Japanese researcher uses neuromuscular activation to assess the impact of cycling on the rectus femoris muscle.
Cycling is a popular fitness activity worldwide. Although the physiological benefits of cycling are known to many, its precise impact on the ‘rectus femoris’ muscle has remained elusive so far. A sports science researcher from Japan has now made a direct comparison between concentric and eccentric cycling, and demonstrated the relatively higher efficiency of eccentric cycling, using neuromuscular activation as a key performance indicator.
Working out has a science of its own. Scientists categorize different workout activities based on how the muscles are used while performing them: to understand this clearly, consider the popular bicep curl. When you are curling the dumbbell towards you, you are contracting the bicep muscle, and this is a concentric activity. Returning the dumbbell to the original position requires your bicep to ‘uncurl’ or go back to its normal length, making this an eccentric activity. Scientists are constantly on the quest to pinpoint which one of these activity types, or more realistically, what combination, gives the best output in terms of neuromuscular improvement.
A sport science researcher from Japan has recently been able to demonstrate the unique neuromuscular activation of the rectus femoris muscle during concentric, or regular, cycling, and eccentric cycling, where one resists the backward movement of the pedal instead of pushing down by contracting the muscles. The results of this study have been published in the Journal of Electromyography and Kinesiology. This paper was made available online on January 30, 2022.
For the uninitiated, the rectus femoris is a long and fleshy muscle bulk that is located in the anterior compartment of the thigh. Its primary function is to extend the leg at the knee joint and to facilitate the flexing the hip joint. This muscle is vulnerable to damage, especially during intense exercise and sports or after a physical trauma.
According to the author of the study Dr. Ryoichi Ema, Associate Professor at the Shizuoka Sangyo University in Japan, “The rectus femoris muscle is an important muscle for sport performance in athletes and physical performance in older adults, indicating that it should be specifically targeted for exercise-related activity.”
Dr. Ema used an ergometer to quantitatively estimate the involvement of various types of muscles. An ergometer is a special device that measures the work or energy expended during a period of physical exercise. In an eccentric cycling ergometer, the pedals automatically spin backward.
The researcher obtained the root mean square (RMS) of the surface electromyographic (EMG) signals from the three types of muscles—proximal and distal regions of the rectus femoris, vastus lateralis, and biceps femoris. The EMG signal measures electrical currents generated during muscular contractions and is used to assess various types of neuromuscular activities.
Dr. Ema also made a quantitative comparison between concentric and eccentric cycling. Although previous studies suggest that eccentric exercise produces less fatigue and is more efficient than concentric exercise (descending a stairway is easier than ascending it), its precise impact on the rectus femoris muscle had not been accurately determined.
Dr. Ema muses, “Eccentric cycling exercise can be performed with less effort as compared to concentric cycling exercise, a popular exercise. However, higher neuromuscular activation of the recuts femoris muscle can be obtained during eccentric cycling, thus suggesting that eccentric cycling exercise is a good for improving the function of the rectus femoris muscle.”
The numbers speak for themselves: the experimental results clearly demonstrated that the RMS-EMG of the rectus femoris muscle was indeed greater during eccentric cycling than during concentric cycling.
“Eccentric cycling exercise would be useful for improving athletic performance and for improving the quality of life in older adults, and for preventing severe damage resulting form intense exercise and sports. Although an eccentric cycling ergometer is still not a routinely used exercise equipment, it is expected to bring in significant benefits, especially during training and rehabilitation,” notes Dr. Ema.
The pandemic has taught us an important lesson: that physical fitness is crucial for human survival. Moreover, if fitness devices can quantitatively determine and compare the neuromuscular function and therefore the performance of various muscle groups, then we should definitely make it a point to incorporate them into our daily exercise regimen. Happy cycling!
Reference: “Unique neuromuscular activation of the rectus femoris during concentric and eccentric cycling” by RyoichiEma, 30 January 2022, Journal of Electromyography and Kinesiology.
This work was supported by the Japan Society for the Promotion of Science KAKENHI grant JP19K20055.
About Shizuoka Sangyo University
Shizuoka Sangyo University (SSU) is a private university with campuses in Shizuoka (Iwata and Fujieda). Its establishment was 1994. Since 2021, Faculty of Sport Science was started. The mission of SSU is fostering persons who contribute to the social community.
About Associate Professor Ryoichi Ema
Dr. Ryoichi Ema works as an Associate Professor at Shizuoka Sangyo University, Japan. He obtained his Ph.D. degree from Waseda University and pursued postdoctoral research as a Research Fellow of Japan Society for the Promotion of Science at the Shibaura Institute of Technology. Dr. Ema primarily conducts research in the area of biomechanics and exercise physiology and has over 35 peer-reviewed publications to his credit.