As part of my job role at DNAfit, I read a lot of different scientific papers from a wide range of disciplines within sports science. At the end of 2015, I reviewed the best bits of research I had come across in 2015 (click for Part One and Part Two), and in this two-part article I will share with you the papers that had the biggest impact on me in 2016.
1. A genetic-based algorithm for personalised resistance training.
The first paper I’m going to share with you is one that has a personal touch; it’s the first paper that I was a named author on, and also the first paper published by DNAfit looking at the value of our test. We had been working hard on this behind the scenes for a few years, so to be able to share it with you was very exciting!
What we did is get two groups of athletes – one group were university athletes, and another were footballers at an academy. We gave them a DNAfit test, which enabled us to decide if they were “power” athletes (more than 50% power score on the test), or “endurance” athletes (more than 50% endurance score on the test). We then either gave them “power” resistance training, which was 10 sets of 2 reps, or “endurance” resistance training, which was 3 sets of 10 reps, increasing to 15 and eventually 20 reps as time progressed. The athletes did this training for eight-weeks, and before and after this training underwent both a test of power – the countermovement jump (CMJ) – and a test of endurance (Aero3).
What we found is that everyone tended to show improvements in these tests following training; this is good news, as it means exercise can improve performance. However, those doing genetically matched training (power athletes doing power training and endurance athletes doing endurance training) saw about three times as much improvement in both tests compared to those doing mismatched training (power athletes doing endurance training, and endurance athletes doing power training). This shows quite nicely that doing generically matched training, as predicted by the DNAfit Peak Performance Algorithm, can enhance the improvements seen after training. You can read a bit more about this study here.
2. Low Carbohydrate, High Fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers.
Low carbohydrate, high fat (LCHF) diets have been doing the rounds for a few years now, with some people suggesting they will be extremely beneficial for endurance athletes. The problem is that there actually isn’t much evidence to support this. There is some research on fat oxidation rates in those that follow a LCHF diet, indicating that they have higher levels of fat oxidation, but next to no research on actual performance measures; and, as Alex Hutchinson writes, you don’t get medals for having an interesting metabolism. So, whilst in theory a LCHF diet might improve how long you can exercise for, we don’t know what effect this has on actual performance, especially as endurance events tend to be won the by the person that covers the distance in the shortest amount of time, not the one who can exercise the longest.
That’s why this study was so interesting; it tested whether a LCHF diet was better for elite endurance athletes. And it turned out that it wasn’t; those on a higher carbohydrate diet performed better in a race than those that had followed a LCHF diet for the preceding three week training block. Whilst this isn’t absolutely conclusive evidence (there are potentially a few small issues with the study design), it does leave us with the reality that currently there isn’t really any evidence for the use of a LCHF diet in endurance athletes.
3. Placebo in sports nutrition: a proof-of-principle study involving caffeine supplementation.
Next up we have a really interesting study that examines the effects of placebo in sports performance. It’s pretty clear from the results of over 100 years of research that caffeine improves exercise performance. However, how do your beliefs impact this? For example, if you think you’ve taken caffeine, but actually haven’t – does this improve your performance? Similarly, if you don’t think you’ve taken caffeine, but actually have, will this reduce your performance? That’s what this study aimed to find out.
In three different trials, the subjects all performed a simulated time trial under three different conditions; having taken caffeine, having taken a placebo, and having taken nothing at all (called the control trial). In all three trials, the subjects were asked to guess whether or not they had taken caffeine. It turns out they weren’t that good at knowing whether they had consumed caffeine; less than half correctly identified they had consumed caffeine before the caffeine trial. Some subjects also thought they had taken caffeine when in actual fact they hadn’t.
This had an impact on the results too. Overall, caffeine improved performance compared to placebo. However, if you thought you had taken caffeine and actually had taken caffeine, your performance improved to a greater extent that the average effects of caffeine. In addition to this, if you thought you had consumed caffeine but actually hadn’t (placebo), you saw a performance improvement compared to the control trial (where you also hadn’t consumed caffeine). So, overall, believing you had taken caffeine led to greater than expected performance improvements. Conversely, if you thought you hadn’t taken caffeine, but actually had, you didn’t see as much of a performance improvement as expected. This shows really clearly the impact of expected outcomes on performance measures, such as improvements following caffeine.
4. Endurance exercise and gut microbiota: A review
There is a vastly greater number of bacteria in our guts than there are cells in our body. For a long time, the role of these bacteria, which together form the microbiome, wasn’t fully understood; we knew they helped to digest food, but that was about it. However, recently research has started to focus on the role these bacteria play in general health, and it is fascinating! These bacteria play a role in the development of obesity, and also our mood, illustrating how all aspects of our body are more closely linked than we might have thought.
One of the big questions in sports science is how this might affect exercise performance, and this review article represents one of the first steps in trying to answer this question. Overall, we know that greater diversity of these bacteria is beneficial, and it appears that exercise helps to increase this diversity. This increased diversity also appears to help with recovery, by increasing antioxidant defence and decreasing inflammation, and also improving immune function – keeping you training for longer. Finally, the composition of the bacteria in our gut can influence how quickly and efficiently we digest foods; if we can do this in a more efficient manner, this can lead to an increase in nutrients that are available during exercise, improving performance. Overall, whilst it is early days in this type of research, it seems clear that the microbiome likely has a big role to play in exercise adaptation and performance – and future research should shed more light on these exciting developments.
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