Skimmed, lactose-free milk ingestion post exercise: Rehydration effectiveness and GI disturbances versus water and a sports drink in physically active people

Abstract

Post-exercise hydration is fundamental to replace fluid loss from sweat. This study evaluated rehydration and gastrointestinal (GI) symptoms for each of three beverages: water (W), sports drink (SD) and skimmed, lactose-free milk (SLM) after moderate-intensity cycling in the heat. Sixteen college students completed three exercise sessions each to lose ≈2% of their body mass (BM). They drank 150% of BM loss of the drink assigned in randomized order; net fluid balance (NFB), diuresis and GI symptoms were measured and followed up for three hours after completion of fluid intake. SLM showed higher fluid retention (~69%) versus W (~40%) (p < .001); SD (~56%) was not different from SLM or W (p > .05). NFB was higher for SLM (-0.26 kg) and SD (-0.42 kg) than water (-0.67 kg) after three hours (p < .001), resulting from a significantly lower diuresis with SLM. Reported GI disturbances were mild and showed no difference among drinks (p > 0.05) despite ingestion of W (1992 ± 425 ml), SD (1999 ± 429 ml) and SLM (1993 ± 426 ml) in 90 minutes. In conclusion, SLM was more effective than water for post-exercise rehydration, showing greater fluid retention for the three-hour follow-up and presenting with low intensity GI symptoms similar to those with W and SD. These results confirm that SLM is an effective option for hydration after exercise in the heat.