Kerksick, C., Mayhew, J., Smith, A., Johnson, B., Hart, C., & Ward, T. (2007). General and specific strength development following resistance training in college men and women. ACSM Annual Meeting New Orleans, Presentation Number, 1778.

"The benefits to be derived from using free weights versus machine weights in a resistance training program remain controversial. Recent investigations indicate that each form of training may have unique benefits at specific phases of strength development". Because of the principle of specificity, there is a strong possibility that training effects derived from various forms and protocols of resistance training differ in much the same way as many forms of aerobic and anaerobic training produce different capacity and performance effects.

The purpose of this study was to determine the amount of strength gain derived in the bench press using free weights and machine weights. College-aged men (N = 181) and women (N = 259) self-selected to train using free weights (N = 165), a seated horizontal chest press machine (N = 173), or a supine vertical chest press machine (N = 102). Ss were tested for general (free-weight) and specific (machine-weight) one-repetition maximum (1 RM) before and after training (three times per week for 12 weeks using a general resistance program). Core lifts in training including the bench press followed a periodized program of 3 x 10-12 RM during the first five weeks, 3 x 6-8 RM during the next four weeks, and 3 x 3-5 RM during the final three weeks.

Men made significantly greater improvements in free weights and horizontal chest press than did women, while women improved significantly more in the supine vertical chest press. The horizontal chest press group made significantly greater improvements than did the supine vertical chest press group, which was significantly greater than the free weights group.

Implication. Different methods of resistance training will produce different amounts of strength improvement in men and women in particular ways. Resistance training does not improve general factors such as "strength". One has to be more specific when defining effects at least indicating what exercises and under what form or contraction/modality changes will occur. Essentially, this means that resistance training effects are specific within resistance training protocols and have little to no possibility of transferring effects to other activities (e.g., throwing, sprinting, cycling, kayaking, etc.). Participating in a resistance training program to improve in a particular sport is likely to be a failure.

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