Intake of whey isolate supplement and muscle mass gains in young healthy adults when combined with resistance training: a blinded randomized clinical trial (pilot study).
Study Goal
The researchers aimed to determine whether whey protein supplementation, rich in branched-chain amino acids, enhances muscle mass and strength when combined with resistance training in trained individuals.
Results Summary
Whey protein supplementation increased muscle thickness in some muscles but had no effect on strength. It also increased lean body mass without altering body fat percentage, though no interaction between training and supplementation was found.
Population
Resistance-trained men and women aged 18-30 years.
Effective Dosage
Not specified
Duration
12 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
whey protein isolate | increase | muscle thickness of vastus intermidius at 50% | resistance trained participants (men and women) between the age of 18 and 30 years old | P=0.045 | increase in muscle thickness | #1 |
whey protein isolate | increase | muscle thickness of vastus intermidius at 30% | resistance trained participants (men and women) between the age of 18 and 30 years old | P=0.075 | trend in increase in muscle thickness | #2 |
whey protein isolate | no change | peak torque | resistance trained participants (men and women) between the age of 18 and 30 years old | - | no effect | #3 |
resistance training | increase | muscle thickness of all muscles | resistance trained participants (men and women) between the age of 18 and 30 years old | - | increase in muscle thickness | #4 |
resistance training | increase | peak torque for all knee flexors/extensors | resistance trained participants (men and women) between the age of 18 and 30 years old | P<0.05 | increase | #5 |
resistance training | increase | peak torque for elbow flexors/extensors at 60º extension and 180º flexion | resistance trained participants (men and women) between the age of 18 and 30 years old | P<0.05 | increase | #6 |
resistance training | increase | lean body mass | resistance trained participants (men and women) between the age of 18 and 30 years old | P=0.015 | increase | #7 |
resistance training | no change | body fat percentage | resistance trained participants (men and women) between the age of 18 and 30 years old | P>0.05 | maintained | #8 |
whey protein supplementation combined with resistance training | increase | muscle mass | - | - | increase | #9 |
whey protein supplementation combined with resistance training | no change | muscle strength | - | - | no effects | #10 |
whey protein supplementation | increase | body composition | - | - | alter body composition in favor of additional fat free mass | #11 |
whey protein supplementation | no change | body fat | - | - | no significant changes | #12 |
BACKGROUND: Whey protein is consumed worldwide by athletes due to its alleged benefits on muscle mass and strength. Because of its rich branched chain amino acids content, namely leucine, whey appears to favor muscle protein synthesis through the mTOR pathway in combination with resistance training, when taken after exercise in sufficient amounts. METHODS: In the present study resistance trained (≥3 months) participants (men and women) between the age of 18 and 30 years old were randomized in a blinded fashion to whey protein isolate (N.=4) and an isocaloric placebo (N.=4) groups. Both groups were subjected to a 12-week RT protocol designed to increase muscle mass and strength. Muscle thickness of the biceps brachii (BB) at 67% of its length and quadriceps muscles, vastus lateralis (VL); vastus intermidius (VI) and rectus femoris (R.F.) at 30% and 50% of its length were assessed using ultrasound technique. Muscle strength was assessed using an isokinetic protocol at angular velocities of 60º.s-1 (5 repetitions) and 180º.s-1 (10 repetitions) with a range of motion of 0º to 100º on a dynamometer to determine peak torque (PT). Lean body mass (LBM) and body fat percentage (%BF) were assessed using a body composition analyzer through segmental multi-frequency bioelectrical impedance method. All variables were assessed before and after interventions. RESULTS: Results show an increase in muscle thickness of all muscles from RT except for V.L. and RF at 30% (P>0.05) with an increase in VI at 50% (P=0.045) and a trend in VI at 30% (P=0.075) related to whey protein intake. PT increased with RT for all knee flexors/extensors (P<0.05) and for elbow flexors/extensors at 60º extension and 180º flexion (P<0.05) with no effect from whey. LBM increased with RT (P=0.015) and %BF was maintained during the trial (P>0.05). No interactions were found between training and supplementation. CONCLUSIONS: Supplementation with whey protein, combined with RT can increase muscle mass with no effects on muscle strength. Whey protein supplementation may alter body composition in favor of additional fat free mass with no significant changes in body fat.