Get your guide!

Receive our FREE 14-day guide, direct to your inbox, on how genetics impact every aspect of fitness and nutrition.

DNAFit Blog

Craig Pickering's Sports Science Review 2015 - Part 1

Posted 754 Days Ago in: Training, Genetics, Industry News

CategoriesTagsSearch

Welcome to Part 1 of my review of the best sports science research in 2015. Note – by best, obviously I mean most interesting to me. Sports science is a large field, and can creep over into other disciplines also. Conducting a review on all the sports science-based research conducted in 2015 would be very time consuming, so just take this as it is. That said, hopefully this provides a nice overview of some contemporary issues in sports science at the moment.


Welcome to Part 1 of my review of the best sports science research in 2015. Note – by best, obviously I mean most interesting to me. Sports science is a large field, and can creep over into other disciplines also. Conducting a review on all the sports science-based research conducted in 2015 would be very time consuming, so just take this as it is. That said, hopefully this provides a nice overview of some contemporary issues in sports science at the moment.

In Part 1, let's take a look at Gluten and Athletes, The Placebo Effect and The Brain in Exercise.

1: Gluten and Athletes

Gluten free eating behaviours are growing, and it seems that, for some people, any ailment can be cured by the elimination of gluten from our diets. A couple of studies in the sport science sphere added some context to this trend this year. The first, Exploring the popularity, experiences, and beliefs surrounding gluten-free diets in nonceliac athletes authored by Lis et al. (2015) made for some sobering reading. The researchers sent a questionnaire to 910 athletes, including 18 World or Olympic medallists, asking them questions about their eating behaviours regarding gluten.

Now, before I tell you the results of the questionnaire, I should introduce some context here - roughly 1% of the populations of the UK, North America and Australia have coeliac disease. Coeliac disease is an autoimmune condition that affects the small intestine, and when people with coeliac disease consume gluten containing foods, they become symptomatic. It’s estimated that a further 10% of the population have something called Non Coeliac Gluten Sensitivity (NCGS), which is a sensitivity to gluten without actually having coeliac disease. It’s fairly controversial whether or not this actually exists, although its certainly true that a sub-section of people do experience symptoms when consuming gluten. However, some very compelling research exists illustrating that this could well be down to the consumption of something called FODMAPs, a type of carbohydrate that is poorly absorbed. Indeed, when people who self report gluten sensitivity remove FODMAPs from their diet, they can consume gluten without any apparent ill effect. Anyway, the main point I am trying to make is that about 10% of people in the general population likely have an issue with gluten.

However, in the Lis study, fully 41% of the athletes questioned consumed a gluten free diet more than 50% of the time. This is a rate four times higher than what we would expect to be required, given the prevalence of gluten sensitivity in the general population. When we look closer at the results, we get an idea why the diet might have been so popular; 57% of the gluten free athletes had self diagnosed their gluten sensitivity. Not only this, but the main sources of information on the need for a gluten free diet for these athletes were, in order of prevalence, the internet, the coach, and other athletes. In other words, people who likely have no formal training in diagnosing gluten sensitivity. The internet is unpoliced, and largely not subject to peer review; anyone can write whatever they want (like what I’m doing now), and it doesn’t necessarily have to be correct. The fact that this is the main source of information for athletes on the requirement for going gluten free is worrying. If you think that’s bad, wait for this kicker; only 0.5% of athletes said their primary source of information on gluten was from a medical professional (7.5% said it was from a naturopath).

The researchers concluded that the decision to adhere to a gluten free diet was often not made on clinical, evidence based recommendations, but generally as a result of a self diagnosed gluten issue. They were also concerned that the belief that gluten was causing GI issues might lead to a mis-diagnosis of an underlying problem (such as IBS), or disordered eating behaviours.

One of the most common reasons given for following a gluten free diet in the above study was the belief that it would improve performance. Presumably, in some sort of exasperated state, the same research group decided to the test this. Their paper is titled No Effects of a Short-Term Gluten-Free Diet on Performance in Nonceliac Athletes (Lis et al. 2015). Given the title of the paper, you can probably guess what they found, but for the sake of completeness let’s take a closer look at the research. The researchers recruited 13 male and female competitive cyclists (which, granted, is a small sample size) who had no history of coeliac disease or irritable bowel syndrome. The cyclists were all placed on a gluten free diet, and then given either a gluten-containing cereal bar (Gluten Containing Diet trial or GCD) or a gluten-free cereal bar (Gluten Free Diet trial or GFD). Neither the researchers nor the cyclists knew which diet they were on. The diet was followed for a week, and culminated in a performance test, which was a 45-minute steady state cycle ride, followed by a 15-minute time trial. The subjects then had 10 days off, where they could eat what they wanted, and then returned to do the opposite diet for 7 days, followed by another performance test. As the title of the study suggests, there were absolutely no differences between the groups on the performance test. To be clear, going gluten free had no effect, positive or negative, on performance. It also had no effect on gastrointestinal wellbeing, overall well being, or any markers of inflammation. The results from this study are clear; in athletes who do not have coeliac disease or gluten sensitivity, there are no performance reasons for eliminating gluten from the diet. Instead, the researchers implore athletes to seek evidence based advice before embarking on a gluten free diet.

