Which of the following best explains why regular exercise is effective in preventing flexibility issues related to stress?

• A. Exercise causes muscles to contract permanently, which prevents flexibility problems.
• B. Engaging in regular exercise eliminates the need for stretching or warm-up routines.
• C. Exercise increases the production of lactic acid, which directly improves flexibility.
• D. Regular exercise helps maintain muscle elasticity and joint range of motion, reducing the risk of stiffness caused by stress.

Answer: (D)

Verified step by step guidance

1. Understand the relationship between stress and muscle flexibility: Stress can cause muscle tension and stiffness, which may reduce flexibility over time.
2. Recognize the role of regular exercise in maintaining muscle and joint health: Exercise promotes blood flow, muscle elasticity, and joint mobility, which are essential for flexibility.
3. Identify why muscle contraction alone does not explain flexibility improvements: Permanent muscle contraction would actually reduce flexibility, so this option is incorrect.
4. Consider the effects of lactic acid: While lactic acid is produced during exercise, it is more associated with muscle fatigue rather than improving flexibility.
5. Conclude that regular exercise helps maintain muscle elasticity and joint range of motion, which reduces stiffness caused by stress and prevents flexibility issues.