Author(s): CHEN, H., LIN, L., WANG, J., Institution: CHANG GUNG UNIVERSITY, Country: TAIWAN, Abstract-ID: 1519

INTRODUCTION:
Eccentric cycling has been increasingly used in older adults and individuals with cardiopulmonary conditions because it imposes both lower cardiopulmonary demand and lower muscle activation than concentric cycling while producing the same power output. However, evidence suggests that training adaptations, including maximal oxygen uptake, quadriceps muscle strength, and quadriceps muscle cross-sectional area, are not superior when eccentric and concentric cycling are performed at the same intensity. Therefore, this study aimed to identify eccentric cycling intensity conditions that match muscle activation levels observed during concentric cycling, providing a basis for eccentric training intensity prescription.
METHODS:
One healthy adult (34 years old) participated in this case report study. Participants first completed a maximal exercise test to determine peak power output (PPO). One week later, concentric and eccentric cycling trials were performed at a controlled cadence of 60 rpm. Concentric cycling was conducted for 2 min at 70% PPO, whereas eccentric cycling was performed at 70% PPO with progressive increases of 10% PPO per stage up to 130% PPO, with each stage lasting 2 minutes. Surface electromyography (EMG; PLUX EMG) was recorded from the vastus lateralis (VL) muscle, with electrode placement following the recommendations of the SENIAM guidelines. EMG amplitude was normalized to maximal voluntary isometric contraction (MVIC). Raw EMG signals were band-pass filtered between 20 and 450 Hz using a zero-phase second-order Butterworth filter, rectified, and subsequently low-pass filtered at 10 Hz to obtain the linear envelope. EMG signals were temporally normalized to the movement cycle using accelerometer data (PLUX ACC), and muscle activation patterns were descriptively compared across different exercise conditions within the same participant.
RESULTS:
The results showed that mean EMG activation of VL during concentric cycling at 70% PPO was 0.218% MVIC. In contrast, eccentric cycling elicited lower EMG activation at equivalent intensities, with values of 0.108% MVIC at 70% PPO and 0.121% MVIC at 80% PPO, followed by a gradual increase across higher intensities (0.146% at 90% PPO, 0.150% at 100% PPO, 0.160% at 110% PPO, 0.188% at 120% PPO, and 0.241% MVIC at 130% PPO).
CONCLUSION:
In this case report, eccentric cycling at approximately 120–130% PPO elicited muscle activation levels comparable to or greater than those observed during concentric cycling. However, as this study involved a single participant, variability in EMG activation should be considered when interpreting the findings. Future studies with larger samples and longitudinal designs are warranted to confirm these preliminary observations and inform eccentric training prescription, which should not rely solely on cardiopulmonary responses but also consider peripheral muscle activation to enable more precise and individualized exercise prescriptions.