By Kate Dzienis
One of the most important things runners know they must do pre and post run is fuel their bodies to keep energy levels maintained for their specific needs.
Carb loading is a particular favourite for most, and is usually done the evening before a big race but what happens post run? And why is there a general expression amongst the majority that they’ve lost their appetites, anywhere from three hours to four days after crossing the finish line?
As much as we want to fill our bellies with that sirloin steak at the pub along with a group of fellow runners to celebrate a race, whether it be a 10k, a half or a 75k, sometimes we just can’t stomach it.
It’s good to know, then, that appetite suppression is a very common and normal response to exercise, and sports physician Dr Simon Jenkin from Sport Exercise Movement (Peppermint Grove, WA), explains a well balanced diet is important and ensuring adequate hydration and electrolyte replacement helps.
“It is important that electrolyte drinks and gels are taken with the appropriate amount of water, as at higher concentrations they can cause a reduced rate of absorption in the stomach and intestine,” he says.
Dr Jenkin, a member of the Australian Medical Association, also explains to Runglobal there are a number of reasons runners may experience a loss of appetite.
“The first of these is related to alterations in blood flow,” he reveals.
“During exercise there is an increase in demand for blood to the muscles in order to provide adequate oxygen, fuel and nutrients to the working muscle, as well as flush out all the waste products produced.
“The body achieves this by increasing heart rate but also by changes in the blood vessels that redirect blood flow toward the muscles and away from areas of less demand, such as the stomach and intestines.
“The result is a decrease movement and function of the stomach and intestines that gives a feeling of ‘fullness’ and reduces the ability to digest food as quickly as normal, both during and after exercise.
“With prolonged intense exercise such as an Ironman, this occasionally results in post-race vomiting with attempts to eat as the stomach rejects food due to mild damage as a result of the prolonged restricted blood flow.”
According to Dr Jenkin, who is a club doctor with the East Perth Football Club and has worked with the Australian Boomers, Young Socceroos and Cirque du Soleil, the second reason relates to hormonal changes that occur during exercise, where the main hormones that regulate appetite (peptide YY and ghrelin) are increased.
So how can a runner, even a seasoned one, prepare their body to ensure they don’t experience loss of appetite?
“A certain degree of appetite suppression is inevitable,” Dr Jenkin says.
“However proper fitness and conditioning appropriate to the event or long run should reduce the chance of significant or prolonged loss of appetite.
“Unusually high training loads increase the risk of significant problems and certainly rapid increases in the length, intensity and frequency of training sessions and races should be avoided to prevent significant appetite suppression as well as other injuries and overtraining problems.”
But even if a runner doesn’t want to eat, it’s still important to keep the body fuelled to remain healthy and free of injury.
In the case of a reduced appetite or feelings of ‘fullness’, runners are encouraged to eat smaller amounts more often and avoid large heavy meals.
Dr Jenkin’s tip is to digest a liquid form, particularly in the hour or two after exercise, so electrolyte drinks or shakes containing both carbohydrates and protein are useful.
*When to seek medical advice
Prolonged appetite suppression could indicate an underlying medical problem and can certainly impact on recovery, general health and wellbeing, as well as limit the positive adaptation response to running training.
Symptoms such as increased fatigue, lethargy, poor sleep, vomiting, diarrhoea or abdominal pain, palpitations, frequent illness such as colds, headaches, dizziness or feelings of anxiety or low mood could indicate a problem such as overtraining, chronic fatigue, iron deficiency, anxiety or depression, or immune suppression.
Worrying signs include unexpected weight loss, pale skin or a higher resting heart rate than usual.
If any of these are present and do not resolve within a few days then it would be wise to seek medical advice. – Dr Simon Jenkin.
* Dr Simon Jenkin has a Bachelor of Medicine, Bachelor of Surgery (UWA) and is currently completing a Fellowship in Sports & Exercise Medicine at the Australasian College of Sports Physicians). He is a professional member of the Australasian College of Sports Physicians, AFL Doctors Association, Australian Medical Association and Sports Medicine Australia.