This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Strengthening muscle exercise 
Select and explain. 
A. Isotonic, B. Isometric, C. Aerobic, D. None
A: Isotonic
Answer: A: Isotonic 
Explanation: Contraction against a constant load with change in muscle length is isotonic. Since work done is product of force times distance, isotonic contraction do work. (REF: GANONG'S REVIEW OF MEDICAL PHYSIOLOGY 24 EDITION, PAGE NO - 104)