Okay, so testosterone. This you've heard a lot about testosterone. And resistance training is a potent stimulant for increasing the muscle size. And also for improving the function of the neuromuscular system. And together, these two effects lead to improved muscular strength, power, hypertrophy, and local muscular endurance. And testosterone is considered a primary anabolic hormone causing all these things to occur. Because it increases protein synthesis and decreases protein degradation. Cortisol is also a primary catabolic hormone, and it's also released at the same time. And it's important because it increases protein degradation and decreases protein synthesis. So you have testosterone as anabolic, and you have cortisol as catabolic. Both are essential to the homeostasis of the cell. Testosterone and cortisol contribute to the force-generating capacity of the skeletal muscle fibers because it helps increase their cross-sectional area. And the motor neuron is also sensitive to testosterone. And increases its size and function and its influence. Now, there's also a small role played by testosterone in women. But growth hormone, and also insulin-like growth factor, is more involved in anabolic processes for women. There's been quite a bit of research exploring how to use resistance training to adapt the body so it releases testosterone, especially when it comes to strength training. The magnitude of testosterone released relates to the size of the muscle mass involved in training. And the general recommendation is to exercise large muscles first followed by small muscles. And the reason for this is that, large muscle mass exercises such as Olympic lifts and dead lifts and jumps, produce large elevations in testosterone compared with the small muscle mass. So performing small muscle mass exercise does not acutely elevate testosterone when your doing that first. If you elevate the testosterone first, by performing large muscle exercises first, this appears to benefit the small muscles. And this is the reasoning behind performing large muscle mass, multi-joint exercises, early in the workout. And the smaller muscle mass exercises later in the workout. It also appears that higher reps with short rest periods produce a greater testosterone response than the high load, low volume training with the longer three minute rest periods. So the training protocol for women is the same however, growth hormone appears to be the dominant hormone for muscle hypertrophy in women. Testosterone has effect but it is a much smaller effect. Resistance training also increases the concentration of receptors for testosterone and insulin-like growth factor on the muscle cells. And this permits testosterone and IGF to have a greater impact on the muscle cell.