The fitness of a group of individuals of various ages and both genders was asses

Question

The fitness of a group of individuals of various ages and both genders was assessed in a step test. The test consisted of stepping up and down 18 inches (46 cm) 15 times per minute, for twenty minutes. The stepping pattern produced shortening of the right quadriceps muscle during the step up. The descent was opposed by contraction of the left quadriceps muscle that was stretched by the force of gravity. The subjects reported feeling weakness in the left quadriceps muscle. The weakness lasted for approximately 2 hours, and maximum voluntary force development was less than the preexercise value. Percutaneous electrical stimulation of the quadriceps elicited reduced forces. Pain developed in the left quadriceps 8 to 10 hours after the exercise, reached maximal intensity between 24 and 48 hours, and persisted for about a week. This delayed onset of muscular soreness (DOMS) induced by exercise was marked in the activities that imposed negative work on the muscle; such activities include descending stairs. The magnitude of the soreness was unrelated to the overall fitness of the individuals, but specific training for this step test prevents soreness in subsequent tests. Evidence of muscle cell injury included an increase in serum levels of soluble proteins, such as creatine kinase and myoglobin. The time course was similar to that of the soreness. Myofibrillar disorganization and sarcolemmal disruption could be observed in biopsy sample from only the left quadriceps.

3. Is an impaired adenosine triphosphate (ATP) supply or synthetic capacity a reasonable explanation for the fatigue of the left quadriceps muscle?

4. One hypothesis for the etiology of DOMS is that increased metabolism results in the accumulation of toxic waste products. Can this explain the soreness?

5. Exercise can raise the temperature of an active muscle by 5° C or more. Is heat injury a plausible explanation for DOMS?

6. Are there clinical signs of a muscle cell injury?

7. What is a plausible mechanism for injury of muscle cells or their tendons?

8. What does DOMS suggest about the adaptability of muscle fibers to use?

9. Pain is usually regarded (teleologically) as a signal to protect the organism from injury. Is this rational explanation for DOMS?

10. What might be responsible for the slow development of stiffness and soreness?

Explanation / Answer

According to chegg rules we cannot answer many questions in a single post:

3. Reduction in ATP supply is not the reason for the fatigue. The stretching of a contracting muscle does not result in ATP hydrolysis. Hence ATP does not come in the scene. Some other factors like glycogen depletion which afects the production of ATP and lastly affects the process of contraction would be the reason.

4. The accumulation of waste products is not the reason for the soreness seen. The metabolism in the right quadriceps muscle is much higher than that of the left quadriceps muscle. Accumulation of wate products might lead to temporary fatigue. But soreness is seen after many hours after exercise.

5. The major part of the energy released during ATP hydrolysis is given off as heat The rise in temperature is due to the reason that the rate of heat removal is not equal to the rate of heat synthesis. Hence, heat is not a plausible reason for DOMS.

6. The clinical signs of muscle cell injury are:

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.