Improved running performance in hot humid conditions following whole body precooling

Abstract

On two separate occasions, eight subjects controlled speed to run the greatest distance possible in 30 min in a hot, humid environment (ambient temperature 32 degrees C, relative humidity 60%). For the experimental test (precooling), exercise was preceeded by cold-water immersion. Precooling increased the distance run by 304 +/- 166 m (P < 0.05). Precooling decreased the pre-exercise rectal and mean skin temperature by 0.7 degrees C and 5.9 degrees C, respectively (P < 0.05). Rectal and mean skin temperature were decreased up to 20 and 25 min during exercise, respectively (P < 0.05). Mean body temperature decreased from 36.5 +/- 0.1 degrees C to 33.8 +/- 0.2 degrees C following precooling (P < 0.05) and remained lower throughout exercise (P < 0.01) and at the end of exercise (by 0.8 degrees C; P < 0.05). The rate of heat storage at the end of exercise increased from 113 +/- 45 to 249 +/- 55 W.m-2 (P < 0.005). Precooling lowered the heart rate at rest (13%), 5 (9%), and 10 min (10%) exercise (P < 0.05) and increased the end of exercise blood lactate from 4.9 +/- 0.5 to 7.4 +/- 0.9 mmol.L-1 (P < 0.01). The VO2 at 10 and 20 min of exercise and total body sweating are not different between tests. In conclusion, water immersion precooling increased exercise endurance in hot, humid conditions with an enhanced rate of heat storage and decreased thermoregulatory strain.

Influence of the ten sessionsof the whole body cryostimulationon aerobic and anaerobic capacity

“…In female subjects, the number of erythrocytes decreased from 4.58 to 4.45 million/mm 3 after the treatments. Significant (P < 0.05) decreases body cooling before endurance exercise allows for a greater thermal stress during prolonged work of submaximal intensity [30,34]. The research presented here indicates a significant increase in anaerobic power as a consequence of ten sessions of the whole body cryostimulation, particularly in male subjects.…”

“…Most researchers have addressed the effects of local cold treatments, where particular parts of the body were cooled or whole body was immersed in cold water on the level of chosen motor abilities or physical work capacity, under different temperatures [30][31][32][33][34][35][36]. Others evaluated the influence of cooling on the rate of recovery following injuries [19,22,27].…”

Challenges to Temperature Regulation When Working in Hot Environments

“…In addition, pre-cooling may delay the onset of fatigue by increasing time to exhaustion in temperate conditions, when working at either fixed 66) or self-selected rates 32) . This benefit has subsequently been extended to include hot environments 11,13,27) . Recently, we have undertaken a series of pre-cooling experiments, using the whole-body immersion method to pre-cool subjects prior to exercise in the heat 12,13,47) .…”

The effects of heat stress on neuromuscular activity during endurance exercise

“…For example previous studies have shown that lowering body temperature by either cooling with ice packs or lowering ambient temperature will improve exercise performance (3,10,12). There have however been no studies that have examined neuromuscular activity in these circumstances (20).…”