Physical performance and peak aerobic power at different body temperatures

Area of Science:

• Exercise Physiology
• Environmental Physiology
• Human Performance

Background:

• Core body temperature regulation is crucial for maintaining physiological function during exercise.
• Understanding the specific effects of esophageal temperature (Tes) and muscle temperature (Tm) on performance is vital for athletes and researchers.
• Previous studies have explored temperature effects, but a comprehensive analysis of combined arm and leg exercise under varying core and skin temperatures is needed.

Purpose of the Study:

• To investigate the impact of varying core (esophageal, Tes) and muscle (Tm) temperatures on physical performance, aerobic power (VO2), heart rate (HR), and blood lactate (LA) during exhaustive combined arm and leg exercise.
• To determine the influence of different mean skin temperatures (Tsk) on these physiological parameters at subnormal body temperatures.
• To establish critical temperature thresholds affecting exercise capacity.

Main Methods:

• Eight male subjects performed exhaustive combined arm and leg exercise under controlled core and muscle temperatures.
• Measurements included time to exhaustion (WT), peak oxygen consumption (VO2), heart rate (HR), and blood lactate (LA).
• Three subjects also underwent testing at different mean skin temperatures (Tsk).

Main Results:

• Peak VO2 and HR showed strong positive correlations with both Tes (r=0.88-0.97) and Tm (r=0.91-0.95).
• Subjects could not achieve control VO2max at Tes < 37.5°C or Tm < 38.0°C.
• Lowering Tes and Tm below these thresholds resulted in a linear decrease in WT (20%/°C), peak VO2 (5-6%/°C), and HR (8 beats/min/°C).
• Blood lactate was significantly higher at Tes 37.5°C compared to lower or higher temperatures.
• Mean skin temperature did not influence peak VO2 or HR at subnormal body temperatures.

Conclusions:

• Core and muscle temperatures are critical determinants of maximal aerobic capacity and endurance performance during combined upper and lower body exercise.
• Significant performance decrements occur when Tes falls below 37.5°C and Tm below 38.0°C.
• These findings highlight the importance of maintaining optimal core and muscle temperatures to achieve peak physical performance.