Oral hydroxycitric acid (HCA) supplementation enhances glycogen synthesis in exercised human skeletal 1 muscle

INTERVENTION: Since we aimed to determine the HCA effect on recovery, HCA and placebo meals were provided to the subjects immediately after exercise. HCA trial provided a meal containing 70% carbohydrate content with 500 mg HCA in half litre of drinking water for a 3‐hour recovery, whereas the placebo trial (placebo, eight comparisons) provided a diet containing 70% carbohydrate content plus same volume of drinking water. In particular, carbohydrate meal contained 2 g carbohydrate per kilogram of body weight. The decision for HCA dosage was based on previous human report which demonstrated positive ergogenic effect on endurance performance. Subjects performed a 60‐mins cycling at 75% VO2max. Muscle biopsy samples, blood samples and gaseous samples were obtained immediately after exercise and during 3 hours after exercise. CONDITION: Glycogen synthesis in human skeletal muscle ; Nutritional, Metabolic, Endocrine ; Glycogen synthesis PRIMARY OUTCOME: Glycogen assay. Approximately 25 mg of skeletal muscle from the deep portion of the vastus lateralis was dissolved in 1 N KOH at 75°C for 30 minutes. Dissolved homogenate was neutralised by glacial acetic acid and incubated overnight in acetate buffer (0.3 M sodium acetate, pH to 4.8) containing amyloglucosidase (Boehringer Mannheim, Indianapolis, IN). The reaction mixture was neutralised with 1 N NaOH. Samples were then analysed by measuring glucosyl units by the Trinder reaction (Sigma, St. Louis, MO). SECONDARY OUTCOME: Molecular expressions of GLUT4, FAT/CD36, measured with reverse transcription‐polymerase chain reaction (RT‐PCR) and western blotting INCLUSION CRITERIA: 1. Healthy male volunteers 2. Aged 22.0 +/‐ 0.3 years 3. Height 171.3 +/‐ 0.7 cm 4. Weight 73.7 +/‐ 1.1 kg 5. Body mass index (BMI) 25.2 +/‐ 0.5 kg/m2 6. Ventilatory equivalent for oxygen (VEO2) 108 7. Peak 45.7 +/‐ 1.5 ml/kg/min