ECSS Paris 2023: OP-AP33
INTRODUCTION: Research in Sports has explored a few frameworks for understanding the force domains, primarily focusing on strength qualities1 (e.g., isometric mid-thigh pull). In contrast, Bosco2 proposed a physiological categorization of force expressions based on concentric propulsive time, applicable to various sports movements (e.g., running, jumping). However, this framework has not been applied to cycling, where research has focused on the relationship between rate of torque production (RTD) and strength measurements3, rather than concentric muscle action. This study investigates the relationship between torque application and different pedaling cadences (RPM) in skilled cyclists, employing a multivariate approach to analyze force expression across varying pedal loads METHODS: Nineteen highly trained4 cyclists completed the trials using an ergometer capable of independent 1000 Hz frequency sampling for each pedal and precise RPM manipulation to impose varying pedal loads. Following familiarization, cyclists performed six trials (three per leg, alternating) of a single maximal-effort downstroke at 30, 60, 90, and 100 RPM in a counterbalanced order. Only propulsive phase (torque > 0 N*m) of the targeted leg was analyzed. Outcome measures included kinetic torque-time variables: peak torque (PT), average rate of torque development (avgRTD; Δtorque/Δtime), impulse (Im; Δtorque*Δtime), and propulsive time (t). Data analysis was conducted using a custom MATLAB script, with statistical testing performed via RM-MANOVA in SPSS. RESULTS: RM-MANOVA revealed a significant multivariate effect of RPM on the combined dependent variables (Pillai’s Trace = .997, p < .001), with strong effect sizes (Partial Eta Squared = .997). Univariate tests confirmed significant differences across RPM conditions for PT (p < .001), Im (p < .001), t (p < .001), and avgRTD (p = .035). Propulsive time values increased with decreasing RPM: t30RPM (.926 ± .188 s), t60RPM (.617 ± .080 s), t90RPM (.483 ± .046 s), and t100RPM (.431 ± .020 s). Notably, PT and Im increased with higher RPM, while avgRTD peaked at 60 RPM (658 N/s). Post-hoc contrasts revealed significant differences between all RPM levels for PT and Im (p < .001), while avgRTD showed significant differences only between extreme RPM conditions (p < .001). CONCLUSION: This study demonstrates that RPM significantly influences force expression during single-leg maximal-effort pedal strokes in highly trained cyclists. Lower RPMs were associated with greater PT and Im, indicating maximal strength expression. The highest RTD occurred at 90 RPM, suggesting an optimal cadence for explosive strength expression. These findings highlight the importance of RPM-specific adaptations in cycling performance. Future research should compare cyclists across expertise levels, competition disciplines, and age groups, providing deeper insights into force expression during cycling. References 1James, L. P.(2023) 2Bosco(1992) 3Connolly(2023).
Read CV Maurizio BertolloECSS Paris 2023: OP-AP33
INTRODUCTION: Cyclists adjust body posture and pedaling strategy to counter air resistance and adapt to varying terrains, which influences performance and injury risk. Changes in cycling posture appears to affect muscle activation in novice but not elite cyclists, who exhibit superior neuromuscular control to maintain performance [1]. Sex may play a role in the effects of posture and pedaling on muscular activation as females exhibit greater pelvic motion in dropped postures and at higher intensities than males [2]. Examining the influence of posture and pedaling strategy on muscle activation in males and females may guide the development of targeted training programs. This study aimed to investigate the effects of different cycling postures, cadences, and resistances on muscle activation in male and female recreational cyclists. METHODS: Eighteen recreational cyclists (nine males, nine females) completed 18 cycling bouts on a training stand in three postures (neutral, comfort, dropped) and six pedaling strategies [combinations of three cadences (self-selected, slow, fast) and two resistance levels (heavy, light)] in randomized order. Surface electromyography (1000 Hz) obtained mean muscle activation of the biceps femoris (BF), vastus lateralis (VL), rectus femoris (RF), tibialis anterior (TA), and gastrocnemius (GAS) during 15 stable pedaling cycles. Data were normalized to maximal muscle activation during 10-second maximum-effort sprints. A three-way repeated-measures ANOVA examined the effects of posture, pedaling, and sex on muscle activation at α=.05. RESULTS: Postures did not affect muscle activation (p=.05–.91, η²p=.01–.17) except for right leg RF (p<.05, η²p=.19), with no significant Bonferroni-corrected post-hoc comparison (p=.06–.10, η²p=.02). Pedaling strategies affected both legs’ BF (p<.001, η²p=.62–.70), RF (p<.001, η²p=.71–.71), TA (p<.001, η²p=.59–.67), GAS (p<.001; η²p=.51–.66), and VL (p<.001; η²p=.13–.86) activation. Sex interacted with the effects of pedaling strategy on RF activation in both legs (p<.05; η²p=.18–.29). Females demonstrated greater left leg RF activation during heavy resistance at all cadences and greater right leg RF activation during all pedaling strategies than males (p<.05, η²p=.27–.28). CONCLUSION: The effects of posture have been marginal, whereas pedaling strategy greatly influenced muscle activation. Females exhibited higher RF activation than males, particularly at heavy resistance (significant in both legs), emphasizing the importance of RF functionality in females and suggesting special consideration of RF in training regimes for females. As pedaling strategies affected RF activation differently between sexes, cadence and resistance should be adjusted considering sex-specific adaptation for trainings that target RF. REFERENCES 1. Chapman, Vicenzino, Blanch, Knox, Dowlan, Hodges. (2008). J Sci Med Sport, 11(6), 519–26. 2. Sauer, Potter, Weisshaar, Ploeg, Thelen. (2007). Med Sci Sports Exerc, 39(12), 2204–11.
