Author(s): CHENG, I., CHEN, G.J., LIN, Z.A., Institution: NATIONAL TAICHUNG UNIVERSITY OF EDUCATION, Country: TAIWAN, Abstract-ID: 185

INTRODUCTION:
Blood flow restriction (BFR) is an alternative training mode that improves muscle strength and endurance performance by restricting blood flow to the exercising muscle through pressure on the proximal upper or lower limb segments. Previous studies demonstrated that flavonoid quercetin was able to enhance the antioxidant property in mice and humans. The authors are interested in whether the quercetin supplement will blunt the muscle adaptation induced by BFR training. Therefore, this study demonstrated the effect of three weeks of post-exercise quercetin supplementation under blood flow restriction cycling training on post-exercise muscle glycogen replenishment in exercised humans.
METHODS:
12 active male subjects were recruited to participate in a single-blind crossover study and were randomly assigned to either the BFR + quercetin group or the BFR + placebo group (1000 mg quercetin or placebo supplement immediately after BFR cycling each day for 3 days per week, for a total of 3 weeks). BFR cycling train mode contains a 60-minute BFR cycling under 75% VO2max, cuff with 13 cm at ~180mmHg; 2 min released per 10 min cycling. A 4-week wash-out period was performed during this crossover study. The next morning, after 3 weeks of treatment, subjects performed a 40-kilometer simulation track cycling competition. Immediately after the exercise challenge, all participants consumed a high glycemic index carbohydrate meal calculated by their own body weight. Biopsied muscle, blood, and gas samples were obtained during a 3-hour recovery period. The transcription factor that regulates PGC-1α gene expression was measured. Periodic acid–Schiff (PAS) staining for muscle glycogen and responses in blood glucose, plasma non-esterified fatty acids, superoxide dismutase (SOD), malondialdehyde (MDA), IL-10, TNF-α, and expired-gas analysis for carbohydrate and fat oxidation rates were assessed in this human study.
RESULTS:
The increased glycogen level was observed during the exercise recovery period in both the BFR+ quercetin and BFR+ placebo trials. However, there were no significant differences in post-exercise glycogen replenishment between the two trials after performing the 40 km cycling time trial. A lower blood SOD response to the 40 km cycling challenge was found in the BFR+ quercetin trial compared to BFR+ placebo, but no significant differences were found in MDA, IL-10, or TNF-α between the two trials. Gene expression of PGC-1α was higher at 3 h than at 0 h after the 40 km cycling challenge in both trials. However, the increase of PGC-1α during the recovery period did not differ between the two trials, suggesting that a single 40 km cycling session obscured the impact of 3 weeks of BFR with quercetin on muscle adaptation.
CONCLUSION:
We conclude that three weeks of BFR cycling training combined with quercetin supplement did not enhance muscle glycogen replenishment in exercised humans.