Effect of increasing workload on knee extensor and flexor muscular activity during cycling as measured with intramuscular electromyography

Abstract

The purpose of this study was to describe the effect of increasing workload on individual thigh muscle activation during a 20 minute incremental cycling test. Intramuscular electromyographic signals were recorded from the knee extensors rectus femoris, vastus lateralis, vastus medialis and vastus intermedius and the knee flexors semimembranosus, semitendinosus, and the short and long heads of the biceps femoris during increasing workloads. Mean activation levels were compared over the whole pedaling cycle and the crank angles at which onset and offset of activation and peak activity occurred were identified for each muscle. These data were compared between three workloads. EMG activation level significantly increased (p<0.05) with increasing workload in the rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, biceps femoris long head, semitendinosus and semimembranosus but not in the biceps femoris short head. A significant change in activation timing was found for the rectus femoris, vastus lateralis, vastus medialis and semitendinosus. Of the knee flexors only the short head of the biceps femoris had its peak activity during the upstroke phase at the two highest workloads indicating a unique contribution to knee flexion.

Impact of Power Output on Muscle Activation and 3D Kinematics During an Incremental Test to Exhaustion in Professional Cyclists

“…However, some authors demonstrated that muscle activation timing could be influenced by fatigue (Billaut et al, 2005 ; Sarre and Lepers, 2005 ). Regarding cycling tests, contradictory findings emerge from the literature including temporal approaches, spectral analysis techniques, and multi-channel recordings (Farina et al, 2004a ; Macdonald et al, 2008 ; Sbriccoli et al, 2009a ; Lenti et al, 2010 ; Lima da Silva et al, 2018 ). These discrepancies regarding the effect of incremental exercises on EMG parameters could be partially attributed to the different protocols applied, in particular with regard to the continuous or intermittent nature of the tests (Martinez-Valdes et al, 2016 ).…”

Characteristics of Pedaling Muscle Stiffness among Cyclists of Different Performance Levels

“…Regarding the antagonist muscle (BF), a lower but longer total activation was observed [39]. Two years later, the same authors performed a similar analysis, this time with more muscle groups that were analyzed after an incremental test until exhaustion [40]. Again, activation of both RF and VL increased together with some parts of the hamstring muscles (long head of the BF, semitendinosus, and semimembranosus), while there was no activation in the short portion of the BF.…”

Heart Rate and Lower Limb Muscle Activity on Cycle Ergometer

“…It can be observed that the RF, a muscle with biarticular function that acts on both the hip and the knee, showed greater activity in the propulsion phase, acting as a knee extensor, together with the VL, in this same phase of the cycle. However, the RF also showed a certain degree of activation in the pedal recovery phase, acting as a hip flexor 31 . Table 5 shows that the rectus femoris showed greater activity in the recovery phase, together with less activation of the vastus medialis (Table 4).…”