Abstract details
| Abstract-ID: | 1934 |
| Title of the paper: | Biomechanical differences between flywheel squat and barbell back squat |
| Authors: | Avela, J., Eriksson, T. |
| Institution: | University of Jyväskylä |
| Department: | Faculty of sport and health sciences |
| Country: | Finland |
| Abstract text | INTRODUCTION: Conventional gravity-based strength training methods have been used for centuries. Barbell (Bb) back squat is considered as the golden standard for lower extremity strength training. A disadvantage of conventional strength training is that the resistance stays constant throughout the movement. Flywheel (FW) training is a strength training method which utilizes moment of inertia as a way of inducing resistance, which varies the external load throughout the movement based on applied muscle force (1). The purpose of this study was to compare biomechanical differences in one repetition maximum (1RM) done with Bb exercise with 1RM done with FW squat. METHODS: 14 male athletes with previous strength training background participated in the study. Subjects performed 1RM of Bb and FW squat. Forces were measured with a force plate in Bb and with a pulling force transducer in FW. A 2D motion analysis was done on a highspeed camera for knee and hip joint angles and angular velocities. Muscle activities were measured with surface EMG electrodes from rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and gluteus maximus (GM) muscles. Squat movement was divided into eccentric and concentric phases with 5 subsections each (ECC 1-5 and CON 1-5). Pre- and post-isometric leg press maximal voluntary contractions were also measured. RESULTS: Greater eccentric forces were seen throughout the eccentric subsections in Bb, however significantly greater forces were seen in FW squat in the last two sections of the concentric phase (19,6 % - 42.7 %, p < 0.05 – 0.001). No significant differences were seen in knee and hip joint angles. However, corresponding angular velocities in concentric subsections showed some significant differences between the two squat types: lower velocities in FW in CON 1 and CON 5, but greater velocities in FW from CON 2 to 4 (p < 0.05 – 0.001). Muscle activities were significantly greater in FW squats in RF (14.8 % - 101.8 %), VL (4.6 % - 45.6 %), VM (2.5 % - 54.4 %), and BF (16.2 % - 48.4 %) in eccentric sections, with RF showing also significantly greater activity in concentric sections (21.3 % - 54.8 %) (p < 0.05). GM activity was significantly lower in FW in eccentric (14.3 % - 40.0 %) and concentric (11.9 % - 58.6 %) sections (p < 0.05–0.001). CONCLUSION: Interestingly FW squats showed less force, but greater muscle activities compared to Bb squats. Thus, resistance type (moment of inertia vs. gravity) might not be the only factor that influences the results. Position of the center of gravity differs between the squat types according to the location of the load. For example, back needs to be more upright position in Bb which is not the case in FW due to the harness used. This can already create differences in operative muscle lengths and thus muscle activities. REFERENCES: 1) Norrbrand et al., Aviation, Space, and Environmental Medicine, 2011 |
| Topic: | Biomechanics |
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