How much protein is needed to maximize muscle protein synthesis in trained women? Original paper

In this randomized controlled trial in resistance-trained women, ingesting 30 grams of whey protein after performing resistance exercise maximally stimulated muscle protein synthesis.

The effect of different amounts of whey protein on postexercise muscle protein synthesis (MPS) rates in resistance-trained women.

24 women (average age of 27; average BMI of 24) with an average of about 7 years of experience in resistance training.

In this randomized controlled trial, the participants performed two bouts of whole-body resistance exercise 4 hours apart. Immediately after each session, the participants ingested either 15, 30, or 60 grams of whey protein.

To assess MPS, blood and saliva samples and a vastus lateralis (the largest quadriceps muscle) biopsy were taken at different time points:

• Before the first exercise bout (baseline)
• 4 hours after postexercise protein ingestion

The participants then performed the second exercise session, and the samples and biopsy were collected:

• 4 hours after ingestion of the second postexercise protein drink (8 hours after the first protein drink)
• The next morning (24 hours after the first protein drink), in a fasted state

After the third sample collection (8 hours after the first protein drink), the participants were provided with food and beverages that contained their total daily energy (calorie) requirements, all of which they consumed before 10 p.m. that evening.

Compared with baseline, MPS had increased at each time point (from 0–4 hours, 0–8 hours, and 0–24 hours) in the 30-gram and 60-gram groups, whereas MPS was not significantly different from baseline at any time point in the 15-gram group. The magnitude of change in MPS did not differ between the 30-gram and 60-gram groups.

The relative total daily protein intake, per kilogram of body weight, was 1.8, 2.3, and 3.2 grams in the 15-gram, 30-gram, and 60-gram groups, respectively.