Yes, it is almost Olympic time, so obviously I have no idea what could have possibly inspired a team of researchers led by Dr Carl Heneghan of Oxford’s centre for evidence-based medicine to look into the claims made for sports related products.
The BMJ has their study and it is entitled “Mythbusting sports and exercise products“. There they examined six claims by looking for evidence in systematic reviews and randomised controlled trial filters. So what were the six claims and what did they find for each?
Claim 1: The colour of urine accurately reflects hydration
General public—Evidence is lacking to suggest that urine colour is a useful, safe, or accurate marker of hydration
Professional athletes—Limited evidence to show that first morning urine colour can be reliably used to assess dehydration and rehydration
Required research—A high quality study evaluating the use of urine colour in detecting hydration with blinding of participants and researchers to other assessment tools when measuring urine colour. Ideally this should look at the relation between urine colour and other markers of hydration including thirst and body mass
Claim 2: You should drink before you feel thirsty (Both Gatorade and Powerade push this claim on their websites)
General public—Drinking ahead of thirst may worsen performance in endurance exercise and carries a rare but serious risk of hyponatraemia. The body’s internal mechanism for staying hydrated is cheaper, easier, and seems to be the best way to optimise performance
Professional athletes—Elite endurance athletes perform best when they drink to thirst; some studies suggest exercise induced dehydration can improve performance
Required research—A high quality randomised trial measuring the performance effects of different hydration regimes during shorter exercise (sprint-type) would determine whether the results of systematic reviews are generalisable beyond endurance athletes
Claim 3: Energy drinks with caffeine and other compounds improve sports performance. (For example Red Bull claims “In extensive studies it has been repeatedly proven that Red Bull increases performance”)
General public—Low quality evidence supports the use of energy drinks containing caffeine, taurine, or guarana to improve acute strength performance and aerobic and anaerobic endurance. No studies compare the effectiveness of these products with ingesting caffeine alone and there are important concerns regarding harms
Professional athletes—Limited, low quality evidence supports the use of energy drinks containing caffeine, taurine, or guarana to improve endurance in moderate intensity activity of around 60 minutes. No studies compare the effectiveness of these products with ingesting caffeine alone and there are important concerns regarding harms
Required research—High quality randomised trials in real-world settings evaluating the comparative effectiveness of energy drinks and caffeine alone on sports performance
Claim 4: Carbohydrate and protein combinations improve post-workout performance and recovery (Myprotein claims “The combination of protein and carbohydrates has been shown to stimulate increased uptake of glucose by the cells, resulting in faster glycogen storage compared to carbohydrates or proteins alone“)
General public—There is a lack of evidence to support combined carbohydrate and protein supplements after exercise to improve recovery and reduce muscle breakdown
Professional athletes—The results of studies of supplements containing a variety of carbohydrate to protein ratios show inconsistent and generally small benefits in some measures of sports performance, but generally do not show benefits over and above a balanced and nutritious diet
Required research—High quality randomised controlled trials evaluating specific ratios of carbohydrates and proteins that are adequately powered to detect a meaningful increase in subsequent sports performance
Claim 5: Branched chain amino acids improve performance or recovery after exercise (Maxifuel claims “Pure branch chain amino acids are claimed to help hard training athletes recover faster after intense exercise, combat muscle damage during exercise, and support peak endurance performance”, also Maximuscle claims “help to sustain a healthy immune system during periods of intense training and play an important role in fatigue and performance“)
General public—High quality evidence is lacking that branched chain amino acids enhance performance or recovery
Professional athletes—There is no evidence that branched chain amino acids enhance performance in competitive settings. There is limited evidence to suggest that muscle soreness and recovery may be reduced and that longer term supplementation may increase some strength and endurance measures
Required research—High quality large randomised trials evaluating the effect on outcomes that are directly relevant to athletes, such as run times or maximal weight lifts in the competitive setting
Claim 6: Compression garments improve performance or enhance recovery (Underarmour claims “This ultra-tight, second-skin fit delivers a locked-in feel that keeps your muscles fresh and your recovery time fast”)
General public—There is a lack of evidence to support use of compression garments to improve sporting performance. They may reduce muscle soreness if worn for 24 hours after an exercise session
Professional athletes—There is no consistent evidence that compression garments improve sporting performance. Muscle soreness seems to be reduced if garments are worn for 24 hours after exercise, but objective measures of recovery are less consistent, and compression garments seem to work no better than other recovery strategies such as low grade exercise or contrast bathing. Potential adverse effects of these garments may include increased skin temperature, decreased thermoregulation, and reduced range of motion
Required research—Larger studies in individual sports and research generalisable to either highly trained athletes or the general population, with outcomes related to sports performance, and examination of adverse effects and acceptability of compression garments
It all gets a nice write-up in the UK’s Guardian here, where they note “There is a striking lack of evidence to support the vast majority of sports-related products that make claims related to enhanced performance or recovery, including drinks, supplements and footwear,“.
It is nice to see evidence based science taking a lead and getting the truth out.