Effects of Caloric Restriction and Overnight Fasting on Cycling Endurance Performance

Abstract

In addition to aerobic endurance and anaerobic capacity, high power-to-weight ratio (PWR) is important for cycling performance. Cyclists often try to lose weight before race season to improve body composition and optimize PWR. Research has demonstrated body fat-reducing benefits of exercise after fasting overnight. We hypothesized that fasted-state exercise in calorie-restricted trained cyclists would not result in performance decrements and that their PWR would improve significantly. We also hypothesized that substrate use during fasted-state submaximal endurance cycling would shift to greater reliance on fat. Ten trained, competitive cyclists completed a protocol consisting of baseline testing, 3 weeks of caloric restriction (CR), and post-CR testing. The testing sessions measured pre- and post-CR values for resting metabolic rate (RMR), body composition, VO2, PWR and power-to-lean weight ratio (PLWR), and power output, as well as 2-hour submaximal cycling performance, rating of perceived exertion (RPE), and respiratory exchange ratio (RER). There were no significant differences between baseline and post-CR for submaximal trial RER, power output, VO2, RMR, VO2max, or workload at VO2max. However, RPE was significantly lower, and PWR was significantly higher post-CR, whereas RER did not change. The cyclists' PWR and body composition improved significantly, and their overall weight, fat weight, and body fat percentage decreased. Lean mass was maintained. The cyclists' RPE decreased significantly during 2 hours of submaximal cycling post-CR, and there was no decrement in submaximal or maximal cycling performance after 3 weeks of CR combined with overnight fasting. Caloric restriction (up to 40% for 3 weeks) and exercising after fasting overnight can improve a cyclist's PWR without compromising endurance cycling performance.

Chronological Changes During 10-Day Intermittent Fasting with Low Energy Intake on High Intensity Aerobic Performance and Lipid Constituents

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The Effect of Ramadan Fasting on Physical Performances, Mood State and Perceived Exertion in Young Footballers

“…Based on the data in the current literature and as reviewed by Waterhouse [2] , Chaouachi et al [3] , Moughan [4] , and Mujika et al [5] , the effects of Ramadan intermittent fasting on metabolism, body mass and performance have been the subject of several studies performed over the last three decades, but the findings have been relatively inconsistent. In this context, although previous studies have failed to observe substantial performance decrements following shorter periods of fasting (11−24 h) [6,7] , other investigators concluded that fasting before exercise causes a decrement in performance [8,9,10] . Most of these studies used sedentary or recreationally active individuals who were undertaking exercise tasks at which they were relatively inexperienced.…”

Bone Health in Elite Norwegian Endurance Cyclists and Runners: A Cross-Sectional Study

“…There are reports of cyclists trying to enhance their power-to-weight ratio at the expense of energy intake. 29 Furthermore, due to prolonged exercise, cyclists may be at risk of having suboptimal energy intake during training, which has been associated with low bone mass. 1 30 Unfortunately, eating habits and the prevalence of RED-S are unknown in our sample.…”