Effects of moderate vs. high iso-inertial loads on power, velocity, work and hamstring contractile function after flywheel resistance exercise

Abstract

Flywheel iso-inertial training has been shown to positively affect muscular strength and sports performance (e.g. agility). However, implementing such eccentrically-biased training during a microcycle needs to be carefully planned due to its purported effects on the neuromuscular system that can last for hours/days post-exercise. This study aimed at using tensiomyography to verify the effects of different inertias during the hip extension exercise on the contractile function of biceps femoris and semitendinosus muscles of the dominant leg for up to 72 hours post-exercise. Thirty participants (24.4 ± 3.4 years) were divided into 0.075 or 0.1 kg·m2 inertia groups and a control group. Magnitude-based analysis was used for the comparisons. Several tensiomyography parameters were changed after both intensities of flywheel exercise (in most cases indicating a decrement in muscle stiffness), whereas most between-group differences suggested that in the semitendinosus muscle, the higher inertia (0.1 kg·m2) influenced the muscle stiffness parameters more (e.g. Dm = maximal radial displacement) while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kg·m2) (e.g. Tc = contraction time). Most changes in contractile properties of the investigated muscles occur within 24 hours post-exercise, but can persist for up to 72 hours. However, higher inertia (0.1 kg·m2) influenced the stiffness of the semitendinosus muscle more, while in the biceps femoris, the greater effect was caused by the lower inertia (0.075 kg·m2). These findings should be considered by practitioners when prescribing flywheel iso-inertial training.

Comparison of Interventional Strategies to Improve Recovery after Eccentric Exercise-Induced Muscle Fatigue

“…In our case all groups showed a decrease in Tc after the eccentric overload exercise. Also, previous studies using eccentric overload exercises showed increased Tc values at 24 h [ 34 ], which are related, together with Dm changes, to muscle damage in both the neuronal and structural systems [ 35 ]. Therefore, the similar correlations shown in the treated leg in the case of MT and PT have great relevance when considering studies such as that of Dupuy et al (2018) [ 36 ], who compared the effects of MT with other therapies including compression garments, cold water immersion, electrostimulation and cold water.…”

“…Previous studies have shown significant increases in Dm values at 24 h after eccentric overload, but no change after 48 or 72 h [ 34 ]. These findings show that the load factor plays a crucial role in muscle changes [ 37 ].…”

Effect of Volume on Eccentric Overload–Induced Postactivation Potentiation of Jumps

“…8,30,31 Although different intensities of EOL squats have previously resulted in no meaningful difference in jump potentiation, 16 they may differentially activate musculature of Page 5 of 10 the lower limbs in individuals. 18 Recording the power output during EOL exercise may help to clarify this.…”

Implementing Eccentric Resistance Training—Part 1: A Brief Review of Existing Methods

“…However, this often leads to “wasted repetitions” (i.e., repetitions needed to get the flywheel up to the desired velocity), training to failure, and poor training load management. Previous research has suggested that lower inertial training loads may produce greater adaptations for peak power, while moderate to high inertial loads may provide greater ECC overload [ 112 , 115 ]. However, as previously noted, larger inertial loads may increase the length of the ECC phase of the movement, which may modify the ECC overload stimulus [ 109 ].…”