Injured runner series: causes of running injuries - part C: Recoverability

If you've spent any time in the exercise performance or longevity research space, you've heard the essentials: sleep, nutrition, stress management, and hydration. I'd argue that all four of these variables share a common mechanism, they increase recoverability. This holds true across the general population and athletes of all types, but it is especially relevant for runners, who accumulate among the highest volumes of cardiorespiratory and musculoskeletal stress of any sport.

The fundamental equation of adaptation is simple: Stress + Rest = Recovery. But rest isn't passive. A more accurate framing is: Stress + Recoverability Measures = Recovery. Here, we'll focus on two of the most evidence-supported recoverability levers available to runners: sleep and nutrition.

Sleep

The relationship between sleep and athletic performance has been studied for decades. Charest & Grandner (2020) commented on a 1991 paper by Mougin et al. which found that reducing sleep by just three hours increased heart rate, lactate production, and ventilation frequency while decreasing VO₂ in cyclists(1). Each of these changes reflects a body working harder than it should at a given workload. a pattern that sustained over time, creates the conditions for injury. Charest & Grandner also found that adolescents aged 12–18 who slept fewer than eight hours per night had a 1.7x higher injury risk compared to peers who slept more than eight hours.

More recent data supports this relationship in runners specifically. A prospective study by Goldberg and colleagues following 339 runners over 26 weeks found that poor sleep quality was significantly associated with increased injury risk (2). Sleep quality was tracked weekly using the Hooper questionnaire, suggesting that self-reported sleep may serve as a practical early warning indicator for injury risk. In collegiate cross-country runners, poor sleep quality was similarly associated with higher injury rates during the competitive season (p=0.04), with 53% of athletes sustaining new injuries over the course of the study(3). Pre-existing injury history, large mileage increases, and poor sleep quality emerged as the primary risk factors (which make up the other major pillars of causes in our Injured Runner Series)

Nutrition

Poor nutrition, and inadequate caloric intake in particular, is one of the most well-documented and underappreciated drivers of injury risk in athletes. The central mechanism is low energy availability (LEA): a state in which energy intake is insufficient to meet the body's needs after accounting for exercise energy expenditure. This is something endurance athletes are particularly at risk for. When the body is chronically under-fueled relative to training load, it begins making physiological tradeoffs that compromise tissue repair, bone health, and immune function.

The prevalence of LEA is striking. A 2025 systematic review and meta-analysis found that 44.7% of athletes across multiple sports met criteria for low energy availability, with those affected showing impaired bone health and elevated risk of bone stress injuries(4). As the authors note, endurance athletes are disproportionately affected. In runners specifically, a 2025 meta-analysis found that injured female runners consumed an average of 303 fewer calories and 20 fewer grams of fat per day compared to their uninjured counterparts(5). Runners of both sexes with lower dietary fiber intake, roughly 3 g/day less than their uninjured counterparts, also showed increased injury risk.

Energy availability below 30 kcal/kg of fat-free mass per day is clinically significant (see example calculation below). Hormonal disruptions, including luteinizing hormone suppression, have been documented after as few as five days of reduced energy availability, with downstream effects on menstrual function and bone mineralization. The 2023 IOC consensus statement on Relative Energy Deficiency in Sport (REDs) (6) reinforces this, identifying LEA as a threat to bone health, immune function, and protein synthesis, all systems with direct implications for injury risk.

One practical way to assess LEA risk is through the energy availability equation: (7)

EA = (Total calories consumed − Exercise energy expenditure) ÷ kg of fat-free mass

As an example: a runner who consumes 2,800 kcal and burns 800 kcal through exercise, with 68 kg of fat-free mass, has an EA of 29.4 kcal/kg FFM , just below the critical threshold of 30. Bringing intake up to approximately 2,900 kcal would push EA above that threshold.

The Bottom Line

Sleep and nutrition are two of the most impactful and most modifiable recoverability variables available to runners. The evidence is consistent: poor sleep quality / quantity and insufficient caloric intake each independently elevate injury risk, and their effects are likely compounded when both are present. For runners looking to stay healthy and train consistently, adequate sleep and sufficient fueling aren't optional recovery strategies, they're foundational ones.