Aim The aim of the present study was to compare performance 5 h after a 90-min endurance training session when either carbohydrate only or carbohydrate with added whey hydrolysate or whey isolate was ingested during the first 2 h of the recovery period. Methods Thirteen highly trained competitive male cyclists completed three exercise and diet interventions (double-blinded, randomized, crossover design) separated by 1 week. The 90-min morning session (EX1) included a 60 min time-trial (TT60). Immediately and 1 h after exercise, participants ingested either (1) 1.2 g carbohydrate·kg-1·h-1 (CHO), (2) 0.8 g carbohydrate·kg-1·h-1 + 0.4 g isolate whey protein·kg-1·h-1 (ISO) or (3) 0.8 g carbohydrate·kg-1·h-1 + 0.4 g hydrolysate whey protein·kg-1·h-1 (HYD). Additional intakes were identical between interventions. After 5 h of recovery, participants completed a time-trial performance (TTP) during which a specific amount of work was performed. Blood and urine were collected throughout the day. Results TTP did not differ significantly between dietary interventions (CHO: 43:54 ± 1:36, ISO: 46:55 ± 2:32, HYD: 44:31 ± 2:01 min). Nitrogen balance during CHO was lower than ISO (p < 0.0001) and HYD (p < 0.0001), with no difference between ISO and HYD (p = 0.317). In recovery, the area under the curve for blood glucose was higher in CHO compared to ISO and HYD. HR, VO2, RER, glucose, and lactate during EX2 were similar between interventions. Conclusion Performance did not differ after 5 h of recovery whether carbohydrate only or isocaloric carbohydrate plus protein was ingested during the first 2 h. Correspondingly, participants were not in negative nitrogen balance in any dietary intervention.
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