Multiple-set regimens may provide greater benefits if time allows. Mode of training The ACSM recommends no specific mode of exercise. Resistance to produce training stimulus can come from the weight of the body or any of its segments, from free weights, elastic tubing, equipment. Overload induces muscles to adapt, to increase their ability to generate force. An online calculator programmed for Brzycki's equation Responses to strength training Functional changes Structural changes more motor units recruited during a task more synchronized recruitment of motor units less activation of antagonist muscles increased activity in muscle's metabolic enzymes increased size and activity in mitochondria hypertrophy of muscle fibers due to myofibril synthesis splitting of fibers, but no true hyperplasia Strength gains that occur in the first two to three weeks of an exercise program are due to functional changes.
Structural changes take longer.
During the walking cycle, the stretch shorten cycle occurs in the ankle plantar flexors, the knee extensors, and the hip flexors. Stored strain energy is estimated by the area under the length-tension curve. The stored energy adds to the force that the muscle produces during the concentric phase of the stretch shorten cycle. American College of Sports Medicine position stand. The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness, and flexibility in healthy adults.