Muscle damaging exercise affects isometric force fluctuation as well as intraindividual variability of cognitive...

Area of Science:

• Exercise Physiology
• Neuromuscular Function

Background:

• Eccentric exercise (EE) is known to cause muscle damage and performance deficits.
• Understanding the time course of recovery and its impact on neuromuscular function is crucial for training and rehabilitation.

Purpose of the Study:

• To investigate the effects of high-repetition eccentric knee extension on quadriceps muscle torque, voluntary activation, and reaction time in untrained men.
• To determine the recovery profile of these parameters over 24 hours post-exercise.

Main Methods:

• Eleven healthy untrained men performed 10 sets of 12 repetitions of knee eccentric extension at 160°/s.
• Measurements included maximal voluntary isometric contraction (MVC), evoked torques (P20, P100), isokinetic torque (IT), voluntary activation (VA), reaction times (RTs, RTc), and torque variability.
• Assessments were conducted pre-exercise, immediately post-exercise, and at 60 minutes and 24 hours post-exercise.

Main Results:

• Maximal voluntary isometric contraction (MVC), isokinetic torque (IT), evoked torques (P20, P100), and voluntary activation (VA) significantly decreased post-EE and remained depressed at 24 hours.
• Torque variability significantly increased immediately after EE.
• Average simple and complex reaction times (RTs, RTc) did not change, but intraindividual variability in RTs and RTc significantly increased post-EE.

Conclusions:

• High-repetition eccentric exercise induces prolonged deficits in quadriceps muscle strength and voluntary activation in untrained individuals.
• While central motor output (VA) is impaired, the lack of change in average reaction times suggests preserved central processing, but with increased response variability.