Figure 3: (a) Changes in serum creatine kinase (CK) activity during 90-minute cycling exercise on three consecutive days (Ex1, Ex2, and Ex3), reprinted from Totsuka et al. with permission from American Physiological Society [6]. (b) Creatine kinase (CK) response to eccentric exercise between immobilisation and control group. PRE refers to the baseline period before exercise. Days 1–4 represent the 4-day immobilization and days 5–9 are the recovery period. Reprinted from Sayers and Clarkson [4]. (c) Creatine kinase (CK) activity in women and in men before (pre), immediately after (post), and 15 days after step exercise. +++ Significant difference from preexercise level ( 𝑃 < 0 . 0 0 1 ). $$$ Significant difference between men and women ( 𝑃 < 0 . 0 0 1 ), reprinted from Fredsted et al. [12].