title: The Effect of Different Post-Exercise Beverages on Fluid Recovery, Nutrient Provision and Subsequent Athletic Performance
Creators: name: McCartney, Danielle
Publisher: name: Griffith University
Year: 2019
Subjects: subject: Fluid recovery
subject: Nutrient provision
subject: Athletic performance
subject: Carbohydrate
subject: Protein

description: Background: Athletes undertaking frequent training or those involved in sporting competitions with multiple heats or games may be required to complete two or more high-quality exercise sessions with limited recovery time between bouts (e.g. ≤4 h). Beverages may be an ideal way in which to consume the fluid and nutrients required to enhance short-term post-exercise recovery and subsequent athletic performance in these situations, owing to their appeal (i.e. capacity to “quench thirst”) and gastrointestinal tolerability. However, studies investigating the ability of different beverages to influence these outcomes typically “prescribe” drinking (i.e. beverage volume and rate of ingestion) and deny participants access to food; an approach with limited ecological validity. The overall objective of this thesis was to develop a better understanding of how different beverages affect fluid restoration, nutrient provision and subsequent athletic performance when consumed between exercise sessions with limited (i.e. ≤4 h) recovery time; particularly, within the context of enhanced ecological validity. Thesis Part I: Initially, the effect of fluid intake during or following dehydration on subsequent athletic performance was examined. The systematic review included 64 controlled trials that measured athletic (categorised as: continuous, intermittent, resistance, sport-specific and balance exercise) or cognitive performance ≤4 h after dehydration of participants with or (versus) without fluid consumption. Meta-analysis identified a significant positive effect of fluid consumption on continuous exercise performance; particularly, under heat-stress conditions. Research investigating the effect of fluid intake on other sports or types of exercise was relatively limited, and a narrative synthesis of the available evidence failed to indicate a clear improvement. Study 2 explored the effect of consuming fluid with carbohydrate (CHO) and protein during or following exercise on subsequent athletic performance. This systematic and meta-analytic review included 67 controlled trials that measured either endurance or anaerobic performance ≤4 h after an initial standardised exercise bout. Initially, the review investigated the effect of “adding” CHO to water, and subsequently, the “addition” of protein to a CHO-containing beverage. Fluid co-ingested with CHO significantly improved subsequent endurance and anaerobic performance compared to fluid intake alone. However, protein added to a CHO-containing beverage did not influence subsequent endurance performance. Collectively, the results of Studies 1 &amp; 2 suggest that individuals with limited recovery time between exercise sessions should prioritise CHO and fluid ingestion to enhance subsequent athletic (endurance) performance. Whether CHO-containing beverages improve short-term post-exercise recovery (i.e. the restoration of fluid and substrate losses) and subsequent athletic performance when consumed under ecologically valid conditions (e.g. ad libitum and with food) remained unclear. Thesis Part II: Recent evidence suggests that different post-exercise beverages promote similar levels of fluid recovery but alter energy and nutrient provision in trained males when consumed ad libitum and with food. Study 3 investigated if similar effects are observed in trained females, who may exhibit contrasting dietary behaviours. On 4 separate occasions, 8 females lost ~2% of their body mass (BM) cycling before completing a 4 h recovery period with ad libitum access to water, a CHO-electrolyte sports beverage or one of two milk-based formulations and food. Results indicated that the different beverages were equally effective at replenishing fluid losses, but that caloric (CHO-containing) alternatives increased short-term (i.e. 4 h) and total daily energy and nutrient consumption. This could potentially affect short-term muscle glycogen resynthesis, and thus, subsequent athletic performance, as well as chronic exercise–nutrient interactions. Study 4 investigated the effect of consuming different post-exercise beverages ad libitum with food on short-term (i.e. ≤4 h) fluid recovery, nutrient provision and subsequent athletic performance. On 2 separate occasions, 16 endurance-trained cyclists (8 males) completed 1 h of fixed-intensity cycling followed by a 4 h recovery period with ad libitum access to water or a CHO-electrolyte sports beverage and food, and later, an endurance cycling performance test. Once again, results indicated that both beverages were effective at replenishing fluid losses and that the sports beverage increased short-term (i.e. 4 h) energy and CHO consumption. However, this additional nutrition did not translate to an improvement in cycling performance; possibly because individuals already consumed enough CHO from food alone to meet post-exercise refuelling recommendations when water was provided. Collectively, the results of Studies 3 &amp; 4 suggest that a CHO-containing post-exercise beverage is more likely to influence nutrient provision than fluid restoration or subsequent athletic performance. Conclusion: The research presented in this thesis indicates that individuals with limited recovery time between exercise sessions should consume CHO and fluid to enhance subsequent athletic performance. However, when consumed ad libitum and with food, CHO-containing beverages do not appear to be any more effective than water at promoting fluid restoration; may not enhance subsequent athletic (endurance) performance; and may increase total daily energy consumption. Thus, access to a CHO-containing post-exercise beverage should consider an athlete’s overall dietary goals (e.g. energy availability and body composition aspirations), ability to tolerate food and fluid pre-/post-exercise, taste preferences (i.e. beverage palatability) and immediate refuelling requirements. Put simply, sports practitioners and dietitians should bear in mind that, as long as athletes obtain an appropriate amount of CHO and fluid to promote recovery between exercise sessions, the source of nutrition is not critically important.