Table 2.
EMG-related variables assessed before (pre-tests) and after (post-tests) cycling to exhaustion in various conditions
| Pre-tests | Post-tests | ANOVA | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Control | Hot | Hypoxia | Hot + hypoxia | Control | Hot | Hypoxia | Hot + hypoxia | ||
| Rest | |||||||||
| M MAX (mV) | 8.75 ± 2.93 | 5.63 ± 1.56 | 7.20 ± 2.90 | 5.38 ± 2.05 | 8.25 ± 2.59 | 5.72 ± 1.47 | 7.07 ± 2.52 | 5.14 ± 2.04 | T |
| H MAX (mV) | 3.31 ± 2.15 | 3.37 ± 1.64 | 3.07 ± 2.06 | 2.23 ± 1.57 | 2.78 ± 2.14 | 1.89 ± 1.13 | 2.57 ± 1.76 | 1.96 ± 1.41 | E |
| H MAX/M MAX (%) | 38.3 ± 18.8 | 59.5 ± 24.2 | 41.2 ± 17.8 | 43.2 ± 31.3 | 32.4 ± 19.8 | 33.0 ± 17.9 | 36.9 ± 19.5 | 40.7 ± 37.6 | E |
| 20 % MVC | |||||||||
| M SUP (mV) | 8.88 ± 3.63 | 6.06 ± 1.74 | 7.53 ± 2.58 | 5.97 ± 2.40 | 8.59 ± 2.80 | 6.19 ± 2.12 | 7.26 ± 2.57 | 5.89 ± 2.04 | T |
| H SUP (mV) | 3.51 ± 2.24 | 2.76 ± 1.40 | 3.15 ± 1.91 | 2.44 ± 1.32 | 3.36 ± 2.31 | 2.72 ± 1.01 | 2.68 ± 1.89 | 2.40 ± 1.63 | |
| H SUP/M SUP (%) | 41.4 ± 18.5 | 43.6 ± 14.2 | 41.3 ± 16.0 | 43.8 ± 24.3 | 39.3 ± 22.8 | 45.0 ± 12.4 | 38.0 ± 23.1 | 39.5 ± 27.0 | |
| 100 % MVC | |||||||||
| M SUP (mV) | 9.73 ± 2.73 | 6.36 ± 1.64 | 7.76 ± 2.57 | 5.93 ± 1.95 | 8.21 ± 2.57 | 7.21 ± 2.41 | 7.97 ± 2.60 | 6.28 ± 2.17 | T |
| H SUP (mV) | 3.99 ± 2.00 | 2.79 ± 1.40 | 3.10 ± 1.43 | 2.92 ± 1.52 | 4.34 ± 1.82 | 3.46 ± 1.03 | 3.30 ± 1.54 | 3.06 ± 1.26 | |
| H SUP/M SUP (%) | 39.4 ± 11.1 | 42.1 ± 18.1 | 42.9 ± 20.6 | 50.7 ± 23.5 | 51.7 ± 13.6 | 49.9 ± 15.6 | 42.7 ± 19.0 | 50.9 ± 21.8 | |
| V SUP (mV) | 2.35 ± 1.79 | 1.61 ± 0.81 | 1.98 ± 0.92 | 1.72 ± 0.70 | 2.11 ± 1.27 | 1.58 ± 0.89 | 1.86 ± 1.02 | 1.53 ± 1.13 | T |
| V SUP/M SUP (%) | 22.2 ± 13.0 | 24.5 ± 11.1 | 25.7 ± 8.2 | 31.1 ± 14.3 | 24.9 ± 11.5 | 23.9 ± 17.8 | 23.8 ± 11.4 | 23.8 ± 14.4 | |
| RMS TA (mV) | 0.047 ± 0.018 | 0.043 ± 0.011 | 0.046 ± 0.013 | 0.043 ± 0.007 | 0.042 ± 0.016 | 0.039 ± 0.013 | 0.041 ± 0.012 | 0.037 ± 0.017 | E |
| RMS SOL (mV) | 0.287 ± 0.138 | 0.195 ± 0.070 | 0.254 ± 0.076 | 0.201 ± 0.080 | 0.261 ± 0.138 | 0.196 ± 0.077 | 0.233 ± 0.081 | 0.186 ± 0.070 | E, T |
| RMS/M SUP (au) | 0.029 ± 0.009 | 0.032 ± 0.010 | 0.035 ± 0.011 | 0.034 ± 0.007 | 0.033 ± 0.015 | 0.028 ± 0.008 | 0.030 ± 0.013 | 0.031 ± 0.013 | |
Values are expressed as mean ± SD. Subjects cycled to exhaustion in four different environmental conditions [temperate/sea level (control), warm/sea level (hot), temperate/moderate altitude (hypoxia) and warm/moderate altitude (hot + hypoxia)] in which temperature [temperate (22 °C/30 % rH) vs. warm (35 °C/40 % rH)] and altitude levels [sea level (FiO2 0.21/simulated altitude ~0 m) vs. moderate altitude (FiO2 0.15/simulated altitude ~2,500 m)] were set
There was neither a main effect of altitude nor any interaction between temperature and altitude on either parameter
M MAX maximal resting M-wave, H MAX maximal resting H-reflex, M SUP maximal superimposed M-wave, H SUP maximal superimposed H-reflex, V SUP maximal superimposed V-wave, RMS TA tibialis anterior root mean square, RMS SOL soleus root mean square
E, P < 0.05; denote a significant main effect of exercise
T, P < 0.05; denote a significant main effect of temperature