Answer:
When skeletal muscles are trained by adding physical stress to them, this is called progressive resistance training (PRT).
Explanation:
During PRT, muscles are exercised against an <em>overload or resistance</em>; the overload is gradually increased in order to allow muscles to adapt. This allows for progressive strength increases over time.
Muscle fatigue is defined as a reduction in the ability to produce force due to exercise. This comprises:
- peripheral fatigue- due to changes at the junction between motor neurons and the muscle.
- central fatigue- caused by a reduced capacity to use voluntary force in relation to the capacity to use involuntary force
- and muscle damage- this is associated with several issues at the cellular level such as disrupted membranes and cytoskeletons; and tissue damage via torn muscle fibers, and collagen.
Overall, these may affect muscle fiber activation and the amount of force they are capable of producing- i.e. sustained strength. However, muscle fatigue can be greatly reduced via the maintenance of PRT. Also, apart from strength gains, PRT is <em>used for weight loss and muscle building</em>; common tools used in PRT include <em>free weights, elastic bands and exercise machines. </em>
The answer would be "B. cocaine". Cocaine is an illegal stimulant unlike the other options listed above.
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