Aerobic Exercise Performance During Load Carriage and Acute Altitude Exposure

Coffman, KE, Luippold, AJ, Salgado, RM, Heavens, KR, Caruso, EM, Fulco, CS, and Kenefick, RW. Aerobic exercise performance during load carriage and acute altitude exposure. J Strength Cond Res 34(4): 946-951, 2020-This study quantified the impact of combined load carriage and acute altitude exposure on 5-km running time-trial (TT) performance and self-selected pacing strategy. Furthermore, this study developed a velocity prediction tool (nomogram) for similar aerobic exercise tasks performed under various combinations of altitude and load stress. Nine volunteers (6M/3F, age: 24 ± 7 years, height: 171 ± 6 cm, body mass: 72 ± 7 kg, and V[Combining Dot Above]O2peak: 50.5 ± 5.2 ml·min·kg) completed a randomized, repeated-measures design protocol. Volunteers performed 3 familiarization (FAM) trials at sea level (SL; 250 m) with no-load carriage. Experimental testing included 3 self-paced, blinded 5-km running TT on a treadmill while carrying a 30% body mass external load at SL, moderate altitude (MA; 2000 m), and high altitude (HA; 3000 m). At SL, load carriage resulted in a 36% decrement in 5-km exercise performance in comparison with FAM trials (43 ± 7 vs. 32 ± 3 minutes; p < 0.001). Time required to complete the 5-km distance while carrying an external load was increased by 11% when performed at HA vs. SL (48 ± 7 vs. 43 ± 7 minutes; p = 0.001). TT pace was not different among experimental conditions (load carriage at SL, MA, and HA) until after 1 km of the running distance had been completed. Heart rate was not different among experimental conditions throughout the entire TT (170 ± 17 b·min). These data quantify the anticipated reduction in aerobic exercise performance under various combinations of acute altitude exposure and load carriage conditions. The self-paced running TT approach used presently allowed for development of an altitude-load nomogram for use in recreational, occupational, or military settings.