One of the main causes of race failure (the dreaded DNF) or even just disrupted training is gastrointestinal (GI) symptoms. These may range from mild bloating & flatulence all the way to profound nausea and vomiting…not to mention runners trots…..
We have all been there, and often are quick to blame what or when we have eaten and vow to never repeat…..but is the best solution? In short, NO.
It is well understood that the strategised intake of nutrition, specifically carbohydrate (CHO), before, during and after exercise has been shown to improve performance by <7%. Avoiding nutrition at these times is likely to work against you, leaving you under fuelled and at high risk of hitting the wall during your training or an event.
So how do we balance getting enough nutrition in to adequately fuel our training while avoiding crippling GI symptoms?
The answer is gut training.
What is gut training?
Exercise places our gut (stomach, small & large bowels) under significant stress both mechanically; physically ‘bouncing it around’ and physiologically; via blood flow redirection. Consequently leading to changes in normal digestive mobility, stomach emptying times alongside altered absorption & secretion of nutrition in the intestines. All of which can manifest in GI symptoms.
However, our gut is a very plastic organ. Like you train your body; your cardiovascular system, your skeletal muscles etc to become more physiologically adapted to the exercise stimulus you are putting it under, so too can your gut become better at digesting and absorbing nutrition during exercise if you challenge it to do so.
Gut training is exactly this; repeatedly challenging your gut with larger volumes of liquid and nutrition, specifically carbohydrate (CHO) over time.
Why should I do it?
The whole point of gut training is to allow you to take on the nutrition and fluid needed for optimal performance without suffering GI symptoms. Repeatedly challenging you gut in this way can lead to the following benefits;
Increased gastric emptying and speed of digestion.
Increased ability of the small bowel to absorb CHO and therefore improve glucose provision to working muscles
Reduction of/ full avoidance of GI symptoms during exercise.
Where do I start?
The important thing here is giving yourself plenty of time to implement gut training strategies and recognising that it's not always going to be plain sailing…..the whole point is that you are ‘challenging’ your gut so this may feel uncomfortable at times.
While gut training strategies should be individualised, recommendations born from controlled and observational studies suggest that you would benefit from minimum one training session per week dedicated to gut training, for at least 5-10 weeks. Benefits have been seen in just 2 weeks in trained athletes.
There are several different strategies and ideally, all should be practised to improve both stomach and lower gut tolerance to nutrition prior to a goal event. These include:
Exercising directly after eating a meal i.e. on a ‘full stomach’
Exercising with large volumes of fluid in the stomach.
These strategies increase the stomachs volume capacity and ability to break down and empty food particles during exercise.
Increasing the CHO content of your baseline diet (<5-7g/ kg body weight/ day).
Training with increasingly more CHO during exercise. e.g. 15g > 30 > 60 > 90g/ hour
Training with different foods and different sources of CHO e.g. glucose & fructose .
These strategies increase CHO availability at the gut wall, in turn increasing the machinery (protein transporters) needed for CHO absorption into the bloodstream where it is available to the working muscles and body tissues.
How aggressively you do this will of course depend on your baseline i.e. do you already take on some CHO during exercise and have a habitually high CHO diet? or do you have no experience taking on nutrition during exercise and tend to avoid CHO in your wider diet?
What's the end goal?
Ultimately gut training will allow you to exercise pain and symptom free while still pushing towards your performance goals.
Reaching your optimal performance relies on strategic provision and timing of nutrition, specifically CHO. If GI symptoms are preventing you from taking on this nutrition, gut training is ESSENTIAL in you achieving your goals.
Want to start gut training but not sure where to start? Get in touch for personalised sports nutrition advice!!
#absorb #carbohydrate #gels #gastrointestinalsymptoms #stomach #guttraining #runnersgut #sportsnutritionadvice #fuellingstrategy #carbohydrates
Interested in the nitty gritty? Good reads below:
Miall, A., et al. (2017). Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scandinavian Journal of Medicine and Science in Sports, 28(2):630-640. doi: 10.1111/sms.12912.
Berg, A., et al. (1999). The gastrointestinal system--an essential target organ of the athlete's health and physical performance. Exercise Immunology Review, 5, 78-95. PMID: 10519063
Brouns, F & Beckers, E. (1993). Is the gut an athletic organ? Digestion, absorption and exercise. Sports Medicine, 15 (4), 242-57. doi: 10.2165/00007256-199315040-00003.
Costa, R. J. S., et al. (2017). Gut-training: the impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Applied Physiology, Nutrition and Metabolism, 42 (5), 547-557. doi: 10.1139/apnm-2016-0453
Jeukendrup, A. (2017), Training the gut for athletes. MySportsScience https://www.mysportscience.com/post/2017/03/25/training-the-gut-for-athletes
Jeukendrup, A. (2017). Training the Gut for Athletes. Sports Medicine, 42(5):547-557. doi: 10.1139/apnm-2016-0453. 47 (Suppl 1):101-110. DOI: 10.1007/s40279-017-0690-6
Miall, A., et al. (2017). Two weeks of repetitive gut-challenge reduce exercise-associated gastrointestinal symptoms and malabsorption. Scandinavian Journal of Medicine and Science in Sports, 28(2):630-640. doi: 10.1111/sms.12912.