Does the diurnal increase in central temperature interact with pre-cooling or passive warm-up of the leg?
Seven male subjects volunteered to participate in an investigation of whether the diurnal increase in core temperature influences the effects of pre-cooling or passive warm-up on muscular power. Morning (07:00-09:00h) and afternoon (17:00-19:00h) evaluation of maximal power output during a cycling sprint was performed on different days in a control condition (room at 21.8 degrees C, 69% rh), after 30min of pre-cooling in a cold bath (16 degrees C), or after 30min of passive warm-up in a hot bath (38 degrees C). Despite an equivalent increase from morning to afternoon in core temperature in all conditions (+0.4 degrees C, P<0.05), power output displayed a diurnal increase in control condition only. A local cooling or heating of the leg in a neutral environment blunted the diurnal variation in muscular power. Because pre-cooling decreases muscle power, force and velocity irrespective of time-of-day, athletes should strictly avoid any cooling before a sprint exercise. In summary, diurnal variation in muscle power output seems to be more influenced by muscle rather than core temperature.
Racinais
Sébastien
S
Laboratoire ACTES, University of the French West Indies, France. contact@sebastienracinais.com
Blonc
Stephen
S
Oksa
Juha
J
Hue
Olivier
O
D000328:Adult; D001642:Bicycling / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D003080:Cold Temperature; D005080:Exercise Test; D006358:Hot Temperature; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D010806:Physical Education and Training; D012881:Skin Temperature / Q000502:physiology*; D013334:Students; D013997:Time Factors; D055815:Young Adult