Explain the reflex response and its association with motor activity.
Describe sensory-motor integration and the receptors responsible for proprioception.
List the nervous system's contributions to the acute responses during a bout of physical activity.
Describe possible neural mechanisms for acute muscle fatigue.
Define delayed-onset muscle soreness and explain its possible causes.
Explain neural adaptations experienced by skeletal muscle as a result of chronic exercise.
Describe neuromuscular adaptations that occur after the cessation of a regular resistance training program.
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Oscar is a 40-year-old father of three who has put off being physically active his entire adult life. He has come to the gym to start lifting weights after deciding to get in better shape to keep up with his very active children.
As part of his New Year's resolution, Oscar has decided to take on the task of improving his upper-body strength by performing free-weight exercises. His first exercise is a chest press performed on a flat bench with 25-pound (11.4-kg) dumbbells. Because he has never tried this movement before, his effort appears uncoordinated and awkward.
During his first set of chest press exercises, Oscar's neuromuscular system transmits a series of electrical impulses to and from the brain and skeletal muscles. Some of these impulses are consciously controlled by Oscar, whereas others involve subconscious reflex activity. With continued practice, the awkwardness of his first set of chest presses will be a thing of the past as Oscar's neuromuscular system learns the new exercise movement and allows him to perform it with efficiency and coordination. If Oscar continues to engage in safe and effective regular strength exercise, he will benefit by increasing the strength of muscles, tendons, and ligaments; enhancing bone density; decreasing the risk for musculoskeletal injury; and improving muscular tone.
How would continuing to engage in safe and effective strength exercise benefit Oscar in the long run, not only in terms of muscular strength, but also via changes in the strength of connective tissues, increased bone density, and injury prevention?
Oscar's intention to perform his first chest-press exercise was a conscious thought that originated in the cerebral cortex of his brain. He had seen fellow gym members performing this exercise, so although he had never tried it before, he had a visual representation of what he wanted to achieve. The electrical impulses responsible for Oscar's first repetition of the chest press traveled from his brain down to the muscles of his chest, shoulders, and triceps through efferent neurons. Feedback from receptors in the skeletal muscles, joints, and skin of his upper extremity about the execution of his movement was sent to Oscar's brain through afferent neurons. This two-way communication between the CNS and PNS ...