COACH’S CORNER - Do We Ever Train Our Gut? by Lisa Sherman

As runners, we invest a lot of time and energy into our training and our running goals. We often follow specific training plans for our planned race, completing regular run sessions each week to train our muscles to run further and faster. Many of us will also incorporate other activities such as strength training, mobility work and regular massages, all to help improve and build on our endurance and capacity.

But how many of us also plan out our nutrition and consider regularly training our gut to help support and optimise our running training and performance?

Many a runner has experienced a gastrointestinal (GI) issue during a run such as gut discomfort, nausea, vomiting, heartburn, bloating, intestinal cramps, side stitch, gas, diarrhoea or constipation. Research shows that 60-90% of runners have experienced some form of GI upset during ultramarathons (1), and we know this can impact our performance as our ability to consume nutrition during (and after) the run may become limited (often due to loss of appetite or flavour fatigue), our energy stores become depleted leading to increased fatigue and perhaps having to withdraw or DNF, or just having a really bad day out running, neither of which is a whole lot of fun.

Exercise does cause stress on the GI system, largely due to the reduction in blood flow to the gut (as blood flow is redistributed to our working muscles and extremities), which may impair our GI function and delay gastric emptying and intestinal transit, and also impair digestion and absorption of nutrients. Whilst the reasons for GI issues during exercise are multifaceted and individualised, our GI system does have the ability to adapt and we can train our gut to better tolerate nutritional intake during a run.

We have all heard the golden rule of nothing new on race day – no new shoes, clothing, kit and this should also extend to our nutrition (both food and fluid intake), so many runners will practice race day nutrition on some of their runs, especially the long runs.

Whilst this is a good step, we should consider every run an opportunity to train the gut to help reduce the occurrence or the likelihood of some of these gut issues and provide some beneficial effects including our muscles’ ability to use energy and improved tolerance of food, leading to enhanced exercise performance. This should include not just what we consume during the run, but also what we eat before a run and importantly, what we eat post run to help maximise recovery.

We can take a more structured approach to help train the gut, such as ingesting a higher amount of carbohydrate over subsequent run days or regularly during our runs so that we improve our body’s ability to tolerate the higher amount (2). General guidelines suggest an intake of 30-90g of carbohydrate per hour for endurance exercise however this is dependent on exercise intensity, and also individual needs and tolerability. For exercise over 4 hours, consuming around 90g of carbohydrate per hour (from a mixed blend of glucose and fructose to help nutrient transport and absorption), is recommended however you do need to practice this higher carbohydrate intake.

We should also plan our nutrition for the week alongside our training plan, taking into consideration what sessions we are doing and what availability we have to eat before and after based on our schedule.

Each run session is an opportunity to trial and practice our nutrition including different food and fluid options, concentrations and quantities so that we can work out what our individual tolerance levels are. I like to think of it as continually experimenting on ourselves, be the n=1 and try new things to work out what you have available in your nutrition tool kit to support you on race day.

It is also important to plan ahead to race day and consider what options will be available on course at aid stations and will you rely on these or be more self-sufficient? What is the likely time duration of the race and will you need to consider alternative food options as the length of the race increases? How long will you need to travel to get to the start line and whether you will need to allow some extra time to eat before, and so on.

Ideally our weekly long runs should mimic race day so you are training your gut to adapt and be ready for what you are going to do on the day, including the day before, the morning of and after you have crossed the finish line. As we know – nothing new on race day!

Regardless of whether you experience GI issues during a run, we can all benefit from continually practicing our nutrition during our runs. Ultrarunning is a demanding sport and optimal nutritional intake is essential to support your training, recovery and performance. Experiment and practice different options and it is always a good idea to chat with a qualified nutritionist or dietician, especially one with sports and performance knowledge to help you work out what’s right for you to support your ultrarunning goals.

Lisa sherman is a qualified nutritionist and recreational running coach, helping women train for their first marathons and trail races in NSW. if you would like more information on being trained by lisa, click through here to our aura endorsed coaches page.