Exposure to unaccustomed eccentric exercise causes muscle damage. Popping sarcomere theory  has been proposed and assumed that eccentric contraction-induced muscle damage predominantly occurs at muscle length on the descending limb of the force-length relationship. This study investigated changes in the mechanical properties following maximum effort eccentric exercise at systematically different muscle lengths for the human ankle dorsiflexors. The results of this study showed that the eccentric exercise of the ankle dorsiflexors decreased the peak torque, shifted the optimal joint angle towards longer muscle length without changes in the level of muscle activation. However, no difference in the shift of the optimal ankle joint angle was observed between the groups that performed eccentric exercise at long muscle length (ECC_L) and at short muscle length (ECC_S). In conclusion, the muscle length at which the eccentric exercise was performed did not produce differential effects on the neuro-mechanical properties of in-vivo human ankle dorsiflexors, and thus the popping sarcomere theory might not be the sole mechanism to account for the eccentric contraction-induced optimal muscle length change.
Bibliographical noteFunding Information:
This work was supported by the Korean Research Foundation Grant by the Korean Government (MOEHRD, Basic Research Promotion Fund) (KRF-2007-314-G00015) and Grant-in-Aid for scientific Research of Japan Society for the Promotion of Science (18300200, Yasuo Kawakami).
All Science Journal Classification (ASJC) codes
- Aerospace Engineering
- Mechanics of Materials
- Mechanical Engineering