High-protein diet based on whey protein isolate preserves muscle mass and its association with resistance training...

To evaluate the effect of administering a high-protein diet (HP) based on whey protein isolate (WPI) associated with ST in rats.

Twenty-two Wistar rats were fed a diet containing either 14% WPI (normoproteic) or 35% WPI (high protein) and were subjected to stair training or kept sedentary for 12 weeks. SN = sedentary normoproteic; SH = sedentary high protein; TN = trained normoproteic; TH = trained high protein.

HP decreases food intake (P < 0.0001). The SH group showed a significant reduction in plasma triglycerides (P = 0.03). Quadriceps weight was greatest in TH, followed by SH and TN (P < 0.0001). Kidney weight was greater in TH, followed by SH and TN, and was greater than in SN (P < 0.0001). Urea levels were lowest in the SN group (P < 0.001). The urinary space was larger in the TH and SH groups. HP and ST increased the cross-sectional area (CSA) of the gastrocnemius (P < 0.0001) and quadriceps (P < 0.0001) muscles. Hepatic glycogen deposits were highest in the SH group (P < 0.0001).

HP with 35% whey promoted satiety and increased hepatic glycogen content without affecting glycemia. Its combination with ST was more efficient in increasing muscle hypertrophy, altering plasma urea levels, and enlarging the urinary space. These findings may be related to the adaptive process of renal physiology stimulated by HP.