King Grub
2014-05-08, 07:20
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, sixteen recreationally active men (age = 26.0±7.8 yr, height = 1.7±0.2 m, mass = 82.6±12.7 kg) were familiarized with the experimental protocols and tested for one-repetition maximum (1-RM) squat lift. The subjects then visited the laboratory on two further occasions under either control or experimental conditions. During these conditions, two sets of three repetitions of either FWR (control) or VR (experimental) squat lifts at 85% of 1-RM were performed; during the experimental condition 35% of the load was generated from band tension. After a 5-min rest, 1-RM, 3D knee joint kinematics, and vastus medialis, vastus lateralis, rectus femoris and semitendinosus electromyogram (EMG) signals were recorded simultaneously. No subject increased 1-RM following FWR, however 13 of 16 (81%) subjects increased 1-RM following 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 1-RM following VR when compared to 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 1-RM without detectable changes in knee extensor muscle activity or knee flexion angle, although eccentric and concentric velocities were reduced. Thus, VR appears to potentiate the neuromuscular system to enhance subsequent maximal lifting performance. Athletes could thus utilize VR during warm-up routines to maximize squat performance.
J Strength Cond Res. 2014 May 2. THE INFLUENCE OF VARIABLE RESISTANCE LOADING ON SUBSEQUENT FREE WEIGHT MAXIMAL BACK SQUAT PERFORMANCE.
J Strength Cond Res. 2014 May 2. THE INFLUENCE OF VARIABLE RESISTANCE LOADING ON SUBSEQUENT FREE WEIGHT MAXIMAL BACK SQUAT PERFORMANCE.