2 Whey Protein Isolate A Day Boosts Muscle Growth
In addition to resistance training, protein ingestion may play an important role as a regulator of muscle mass and recovery from exercise. Whey is considered to be a high-quality protein source containing large amounts of essential amino acids, important in the protein synthesis, and also fast acting compared to many other protein sources such as casein. It is thus possible that addition of whey, when used chronically in conjunction with resistance exercise may be more anabolic for skeletal muscle than ingesting only normal mixed meals throughout the day. Most people get plenty of protein in their diet, but researchers wanted to examine long-term adaptations from resistance training in terms of whole-muscle size, force production, and muscle hypertrophy related gene expression that may occur when high-quality protein isolate is added to a ‘‘normal diet’’ both immediately before and after each resistance exercise session.
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The subjects were randomly assigned after control testing sessions to either a whey protein isolate group, placebo group, or a control group. There was no resistance training in the controls, but they continued their habitual activity such as jogging, swimming or ballgames. During the 21-week-resistance training period, total-body heavy resistance exercise workouts were carried out twice a week. Subjects trained all their large muscle groups, with the leg-press, leg-extension, leg-curl, chest-press, shoulder-press, lat-pulldown, biceps-curl and triceps-extension, calf-raises and finally the leg-abduction and leg-adduction.
A minimum of 2 days of rest was required between the two sessions each week. Either 15 grams of whey isolate protein dissolved in water or an equivalent amount of non-energetic placebo was ingested immediately before and after each bout of RE in the gym. The researchers examined muscle growth, and muscle anabolic signaling genes, and also the muscle catabolism gene myostatin. The major findings of the present study investigating both acute and long-term effects in previously untrained young men were as follows:
- Both groups increased lean muscle mass, but they whey protein group improved more. At the end of the 21 weeks, the placebo group had gained 2.57 kg lean body mass. The whey protein isolate group had gained 3.1 kg lean body mass. Timed intake of 15 g of whey protein isolate both immediately before and after each exercise session further increased resistance training-induced vastus lateralis (i.e. quadriceps) muscle hypertrophy.
- Anabolic gene responses were further enhanced with whey protein isolate compared to the control group.
In conclusion, high-quality whey protein intake before and after resistance exercise appears to further augment resistance training-induced muscle hypertrophy in previously untrained subjects. Whey protein isolate intake close to resistance exercise workouts may alter mRNA expression in a manner advantageous for muscle hypertrophy.