Final answer:
During the toughening phase of training, a variety of training activities with precise standards of execution ensure that the individual strengthens their muscles and improves their endurance.
Step-by-step explanation:
During the toughening phase of training, a variety of training activities with precise standards of execution ensure that the individual strengthens their muscles and improves their endurance.
The training activities may include short periods of vigorous muscular work followed by longer periods of medium to varied muscular work. This helps in gradually introducing a dense network of dislocations throughout the muscles, making them tough and hard, a process known as work hardening.
By following precise standards of execution and gradually increasing the intensity of the training, the individual can improve their physical fitness and performance, preparing them for the demands of the specific activity or sport they are training for.