Repeated muscle glycogen supercompensation with four days' recovery between exhaustive exercise. Issue 8 (August 2019)

• Record Type: Journal Article
• Authors: Doering, Thomas M.; Cox, Gregory R.; Areta, José L.; Coffey, Vernon G.
• Is Part Of: Journal of science and medicine in sport. Volume 22:Issue 8(2019)
• Page Start: 907
• Page End: 911
• Publication Date: 2019-08
• Subjects: Aerobic exercise -- Athletic performance -- Carbohydrate loading -- Cycling; Sports sciences -- Periodicals; Sports medicine -- Periodicals; Exercise -- Physiological aspects -- Periodicals; Sports -- physiology -- Periodicals; Sports Medicine -- Periodicals; Sportgeneeskunde; 617.102705
• DOI: 10.1016/j.jsams.2019.03.009
• Languages: English
• ISSNs: 1440-2440

Abstract

Abstract: Objectives: To determine if a 4 d period of high carbohydrate intake can supercompensate muscle glycogen and exercise work capacity on back-to-back occasions. Design: Seven trained cyclists (6 male, VO2 peak: 57 ± 4 mL kg −1 min −1 ) completed a 9-d experimental period, consisting of three intermittent exhaustive cycling trials on days 1 (trial 1), 5 (trial 2) and 9 (trial 3). Following trial 1 cyclists were fed a high carbohydrate diet (˜10 g kg −1 day −1 ) for eight days to assess their capacity to repeatedly supercompensate muscle glycogen with 4 d recovery. Methods: A resting muscle biopsy was obtained prior to each trial consisting of 2 min work intervals (90–60% peak power output) interspersed with 2 min recovery (40% peak power output) repeated until exhaustion. Each 72-h period between trial days included two days of low volume cycling and a rest day. Resting muscle glycogen and total work completed was determined for each trial day. Results: Baseline muscle glycogen on day 1 (583.6 ± 111.0 mmol kg −1 dry mass) was supercompensated on day 5 (835.1 ± 112.8 mmol kg −1 dry mass; p = 0.04, d = 2.25) and again on day 9 (848.3 ± 111.4 mmol kg −1 dry mass; p = 0.01, d = 2.38). Total cycling work capacity increased from trial 1 to trial 2 (+8.7 ± 5.4 kJ kg −1 ; p = 0.01; d = 1.41); a large effect was observed in trial 3 compared to trial 1 (+6.4 ± 6.8 kJ kg −1 ; p = 0.10; d = 1.10). Conclusions: A 4 d high carbohydrate feeding strategy is sufficient to repeatedly supercompensate muscle glycogen content following exhaustive exercise and results in enhanced work capacity.