Quercetin's effect on cycling efficiency and substrate utilization.

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry

Background:

• Quercetin, a flavonoid, is suggested to enhance human performance.
• Its effects on fuel utilization and gross efficiency (GE) during prolonged exercise require further investigation.

Purpose of the Study:

• To investigate the impact of 3 weeks of quercetin supplementation on fuel utilization, GE, and perceived effort in cyclists.
• To assess quercetin's effects during a demanding 3-hour cycling protocol over three consecutive days.

Main Methods:

• Forty trained cyclists were randomized into quercetin (1000 mg/day) and placebo groups for 3 weeks.
• Participants completed three 3-hour cycling sessions at 57% maximum power, with metabolic measurements taken regularly.
• Muscle biopsies were analyzed for glycogen content pre- and post-exercise on days 1 and 3.

Main Results:

• Gross efficiency (GE), cadence, respiratory exchange ratio, blood glucose, and muscle glycogen significantly decreased over the 3-hour rides.
• Heart rate and oxygen consumption significantly increased over time.
• No significant differences were observed between the quercetin and placebo groups for any measured outcome.

Conclusions:

• Gross efficiency (GE) declines during prolonged, exhausting exercise.
• Quercetin supplementation did not alter fuel utilization, GE, or perceived effort in well-trained cyclists during this protocol.