A Comparative Analysis Between the Effects of Galactose and Glucose Supplementation on Endurance Performance

in International Journal of Sport Nutrition and Exercise Metabolism
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To determine beneficial effects of short-term galactose (GAL) supplementation over a 50:50 glucose–maltodextrin (GLUC) equivalent on self-paced endurance cycling performance.


On 2 separate occasions, subjects performed a 100-km self-paced time trial (randomized and balanced order). This was interspersed with four 1-km and four 4-km maximal efforts reflecting the physical requirements of racing. Before each trial 38 ± 3 g of GAL or GLUC was ingested in a 6% concentrate fluid form 1 hr preexercise and then during exercise at a rate of 37 ± 3 g/hr. Performance variables were recorded for all 1- and 4-km efforts, all interspersed intervals, and the total 100-km distance. Noninvasive indicators of work intensity (heart rate [HR] and rating of perceived exertion) were also recorded.


Times taken to complete the 100-km performance trial were 8,298 ± 502 and 8,509 ± 578 s (p = .132), with mean power outputs of 271 ± 37 and 256 ± 45 W (p = .200), for GAL and GLUC, respectively. Mean HR did not differ (GAL 157 ± 7 and GLUC 157 ± 7 beats/min, p = .886). A main effect of carbohydrate (CHO) type on time to complete 4-km efforts occurred, with no CHO Type × Effort Order interaction observed. No main effect of CHO type or interaction of CHO Type × Sequential Order occurred for 1-km efforts.


A 6% GAL drink does not enhance performance time during a self-paced cycling performance trial in highly trained endurance cyclists compared with a formula typically used by endurance athletes but may improve the ability to produce intermediate self-paced efforts.

Macdermid is with the School of Sport and Exercise, Massey University Manawatu (Turitea), Manawatu, New Zealand. Stannard is with the Inst. of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. Rankin and Shillington are with Applied Science, Universal College of Learning, Manawatu, New Zealand.