The Impact of Low Energy Availability on Female Endurance Athletes: Immune Function and Performance Risks
Welcome back to another little research review! This week i’m diving into a paper that investigated the impact of low energy availability on exercise performance in female endurance athletes by Jeppesen et al (2024)
Low energy availability is something that I am often looking to combat when working with ultra endurance athletes as we know it can seriously affect a tonne of contributors to performance. Here we’ll establish what exactly it is and see what new insights this paper has provided!
What Is Low Energy Availability and Why Does It Matter for Athletes?
Low energy availability (LEA) refers to a state where an athlete’s dietary intake is insufficient to meet the energy demands of their training and day to day life. This leads to several potential issues that when grouped together are called Relative Energy Deficiency in Sport, or RED-S.
In female athletes, it used to be known as the female athlete triad as the three main components of RED-S were:
Low energy availability itself!
Menstrual dysfunction
And low bone mineral density
However when RED-S occurs we now know it can impact a number of other things and contribute to fatigue, reduced CNS drive, increased injury risk, decreased co-ordination, poor concentration and reduced strength among many other things!
What This Study Was Looking Into
The study we’re diving into was investigating the impact of 14 days of LEA on immune function and exercise performance. They tracked several markers including reactive oxygen species in immune cells, cortisol levels, body composition, time to exhaustion and more.
They focussed a lot on the impact at a cellular level to identify if there were any serious impacts on LEA on immune function.
What Did They Find?
After the 14 days of LEA they saw increased markers of oxidative stress as a rise in reactive oxygen species. They also saw a 22% increase in systemic cortisol, an impaired immune response in the form of reduced leukocyte mobilisation, and of course a reduce in exercise performance.
They also found that the reduction in performance still persisted after three days of refuelling.
What Are The Key Takeaways
This paper essentially just serves to reinforce what we already know about LEA and RED-S. It’s damaging, not only to performance but to our health too! The insight into how detriments to performance persisted even after 3 days of refuelling is also eye opening and reinforces that the best way to deal with LEA is to not put athletes in that position in the first place.
In terms of real world applications this is something that I always consider with my athletes. When i’m working with endurance or ultra endurance athletes, there may be some benefit in putting them in a deficit at certain points across the year to lean out. But IF this is something we do, then we make sure to periodise nutrition so that it occurs away from both peaks in their training volume and competition to ensure that when needed they are fuelled and ready to go! I will NEVER put an athlete in a state of low energy availability around competition or during a particularly intense training block.
What Are The Signs To Look Out For Of Low Energy Availability
At the top of this blog we mentioned the female athlete triad, which are good markers of LEA in females, but there are more to look out for, especially for male athletes. These include:
Low energy and general feelings of weakness and fatigue
Poor recovery and repair from training i.e. feeling sore and drained going into and during sessions
Plateau or reduced strength and/or muscle size
Catching coughs, colds and infections more often (decrease immune function)
Lack of sex drive
Depression
Irregular periods/ change in cycle or period length
Increase in injuries
Stress fractures
Restricting eating to certain food groups
Feelings of guilt after eating certain foods or missing training
if you notice any of these signs then it may be a sign of under-fueling! So either dial back the training or add in some fuel, or both! Don’t let low energy availability impact your goals!
Need Help Optimising Your Nutrition?
I’ve worked with countless athletes to combat LEA and optimise their performance. See how I can help here.
