There’s no doubt ultramarathon running is a tough sport. As ultra’s get longer and harder, a specific understanding of fatigue and recovery for these events will help runners better complete, and compete in these amazing feats.

A new study just published investigated the differences between single-stage and multistage ultramarathon events on fatigue and recovery.

The 2020 French study published in Medicine & Science in Sports & Exercise provides some interesting insight into how the two different types of ultramarathons- single (SSR) and multi-stage (MSR) races- result in differing levels of fatigue and recovery for its participants. It’s the first study looking to compare the way these two endurance events impact the body and how this impact may differ.

For the study, researchers divided 31 runners into two groups to run a 169-kilometre course. One group of 17 ran it in a single-stage day while the other group of 14 completed the course over four days, averaging approximately 40 km/day.

Researchers assessed the participants’ neuromuscular function before and after completing the course, as well as two, five and ten days after the race, using electrical nerve stimulation on the runners’ knee extensors and plantar flexors.

Before I tackle the results of the study, let’s first discuss two types of neuromuscular fatigue – central and peripheral.

Central fatigue occurs in the brain and spinal cord (central nervous system) and results in general body fatigue from both neural and psychological mechanisms. It’s more an overall feeling of being tired and not wanting to continue, which can/will result in muscle weakness and fatigue.

Peripheral fatigue occurs in the actual muscles where muscle energy supplies are exhausted. This type of fatigue is local, such as when you run 200m as fast as you can and lose power in the last 10m.

Both types of fatigue will affect muscle force, and reduce performance.

Back to the study - the results demonstrated that single-stage runners exhibited greater levels of central fatigue in their tests directly after completing the course, but the multi-stage runners were found to have prolonged impairments of muscle contraction (peripheral fatigue) which resulted in longer neuromuscular recovery times.

So why the difference? It may be that that the multi stage racers went ‘harder’ each day, further depleting local muscle energy stores, whereas the single stage racers were better at keeping up nutrition and replenishing energy stores but the CNS just kept getting stimulated (emotional toll of no rest, constant processing of nutrition, lack of sleep etc).

If you want to read more into the study click here for the link.

This study raises a couple of important considerations for all endurance athletes. Firstly, it’s important to get an understanding of what type of fatigue you’re experiencing. If your fatigue has a peripheral bias, targeting the neuromuscular junction and local muscle energy stores with energy dinks/gels may assist in the short term. If it’s more central, getting a quick boost may not be as easy – as rest and sleep are the two key strategies to help with central fatigue.

Secondly, and in particular relation to central fatigue, what ‘shape’ you go into an event will have an enormous influence on how much you experience central fatigue. If your CNS is in overdrive before you race or train – stressed, lacking of sleep, overstimulated on the day by the event itself, and/or chronically tired from training, you’re likely to get flat and weary very quickly.

Everyone will experience fatigue when undertaking ultramarathons and endurance events, however preparation is (again) crucial reducing the impact of fatigue on the day. Aim to go into each event calm, well rested, and well trained to combat central fatigue and have your nutrition regime dialled in to help reduce peripheral fatigue.

Recovery = rest and sleep. Anything else is a marginal gain.

Photo: #PremaxAthlete James MacKeddie