Post-exercise Recovery At High-altitude Is Equivalent After Consuming Carbohydrate Or Carbohydrate Plus Protein Beverages.

Unacclimatized lowlanders exercising at high altitude (HA) exhibit reductions in peripheral glucose uptake and post-exercise muscle anabolism suggesting traditional HA recommendations prioritizing carbohydrate (CHO) consumption post-exercise to facilitate muscle recovery may be inadequate. However, it is unknown if replacing some CHO with protein (PRO) would enhance recovery. PURPOSE: Determine how ingesting CHO or an isocaloric quantity of CHO + PRO post-aerobic exercise affects muscle glycogen content and molecular regulation of glycogen and muscle protein synthesis during acute HA exposure. METHODS: Eight participants (3F/5M; age: 23 ± 5 yrs) completed this randomized double-blind crossover study. Following 2 days of controlled exercise and diet, a fasted muscle biopsy and blood draw were collected at Sea Level (SL). Participants then ascended to simulated HA (hypobaric chamber, 460 mmHg, ~4300 m), where they cycled for 60 minutes at alternating intensities of 107 ± 27 and 46 ± 18 watts (2 minutes each). Blood and muscle were collected immediately post-exercise (0 min). Participants then consumed CHO (1.2 g CHO/kg/hr) or CHO + PRO (0.9 g CHO/kg/hr + 0.3 g PRO/kg/hr) beverages during the first 180 minutes of recovery. During recovery, blood samples were collected at 60, 120, 180, 240, 300, and 360 minutes, and muscle biopsies were collected at 240 and 360 minutes. RESULTS: Chamber conditions and exercise parameters were similar between treatments (P > 0.05). Glycogen content decreased (P < 0.001) at 0, 240, and 360 minutes similarly in CHO and CHO + PRO compared to SL. Circulating glucose and lactic acid concentrations increased and were higher in CHO vs CHO + PRO (P < 0.001). Circulating insulin and glycerol increased similarly between treatment (P < 0.001). Anabolic markers p-RPS6Ser235/236 and p-P70S6KThr389 increased (P < 0.001) at 0, 240, and 360 minutes compared to SL, regardless of treatment. Muscle p-Glycogen Synthase (p-GSSer641) decreased at 0, 240, and 360 minutes similarly between treatment (P = 0.02) compared to SL. CONCLUSION: These data indicate replacing carbohydrates with an isocaloric amount of protein does not negatively impact glycogen content or positively enhance overall muscle recovery within the first six hours of exercise recovery at HA compared with carbohydrate consumption alone. Supported by: DHP JPC-5/MOMRP