A method for detecting the temporal sequence of muscle activation during cycling using MRI
Christopher P Elder1, Ryan N Cook, Kenneth L Wilkens
1Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA.
This study shows magnetic resonance imaging (MRI) can measure muscle activation during cycling by tracking changes in transverse relaxation time constant (T2). This MRI method complements surface electromyography (EMG) for assessing deep muscle recruitment patterns.
Area of Science:
- Biomedical Engineering
- Sports Science
- Medical Imaging
Background:
- Surface electromyography (EMG) is limited in assessing deep muscle recruitment and electrically stimulated contractions during cycling.
- Understanding muscle activation patterns is crucial for optimizing cycling performance and rehabilitation.
- Novel methods are needed to accurately measure muscle recruitment during dynamic activities like cycling.
Purpose of the Study:
- To determine if MRI-measured transverse relaxation time constant (T2) changes can infer muscle recruitment timing during cycling.
- To compare MRI-derived T2 changes with integrated EMG (IEMG) for assessing muscle activity.
- To evaluate the effectiveness of a modified cycle ergometer in varying power output across pedal angles.
Main Methods:
- Six subjects performed single-leg cycling on a modified cycle ergometer with variable power output across pedal angles (E0°-230° and E90°-230°).
- Muscle recruitment was assessed using surface EMG (integrated EMG - IEMG) and MRI-measured T2 changes (ΔT2).
- A virtual power output condition (V0°-180°) was created to isolate specific muscle activation phases.
Main Results:
- Vastus medialis/lateralis (VM/VL) showed significantly higher IEMG and ΔT2 in the E0°-230° condition compared to E90°-230°.
- Biceps femoris/long head (BF(L)) exhibited no significant differences in IEMG or ΔT2 between conditions, though MRI indicated hamstring activation.
- MRI and EMG data collectively indicated VM/VL activity from 0-180° and hamstring activity from 90-230° of the pedal cycle.
Conclusions:
- Combining MRI-measured ΔT2 with variable cycle ergometer loading allows inference of spatial and temporal muscle recruitment patterns.
- This MRI-based approach offers a valuable alternative to EMG for studying deep muscle activation during cycling.
- The findings support the use of MRI for detailed analysis of muscle function in dynamic movements.
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