Strength outcomes in fixed versus free-form resistance equipment

J Strength Cond Res. 2008 Jan;22(1):75-81. doi: 10.1519/JSC.0b013e31815ef5e7.


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 < or = 0.003). The control (C) 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.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Anaerobic Threshold / physiology
  • Analysis of Variance
  • Equipment Design
  • Exercise / physiology*
  • Exercise Tolerance / physiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Muscle Fatigue / physiology
  • Muscle Strength / physiology*
  • Muscle, Skeletal / physiology
  • Oxygen Consumption / physiology
  • Physical Fitness / physiology*
  • Probability
  • Reference Values
  • Sensitivity and Specificity
  • Weight Lifting*