 78 (SD 4)%, 75 (SD 14)% and 84 (SD 7)% (P < 0.05) in normoxia, hypoxia and hyperoxia, respectively. A strong correlation between Fmax and VO2 was found in normoxia but not in hypoxia and hyperoxia. The mean sum-iEMG tended to be lower (P < 0.05) in hypoxia than in normoxia but hyperoxia had no significant effect on it. In general, F(I)O2 did not affect MPF of individual muscles. In conclusion, it was found that force output during ergometer rowing was impaired during hypoxia and improved during hyperoxia when compared with normoxia. Moreover, the changes in force output were only partly accompanied by changes in muscle electrical activity as sum-iEMG was affected by hypoxic but not by hyperoxic gas. The lack of a significant correlation between Fmax and VO2 during hypoxia and hyperoxia may suggest a partial uncoupling of these processes and the existence of other limiting factors in addition to VO2.
六名男性赛艇运动员在常氧（吸入气中氧分数，F(I)O2 0.209）、高氧（F(I)O2 0.622）和低氧（F(I)O2 0.158）条件下，以随机单盲方式在测力计测试中进行了2500米的最大强度划船。每隔500米测量一次耗氧量（VO2）、划桨力产生以及七块肌肉的积分肌电图（iEMG）和平均功率频率（MPF）。将各肌肉的iEMG信号相加，以代表这些肌肉的整体电活动（总和iEMG）。一次划桨的最大力量（Fmax）从运动前最大值的100%分别降至常氧、低氧和高氧条件下的67（标准差12）%、63（标准差15）%和76（标准差13）%（与常氧相比，P < 0.05，方差分析），冲量分别降至78（标准差4）%、75（标准差14）%和84（标准差7）%（P < 0.05）。在常氧条件下发现Fmax与VO2之间有很强的相关性，但在低氧和高氧条件下没有。低氧条件下的平均总和iEMG往往低于常氧（P < 0.05），但高氧对其没有显著影响。一般来说，F(I)O2不影响各肌肉的MPF。总之，研究发现，与常氧相比，测力计划船时的力量输出在低氧条件下受损，在高氧条件下改善。此外，力量输出的变化仅部分伴随着肌肉电活动的变化，因为总和iEMG受低氧气体影响，而不受高氧气体影响。低氧和高氧条件下Fmax与VO2之间缺乏显著相关性，可能表明这些过程部分解偶联，并且除VO2外还存在其他限制因素。
