Cold affects physical performance through the neuromuscular system

Exercise capacity is reduced at low ambient temperature, even though most studies feature only transient or mild exposure to cold environments before exercise and increases of metabolic heat production. With actual hypothermia combined with cold environments, endurance capacity is clearly impaired, with reduced tolerance times and maximal aerobic capacity, along with higher oxygen uptake at submaximal workloads. Altered neuromuscular function is likely a primary contributor to this impairment, with a reduction in dynamic strength, power output, jumping and sprinting performance, and maximal isometric strength within a functional muscle temperature range of 39°C down to 30°C. Cold-induced neuromuscular dysfunction stems from changes in biophysical, electrophysiological, and contractile properties of nerves and muscles, ultimately regulating force capacity of individual muscle fibers, recruitment pattern of motor units, balance, nerve conduction velocity, muscle and tendon stiffness, and central neural activation of muscles. Some variability has been observed across individuals, which may stem from sex, age, degree of acclimation, muscle fiber typing, and possibly a lack of methodological standardization in tissue temperature assessment across studies. Suggestions for standardization of muscle temperature measurement and reporting are provided. Alongside neurological factors, muscle vasoconstriction and impaired oxygen convection further limit muscle functions, but hyperoxia and possibly increased oxygen diffusion may restore performance. While core cooling and excessive skin cooling should be avoided, some distal cooling or activating TRPM8 may provide ergogenic aid to physical performance via central mechanisms such as modulation of arousal or sympathetic activation, and peripheral, including motor-unit activation or relaxation rate.