Figure 2. Three weeks of one-legged knee extensor exercise training in humans increases Nampt protein in trained, but not untrained, skeletal muscle.

Human volunteers performed 15 sessions of one-legged knee extensor endurance training over the course of 3 weeks. Skeletal muscle biopsies were obtained from both vastus lateralis muscles before and after training (n= 8). * Indicates treatment × time interaction effect (P < 0.05).