Acute effect of strength exercises with superimposed vibration: amplitude of oscillations
Keywords: vibration training, muscular strength, isometric and isotonic contraction
AbstractThe aim of this study was to delineate the effect of different combinations of frequency and amplitude of superimposed vibration on attainment of maximal strength in exercises with isometric or isotonic concentric muscular contraction. The study was conducted on male trained adult volunteers (n=8, age=33.5±3.8). The athletes performed one arm pulling action without or with superimposed vibration that was transmitted from vibratory stimulation apparatus via cable and handle on the proximally located muscles of upper body. The exercises mode was isometric or isotonic concentric; in both cases the subjects developed maximal voluntary efforts. Vibration frequency varied between 17–38 Hz, and vibration amplitude between 2–8 mm. The ergogenic effect was evaluated as difference between force/power values attained in control and vibratory stimulated attempts. The findings display significant stimulatory effect of superimposed vibration in isotonic concentric exercise (increase varied between 8.8–38.3%) and, in much lesser extent, in isometric drill (increase varied between 1.7–5.8%). In isotonic exercise increase of vibration frequency and amplitude within the range of 17–38 Hz and 2–8 mm produced gradual elevation of motor output, whereas in isometric exercise only the proper combinations of frequency and amplitude provided appropriate intensity of mechanical signal, which determined maximal stimulatory effect.