During strength training, several physiological changes occur. Initially, there's an increase in muscle tension, which triggers the process of muscle hypertrophy – the enlargement of muscle fibers. Additionally, strength training stimulates the release of hormones like testosterone and growth hormone, which aid in muscle recovery and growth. There's also an improvement in the efficiency of the nervous system in recruiting muscle fibers. Over time, adaptations such as increased bone density, enhanced metabolic rate, and improved overall strength occur, contributing to better functional fitness.