This is a repost of the original article by predator nutrition
This article is based on a recent TV documentary by the BBC looking at the effectiveness of sport supplements.
I have already written a quick programme review of the Panorama sports drinks documentary which can be read at our blog here. I encourage everyone to read this and share, tweet, and like this to all your friends as a refute to those who may believe you would be better off on a diet of jam and bread!
Based on some of the feedback received from various people I thought it would be a good time to examine the actual source document which the show was based on and which the presenter, Shelley Jofrie has referred people to read on her twitter feed. This way we can actually explore the raw data which drove Panorama’s conclusions as opposed to discuss the programme itself.
Research Review – Mythbusting Sports And Exercise Products
Was the team leading this review qualified to do so?
The researchers were led by Carl Heneghan from the Centre for Evidence Based Medicine, who the paper describes as a “clinical reader”. A detailed review of his background shows that Heneghan’s training and experience relates to general medical practice only. He has no experience in exercise science or anything related to sport at all. This makes him a curious choice to sift through evidence in a field he has no formal knowledge of, let alone any actual expertise in working with athletes. For what the show purported was an exhaustive review of decades worth of data, the reality is it was led by someone with no knowledge or expertise in the field being researched. To compound matters, rather than have a support team who could assist him to examine the data that did have years of experience in the field, the only other people cited in the paper were a collection of PhD candidates and those colleagues who, like Henaghen, only had training in medicine.
In the same way you wouldn’t expect someone with a sports science background to lead a study on the effectiveness of medical treatments, it seems immediately apparent that the choice of people to conduct this investigation were ones not qualified to assess the data.
Leaving aside the people who led the review let’s move forward to discuss the actual content of their paper.
Hydration Status And Dehydration
The paper starts off by claiming that people may be fooled into thinking it is more important to heed hydration advice than to actually exercise. This is a surprising statement and something I have not once heard a single person or company state. I have no idea why they said this and they did not support this statement by providing any evidence at all.
The researchers go on to state that they wished to investigate claims that the colour of urine reflects hydration and whether you should hydrate before exercise or just when you feel thirsty. A discussion of the research follows before the researchers highlight that the sports drink manufacturers, Gatorade and Powerade advise drinking before thirst develops and to drink before, during, and after endurance competition. In their review of the data on the impact of dehydration on performance they state:
“One systematic review of the effects of glycerol induced hyperhydration on fluid retention and endurance performance in long cycling time trials found performance was maintained provided loss of body water is kept between 1.8% and 3.2% of body weight performance was maintained (1)“
The first reference presented here related to a study on patients with hyponatremia referred to for renal consultation. It has no discussion whatsoever of what the BMJ authors present in their paper. It has literally no relevance to cycling time trials and performance at all. See the reference at the bottom to explore this for yourselves. Not exactly an encouraging start to the review of this paper.
The CEBM group go on to state:
“..exercise induced dehydration of up to 2.3% of body weight significantly improved performance (2).”
The study referenced here was a meta-review of five studies which encompassed a grand total of 39 subjects. That means that there was an average of less than eight participants per study. Given the programme by Panorama made great play of the fact that the CEBM team discounted the evidence from many sports science studies as being inadequate for using small sample sizes, their justification for using this review with a very small sample size indeed beggars belief.
In any case if we explore the meta-review on its merits we see that the results do indeed show moderate dehydration enhances performance. However, this study also shows some flaws which need pointing out.
1. The five studies reviewed all used the same exercise, namely a cycling time trial to assess performance. Cycling is a sport where body weight plays a significant role in performance. Would the same outcome occur in sports where there is more skill components involved and where body weight matters less?
2. The actual intensity of the cycling time trials was relatively low. Would dehydration matter more during intensive exercise?
Research on 34 female soccer players from Canada (3) showed that even in a cool environment where there was under 1% weight loss during training sessions, players didn’t drink enough to avoid hydration and sodium deficits during training. Another recent study conducted on elite football players (4) showed that their vertical jump performance was poorer when dehydrated with a body weight loss of 3% versus baseline or when loss of body weight was less. Note that the vertical jump is a test of explosive strength which was not measured during the review of the cycling studies which the CEBM looked at.
Dehydration is also linked to declines in cognitive performance. A recent study in the Journal of Nutrition (5) showed that even moderate dehydration under 2% was associated with mood disturbances, increased perception of task difficulty, and lower concentration in young women. In sports where cognitive performance is more important than riding a stationary bike, such as ball and team sports, dehydration, even mild, could cause significantly poorer performance. Indeed, a study on basketball players (6) showed those who remained hydrated through exercise performed much better than those who did not.