2: The Placebo Effect

I’ve long suspected that part of the reason doping appears to improve performance in athletes is because of the placebo effect. If you inject athletes with something and tell them it will make them train harder, or more, or recover faster, or feel better, it likely will improve performance. It’s similar to how placebo drugs work in medicine, or how homeopathy “works”. So it was really interesting to read a research paper entitled Effects of an Injected Placebo on Endurance Running Performance (Ross et all. 2015), which examined the effects of a placebo on endurance running performance. The athletes all believed they were taking part in a research study examining the effects of a drug called OxyRBX, purported to be similar in action to EPO, the drug of choice for many an endurance cheat. After a 3km race, a group of 15 well-trained endurance runners were either injected with OxyRBX (which was actually just salt water) or had no injections over a seven-day period. They then did another 3km race, followed by two weeks “wash out” with no injections. The groups then swapped over for another 7-day period, with those who had no injections in the first week now getting OxyRBX, and vice versa, before another 3km race.

The researchers found that the use of placebo injections improved performance in the 3km race by 1.2% compared to the control group who had no injections. Whilst a 1.2% improvement might not sound like much, it was greater than the difference between 1st and 4th (or medal and no medal) in every running event from 1500m to 10,000m for both men and women at the 2012 London Olympic Games. The researchers believed that this improvement stemmed from a reduction in perceived effort, as well as an increase in motivation. However, it is worth pointing out that the improvement of 1.2% with placebo is still less than is generally seen with EPO use, so doping likely does exhibit some physiological improvements not related to the placebo effect.

3: The Brain & Exercise

In recent years, focus has shifted from the body to the brain with regards to exercise, particularly in the role it plays in fatigue. This began a few years ago with the Central Governor model proposed by Professor Tim Noakes, and has been refined somewhat in recent years. Today, the main model is called the Psycho-biological model, which looks at how the brain interacts with the body to govern fatigue, primarily in endurance events. A lot of this comes down to perception of effort; for example if we consume caffeine, this likely reduces how hard a given exercise feels, which in turn means we can exercise for longer before we get too fatigued and have to stop. Similarly, when exercising in hot temperatures, performance drops initially because exercise feels harder, and the brain is also concerned with stopping the body from damaging itself. However, by exercising in hot temperatures, positive adaptations occur to make it feel less hard; we sweat easier for instance. Similarly, the brain also knows that we can handle this given intensity in this given heat, as we have done it before, so it lets the athlete perform harder. The same is likely true for strength training – whilst we do need to increase muscle size and strength to handle heavy weights, exposure to heavy weights also potentially has an effect on the brain too, making it less fearful of damage. All of this is very interesting, because before training used to focus almost exclusively on the body, especially with regards to fatigue. Take carbohydrates for example; we used to think that when carbohydrate stores are depleted within the muscle, that is caused fatigue. However, if we then stimulate those muscles electrically, bypassing the brain, they still contract, illustrating quite nicely the influence of the brain.

The effect of the brain on endurance performance was further elucidated in 2015 in a review article entitled Psychological Determinants of Whole-Body Endurance Performance (Marcora et al. 2015). Even though review articles don’t conduct any new experiments, can be useful because they gather together all the research in that particular area to give a current overview as to what is happening. This particular review article looked at 46 different studies, and reported that psychological interventions generally improve endurance performance. These psychological interventions include goal setting, imagery and self talk. The review also found that mental fatigue inhibits endurance performance, which has been found a number of times before. Back in 2009, Sam Marcora, one of the authors of this review, found that being required to do a mentally demanding task during exercise made people reach fatigue quicker.

All of this goes to show that future research in this area is going to be very interesting, especially from a public health point of view. If we know that perceived exertion rather than actual exertion can determine fatigue levels, and we think that obese people find exercise “harder” than fitter people (and thus are less likely to exercise), can we affect their brain in positive ways in order to get them to find exercise easier or more enjoyable? Marcora certainly thinks so proposing that the use of psychoactive drugs (like caffeine) might increase exercise adherence in these individuals.

That's it for Part 1, check back in tomorrow for Part 2, where we'll cover The ACTN3 Gene, Ice Baths, Stretching and the age-old question - can you outrun a bad diet?

As always, if you've found this interesting so far - please do share so others can enjoy too.

Thanks for reading, and see you tomorrow!

Craig Pickering

http://craigpickering.com

@craig100m

 

Tags:

Training Genetics Sport Athletes Nutrition Gluten Placebo

Share:




Other Articles

Posted 721 Days Ago in: Training, Genetics

Alcohol and Exercise – Will you jeopardise your training by drinking?

in medium to large amounts and in close proximity to training, yes more than likely! As always there is slightly more to consider. Alcohol (ethanol) is both a drug and a nutrient (providing 7 kcal per gram), however it is not an essential part of the diet. Alcohol has effects across a wide variety of systems within the body, but for the context of this article I will focus on the effects of alcohol on training and recovery.

Read More

Posted 655 Days Ago in: Training, Genetics

Can exercise alter your DNA?

Whether or not we ride a bike, go running or hiking does not cause changes in the DNA sequence of our cells. But what does exercising do to our body so we grow more muscles and loose extra weight? Recent studies have even showed that exercising positively affects our cognitive abilities. What is happening inside our body and inside our cells when we exercise?

Read More


Get your guide!

Receive our FREE 14-day guide, direct to your inbox, on how genetics impact every aspect of fitness and nutrition.