Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise

Abstract

This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.

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

“…Another consideration specific to training status is the relative strength levels of the individuals. While several studies provide some measure of the participants' maximal absolute strength [94,95,97,110,111], a paucity of research provides relative strength measurements [112]. It should be noted that stronger individuals may require greater CON velocities or use larger inertial loads while using flywheel devise to experience an ECC overload stimulus.…”

“…When interpreting the findings of the comparative FIT literature, it is important to consider the quality of the prescribed training programs. For example, a number of existing training studies compared training with the flywheel device with weight stack machine training [93,95,110,113] while other studies compared FIT to a control condition that included no additional training [98,111]. The previous studies comparing flywheel and weight stack machine training indicated that greater results were produced with the flywheel device; however, it should be noted that the majority of the training Something to consider when interpreting the results of the existing FIT studies is the training status of the individuals being tested.…”

“…When interpreting the findings of the comparative FIT literature, it is important to consider the quality of the prescribed training programs. For example, a number of existing training studies compared training with the flywheel device with weight stack machine training [93,95,110,113] while other studies compared FIT to a control condition that included no additional training [98,111].…”

Implementing Eccentric Resistance Training—Part 2: Practical Recommendations

“…Previous studies have investigated the effects of FIT performed using four sets of seven repetitions on muscle size (e.g., cross-sectional area, volume, mass) [31][32][33][34][35][36][37][38][39][40][41]. While these studies have displayed positive increases in muscle size, the participants trained using isolated, single-joint movements (e.g., knee extension) or small muscle group exercises (e.g., shoulder abduction).…”

“…While it appears that four sets of seven repetitions may be an effective FIT protocol for hypertrophy, strength, and power output, limited information exists on whether this is optimal for all populations. To the authors' knowledge, only one study has provided information regarding the relative strength of their participants [44], despite several others providing measures of absolute strength [31,34,41,48,57]. From a strength perspective, stronger athletes require a greater overload stimulus than weaker athletes due to their capacity to tolerate heavier loads.…”