On the reliability and validity of central fatigue determination

Area of Science:

• Exercise Physiology
• Neuroscience

Background:

• Physical fatigue comprises peripheral and central components.
• Central fatigue is complex, involving cognitive, sensory, and neuro-physiological factors.
• Assessing central fatigue is challenging due to its elusive nature.

Purpose of the Study:

• To review the reliability and validity of the interpolated twitch technique (ITT) for assessing central fatigue.
• To question the assumption that decreasing volitional muscle activation (VA) reflects central fatigue.
• To highlight paradoxes in current central fatigue assessment methods.

Main Methods:

• Review of existing literature on central fatigue and the interpolated twitch technique (ITT).
• Analysis of the validity of volitional muscle activation (VA) determination under fatigued conditions.
• Examination of studies involving children and endurance athletes in relation to central fatigue.

Main Results:

• The validity of VA determination using ITT in fatigued muscles is questionable and not empirically proven.
• The assumption that reduced VA directly indicates increased central fatigue is challenged.
• Children and endurance athletes, paradoxically, are often considered more centrally fatigable than untrained adults.

Conclusions:

• The reliability and validity of ITT for assessing central fatigue are debated.
• Current methods may not accurately reflect the complex nature of central fatigue.
• Further research is needed to develop reliable methods for quantifying central fatigue and its components.