Twenty-four well trained runners (VO2max 60.73.7 ml O2 Kg-1 min1) completed a six week block randomized controlled intervention period. Subjects were randomly assigned to either PRO-CHO or CHO and matched in pairs for gender, age, VO2max, training and performance status. The PRO- CHO group ingested a protein beverage (0.3g kg-1) before and protein-carbohydrate beverage (0.3g protein kg-1 and 0.1g carbohydrate kg-1) after each exercise session. The CHO group ingested energy matched carbohydrate. Post-absorptive muscle biopsies were obtained pre and post intervention for analysis HAD, CS and PGC-1. Subjects completed two physical tests 6 km performance test (pre, week 1 and week 6) and aVo2max test (pre and post intervention).

Inclusion Criteria:

1. maximal oxygen uptake (VO2max) of >50ml O2 kg-1 min-1 for women and >55ml O2 kg-1 min-1 for men,
2. running at least 3 times a week and
3. running being the primarily training form

Exclusion Criteria:

1. use of medicine
2. diagnosed metabolic diseases
3. injuries which hindered running and body mass index (BMI) < 25 kg m-2

Single blinded