Isokinetics and Exercise Science - Volume 29, issue 4

Authors: Mehmet, Kale

Article Type: Research Article

Abstract: BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of …eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC’s). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC’s (p < 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p < 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities. Show more

Keywords: Maximum voluntary force, rate of force development, electromechanical delay, neural activation

DOI: 10.3233/IES-203225

Citation: Isokinetics and Exercise Science, vol. 29, no. 4, pp. 443-453, 2021

Authors: Javaloyes, Alejandro | Mateo-March, Manuel | Carpes, Felipe P. | Moya-Ramon, Manuel | Lopez-Grueso, Raúl | Zabala, Mikel

Article Type: Research Article

Abstract: BACKGROUND: Pedalling asymmetries are a topic of interest to cycling coaches and athletes due to a potential link with performance and injury prevention. OBJECTIVES: The aim of this study is to describe the bilateral asymmetry of professional cyclists during two editions of a Grand Tour. METHODS: Here we set out to determine the power balance (power produced by each lower limb) between stronger and weaker leg (dominant vs. non-dominant) of 12 UCI professional cyclists competing at two Giro d’Italia editions. Power data were recorded during competition stages. Further analysis considered power data clustered …into individual intensity zones (from Z1 to Z7). RESULTS: Higher intensity elicited better power balance (lower asymmetry) regardless of the stage profile. Intensity distribution analysed according to the role of the cyclist was lower for climbers in Z2 (p = 0.006) and Z7 (p = 0.002) and higher in Z5 (p = 0.023) compared to team helpers. Power balance ranged from 0 to 9 % across the different athletes. CONCLUSIONS: Increase in power output improves power balance, especially in team helpers, and the lower power balance at lower exercise intensities, which are most of the race time, may elicit significant cumulative loading on a given leg of the cyclists, which requires further attention regarding risks of overuse injury. Show more

Keywords: Bicycling, endurance, functional lateralization, functional threshold power, lower limbs

DOI: 10.3233/IES-202234

Citation: Isokinetics and Exercise Science, vol. 29, no. 4, pp. 455-461, 2021