Variable Time Point WP CHO p-value IRS-1 Baseline 15.68 ± 9.6 19.52 ± 6.4 Supplement (S) = 0.88   15 min CB-839 in vitro post-exercise 29.04 ± 6.6† 22.28 ± 11.2 Test (T) = 0.04†#   120 min post-exercise 25.40 ± 6.0 19.65 ± 9.2 S × T = 0.44 Akt Baseline 5.04 ± 1.9 6.88 ± 1.1 Supplement (S) = 0.21   15 min post-exercise 6.04 ± 2.6 5.61 ± 4.1 Test (T) = 0.35   120 min post-exercise

4.78 ± 1.4 4.58 AR-13324 chemical structure ± 2.1 S × T = 0.82 mTOR Baseline 3.34 ± 0.34 3.62 ± 0.19 Supplement (S) = 0.93   15 min post-exercise 3.75 ± 0.62 3.66 ± 0.27 Test (T) = 0.002†   120 min post-exercise 3.33 ± 0.19 3.52 ± 0.28 S × T = 0.34 P70S6K Baseline 8.51 ± 3.2 10.41 ± 3.2 Supplement (S) = 0.96   15 min post-exercise 14.14 ± 6.6 11.18 ± 2.9 Test (T) = 0.04   120 min post-exercise 13.32 ± 6.1 11.24 ± 5.0 S × T = 0.74 4E-BP1 Baseline 4.30 ± 2.4 5.33 ± 1.7 Supplement (S) = 0.28   15 min post-exercise 2.66 ± 1.3† 2.28 ± 1.0 Test (T) = 0.001†   120 min post-exercise 4.07 ± 1.9# 4.90 ± 1.8 S × T = 0.64 Data are means ± standard deviations. mTOR is expressed as absorbance units at 450 nm/mg. † represents significant difference from baseline at 15 JIB04 in vitro min post-exercise.

# represents significant difference from baseline at 120 min post-exercise. Discussion In the present study, we chose to assess changes in the activity of Akt/mTOR pathway intermediates as markers of MPS in response to resistance exercise after ingesting 10 g of whey protein. As a result, we observed resistance exercise to effectively activate signaling PIK3C2G intermediates of the Akt/mTOR pathway. Specifically, we demonstrated increased phosphorylation of IRS-1, AKT, and mTOR. Relative to their downstream targets, p70S6K was hyper-phosphorylated at 15 min post-exercise, whereas 4E-BP1 was hypo-phosphorylated at 15 min post-exercise. Conversely, we also observed that ingesting 10 g of whey protein was unable to induce a greater response in such kinase phosphorylation when compared to ingesting carbohydrate. Therefore, our results

suggest that ingestion of 10 g of whey protein (5.25 g EAAs) is no different than an equal amount of carbohydrate at enhancing the activity of systemic and cellular signaling markers indicative of MPS following resistance exercise. Resistance exercise and amino acids effectively stimulate MPS [30]. Based on previous studies, the role that nutrient ingestion plays in activating the Akt/mTOR pathway [15, 18–20] is not completely understood, and may likely be related to the amount of amino acids available or whether co-ingested with carbohydrate. Previous studies have demonstrated that 20 g of whey protein (8.6 g EAAs) [10] and 10 g EAAs [26] maximally stimulated MPS, but that MPS was also increased even at whey protein doses of 5 g (2.2 g EAAs) and 10 g (4.3 g EAAs) [10] and an EAA dose of 5 g [26].