There is an abundance of research which supports the need to ensure optimal hydration during exercise as wide ranging as tennis (7), squash (8), and bench press performance (9).
Professor Tim Noakes, interviewed on the Panorama programme made an appeal to athletes to avoid over hydrating and to drink according to thirst. Noakes bases this on research showing that drinking according to thirst was associated with better outcomes than other strategies. His appearance on the show was also marked out by warning to avoid overhydration, remarking it can cause death.
There is no reason to doubt Noakes’ rationale that thirst is a reliable indicator of hydration status, with the only trouble being it tends to set in at a point where we are already moderately dehydrated (1-2% of weight loss). While being moderately dehydrated has been shown to have little or no negative impact on endurance performance, the Noakes/CEBM view does not have any support when it comes to sports requiring intermittent bursts such as those which studies have shown can lead to dehydration.
We should point out here that while the research on dehydration was presented in the show as being influenced by drinks companies, a recent study conducted by a government agency showed that replacing a carbohydrate drink containing 2.4 litres of water with a matched energy carbohydrate gel supplying only 0.4l of water resulted in performance declining by a large degree. This was despite the group consuming the gels being nearly 2kg lighter. A significant thing to note in this trial is that the group performed a hill cycling time trial where the effect of being 2kg lighter should have resulted in an advantage.
As can be seen by now the programme took some liberties with the data and the actual referencing and studies used to support the hypothesis made by the CEBM during this show failed to match the hype of them only considering high quality studies where there were many participants. The data among endurance athletes is mixed as to the effects of hydration status on performance but in other sports which are primarily anaerobic in nature or require significant cognitive work, there is little doubt that being hydrated will help to deliver better performances.
A final word on hydration – the paper, which remember is written by people with no exercise or sports science training, goes against the advice of almost every single academically trained exercise scientist, as well as against advice given by leading sports organisations such as the BOA and FA. As much as academic studies are important we should also consider how elite athletes actually practice their sports. If the reality was that being moderately dehydrated was good for performance and we should drink according to thirst we would see professional sportsmen adopting this in droves of there was a performance advantage to be gained. The fact this doesn’t happen is something the writers of the paper, who have no athletic background whatsoever, failed to appreciate.
Energy Drinks Containing Caffeine And Other Compounds
The paper discussed caffeine products such as Red Bull in the next segment of the paper and came to the conclusion that stimulant based products such as this have been shown to enhance performance. This is no surprise to anyone, with stimulant usage among athletes going back over a hundred years.
The fact the paper identified only caffeine and later creatine as proven supplements will certainly come as a shock to those who have used many different types of energy supplements.
Carbohydrates And Protein Consumption To Improve Recovery And Performance
Next up the study authors reviewed the evidence for whether protein supplements can enhance recovery after training. As seen earlier, the CEBM team continued their obsession with studies where endurance cycling was used to determine the effectiveness of a nutrition program. Given that the vast majority of people consuming protein powder supplements are engaged in sports requiring increased levels of strength and muscle mass, it is a curious omission to focus their work only on cyclists again.
Before considering the use of endurance studies to present their evidence the researchers made the conclusion that one particular study(10) states:
“One systematic review concluded that the available evidence fails to show a relation between increased muscle glycogen synthesis and improved sports performance.”
I would encourage everyone to read the actual study itself, listed in the references to this article. Contrary to what the BMJ paper says it actually says:
“ Dietary carbohydrate represents a central component of post-exercise nutrition. Therefore, carbohydrate should be ingested as early as possible in the post-exercise period and at frequent (i.e. 15- to 30-minute) intervals throughout recovery to maximize the rate of muscle glycogen resynthesis.”
Furthermore the study they discuss also states:
“…studies have reported improved physical performance with ingestion of carbohydrate-protein mixtures”
“The underlying mechanism for such effects may be partly due to increased muscle glycogen resynthesis during recovery, although there is varied support for other factors such as an increased central drive to exercise, a blunting of exercise-induced muscle damage, altered metabolism during exercise subsequent to recovery, or a combination of these mechanisms”
In a discussion on the topic of protein and carbohydrate combinations it seems unclear exactly why the above points were ignored in the BMJ article, or why they ignored the actual conclusion to consume carbohydrate in the post-workout period.
