Whey protein isolate attenuates strength decline after eccentrically-induced muscle damage in healthy individuals.
BACKGROUND
We examined the effects of short-term consumption of whey protein isolate on muscle proteins and force recovery after eccentrically-induced muscle damage in healthy individuals.


METHODS
Seventeen untrained male participants (23 ± 5 yr, 180 ± 6 cm, 80 ± 11 kg) were randomly separated into two supplement groups: i) whey protein isolate (WPH; n = 9); or ii) carbohydrate (CHO; n = 8). Participants consumed 1.5 g/kg.bw/day supplement (~30 g consumed immediately, and then once with breakfast, lunch, in the afternoon and after the evening meal) for a period of 14 days following a unilateral eccentric contraction-based resistance exercise session, consisting of 4 sets of 10 repetitions at 120% of maximum voluntary contraction on the leg press, leg extension and leg flexion exercise machine. Plasma creatine kinase and lactate dehydrogenase (LDH) levels were assessed as blood markers of muscle damage. Muscle strength was examined by voluntary isokinetic knee extension using a Cybex dynamometer. Data were analyzed using repeated measures ANOVA with an alpha of 0.05.


RESULTS
Isometric knee extension strength was significantly higher following WPH supplementation 3 (P < 0.05) and 7 (P < 0.01) days into recovery from exercise-induced muscle damage compared to CHO supplementation. In addition, strong tendencies for higher isokinetic forces (extension and flexion) were observed during the recovery period following WPH supplementation, with knee extension strength being significantly greater (P < 0.05) after 7 days recovery. Plasma LDH levels tended to be lower (P = 0.06) in the WPH supplemented group during recovery.


CONCLUSIONS
The major finding of this investigation was that whey protein isolate supplementation attenuated the impairment in isometric and isokinetic muscle forces during recovery from exercise-induced muscle injury.
Cooke
Matthew B
MB
Exercise Metabolism Unit, Institute for Sport, Exercise and Active Living, School of Biomedical and Health Sciences, Victoria University, Melbourne, Australia.|Schools of Medicine and Human Movement Studies, Princess Alexandra Hospital, the University of Queensland, Brisbane, Australia.
Rybalka
Emma
E
Exercise Metabolism Unit, Institute for Sport, Exercise and Active Living, School of Biomedical and Health Sciences, Victoria University, Melbourne, Australia.
Stathis
Christos G
CG
Exercise Metabolism Unit, Institute for Sport, Exercise and Active Living, School of Biomedical and Health Sciences, Victoria University, Melbourne, Australia.
Cribb
Paul J
PJ
Exercise Metabolism Unit, Institute for Sport, Exercise and Active Living, School of Biomedical and Health Sciences, Victoria University, Melbourne, Australia.
Hayes
Alan
A
Exercise Metabolism Unit, Institute for Sport, Exercise and Active Living, School of Biomedical and Health Sciences, Victoria University, Melbourne, Australia.