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What you need to know as a trail runner about low energy availability and RED-S

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What you need to know as a trail runner about low energy availability and RED-S

By Tina Buch on 9th September 2022 Nutrition

What you need to know as a trail runner about low energy availability and RED-S


Guest Article

Tina Buch is a NZ Registered Nutritionist, completing her master's thesis in nutrition at Massey University. Tina is studying recreational trail runners and the risk of low energy availability, whilst also aiming to give back to the trail running community by creating some simple resources and tips to support trail runners with improving their performance.

You probably have heard the terms low energy availability (LEA) or relative energy deficiency in sport (RED-S) floating around lately. In fact you may have seen some social media post/s or read about the topic in some of New Zealand’s high performance sports such as rowing, running, and cycling. As a nutritionist and researcher, I am always thrilled to see discussions on this area that I hope drive increased awareness on the topic for athletes (elite through to the everyday person).

To start off, I thought it would be a good idea to clarify what these two terms mean:

We know that we eat food to give us enough energy to exercise and for our body to function. As a nutritionist when I use the term ‘energy availability’, I am not describing all the energy you have available for exercise and normal body functions. Instead, once I have eaten my food for the day and then used energy to exercise or do my daily activities (e.g. work, housework, playing with kids, gardening, commute to work), I should have some energy left over that can be used for my normal body functions (e.g. breathing, muscle recovery, growth). The energy that is left over from the food we eat and is available for our bodies to use for normal body functions is energy availability.

When someone describes themselves as having low energy availability, typically what they mean is that they have not eaten enough to provide energy for exercise and normal body functions. Since our body does not have enough energy for normal body functions, we start to see these gradually shut down.

To describe the effect of low energy availability on our body, scientists and nutritionists have grouped all of the common health and exercise performance symptoms and given it the name RED- S. The best treatment and prevention of RED-S is knowing what to look out for (symptoms) and education on nutrition.

Health Consequences (source: https://bjsm.bmj.com/content/52/11/687)

Potential performance consequences (source: https://bjsm.bmj.com/content/52/11/687)

As a trail runner what do I need to know?

Athletes and people at higher risk of RED-S tend to be those who are involved in sports that have a ‘lean’ stereotype or are ‘weight-focused’. As trail runners we could be at a higher risk for RED-S due to the high energy demand of our sport. This comes from running over varied terrain, in various weather conditions, in remote locations, and over long distances. We also tend to have high training mileage. All of these training and racing demands mean we should have a high food intake to provide enough energy for our sport and for normal functioning of our bodies.

You may think this doesn’t apply to you as you are ‘just’ a recreational trail runner. But research has shown that both elite and recreational runners can be affected by RED-S. In fact, as a recreational runner you may be at a higher risk, because you may not have nutrition coaching support like many elite athletes do.

Nutrition knowledge may be a key factor in helping you to understand when and how much food to eat. There is research that tells us that athletes/people with higher levels of (sports) nutrition knowledge have a more nutritious diet. But knowledge doesn’t always change behaviour. Food intake is also impacted by the cost of food, cooking skills, taste preferences, lack of appetite, gastrointestinal issues, pressure (own or others) to stay lean, social media trends, popular diets (e.g. vegan, low carb), and changes in training.

Increasing your sports nutrition knowledge can be very valuable for your sport performance and health. But the question people often ask me is: Where should I look to get this information? The internet is a minefield of both correct and incorrect info! I would advise using websites like Sports Dietitians Australia. This has a range of science-based factsheets covering a variety of useful topics. Alternatively, I would also suggest getting some personalised advice from a Registered Dietitian or Registered Nutritionist.

Am I at risk?

Normally we see RED-S symptoms after athletes or active people have been in low energy availability for a long period of time (weeks-years). Or they may have very quickly and dramatically reduced their food intake, known as severe low energy availability. Being in low energy availability can happen if someone is worried about how their body looks while doing sport. Or they may try to lose large amounts of weight for sport performance. It could also happen by mistake. People may not know or feel like increasing their food intake when they start doing more exercise. The result is they may accidently end up in low energy availability.

The symptoms you may show if you are in low energy availability include (but are not limited to) low mood, reduced performance, delayed recovery, ongoing fatigue, frequent illness or injury, irregular menstruation, and lowered libido. Try out this checklist from the Australian Institute of Sport to see if you’re eating enough for your exercise and normal functioning. If you feel like you are ticking a lot of these boxes, it doesn’t necessarily mean that you are in low energy availability. But it may be worth investigating and looking at your food intake. If you would like personalised support, then I would strongly encourage you to seek advice from a Registered Dietitian or Registered Nutritionist.

It is important to remember that as trail runners we need to look after our bodies. It’s not just about going the longest distances or crossing the finish line first. If we fuel our bodies with nutritious food and adequate energy it will ultimately make running more enjoyable but also improve our performance and optimise our health.

Trail NZ Nutrition Survey

If you’re interested in the topic of this blog, perhaps you will also be interested in participating in an exciting new study which looks at how nutrition knowledge influence health and performance in trail runners and walkers in Aotearoa.

I’m currently doing my master’s research on this topic and I’m looking for trail runners and walkers of all experience levels to participate in my online survey.

To participate you should be:

  • 16 years or older
  • Based in Aotearoa/New Zealand
  • Training for trail running/walking at least 2½ hours per week

If you meet these criteria and would like to participate, please click this link to find out more information about the study and take our online survey.

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