Muscle damage is the main impediment to performance in ultramarathons
As anyone who has run an ultramarathon can testify, running longer than a marathon presents unique challenges compared with standard endurance events. The recent paper by Tiller and Millet (2004), highlights that muscle damage—more than aerobic capacity or running economy—is the main impediment to performance in ultramarathons exceeding 100 km. This type of muscle damage leads to peripheral fatigue, pain, and decreased muscle function, often occurring even second 3rd of the race. Unlike issues like gastrointestinal distress, muscle damage cannot be resolved during the race, making preparation essential.
Understanding Muscle Damage
During long ultramarathons, muscle damage stems from mechanical, metabolic, and oxidative stress. Indicators such as creatine kinase (CK) can rise from normal resting levels (34–171 U/L) to over 10,000 U/L following an event, showcasing the severe impact on muscle integrity. This damage disrupts force transmission, induces soreness, and reduces range of motion, leading to significant performance decline. Tiller and Millets’ paper suggests that athletes, despite having very high V02max, will sacrifice optimal running economy by using tools such as poles, or altering gait by taking shorter strides, to limit muscle stress during prolonged races. This results in a slower pace, but greater durability for the longer distances required.
Training Strategies for Resilience
To counter muscle damage, you want to integrate strategies such as progressive downhill running to get used to the eccentric forces, as well as the basic foundation of gradually increase weekly mileage. There is an unavoidable correlation between greater weekly mileage and faster finishing times (for most people… there will always be exceptions who can perform on lower mileage). These practices help condition the muscles to endure the eccentric loads typical of ultramarathon courses. The paper emphasizes that while improving aerobic metrics is valuable, muscle damage tolerance is critical for sustained performance.
Mid-Race Nutrition: The Role of Protein
Protein intake during long events has been posited to aid in reducing muscle protein breakdown. Though empirical data is limited, it’s recommended that athletes consider consuming approximately 0.1–0.4 grams of protein per kilogram of body weight per hour during races. This equates to around 20–30 grams of protein every 3hrs for an average athlete, particularly when combined with carbohydrates to enhance absorption and maintain energy levels. This will often fit with an aid station falling around a usual meal time (Breakfast, Lunch, Dinner). While not a guaranteed solution to muscle damage, this approach may support muscle preservation over ultra-endurance events.
Practical Tips for Runners
Training: Integrate gradual increases in running mileage and downhill running to build muscle resilience.
Racing: Use trekking poles and adjust stride length to manage muscle load effectively.
Nutrition: Supplement with protein (15–30 grams/hour) alongside carbohydrates to sustain muscle function.
Muscle damage is an unavoidable aspect of ultramarathons, but understanding its implications and employing tailored strategies can help athletes optimise their training, manage mid-race fatigue, and ultimately enhance performance.
Tiller, N.B., Millet, G.Y. (2004) Decoding Ultramarathon: Muscle Damage as the Main Impediment to Performance. Sports Med
