The Effect of a Low‐Glycemic Index Pulse‐Based Diet on Performance and Body Composition in Soccer Players

Low‐glycemic index foods, such as pulses (i.e. lentils, peas, chickpeas, beans), have potential to improve endurance exercise performance because they do not induce a large release of insulin; this allows greater fat oxidation and preservation of muscle glycogen during endurance exercise. In addition to containing low‐glycemic index carbohydrate, pulses are a good source of protein and contain low levels of fat; therefore, they have potential to improve body composition. The objective of our study was to determine the effect of a one‐month pulse‐based diet on endurance performance and body composition in soccer players. Seventeen soccer players (11 females) who were university or city‐league players were randomized to consume their regular diet or were given a pulse‐based diet (i.e. 25% of daily caloric intake, as calculated from 3‐d food logs, was given as pulses, including beans, lentils, chickpeas, or peas) for one month, followed by a wash‐out of 2 weeks, and then the opposite diet for another month. Before and after each one‐month phase body composition was assessed by dual energy X‐ray absorptiometry. During each diet phase soccer performance was assessed as distance the players were able to cover during games by a global positioning system (Catapult Sports Optimeye X5). An hour before each game, players consumed 1.0 g available carbohydrate per kg of body mass, from either a pulse‐based sport nutrition bar (i.e. during the pulse‐diet phase) or a commercially‐available high‐glycemic index sport nutrition bar (i.e. during the regular diet phase). Distance covered during games was analyzed by magnitude‐based inferences, assuming a smallest substantial change in distance of 102 meters, based on game‐to‐game variability in distance covered. Results Male soccer players significantly decreased percent body fat during the pulse‐based diet phase (14.3 SD 2.2 to 13.4 SD 2.2%) compared to the regular‐diet phase (13.7 SD 2.1 to 14.1 SD 2.2%) (p=0.01); whereas, change in percent body fat was not different for females between the two diet phases (i.e. 24.5 SD 3.4 to 23.2 SD 4.3% during the pulse diet phase vs. 24.0 SD 3.8 to 23.1 SD 4.6% during the regular diet phase). During the pulse diet phase the soccer players covered an average of 9590 SD 1450 m during 90‐minutes of match time compared to 9360 SD 1471 m during the regular diet phase. The mean difference in distance covered between the pulse diet and regular diet phase (230 m, 90% CI −206 to 667 m) represents a 70% chance that the pulse diet was superior to the regular diet for increasing distance covered per game. We conclude that a pulse‐based diet improves body composition in male, but not female soccer players and that a pulse‐based diet may allow players to run a greater distance during soccer matches. Support or Funding Information Supported by the Saskatchewan Pulse Growers and the Western Grains Research Foundation