Strength outcomes in fixed versus free-form resistance equipment.
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Strength outcomes in fixed versus free-form resistance equipment.
J Strength Cond Res. 2008 Jan;22(1):75-81.
PMID: 18296958
The purpose of this study was to compare measures of strength and balance between subjects using fixed form or free-form resistance training equipment to determine whether there is a difference in strength or balance outcomes. Thirty previously untrained subjects, mean age = 49 (+/-3.7 years), were randomly placed in either a free-form strength group (FF n = 10) utilizing a commercially available free-form plate loaded resistance device, a fixed form strength group (FX n = 10) utilizing a commercially available fixed range selectorized resistance device or a control group (C; n = 10) who did not exercise. All groups were assessed during a pretest (T1) and a posttest (T2). The exercise groups were asked to exercise over a 16-week period, increasing resistance based on a standardized 8-12 repetition protocol. The same muscles were targeted in both exercise groups, all groups were instructed not to change their dietary habits. A one-way ANOVA was used to detect differences among the groups using baseline and end results data. FX group increased strength 57% from baseline while the FF group increased strength 115% from baseline. A statistically significant difference (P = 0.000001) was detected for strength production in the FF over the FX group and (P = 0.0000144) over the training and control groups. Balance improved 49% in the FX versus 245% in the FF groups. Testing revealed a statistically significant difference (P </= 0.003). The control © group did not show significant improvement in either strength or balance. Results of this study indicate a greater improvement in FF over FX in strength (58%), and balance (196%). Additionally, the FX reported increased pain levels while the FF group reported lowered overall pain levels
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No Difference in 1RM Strength and Muscle Activation During the Barbell Chest Press on a Stable and Unstable Surface.
J Strength Cond Res. 2008 Jan;22(1):88-94.
PMID: 18296960
Exercise or Swiss balls are increasingly being used with conventional resistance exercises. There is little evidence supporting the efficacy of this approach compared to traditional resistance training on a stable surface. Previous studies have shown that force output may be reduced with no change in muscle electromyography (EMG) activity while others have shown increased muscle EMG activity when performing resistance exercises on an unstable surface. This study compared 1RM strength, and upper body and trunk muscle EMG activity during the barbell chest press exercise on a stable (flat bench) and unstable surface (exercise ball). After familiarization, 13 subjects underwent testing for 1RM strength for the barbell chest press on both a stable bench and an exercise ball, each separated by at least 7 days. Surface EMG was recorded for 5 upper body muscles and one trunk muscle from which average root mean square of the muscle activity was calculated for the whole 1RM lift and the concentric and eccentric phases. Elbow angle during each lift was recorded to examine any range-of-motion differences between the two surfaces. The results show that there was no difference in 1RM strength or muscle EMG activity for the stable and unstable surfaces. In addition, there was no difference in elbow range-of-motion between the two surfaces. Taken together, these results indicate that there is no reduction in 1RM strength or any differences in muscle EMG activity for the barbell chest press exercise on an unstable exercise ball when compared to a stable flat surface. Moreover, these results do not support the notion that resistance exercises performed on an exercise ball are more efficacious than traditional stable exercises.