Moving on to the cycling studies which the CEBM team reviewed, they state that the first two studies, conducted by John Berardi (11,12) were “inconclusive”. Yet the 2006 study states:
“C+P supplements, given early after exercise, enhance glycogen resynthesis relative to CHO and PLB”
While the 2008 study states:
“ liquid C+P ingestion immediately after exercise increases fat oxidation, increases recovery, and improves subsequent same day, 60 min efforts relative to isoenergetic CHO ingestion.”
The next study (13) they looked at compared carbohydrate versus protein supplied post workout for endurance cyclists. This is the type of group which has a high carbohydrate requirement and yet even the BMJ paper states performance was improved in the group consuming protein 60 hours after the subjects consumed a protein drink, compared to those consuming post-workout carbohydrates. The study itself was fairly poorly designed as nobody in the sports nutrition world would recommend protein by itself post-workout after a bout of endurance activity. Why these particular researchers didn’t run an isoenergetic mixed carbohydrate/protein comparison is difficult to fathom as that is the type of recovery drink commonly sold. It also flies in the face of their own statement that they were looking at carbohydrate and protein combinations in the post-workout period which this study did not even feature!
The next study cited in their review (14) of carbohydrate and protein combinations did compare a mixed protein/carbohydrate source versus a high carb feeding combination. This study showed that the high protein group had higher testosterone and less muscle soreness and tiredness the following day.
Far from being inconclusive all these studies showed some benefit of supplementing protein in the diet of these endurance athletes.
Contrasting Results Or Deliberate Avoidance Of The Study Detail?
The BMJ paper then discusses a number of studies (15,16,17,18) which they state provided “contrasting results”. They add only one trial measured performance and showed no improvement.
If we look into the studies in more detail we find that the first one showed less soreness in the group consuming extra protein compared to the carbohydrate only trial. The second study states that a chocolate flavoured fat free milk protein drink led to greater muscle protein synthesis and less muscle breakdown compared to the carb only group. The one study which measured performance backed up others showing less muscle soreness in those supplementing with extra protein and concluded:
“ We conclude that muscle damage incurred during training was attenuated with postexercise CHO+P+A ingestion, which could lead to performance improvements in high-mileage runners.”
The next study by Williams showed greater performance as well as heightened glycogen synthesis in the group consuming protein and carbohydrates.
Finally the study by Thomas et.al showed a protein/carb beverage outperforming both a carbohydrate and water treatment in a study on, you guessed it, cyclists.
While the BMJ paper covered these with the catch all phrase of contrasting results, further examination of each study showed that they all provided some performance or recovery benefit to those consuming mixed carbohydrate-protein combinations.
Summary Of The Stance On Carbohydrate And Protein
A review of these studies and others they go on to examine show that far from being inconclusive all showed some benefit for those consuming protein. While the CEBM highlighted the impact on performance, nobody who has trained for a long period of time would expect overnight results from a change in diet, training, or supplementation regime. Even the use of powerful drugs cannot alter human physiology so quickly as to make someone a world beater overnight. The fact all these studies were cherry picked to show only those which had a small number of participants and were run for a short time, typically less than 24 hours, is misleading and goes against the actual view propounded in the Panorama show that the CEBM only considered high quality studies. The studies above are all shown at the bottom of this page and we encourage readers to read up on them in more detail themselves.
The fact of the matter is that the CEBM team deliberately ignored multiple studies showing the benefits of providing protein for athletes engaged in anaerobic sports. Even the studies they did examine in endurance sports showed benefits of some kind or other for protein supplementation.
Why they failed to consider studies providing protein over a longer term to these athletes is unclear as benefits such as less muscle soreness and improved testosterone levels that these studies showed on an acute basis would become increasingly significant over the longer term.
Concluding part one of the review of this paper we have seen that the evidence presented by the BMJ in their paper contains a number of flaws, not least failing to uphold their claimed standards of only accepting high quality studies with extensive numbers of participants. After reading part one of this there are some tough questions to ask of the BBC and the CEBM team in terms of how they both presented the information they did study and how they selectively picked studies to try to confirm their point rather than look at both sides of the coin.
The fact they failed to consider studies in anaerobic sports looks as though it was designed to show that protein is not required by athletes.
Generally selecting poor quality studies is another example of poor judgment in the CEBM team. Why was chocolate milk the primary protein source looked at in many of the studies cited, ignoring the fact that the vast majority of the weight training and athletic population would use a whey protein, or micellar casein based shake for their protein sources?
