SCIENCE

ISOINERTIAL RESISTENCE

The isoinertial flywheel machines, to which LITE INERTIA belongs, use, as resistance, the moment of inertia of a rotating flywheel, during the concentric and eccentric phase of the movement (Nuñez and Saez de Villarreal 2017).

In the concentric phase the resistance is generated by unrolling a rope from a rotation shaft connected to the flywheel, while in the eccentric phase by decelerating the re-rolling of the rope in the opposite direction (Nuñez et al., 2017). This type of resistance is linear as it increases with increasing speed of exercise (Nuñez et al. 2017).

The kinetic energy produced in the concentric phase of the exercise is transferred to the eccentric phase, and therefore, in this second phase it is necessary to apply a force equal to that of the concentric phase to stop the rotation of the moment of inertia of the flywheel (Nuñez et al. 2017). If the time of application of the force during the concentric and eccentric phase is the same then a similar concentric and eccentric load is obtained; however, if the application of the force to decelerate the flywheel during the eccentric phase occurs in a shorter time than that used to accelerate the flywheel, then an eccentric overload is obtained, as all the energy generated during the eccentric phase will be counteracted in a shorter time span (Nuñez et al. 2019).

DISCOVER INERTIA

The possibility of creating eccentric overloads represents one of the mechanical advantages for which the use of isoinertial systems is recommended (Maroto-Izquierdo et al., 2017). In fact, during the eccentric contraction the muscle produces forces that can be up to 30% greater than those produced during the concentric phase, which elicit gains in strength and hypertrophy (Hody et al., 2019).

Specifically, isoinertial flywheel devices such as LITE INERTIA, equipped with a cylindrical-shaped rotation shaft, allow to exert eccentric overloads more easily, compared to similar devices with a conical-shaped rotation shaft (Muñoz-López, et al., 2021).

Another advantage of isoinertial flyheel training is that of being able to adapt the load based on the speed of execution of the exercise within the same repetition or between repetitions in series (Martinez-Aranda, Fernandez-Gonzalo R, 2016). It follows that it is possible to produce maximal forces from the first to the last repetition (the load will decrease with fatigue as a consequence of the reduced speed with which it will be possible to carry out the exercise – albeit the effort always remaining maximal) (Norrbrand, 2010). Furthermore, considering that the muscle is stronger at some angles of contraction and weaker at others, with the isoinertial load it is possible to overcome the sticking point without the help of third parties, simply by decreasing the speed of contraction at weaker working angles; this is not possible, however, with an isotonic load (i.e. dependent on gravity) (Kompf, & Arandjelović, 2016).

As a consequence of the countless advantages offered by flywheel isoinertial systems it is not surprising that recent scientific meta-analysis indicate their high efficacy for strength and hypertrophy improvements even among well-trained individuals (Petré, Wernstål, & Mattsson, 2018), regardless of gender ( Raya-González et al., 2022; de Keijzer, Gonzalez, & Beato, 2022), with sports performance benefits consistently reported following 1-2 weekly sessions for 5-10 weeks of inertial training (Coratella et al . 2019).

CONSULT BIBLIOGRAPHY

Coratella G, Beato M, Cè E, Scurati R, Milanese C, Schena F et al (2019) Effects of in-season enhanced negative work-based versus traditional weight training on change of direction and hamstrings-to-quadriceps ratio in soccer players. Biol Sport 36(3):241–248

De Keijzer, K. L., Gonzalez, J. R., & Beato, M. (2022). The effect of flywheel training on strength and physical capacities in sporting and healthy populations: An umbrella review. PloS one, 17(2), e0264375.

Hody, S., Croisier, J-L., Bury, T., Rogister, B., and Leprince, P. (2019). Eccentric muscle contractions: risks and benefits.  Physiol.10:536. doi: 10.3389/fphys.2019.00536

Kompf, J., & Arandjelović, O. (2016). Understanding and overcoming the sticking point in resistance exercise. Sports Medicine, 46(6), 751-762.

Maroto-Izquierdo S, García-López D, Fernandez-Gonzalo R, Moreira OC, González-Gallego J, de Paz JA (2017) Skeletal muscle functional and structural adaptations after eccentric overload flywheel resistance training: a systematic review and meta-analysis. J Sci Med Sport 20(10): 943–951

Martinez-Aranda LM, Fernandez-Gonzalo R (2016) Effects of inertial setting on power, force, work and eccentric overload during flywheel resistance exercise in women and men. J strength Cond Res 31(6):1653–1661

Muñoz-López, A., de Souza Fonseca, F., Ramírez-Campillo, R., Gantois, P., Nuñez, F. J., & Nakamura, F. Y. (2021). The use of real-time monitoring during flywheel resistance training programmes: how can we measure eccentric overload? A systematic review and meta-analysis. Biology of Sport, 38(4), 639-652.

Norrbrand L. Acute and early chronic responses to resistance exercise using flywheel or weights, Mid Sweden University, 2010.

Nuñez FJ, Hoyo M, López AM, Sañudo B, Otero-Esquina C, Sanchez H et al (2019) Eccentric-concentric ratio: a key factor for defining strength training in soccer. Int J Sports Med 40(12):796–802

Nuñez FJ, Suarez-Arrones LJ, Cater P, Mendez-Villanueva A (2017) The high-pull exercise: a comparison between a versapulley flywheel device and the free weight. Int J Sports Physiol Perform 12(4):527–532

Nuñez FJS, Saez de Villarreal E (2017) Does flywheel paradigm training improve muscle volume and force? A meta-analysis. J Strength Cond Res 31(11):3177–3186

Petré, H., Wernstål, F., & Mattsson, C. M. (2018). Effects of flywheel training on strength-related variables: A meta-analysis. Sports medicine-open, 4(1), 1-15.

Raya-González, J., de Keijzer, K. L., Bishop, C., & Beato, M. (2022). Effects of flywheel training on strength-related variables in female populations. A systematic review. Research in Sports Medicine, 30(4), 353-370.