Abstract
BackgroundThe 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.MethodsEighteen 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.ResultsThe 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.ConclusionsThese 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.
Highlights
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
Muscle strength was demonstrated a decrease after the eccentric exercise, but no group (p = 0.73) or group × time interaction (p = 0.90) was observed for each ingestion
The mean percentage of muscle strength loss in all groups was showed −36.7 ± 4.3 % at day 1, after that it was slightly increased at day 2 (−24.2 ± 7.5 %) and day3 (−23.9 ± 3.4 %), but it was decreased at day 5 (−33.3 ± 1.0 %) compared to the pre values
Summary
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. High-intensity resistance training involving eccentric contractions appears essential for increasing muscular strength and hypertrophy. Such intense exercise disrupts the microstructure of muscle fibers and can result in severe muscle soreness, reduced strength, and reduced overall performance. Minimizing muscle soreness and enhancing muscle recovery may optimize strength and hypertrophy after exercise sessions. Whey protein isolate with high protein purity contains abundant essential and branched-chain amino acids [6] and has rapid absorption kinetics than casein protein [7]. Whey protein isolate ingestion increases blood amino acid concentration and stimulates muscle protein synthesis [6]. Ingestion of whey protein isolate of 15 g has been reported to enhance signaling for muscle protein synthesis through mammalian target
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