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Aerobic Exercise Performance During Load Carriage and Acute Altitude Exposure
Kirsten E Coffman1, Adam J Luippold, Roy M Salgado
1Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts.
Carrying external loads significantly reduces 5-km running performance at sea level. Acute altitude exposure further impairs aerobic exercise capacity, with high altitude increasing completion time when load carriage is involved.
Area of Science:
- Exercise Physiology
- Environmental Physiology
Background:
- Load carriage and altitude exposure are common stressors in occupational and military settings.
- Understanding their combined impact on aerobic performance is crucial for safety and efficacy.
Purpose of the Study:
- To quantify the effect of combined load carriage and acute altitude exposure on 5-km running time-trial (TT) performance.
- To develop a predictive tool (nomogram) for aerobic exercise under varying altitude and load conditions.
Main Methods:
- Nine healthy volunteers completed self-paced, blinded 5-km running TTs on a treadmill.
- Testing occurred at sea level (SL), moderate altitude (MA; 2000m), and high altitude (HA; 3000m) while carrying a 30% body mass external load.
- Familiarization trials without load carriage were used as a baseline.
Main Results:
- Load carriage at SL decreased 5-km TT performance by 36% compared to non-loaded familiarization trials.
- High altitude (3000m) increased 5-km TT completion time by 11% compared to sea level under load carriage.
- Pacing strategy and heart rate did not significantly differ across experimental conditions during the TT.
Conclusions:
- Combined load carriage and acute altitude exposure significantly reduce aerobic exercise performance.
- The developed altitude-load nomogram can predict performance decrements in recreational, occupational, or military scenarios.
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