Cold and muscle performance.

Area of Science:

• Exercise Physiology
• Muscle Physiology
• Biophysics

Background:

• Muscle temperature significantly influences metabolic and mechanical power.
• The rate of adenosine triphosphate (ATP) hydrolysis and resynthesis is temperature-dependent.
• Reduced muscle temperature is generally expected to decrease power output.

Purpose of the Study:

• To investigate the impact of muscle temperature on muscular power development during exercise.
• To explore the mechanisms behind observed power outputs at varying muscle temperatures.
• To differentiate the effects of temperature on submaximal versus maximal exercise power.

Main Methods:

• The study discusses the theoretical effects of muscle temperature on ATP kinetics.
• It analyzes physiological responses during submaximal and maximal aerobic and anaerobic exercise.
• The concept of varying muscle mass activation at different temperatures is considered.

Main Results:

• Submaximal aerobic exercise power output remains unchanged at cold muscle temperatures, despite slower ATP turnover.
• Maximal aerobic and anaerobic power outputs decrease significantly with decreasing muscle temperature (average Q10 of 1.4).
• Reduced oxygen supply (cardiac output, muscle blood flow) may explain decreased maximal aerobic power in the cold.

Conclusions:

• Increased muscle activation may compensate for reduced ATP hydrolysis rates during submaximal aerobic exercise in the cold.
• Maximal power is limited by a fixed muscle mass, preventing compensation and leading to decreased output at lower temperatures.
• The observed Q10 for maximal anaerobic power suggests factors beyond just ATP hydrolysis rate are involved.