Local heat application enhances glycogenesis

The purpose of this study was to determine the impact of increased local muscle temperature independent of core temperature on glycogenesis during recovery from exercise when adequate carbohydrate provisions were supplied. Nine recreationally active males (age, 23 ± 4 years; height, 178 ± 6 cm; weight 79 ± 9 kg) cycled for 92 min and recovered for 4 h. During recovery the subject's legs were randomly assigned as the heated limb (heat pack application) and control limb (exposed to room air). Participants received 2 carbohydrate feedings (1.8 g·kg ^-1 of body weight) at 0 and 2 h of recovery. Core temperature, intramuscular temperature, and leg circumference were monitored throughout recovery. Skeletal muscle biopsies samples of the vastus lateralis were obtained at the beginning and end of the 4-h recovery period on both legs and analyzed for glycogen and lactate. Core temperature did not change from throughout recovery. Muscle temperature in the heated limb was higher by 15 min and remained elevated throughout recovery compared with the control limb (p < 0.05). Leg circumference was not different between limbs. Lactate increased from postexercise to 4 h postexercise regardless of trial (p < 0.05). Muscle glycogen concentration increased with recovery and carbohydrate feeding in both limbs (p < 0.05) but was 22% higher in the heated limb compared with the control limb (p < 0.05). This study demonstrates increased glycogenesis when local muscle temperature is increased independent of core temperature.