EFFECTS OF VARIED MUSIC TEMPOS AND VOLUMES ON VERTICAL IMPACT FORCES PRODUCED IN STEP AEROBICS
AbstractINTRODUCTION This study examined the effects of selected combinations of music tempos and volumes used during a step aerobics routine on the peak ground reaction forces (GRF') exerted on a force plate while stepping METHODS 'helve college females having beginning step aerobics experience performed a 20 min. Basic step routine on a .15 m bench. The subjects performed a step aerobics routine to cadences of 122 and 130 bpm and the music volume was varied from 68 to 83 dB while landing on a Kistler piezoelectric force plate connected to an Ariel APAS. The GRFs were sampled at 500 Hz for three 20 sec intervals during 5 min application of each tempo1 decibel condition. The middle 3 impacts of the right and left strides within each 20 sec interval were analyzed, resulting in a total of 9 right and 9 left footfall GRFs. RESULTS The subjects' mean age was 22.8 2.8 years, height was 164.9 4.9 cm, and weight was 60.8 6.4 kg. The peak vertical GRFs were analyzed using a 2 x 2x 2Ax9 ANOVA (Volume x Tempo x Ft x Trial) with repeated measures on all factors. No significant effects were found for factors of volume (p = .424), stride (p = .217), or trial (p = .733). Significant differences for the varied tempo factor were found to exist at the .09 level when the tempo of the music was increased from 122 to 130 bpm. The mean peak vertical impact GRFs were 908.2 149.6 Nt (167% BWT), 930.8 147.3Nt(171%BWT), 921.5 167.0Nt(170%BWT),and943.3 187.1 Nt(174%BWT)forthe treatment conditions of 68 dB1122 bpm, 83 dB1122 bpm, 68 dB1130 bpm, and 83 dbl130 bpm, respectively. CONCLUSIONS The findings suggest that the faster loading and unloading rates of the musculature due to the faster tempo caused less control of the movement and this resulted in a 4% increase in the vertical GRFs. Therefore, the use of faster tempos in a beginning level step aerobics class could be a source for elevated risk for potential injury. REFERENCES Finch A., & Hecko, K. (1996). Effects of prolonged bench stepping on impact forces. Biomechanics in Sports MV ISBS in Sports, Madeira Portugal, 248-25 1. Newton, R., & Humphries, B. (1991). Peak ground reaction forces during step aerobics, walking, and jogging. Proceedings of Ninth ISBS Symposium. Ames, Iowa, 67-71.
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