The selection of chocolate milk again looks like an example of where the CEBM deliberately set out to try to prove their case. Why ignore studies showing greater muscle retention with high protein diets (19), greater muscle protein synthesis with whey protein intake (20), strength and muscle mass increases linked to a group consuming whey protein and leucine (a branched chain amino acid) combination (21), whey protein can stimulate greater muscle growth and recovery (22), and use of casein protein enhances recovery when used before sleeping (23).
If we keep the focus on the endurance activities the show looked at, studies show that a protein-carb combination was superior to carbohydrates alone when used to look at performance on hikes (24), improved recovery in a protein-carb supplement compared to carbohydrates alone (25), enhanced performance using a carbohydrate-electrolyte beverage compared to placebo (26), and finally, one study showed improved performance in lower level athletes using a protein + carbohydrate drink but not elite athletes (27). This last study is particularly noteworthy as one of the often repeated refrains from the TV show is that while elite athletes may benefit from some supplements it would be of no benefit to the average person. This last study shows the exact opposite.
I know this article is probably a little heavy going but I would urge you all to read carefully the references at the bottom and share this article to your friends to enable them to see also the bias and inaccuracies of the paper which the Panorama show was based on.
1. Arieff AI, Llach F, Massry SG (1976): Neurological manifestations and morbidity of hyponatremia: correlation with brain water and electrolytes.
2. Goulet ED. Effect of exercise-induced dehydration on time-trial exercise performance: a meta-analysis.
3. Gibson JC et.al (2012): Hydration status and fluid and sodium balance in elite Canadian junior women’s soccer players in a cool environment.
4. Mohr M, Krustrup P (2012): Heat stress impairs repeated jump ability after competitive elite soccer games
5. Armstrong LE et.al (2012): Mild dehydration affects mood in healthy young women.
6. Dehydration impairs vigilance-related attention in male basketball players.
7. Kovacs M (2005): Hydration and Temperature in Tennis.
8. S Fritz et.al (2009): Effects of hydration strategies on squash performance.
9. James E Schoffstall et.al (2001): Effects of Dehydration and Rehydration on the One-Repetition Maximum Bench Press of Weight-Trained Males.
10. Betts JA, Williams C (2010): Short-term recovery from prolonged exercise: exploring the potential for protein ingestion to accentuate the benefits of carbohydrate supplements.
11. Berardi JM, Noreen EE, Lemon PW (2008): Recovery from a cycling time trial is enhanced with carbohydrate-protein supplementation vs. isoenergetic carbohydrate supplementation.
12. Berardi JM, Price TB, Noreen EE, Lemon PW (2006): Postexercise muscle glycogen recovery enhanced with a carbohydrate-protein supplement.
13. Rowlands DS et al. (2008): Effect of dietary protein content during recovery from high-intensity cycling on subsequent performance and markers of stress, inflammation, and muscle damage in well-trained men.
14. Rowlands DS, Rossler K, Graham DF, Rockell MJ. Effect of protein-rich feeding on
recovery after intense exercise.
15. Millard Stafford M et.al (2005):Recovery from run training: Efficacy of a carbohydrate-protein beverage?
16. Luden ND, Todd MK. Postexercise carbohydrate-protein antioxidant ingestion decreases
CK and muscle soreness in cross country runners.
17. Williams MB, Fogt DL, Ivy JL. Effects of recovery beverages on glycogen restoration and
endurance exercise performance.
18. Thomas K, Stevenson E. Improved endurance capacity following chocolate milk
consumption compared with 2 commercially available sport drinks.
19. Mojtahedi MC et.al (2011): The effects of a higher protein intake during energy restriction on changes in body composition and physical function in older women.
20. Reitelseder S et.al (2011): Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion.
21. Walker TB et.al (2010): The influence of 8 weeks of whey-protein and leucine supplementation on physical and cognitive performance.
22. Hulmi JJ et.al (2010): Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein.
23. RES PT et.al (2012): Protein Ingestion before Sleep Improves Postexercise Overnight Recovery.
24. Jimenez-Flores R et.al (2012): A comparison of the effects of a high carbohydrate vs. a higher protein milk supplement following simulated mountain skirmishes.
25. Kerasioti E et.al (2012): Effect of a special carbohydrate-protein cake on oxidative stress markers after exhaustive cycling in humans.
26. Roberts JD et.al (2012): An investigative study into the influence of a commercially available carbohydrate-protein-electrolyte beverage on short term repeated exercise performance.
27.Vegge J et.al (2012): Improved cycling performance with ingestion of hydrolyzed marine protein depends on performance level.