Date of Award

2024

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Medical and Health Sciences

First Supervisor

Chris Abbiss

Second Supervisor

Peter Peeling

Third Supervisor

Martyn Binnie

Fourth Supervisor

Paul Goods

Abstract

The magnitude and rate at which a cyclist can apply force to the pedal to produce bicycle crank torque are critical factors affecting power production and bicycle speed. While the maximal crank torques produced by sprint cyclists are known, less information is available regarding the rate of torque development (RTD) at the crank. Specifically, little is known about how a range of methodological considerations impact the measurement of cycling RTD, whether cycling RTD relates to gym and laboratory measures of neuromuscular function, and the extent that training impacts these measures. Thus, the aims of this PhD were to investigate the factors affecting cycling RTD measurement, determine the relationship between cycling, gym, and laboratory neuromuscular function measures, and ascertain the effects of training on gym and cycling measures of force or torque.

Study one examined the magnitude and between-day reliability of the RTD at the start of a cycling sprint when sprint resistance, sprint duration, and the pedal downstroke were altered. Nineteen well-trained cyclists completed one familiarisation and three testing sessions. Each session involved one set of 1-s sprints and one set of 5-s sprints. Each set contained one moderate (0.3 Nm.kg-1 ), one heavy (0.6 Nm.kg-1 ), and one very heavy (1.0 Nm.kg-1 ) resistance sprint. RTD measures (average and peak RTD, early [RTD 0-100 ms] and late RTD [RTD 0- 200 ms]) were calculated for downstroke one in the 1-s sprint. For the 5-s sprints, RTD measures were calculated for each of the first three downstrokes, as an average of downstrokes one and two, and as an average of downstrokes two and three. Whilst RTDs were greatest in downstroke three at all resistances, the greatest number of reliable RTD measures were obtained using the average of downstrokes two and three with heavy or very heavy resistances, where average and peak RTD, and late RTD were deemed reliable (ICC ≥ 0.8, CV ≤ 10%). Since only one to two downstrokes can be completed within 1 s, the greatest RTD reliability cannot be achieved using a 1-s sprint; therefore, the average of downstrokes two and three during a > 2-s cycling sprint (e.g., 5-s protocol) with heavy or very heavy resistance is recommended for the assessment of RTD in sprint cyclists. Study one findings informed the sprint cycling protocol methodology for study two and study three.

Study two examined: (i) the relationship between quadriceps central and peripheral neuromuscular function assessed in an isometric knee extension protocol with rate of force development (RFD)/RTD in isometric knee extension, isometric mid-thigh pull (IMTP), and sprint cycling protocols; and (ii) the relationship among RFD/RTD, and peak force/torque between protocols. Eighteen trained cyclists completed two familiarisation and two testing sessions. Each session involved an isometric knee extension, IMTP, and sprint cycling protocol, where peak force/torque, average and peak RFD/RTD, and early and late RFD/RTD were measured. Additionally, measures of quadriceps central and peripheral neuromuscular function were assessed during the knee extension. Strong relationships were observed between quadriceps early EMG activity (EMG50/M) and knee extension RTD (r or ρ = 0.51–0.65; p < 0.05) and IMTP late RFD (r = 0.51; p=0.04), and between cycling early or late RTD and peak twitch torque (r or ρ = 0.70–0.75; p < 0.01). Strong-to-very strong relationships were observed between knee extension, IMTP, and sprint cycling for peak force/torque, early and late RFD/RTD, and peak RFD/RTD (r or ρ = 0.59–0.80; p < 0.05). In trained cyclists, knee extension RTD or IMTP late RFD are related to measures of quadriceps central neuromuscular function, while cycling RTD is related to measures of quadriceps peripheral neuromuscular function. Further, the strong associations among force/torque measures between tasks indicate a level of transferability across tasks.

Finally, having determined a strong association between the IMTP force and sprint cycling torque at one timepoint in study two, the purpose of study three was to examine the associations in the relative changes of sprint cycling torque and IMTP force measures following six weeks of sprint cycling and resistance training in strength-trained, novice cyclists (n=14). Sprint cycling power, cadence, and torque, and IMTP force (peak force/torque, average and peak RFD/RTD, and early and late RFD/RTD) were assessed before and after training. Training consisted of three resistance and three sprint cycling sessions per week. Training resulted in improvements in IMTP peak force (13.1%) and RFD measures (23.7-32.5%), cycling absolute (10.7%) and relative (10.5%) peak power, peak torque (11.7%), and RTD measures (27.9-56.7%). Strong-to-very strong relationships were observed between IMTP force and cycling torque measures pre- (r=0.57-0.84; p < 0.05) and post-training (r=0.63-0.87; p < 0.05), but no relationship (r= < 0.19; p > 0.05) ) existed between training-induced changes in sprint cycling torque and IMTP force measures. This study demonstrates the extent to which a six week resistance and sprint cycling training program improves cycling power and torque and IMTP force measures in strength-trained, novice cyclists. Divergent training-induced changes in IMTP force and sprint cycling torque indicate that these measures assess distinct neuromuscular attributes. Our data indicate that training-induced changes in IMTP force are not indicative of training-induced changes in sprint cycling torque.

This series of research studies contributes new knowledge to the literature by demonstrating that: (i) cycling RTD can be reliably measured on a stationary ergometer using a specific protocol in trained cyclists; (ii) cycling RTD was strongly related to IMTP RFD and knee extension RTD in trained cyclists; (iii) cycling RTD was related to measures of quadricep peripheral neuromuscular function, while IMTP and knee extension RTD/RTD was related to measures of central neuromuscular function in trained cyclists; (iv) IMTP force and sprint cycling torque measures change at a different rate in response to training in strength trained, novice cyclists. The outcomes of these three investigations provides coaches and practitioners with practical information which can be used to make evidence-informed decisions when measuring neuromuscular function in novice and well-trained cyclists.

DOI

10.25958/r2xm-kt25

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