Changes in Muscle Power and Muscle Morphology with Different Volumes of Fast Eccentric Half-Squats

Abstract

The aim of the study was to evaluate power performance and muscle morphology adaptations in response to 5 weeks of fast-eccentric squat training (FEST) performed twice per week, with three different training volumes. Twenty-five moderately trained females were assigned into three groups performing eight repetitions of FEST of either four sets (4 × 8 group; N = 9), 6 sets (6 × 8 group; N = 8) or eight sets (8 × 8 group, N = 8). Before and after the intervention, countermovement jumping height (CMJh) and power (CMJp), half squat maximal strength (1-RM), quadriceps cross-sectional area (QCSA) and vastus lateralis (VL) architecture and fiber type composition were evaluated. Significant increases (p < 0.05) were found for all groups, with no differences among them in 1-RM (4 × 8: 14.8 ± 8.2%, 6 × 8: 13.1 ± 9.2% and 8 × 8: 21.6 ± 7.0%), CMJh (4 × 8: 12.5 ± 8.5%, 6 × 8: 11.3 ± 9.3% and 8 × 8: 7.0 ± 6.2%), CMJp (4 × 8: 9.1 ± 6.0%, 6 × 8: 7.1 ± 5.2% and 8 × 8: 5.0 ± 3.9%) and QCSA (4 × 8: 7.7 ± 4.7%, 6 × 8: 9.0 ± 6.8% and 8 × 8: 8.2 ± 6.5%). Muscle fiber type distribution remained unaltered after training in all groups. VL fascicle length increased and fascicle angle decreased only in 6 × 8 and 8 × 8 groups. In conclusion, four sets of eight fast-eccentric squats/week increase lower body power and strength performance and maintain type IIX muscle fibers after 5 weeks, at least in moderately trained females.

Can Countermovement Jump Neuromuscular Performance Qualities Differentiate Maximal Horizontal Deceleration Ability in Team Sport Athletes?

“…In this context, the specificity of training would include fast eccentric only squats, where participants are instructed to “squat fast and stop rapidly at a half-squat position”, a modality shown in untrained subjects to induce greater adaptations to fast-twitch type IIX muscle fibres and explosive isometric RFD than slow eccentric-only squats [ 43 ]. Furthermore, these enhancements were also evident following low volume (4 × 8 reps, twice per week) interventions in moderately trained individuals [ 44 ].…”

Can Exercise-Induced Muscle Damage Be a Good Model for the Investigation of the Anti-Inflammatory Properties of Diet in Humans?

“…Apart from the classical blood or saliva samples, that are usually collected before and several time points after the exercise trial this type of experiments allow you to take samples of the inflamed tissue, namely muscle biopsies. This technique has been used in many studies, investigating either the training-induced adaptations on muscle fibers (for example [ 89 , 122 , 257 , 258 , 259 , 260 , 261 , 262 , 263 ]), or muscle damage-inflammation (for example [ 63 , 122 , 128 , 231 , 248 , 264 , 265 , 266 , 267 , 268 , 269 , 270 , 271 ]. Muscle samples for such type of studies are usually obtained with Bergstrom needles from vastus lateralis of lower extremities, under local anesthesia, easy and quite safe for the volunteers, while in the majority of the countries, this is well accepted from the bioethics committees.…”

Weak Association between Vastus Lateralis Muscle Fiber Composition and Fascicle Length in Young Untrained Females

“…For example, it has been reported that in a world champion shot putter, with a predominance of type I muscle fibers (~60%), his hypertrophied type II muscle fibers occupied 67% of VL the area, making him able to achieve greater power and shot put performance, compared to another shot-putter with a predominance of type II fibers but with smaller type II fiber CSA [ 45 ]. Additionally, changes in the %CSA of muscle fibers seem to be linked with the accompanying changes in power performance [ 28 , 38 , 44 , 46 ]. The physiological background of muscle fiber %CSA importance in power performance is based on both, the properties of the large fibers, and of the mechanical characteristics of each fiber type.…”

“…1-RM Half Squat Strength. This test was performed according to the methodology previously described [ 10 , 28 , 32 , 33 , 38 ]. Thirty minutes after the end of the CMJ testing, maximal half-squat strength was assessed in a Smith squat rack.…”

“…The procedure was done according to previous reports from our laboratory [ 2 , 28 , 30 , 33 , 37 , 38 , 39 ]. Muscle samples were obtained with Bergström needles, from the middle part of the non-dominant lower extremity vastus lateralis, at the exact point of ultrasound imaging, and under local anesthesia by a trained physician.…”