Northampton Electronic Collection of Theses and Research

Influence of variable resistance loading on subsequent free weight maximal back squat performance

Mina, M. A., Blazevich, A. J., Giakas, G. and Kay, A. D. (2014) Influence of variable resistance loading on subsequent free weight maximal back squat performance. Journal of Strength and Conditioning Research. 28(10), pp. 2988-2995. 1064-8011.

Item Type: Article
Abstract: The purpose of the study was to determine the potentiating effects of variable resistance (VR) exercise during a warm-up on subsequent free-weight resistance (FWR) maximal squat performance. In the first session, 16 recreationally active men (age = 26.0 ± 7.8 years; height = 1.7 ± 0.2 m; mass = 82.6 ± 12.7 kg) were familiarized with the experimental protocols and tested for 1 repetition maximum (1RM) squat lift. The subjects then visited the laboratory on 2 further occasions under either control or experimental conditions. During these conditions, 2 sets of 3 repetitions of either FWR (control) or VR (experimental) squat lifts at 85% of 1RM were performed; during the experimental condition, 35% of the load was generated from band tension. After a 5-minute rest, 1RM, 3D knee joint kinematics, and vastus medialis, vastus lateralis, rectus femoris, and semitendinosus electromyogram (EMG) signals were recorded simultaneously. No subject increased 1RM after FWR, however, 13 of 16 (81%) subjects increased 1RM after VR (mean = 7.7%; p < 0.01). Lower peak and mean eccentric (16-19%; p ≤ 0.05) and concentric (12-21%; p ≤ 0.05) knee angular velocities were observed during the 1RM following VR when compared with FWR, however, no differences in knee flexion angle (1.8°; p > 0.05) or EMG amplitudes (mean = 5.9%; p > 0.05) occurred. Preconditioning using VR significantly increased 1RM without detectable changes in knee extensor muscle activity or knee flexion angle, although eccentric and concentric velocities were reduced. Thus, VR seems to potentiate the neuromuscular system to enhance subsequent maximal lifting performance. Athletes could thus use VR during warm-up routines to maximize squat performance.
Uncontrolled Keywords: 1RM, elastic bands, postactivation potentiation, preconditioning, strength training
Creators: Mina, M A, Blazevich, Anthony J, Giakas, G and Kay, Anthony D
Faculties, Divisions and Institutes: Faculties > Faculty of Health & Society > Sports, Exercise & Life Sciences
Research Centres > Centre for Physical Activity and Life Sciences
Date: 1 October 2014
Date Type: Publication
Page Range: pp. 2988-2995
Journal or Publication Title: Journal of Strength and Conditioning Research
Volume: 28
Number: 10
Number of Pages: 8
Language: English
ISSN: 1064-8011
Status: Published / Disseminated
Refereed: Yes

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