Effects of Different Pedaling Positions on Muscle Usage and Energy Expenditure in Amateur Cyclists

Abstract

Background: Inappropriate cycling positions may affect muscle usage strategy and raise the level of fatigue or risk of sport injury. Dynamic bike fitting is a growing trend meant to help cyclists select proper bikes and adjust them to fit their ergometry. The purpose of this study is to investigate how the “knee forward of foot” (KFOF) distance, an important dynamic bike fitting variable, influences the muscle activation, muscle usage strategy, and rate of energy expenditure during cycling. Methods: Six amateur cyclists were recruited to perform the short-distance ride test (SRT) and the graded exercise tests (GXT) with pedaling positions at four different KFOF distances (+20, 0, −20, and −40 mm). The surface electromyographic (EMG) and portable energy metabolism systems were used to monitor the muscle activation and energy expenditure. The outcome measures included the EMG root-mean-square (RMS) amplitudes of eight muscles in the lower extremity during the SRT, the regression line of the changes in the EMG RMS amplitude and median frequency (MF), and the heart rate and oxygen consumption during the GXT. Results: Our results revealed significant differences in the muscle activation of vastus lateralis, vastus medialis, and semitendinosus among four different pedaling positions during the SRT. During GXT, no statistically significant differences in muscle usage strategy and energy expenditure were found among different KFOF. However, most cyclists had the highest rate of energy expenditure with either KFOF at −40 mm or 20 mm. Conclusions: The KFOF distance altered muscle activation in the SRT; however, no significant influence on the muscle usage strategy was found in the GXT. A higher rate of energy expenditure in the extreme pedaling positions of KFOF was observed in most amateur cyclists, so professional assistance for proper bike fitting was recommended.

Continuous blood flow restriction during repeated‐sprint exercise increases peripheral but not systemic physiological and perceptual demands

“…Additional fatigue or compression with BFR could contribute to differences in muscle activation by altering cycling kinematics during RSE. Indeed, pedaling with the knee positioned further forward over the foot enhances quadriceps EMG RMS during moderate cycling intensities (180 W) (Tang et al., 2022), thus warranting further investigation during RSE with BFR.…”

“…Considering the maximal intensity demands and further muscle deoxygenation with BFR, there is likely a heightened reliance on type II fibers during RSE to compensate for the decreased contractility of oxygen‐deprived type I fibers (Mendez‐Villanueva et al., 2012). Unfortunately, this study did not include muscle biopsies, thus further research should determine if fiber type distribution impacts muscle activation during RSE with BFR (Tang et al., 2022). In our study, vastus lateralis and biceps femoris EMG RMS did not decrease in parallel with mechanical output across RSE, likely due to the mild (<10%) S dec score observed for both conditions (Girard et al., 2011).…”