In this edition, we explore why marathon fatigue can linger long after race day, how and when to use “sleep low, train low” approaches effectively, and simple ways to optimise nutrient absorption to support both performance and recovery.

After a big race, lingering markers of fatigue can last weeks and whilst muscle soreness may have subsided, CNS fatigue means your legs can still feel ‘flat’.

Ignoring your body's fatigue signals can lead to incomplete recovery, chronic energy availability issues and, in some cases, injury.

So, should you just get on with it and keep training? No.

In the days post-race the body craves carbohydrates to replenish glycogen stores and restore energy availability. Many runners cut carbs after race day as training volume drops, but post-marathon your fuel tank is empty and still needs refuelling.

Prioritising sleep, nutrition and hydration alongside a gradual return to training is key to promoting recovery and being ready to perform when the next big challenge comes your way.

The default approach to endurance nutrition has long been simple: eat plenty of carbohydrate, train a lot, recover, repeat. But strategic restriction of carbohydrate around certain sessions may enhance the adaptations your body makes to training. This is the principle behind sleep low, train low and we’re seeing a re-emergence of interest in this strategy.

An athlete completes a high-intensity evening session, restricts carbohydrate overnight, then trains again the following morning in a low-glycogen state. The result is an extended window (potentially 12 to 14 hours) during which muscle glycogen remains suppressed.

When glycogen falls below a threshold, key molecular sensors become more active, triggering pathways that regulate mitochondrial biogenesis (new mitochondria) and fat burning or ‘oxidation’. The muscle is signalled to adapt more aggressively to the training stress it has experienced.

Short periods of sleep low training have improved cycling time trial and running performance compared to traditional high-carbohydrate approaches in trained athletes. In fact, I was an investigator in a study that showed exactly this; our short-term “sleep low-train low” intervention improved functional threshold power compared with typically “normal” CHO availability during exercise. The metabolic adaptations are most likely to translate to meaningful gains over longer durations where metabolic flexibility becomes a genuine performance determinant.

Sleep low works best around low-intensity, steady-state morning sessions where glycogen restriction will not compromise training quality. It is not appropriate before high-intensity intervals.

Within a well-periodised training week, the guiding principle remains fuel for the work required i.e. high carbohydrate availability when intensity matters, strategic restriction when adaptation is the goal.

Sleep low, train low is an evidence-based tool, but it requires precision. Used strategically, it creates a metabolic environment conducive to greater adaptation. Used carelessly, it risks undermining training quality and health.

👉At The Edge HPL, we can help you implement such strategies through our consultation services.

Add a source of vitamin C to meals, such as a lime/lemon wedge, handful of citrus fruit or berries, to help increase iron absorption and support your immune function.