• Satoru Ato, Yuki Maruyama, Hideo Yoshizato, and Riki Ogasawara.
• Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.
• Nutrition. 2020 Oct 1; 78: 110795.

ObjectivesResistance training combined with consumption of a high-protein diet (HPD) is typically recommended to increase muscle mass, as both acute resistance exercise (RE) and dietary protein intake stimulate mechanistic target of rapamycin complex 1 (mTORC1) and muscle protein synthesis (MPS). However, the effect of chronic HPD consumption on MPS response to an acute RE remains to be determined.MethodsMale Sprague-Dawley rats aged 10 wk were fed HPD (50 kcal % protein, for 4 wk) or normal protein diet (NPD; 20 kcal % protein). After the 4-wk dietary intervention, the rats were fasted overnight and the right gastrocnemius muscle was subjected to percutaneous electrical stimulation to mimic acute RE, whereas the left gastrocnemius muscle served as control. The rats were sacrificed 6 h after exercise and the tissues were sampled immediately.ResultsThe HPD group showed significantly lower fat mass and higher skeletal muscle mass than the NPD group without affecting body weight. Resting mTORC1 activity did not differ between the groups. Additionally, resting MPS was also unchanged after HPD. Acute RE significantly increased mTORC1 activity and MPS in both groups. However, differences in diet did not influence the response of mTORC1 activation to acute RE. Furthermore, HPD did not affect the response of MPS to acute RE.ConclusionThe present results suggested that although 4 wk of HPD reduces body fat and increases skeletal muscle mass, it does not affect muscle protein synthesis at basal state, and in response to acute RE.Copyright © 2020 Elsevier Inc. All rights reserved.

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