Inertial flywheel knee- and hip-dominant hamstring strength exercises in professional soccer players: Muscle use and velocity-based (mechanical) eccentric overload

Abstract

The primary aim of the present study was to analyze mechanical responses during inertial knee-and hip-dominant hamstring strengthening exercises (flywheel leg-curl and hip-extension in conic-pulley), and the secondary aim was to measure and compare regional muscle use using functional magnetic resonance imaging. Mean power, peak power, mean velocity, peak velocity and time in the concentric (CON) and eccentric (ECC) phases were measured. The transverse relaxation time (T2) shift from pre-to post-exercise were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. Peak and mean power in flywheel leg-curl were higher during the CON than the ECC phase (p<0.01). ECC peak power was higher than CON phase (p<0.01) in conic-pulley hip-extension exercise, while mean power was higher during the CON than ECC phase (p<0.01). Flywheel leg-curl showed a higher T2 values in ST and BFs and BFl (p<0.05), while the conic-pulley hipextension had a higher T2 values in the proximal region of the ST and BFl (p<0.05). In conclusion, ECC overload was only observed in peak power during the conic-pulley hip-extension exercise. Flywheel leg-curl involved a greater overall use of the 4 muscle bellies, more specifically in the ST and BFs, with a selective augmented activity (compared with the conic-pulley) in the 3 regions of the BFs, while conic-pulley hip-extension exercise selectively targeted the proximal and medial regions of the BFl. Physiotherapists and strength and conditioning coaches should consider this when optimizing the training and recovery process for hamstring muscles, especially after injury.

The Effect of Flywheel Inertia on Peak Power and Its Inter-session Reliability During Two Unilateral Hamstring Exercises: Leg Curl and Hip Extension

“…In contrast to the present findings, other investigations reported that no eccentric overload was obtained when using a unilateral (Suarez-Arrones et al, 2020) or bilateral flywheel leg curl (Tous-Fajardo et al, 2006). Although the moment of inertia (0.072 kg•m 2 ) used previously in unilateral protocols is within the range of the present investigation (0.029-0.089 kg•m 2 ), other factors may have influenced the outcomes between investigations.…”

“…Specifically, the participants' flywheel training experience, the device characteristics and technique utilized are important to consider (Muñoz-López et al, 2021a). For example, considering the need for a maximal and prolonged familiarization to optimize eccentric peak power outputs (Sabido et al, 2018;Piqueras-Sanchiz et al, 2020), the submaximal familiarization (2 sets of 6-8 submaximal repetitions) previously utilized may have influenced eccentric peak power obtained (Suarez-Arrones et al, 2020). The present investigation reports that an eccentric overload of peak power may be achieved regardless of moment of inertia utilized with unilateral flywheel leg curl after sufficient familiarization (Figure 4).…”

“…It is also possible that although there are no significant differences in eccentric overload attained between moments of inertia at the group level, such changes may occur for some individuals. Therefore, if practitioners wish to optimize training prescription, it would be ideal to verify if there are optimal moments of inertia to develop peak power with their athletes (Piqueras-Sanchiz et al, 2020;Suarez-Arrones et al, 2020).…”

Flywheel Training Periodization in Team Sports

“…Finally, exercise selection should be considered by practitioners to optimally design their training programs. Multi-joint exercises such as the flywheel squats, deadlifts, and lunges should be prioritized in training sessions seeking strength and power development (Maroto-Izquierdo et al, 2017b ; Beato and Dello Iacono, 2020 ; Madruga-Parera et al, 2020 ), in particular because greater transfer from strength training to sports performance occurs, while less functional single-joint exercises such as the flywheel leg curl and flywheel hip extension (Askling et al, 2003 ; Piqueras-Sanchiz et al, 2020 ; Suarez-Arrones et al, 2020 ; Beato et al, 2021 ) may be preferentially used as injury prevention exercises.…”

Autoregulation in Resistance Training for Lower Limb Tendinopathy: A Potential Method for Addressing Individual Factors, Intervention Issues, and Inadequate Outcomes

“…Technological devices are available to allow quantitative visualization of the effort of an individual, by recording repetition velocity (Jovanovic and Jukic, 2020). Research and practical application of VBT are becoming increasingly popular in S&C and, when VBT is applied systematically, it allows for an immediate feedback, a fatigue control, and the monitoring of biomechanical changes, and can guide the training process (Banyard et al, 2020;Lahti et al, 2020;Martinez-Cava et al, 2020;Perez-Castilla et al, 2020;Sindiani et al, 2020;Suarez-Arrones et al, 2020;Tsoukos et al, 2020). However, for obtaining accurate measurements, individuals must perform fast concentric actions with a good technique, and training adherence and motivation, which may be a barrier for use in rehabilitation (Kawamori et al, 2006).…”