Background: Physical performance of military tasks can deteriorate during field training.
Hypothesis: Drinking a carbohydrate-electrolyte (CHO-E) beverage during military relevant training would improve fluid and caloric intake, and better sustain physical performance.
Methods: Some 27 volunteers restricted to approximately 2600 kcal.d-1 were randomly assigned to one of three groups: CHO-E, placebo, or water. Fluid intake was ad libitum. The volunteers completed 3 d of field training in hot humid conditions (30 degrees C, 60% rh). Training days 1 and 2 each included a 16-21 km march over hilly terrain, marksmanship training, and 2 h of rock climbing. Day 3 included a 14.5 km march followed by marksmanship tests, a timed rock climb and a 0.7 km uphill (21% grade) run.
Results: The CHO-E beverage provided an additional approximately 2800 kcal (p < 0.05) for the 3 d of training. There were no differences (ANOVA, p > 0.05) between the groups absolute or changes from pre-training values for fluid intake, body weight, climb time, run time, marksmanship, or mood. Those drinking CHO-E were, however, more likely to maintain uphill run performance after training (chi 2 = 7.2; p < 0.05) and more likely to maintain both uphill run and marksmanship ability (chi 2 = 17.2; p < 0.05). There was also an inverse relationship between caloric intake and deterioration of uphill run performance (r = -0.75; p < 0.05).
Conclusions: Persons drinking CHO-E or practicing good food discipline are more likely to sustain physical performance than those eating only a portion of their food. CHO-E provides an accessible source of calories which can be advantageous when limited food is available or inadaquate food consumption is likely.