How Physical Activities Affect Mental Fatigue Based on EEG Energy, Connectivity, and Complexity

Area of Science:

• Neuroscience
• Exercise Physiology
• Cognitive Science

Background:

• The interaction between physical activity and mental fatigue is established, but its specific effects on mental fatigue remain under-explored.
• Existing research often overlooks how physical exertion influences cognitive load and subsequent mental fatigue.

Purpose of the Study:

• To analyze mental fatigue states using electroencephalography (EEG).
• To investigate the impact of concurrent physical activity on the progression of mental fatigue.

Main Methods:

• Fourteen healthy participants performed a 2-back task (control) and a combined cycling and 2-back task (physical-mental task).
• Fatigue was induced through repeated 20-minute sessions.
• EEG parameters including Wavelet Packet Energy (WPE), Spectral Coherence Value (SCV), and Lempel-Ziv Complexity (LZC) were measured before and after tasks.

Main Results:

• EEG indices (beta band energy, energy ratio, inter-hemispheric SCV, and LZC) indicated increased mental fatigue during the physical-mental task.
• Statistical analysis revealed a significantly faster increase in mental fatigue markers when physical activity was combined with the mental task.
• The slopes of linear fits for these indices confirmed an accelerated fatigue process in the physical-mental condition.

Conclusions:

• Physical activity can exacerbate mental fatigue, speeding up the cognitive decline process.
• This effect is observable through changes in brain activation, functional connectivity, and complexity.
• Findings challenge the notion that physical activity is neutral to mental fatigue, suggesting it can actively increase it, informing fatigue management strategies.