Lower-limb muscle function is influenced by changing mechanical demands in cycling

Abstract

Although cycling is a seemingly simple, reciprocal task, muscles must adapt their function to satisfy changes in mechanical demands induced by higher crank torques and faster pedalling cadences. We examined whether muscle function was sensitive to these changes in mechanical demands across a wide range of pedalling conditions. We collected experimental data of cycling where crank torque and pedalling cadence were independently varied from 13 to 44 N m and 60 to 140 rpm. These data were used in conjunction with musculoskeletal simulations and a recently developed functional index-based approach to characterise the role of human lower-limb muscles. We found that in muscles that generate most of the mechanical power and work during cycling, greater crank torque induced shifts towards greater muscle activation, greater positive muscle–tendon unit (MTU) work and a more motor-like function, particularly in the limb extensors. Conversely, with faster pedalling cadence, the same muscles exhibited a phase advance in muscle activity prior to crank top dead centre, which led to greater negative MTU power and work and shifted the muscles to contract with more spring-like behaviour. Our results illustrate the capacity for muscles to adapt their function to satisfy the mechanical demands of the task, even during highly constrained reciprocal tasks such as cycling. Understanding how muscles shift their contractile performance under varied mechanical and environmental demands may inform decisions on how to optimise pedalling performance and to design targeted cycling rehabilitation therapies for muscle-specific injuries or deficits.

Assessing the rate of torque development in sprint cycling: a methodological study

“…Consistent with this, while RTD avg and RTD 0–200 were deemed to have acceptable reliability for a range of downstrokes analysed, acceptable RTD peak reliability was achieved only when using the average of downstrokes 2 and 3 (Figure 2) . It is somewhat surprising that RTD was highest in downstroke 3 at higher muscle shortening velocities; however, based on previous findings (Brennan, Cresswell, Farris, & Lichtwark, 2018; Lai, Dick, Brown, Biewener, & Wakeling, 2021), we propose that a faster crank velocity resulted in greater storage and release of elastic energy or greater muscle‐tendon unit stiffness during pedal upstrokes, resulting in faster recoil and thus higher pedal force and crank torques during pedal downstrokes. While our data indicate that RTD increased from downstrokes 1–3 (Figure 4), further research should determine the magnitude of RTD when analysing more than the first 3 downstrokes of a sprint.…”

Return to cycling after hip arthroplasty: a case report of femoroacetabular impingement

“…The overall rate of return to cycling after hip arthroscopy is 97%, with 41% of subjects returning to the same level of performance and another 59% achieving a performance even higher than preoperative levels (Diamond et al, 2015). This high rates of return to sport after surgery may be explained by the nonweight bearing and smooth action in cycling (So et al, 2005) associated with the constrained reciprocal limb extension and flexion phases of a repeatable kinematic movement (Lai et al, 2020).…”

Static to dynamic: an application of the two-joint link model of mono- and biarticular muscles to pedaling biomechanics

“…Therefore, the static two-joint link model can be visualized in dynamic pedaling activities. The biomechanics of pedaling has been well studied and standard biomechanical parameters associated with pedaling biomechanics provide us with an opportunity of how well the static model could be applied to an analysis of dynamic pedaling activities (Jorge and Hull, 1986;van Ingen Schenau et al, 1995;Hug and Dorel, 2009;Fonda and Sarabon, 2010;Hug et al, 2011;Bini and Carpes, 2014;Bini and Hume, 2016;Tsumugiwa et al, 2016;Garcia-Lopez and del Blanco, 2017;Sato and Tokuyasu, 2017;Bini and Hume, 2020;Lai et al, 2021). Since the present application and comparison requires EMG data, observed forces and directions at the ankle or the tip of the foot or pedal and/or relative positions of hip, knee and ankle joints during pedaling, the present review chose three groups of biomechanical studies: van Ingen Schenau et al (1995), Dorel et al (2008) and Hug and Dorel (2009) and Tsumugiwa et al (2016).…”