Downhill walking training with and without exercise-induced muscle damage similarly increase knee extensor strength

ABSTRACT

This study examined whether avoiding or experiencing exercise-induced muscle damage (EIMD) influences strength gain after downhill walking training. Healthy young males performed treadmill downhill walking (gradient: −28%, velocity: 5 km · h⁻¹ and load: 10% of body mass) 1 session per week for four weeks using either a ramp-up protocol (n = 16), where exercise duration was gradually increased from 10 to 30, 50 and 70 min over four sessions, or a constant protocol (n = 14), where exercise duration was 40 min for all four sessions. Indirect markers of EIMD were measured throughout the training period. Maximal knee extension torque in eccentric (−1.05 rad·s⁻¹), isometric and concentric (1.05 rad·s⁻¹) conditions were measured at pre- and post-training. The ramp-up group showed no indications of EIMD throughout the training period (e.g., plasma creatine kinase (CK) activity: always <185 U · L⁻¹) while EIMD was evident after the first session in the constant group (CK: peak 485 U · L⁻¹). Both groups significantly increased maximal knee extension torque in all conditions with greater gains in eccentric (ramp-up: +19%, constant: +21%) than isometric (+16%, +15%) and concentric (+12%, +10%) strength without any significant group-difference. The current results suggest that EIMD can be avoided by the ramp-up protocol and is not a major determinant of training-induced strength gain.

KEYWORDS:

• Lengthening contraction
• eccentric strength
• repeated-bout effect
• ramp-up protocol
• knee extension

Disclosure statement

No potential conflict of interest was reported by the authors

Additional information

Funding

This work was supported by the Descente and Ishimoto Memorial Foundation of Sports Science [26-2-5] and the Nakatomi Foundation [26-1-5-12].