There is no conclusive evidence about the effect of intake of protein-enriched drink after and acute high intensity exercise bout on muscle function and damage. The investigators aimed to study the effect of a protein-enriched drink on muscle function recovery following an acute high intensity exercise bout. The present counterbalanced, crossover, and double blind study will involve a total of 12 active men.

Participants will run downhill (-10%) during 30 min at a intensity equivalent to 75-80% of their maximum heart rate (previously determined). After the exercise bout, participants will have either the placebo or the experimental drink. The investigators will measure muscle function and damage-related parameters right after the exercise as well as the three following days. This protocol will be repeated after a wash out period of 3 weeks, where the participants will have the other drink. The investigators will control exercise and diet three weeks before study entry, during the experimental week as the investigators as during the wash out period.

Inclusion Criteria:

• Recreational triathletes with 2 years of experience
• Maximum oxygen uptake : ≥55 ml/kg/min
• Fat mass: 8-20% measured by dual energy x-ray absorptiometry
• Not participating in another study
• Not having ergogenic aids
• Not participating in a weight loss program
• Normal electrocardiogram
• Participants must be capable and willing to provide consent, understand exclusion criteria and accept the randomized group assignment

Exclusion Criteria:

• History of cardiovascular disease
• Diabetes or hypertension
• Medication for hypertension, hyperlipidemia, hyperuricemia or other illness.
• Smoking
• Other significant medical conditions that are life-threatening or that can interfere with or be aggravated by exercise.
• Unwillingness to either complete the study requirements or to be randomized into control or training group.