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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. [ABSTRACT FROM AUTHOR]

We recently reported the circulatory and muscle oxidative capacities of the arm after prolonged low-intensity skiing in the arctic ( Boushel et al., 2014). In the present study, leg VO2 was measured by the Fick method during leg cycling while muscle mitochondrial capacity was examined on a biopsy of the vastus lateralis in healthy volunteers (7 male, 2 female) before and after 42 days of skiing at 60% HR max. Peak pulmonary VO2 (3.52 ± 0.18 L.min−1 pre vs 3.52 ± 0.19 post) and VO2 across the leg (2.8 ± 0.4L.min−1 pre vs 3.0 ± 0.2 post) were unchanged after the ski journey. Peak leg O2 delivery (3.6 ± 0.2 L.min−1 pre vs 3.8 ± 0.4 post), O2 extraction (82 ± 1% pre vs 83 ± 1 post), and muscle capillaries per mm2 (576 ± 17 pre vs 612 ± 28 post) were also unchanged; however, leg muscle mitochondrial OXPHOS capacity was reduced (90 ± 3 pmol.sec−1.mg−1 pre vs 70 ± 2 post, P < 0.05) as was citrate synthase activity (40 ± 3 μmol.min−1.g−1 pre vs 34 ± 3 vs P < 0.05). These findings indicate that peak muscle VO2 can be sustained with a substantial reduction in mitochondrial OXPHOS capacity. This is achieved at a similar O2 delivery and a higher relative ADP-stimulated mitochondrial respiration at a higher mitochondrial p50. These findings support the concept that muscle mitochondrial respiration is submaximal at VO2max, and that mitochondrial volume can be downregulated by chronic energy demand. [ABSTRACT FROM AUTHOR]