5. Tick the correct answer:
(b) During heavy exercise, we get cramps in the legs due to the accumulation of
(i) carbon dioxide
(ii) lactic acid
(iii) alcohol
(iv) water
(b) During heavy exercise, we get cramps in the legs due to the accumulation of (ii) lactic acid
During heavy exercise, muscle cells respire anaerobically because oxygen is used faster as compared to its supply by the blood. The partial breakdown of glucose produces lactic acid whose accumulation causes muscle cramps.