ABSTRACT
Aerobic (Aer) and anaerobic (Anae) energy release were measured while swimming at altitude (A) (2000m, Pb=592mmHg) and in acute simulated sea level (ASSL) exposure (Pb=760mmHg) in moderate altitude acclimatized males. Subjects (n=10, 16.7+1.2 yr) resided ( 10.5+6.3yr) and swim trained (5.9+2.9yr) at altitude (2000m). An environmental chamber housing a swimming treadmill was used for all testing. Five submax (~20 to 70 %VO2 peak) and a max swim for determination of VO2 peak was performed. Anaerobic energy release for a max swim (100%VO2 peak) was derived by calculating the accumulated 02 deficit (AOD). A and ASSL VO2 peak was 3.70+0.11 (SE) and 4.17+0.13 l.min–1, (p<0.05). RPEmax, peak BLa (mM) and peak AOD at A and ASSL did not differ, (AOD, 4.32+0.33 vs 4.15+0.58 102 Eq). HRmax was lower during A (179.3+2.3bpm) vs ASSL (187.0+2.8bpm) (p<0.05). Saturation of hemoglobin with oxygen (SaO2) was 5% greater at ASSL vs A immediately following the VO2 peak swim (p<0.05). Percent relative VO2 peak, BLa and RPE submax were lower during ASSL (p<0.05). In summary: 1) peak aerobic energy delivery was increased in ASSL due to increased oxygen availability to the working musculature (enhanced SaO2 and HRmaX); 2) peak anaerobic energy release was independent of environmental condition; and 3) relative metabolic demand for submax swimming was lower in ASSL, suggesting faster swimming at a given percent of VO2 peak during acute sea level exposure in altitude acclimatized, trained swimmers.
