Surface EMG variability while running on grass, concrete and treadmill.

Area of Science:

• Biomechanics
• Human Movement Science
• Exercise Physiology

Background:

• Inter-trial variability in muscle activity (electromyography, EMG) is crucial for understanding running mechanics.
• Previous research has explored EMG variability, but the influence of running surface and step count requires further investigation.

Purpose of the Study:

• To determine if the number of acquired steps and the running surface affect inter-trial variability in muscle activity during running.
• To compare muscle activity variability between treadmill and overground running conditions.

Main Methods:

• Nine healthy participants ran at a preferred speed on a treadmill, concrete, and grass.
• Surface electromyography (EMG) from 12 lower limb muscles and tibial acceleration were recorded.
• The coefficient of variation (CV) for average and peak EMG was calculated for 5, 10, 25, 50, and 100 steps. Data average stability was assessed using the sequential estimation technique (SET).

Main Results:

• Treadmill running exhibited lower average and peak EMG variability compared to running on grass or concrete (p < 0.05).
• No significant differences in EMG variability were found across varying step counts (5-100 steps).
• Specific muscles showed varied responses: peroneus longus had lower peak EMG CV on concrete, while gluteus maximus showed greater variability on grass compared to concrete.

Conclusions:

• Treadmill running leads to greater muscle activity variability compared to overground running.
• The number of steps acquired does not influence EMG variability during running.
• Average EMG stability can be achieved with as few as 10 steps across different running conditions.