Abstract
•Wavelet Intensity is affected by movement speed, loading method, and repetition.•Pneumatic equipment affects wavelet Intensity to a greater extent at high speeds.•The assumption of stationary waveforms during dynamic lifting is inappropriate.•Momentum associated with plate-loaded weight machines affects wavelet Intensity.•For increasing isoinertial power high-speed pneumatics appear the best alternative.
High-speed resistance training is used to increase power; however, momentum can reduce the effectiveness of high-speed (HS) training when using weight-stack (WS) machines. This study used a non-linear scaled wavelet analysis to assess differences between pneumatic (P) and WS during seven HS or controlled speed (CS) repetitions. Vastus medialis (VM) and lateralis (VL), and rectus femoris (RF) EMG data were collected during leg extension exercises performed by five regular weight-trainers (mean age±SD, 23.2±2.9years). Data were analyzed using continuous wavelet analysis to assess temporal Intensity distribution across eight frequency bands. Significant differences occurred due to speed for all muscles (p<.0001). P produced higher Intensity than WS for all muscles during HS (p<.0001), and VM and RF during CS (p<.001). The CON phase produced higher Intensity than ECC for the vasti muscles during CS (p<.0003), and VM and RF during HS (p<.0001). Intensity increased across repetitions plateauing earlier for the vasti than RF during CS. Regardless of the machine, Intensity levels peaked between the 25–53Hz and 46–82Hz (2nd and 3rd wavelets) bands. The results indicate that when the objective is increasing power through isoinertial training, P machines at HS appear to be the most effective alternative.
