Co-ingestion of carbohydrate and whey protein isolates enhance PGC-1α mRNA expression: a randomised, single blind, cross over study

Karen M Hill,Christos G Stathis,Esther Grinfeld,Andrew J Mcainch,Alan Hayes

doi:10.1186/1550-2783-10-8

Abstract

BackgroundWhey protein isolates (WPI) supplementation is known to improve resistance training adaptations. However, limited information is available on the effects of WPI plus carbohydrate (CHO) supplementation on endurance training adaptations.MethodSix endurance trained male cyclists and triathletes (age 29 ± 4 years, weight 74 ± 2 kg, VO2 max 63 ± 3 ml oxygen. kg-1. Min-1, height 183 ± 5 cm; mean ± SEM) were randomly assigned to one of two dietary interventions in a single blind cross over design; CHO or CHO + WPI. Each dietary intervention was followed for 16 days which included the last 2 days having increased CHO content, representing a CHO loading phase. The dietary interventions were iso-caloric and carbohydrate content matched. On completion of the dietary intervention, participants performed an exercise bout, consisting of cycling for 60 min at 70% VO2 max, followed by time trial to exhaustion at 90% VO2 max and recovered in the laboratory for 6 hours. Blood samples and muscle biopsies were taken at various time points at rest and through the exercise trial and recovery.ResultsCompared to CHO, CHO + WPI increased plasma insulin during recovery at 180 mins (P < 0.05) and peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) mRNA expression at the end of 6 hours of recovery (P < 0.05). Muscle glycogen did not differ between the two trials.ConclusionThis study showed co-ingestion of CHO + WPI may have beneficial effects on recovery and adaptations to endurance exercise via, increased insulin response and up regulation of PGC-1α mRNA expression.

Highlights

Whey protein isolates (WPI) supplementation is known to improve resistance training adaptations
For both content matched group (CHO) and CHO + WPI groups, plasma glucose was significantly increased during cycling at 90% VO2 max and remained elevated compared to rest until 40 min during recovery, with the CHO group remaining elevated until 60 min during recovery
The results from the current study demonstrated co-ingestion of CHO + WPI elevated Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) Messenger RNA (mRNA) expression compared to CHO at the end of the 6 h recovery period

Summary

Introduction

Whey protein isolates (WPI) supplementation is known to improve resistance training adaptations. Limited information is available on the effects of WPI plus carbohydrate (CHO) supplementation on endurance training adaptations. Optimal nutrition is required for normal physiological functioning, but the nutritional status of an endurance athlete can negatively or positively impact their sporting performance [1]. Nutritional requirements of endurance athletes include higher energy needs to fuel exercise and replace glycogen stores and increased protein intake to support muscle protein turnover. During endurance exercise major disturbances to cellular homeostasis, substrate stores and utilization occur in the muscle [2]. Repeated bouts of endurance exercise result in structural, metabolic and physiological adaptations that enable improved performance [4]. During recovery the activation of several major signalling pathways occurs in the first few hours before returning to baseline within 24 hours [2]

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Conclusion