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Exercise Fatigue - Fact or Fiction

16 January 2014


Dr Shaun Phillips, who lectures here at Abertay in Sport and Exercise Science, researches and writes on the keenly debated subject of exercise fatigue.

With the Australian Open underway, the Winter Olympics and Six Nations coming up and, of course, the Commonwealth Games taking place this summer, now seemed like the perfect time to let more people know about some of the latest findings from this fascinating field.

So here, Shaun gives us a bit of background and explains why exercise fatigue is actually something of a sports science mystery.

"My main research interests are the causes of fatigue in short-duration and endurance exercise, and how to minimise the impact of these mechanisms on exercise performance.

"I also focus on energy metabolism during exercise, lactate metabolism during exercise - particularly regarding its role as a fuel source - and paediatric exercise physiology.

"Over time, I've begun to focus on one of the most fundamental questions in human exercise physiology and the difficulties of trying to answer it: why do we fatigue during exercise?

"At face value, this seems like a relatively simple question to answer. After all, anyone who has taken part in almost any type of exercise will probably be aware of some of the common sensations that we associate with fatigue: breathlessness, sore muscles, heavy tired limbs, an overwhelming desire to stop and have a nice sit down, among others! Surely then, all we have to do is trace the physical causes of these sensations, and this would lead us down the path to solving this sports science mystery.

"Well, in one way or another this is what fatigue research has been doing for over a century and, in so doing - particularly with the advent of new and more sophisticated means of measuring human physiology - has opened our eyes to the complex and numerous probable causes that lie behind exercise fatigue.

"The incredibly complex functioning of the human body is partly responsible for the complexity of this area of study and, as a result, we don't have a definitive answer to why we fatigue during exercise, and this topic is more keenly debated within the world of sports science now than it probably ever has been.

"Unfortunately, this isn’t widely known outside research circles. If you ask a member of the public, a gym-goer, or even a high performance athlete / coach what causes fatigue during exercise, you will probably get one of a few recurring answers: "we fatigue when our muscles run out of energy", "lactic acid causes your muscles to stop working properly and you get tired", "if you become too dehydrated during exercise your body shuts down".

"These are a few of the common explanations, heard during almost every major sporting event from experienced former athletes in commentary, or from current Olympians and their coaches.

"The problem is, none of these suggestions are universally accepted as causing fatigue during exercise. Simply put, we don’t actually know why we fatigue during exercise!

"So I write about the subject to offer an insight into some of the key areas of research that are going on at the moment and to offer an alternative point of view that will challenge what we think we know about exercise fatigue."

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