Read CV Meng Yu ChenECSS Paris 2023: OP-AP33
INTRODUCTION: An adequate saddle height is crucial for cycling performance, comfort, and injury prevention [2]. Despite its importance, most methods for determining saddle height have been developed through practical experience rather than scientific evidence [3]. This study examined the impact of four different saddle height determination methods (LeMond LM; Trochanteric TM; Heel HM; Minimal knee angle (α = 30°) AM) on cycling biomechanics and physiological responses. METHODS: In an acute randomized crossover design, 23 physically active individuals (f =11; m =12; age: 22 ± 1.9 years; body mass 71.3 ± 9.6 kg; height 174 ± 8.7 cm) cycled on an adjustable trainer at the four different saddle heights and two resistance levels (low: 100% of body mass in Watts; high: 200% of body mass in Watts). Heart rate, oxygen uptake, perceived exertion, and discomfort for each saddle height were analyzed using an ANOVA, while differences in electromyography (EMG) data of the lower extremity muscles (Vastus Lateralis and Medialis Obliquus, Gastrocnemius Medialis, Rectus Femoris, Semitendinosus, Tibialis Anterior), knee and ankle angles, and torque were analyzed continuously over the revolution using statistical parametric mapping (SPM). RESULTS: The largest differences in saddle height were found between AM and TM (98.4 ± 4.6 vs.102.9 ± 4.2 cm; 4.5%, SMD = 1.02, p < .01). Oxygen uptake showed significant differences at low load between AM and TM (1.45 ± 0.21 vs.1.55 ± 0.25 l/min, SMD = 0.43, p < .02), but no significant differences at high load. Discomfort [1-10; very comfortable - uncomfortable] was rated significantly higher for LM (5.52 ± 2.50) and TM (6.13 ± 2.44) compared to HM (3.70 ± 1.82) and AM (4.01 ± 2.39) (SMD = .83 -1.13; p < .05). No significant differences in RPE were found. At low load for torque, the one-way repeated measures ANOVA using SPM1D revealed a significant main effect of saddle height (SPM{F}; df = 3, 66; FWHM = 23.89; 7.49 resels) with a critical threshold (SPM.z* = 5.24 at α = 0.05) (set-level p = 0.001; cluster-level p < 0.001 and 0.036) between 123° and 173°. Subsequent paired t-tests showed significant differences between AM and TM (t* = 3.84, df = 1, 43.545, p = 0.004). CONCLUSION: Methods resulting in higher saddle heights were associated with increased discomfort. The results indicated superior cycling efficiency and comfort in favor of AM and HM. Therefore, practitioners should consider saddle height adjustments based on knee flexion angle (~30°) to optimize cycling efficiency, comfort, and injury prevention. [1] Dettori, N. J., & Norvell, D. C. (2006). Non-traumatic bicycle injuries: A review of the literature. Sports Medicine (Auckland, N.Z.), 36(1), 7–18. https://doi.org/10.2165/00007256-200636010-00002 [2] Bini, R., Hume, P. A., & Croft, J. L. (2011). Effects of bicycle saddle height on knee injury risk and cycling performance. Sports Medicine (Auckland, N.Z.), 41(6), 463–476. https://doi.org/10.2165/11588740-000000000-00000
Read CV Lina FayECSS Paris 2023: OP-AP33