Effects of combined β-hydroxy-β-methylbutyrate (HMB) and whey protein ingestion on symptoms of eccentric exercise-induced muscle damage

Background: the purpose of this study was to examine the effects of combined β-hydroxy-β-methylbutyrate (hmb) and whey protein ingestion on muscle strength and damage following a single bout of eccentric exercise. methods: eighteen untrained male subjects were assigned to hmb and whey protein (hmb + whey; 3 g/day hmb and 36.6 g/day whey protein,n = 6),hmb (3 g/day,n = 6),or whey protein (36.6 g/day,n = 6) groups. ingestion commenced 7 days before non-dominant elbow flexor eccentric exercise (30 deg/sec,6 reps × 7 sets) and continued until 4 days post-exercise. the maximal isometric strength,muscle soreness,plasma creatine kinase (ck),lactate dehydrogenase (ldh) were assessed pre-exercise,and at 1,2,3,and 5 days after exercise. results: the change scores of maximal isometric strength significantly decreased at day 1,2,and 5 in the whey protein group compared to pre value and that in hmb + whey protein and hmb groups decreased at day 1 and 5. the muscle soreness significantly increased in the whey and hmb + whey protein groups at day 3 compared to pre value (p < 0.05). ck and ldh significantly increased (time effect: p < 0.05) after exercise. however,all data were not significant difference among the groups. conclusions: these results suggest that ingestion of combined hmb and whey protein does not have a role to inhibit muscle strength loss and soreness,and decrease in muscle damage markers after eccentric exercise in comparison with hmb and whey protein alone. © 2016 shirato et al.