Abstract
PURPOSE: Strength training is recognized by the American Heart Association and the American College of Sports Medicine as an essential component of lifelong health and functional capacity. The effectiveness of resistance training depends on appropriate dosing of intensity and overload to elicit targeted neuromuscular adaptations. This study examined interlimb symmetry in force production during bilateral chest press exercise, assessing whether dominant and non-dominant upper extremities generate comparable forces under isometric and dynamic (3-repetition) conditions.
METHODS: Thirty healthy college students (20 males, 10 females) participated. Twenty-four were right-hand dominant and six were left-hand dominant; 28 participants reported engaging in resistance training more than once per week. A Matrix® chest press machine (Matrix Fitness, Cottage Grove, WI) was instrumented with Novel force pad transducers (Novel) affixed to the handles, which were adjusted to a position level with the mid-sternum to standardize shoulder joint alignment. Force data (in newtons) were collected via the Novel ForcePad mobile application during maximal isometric and three-repetition isotonic chest press trials. Paired-samples t-tests (α = 0.05) were used to compare right and left-arm peak forces.
RESULTS: A statistically significant difference in force output between upper extremities was observed for both isometric (mean difference = 31.93 N, t(29) = 2.65, p =.006) and isotonic 3-repetition conditions (mean difference = 39.42 N, t(29) = 3.42, p <.001). Hand dominance did not significantly influence the observed asymmetry.
CONCLUSIONS: Findings indicate that bilateral chest press machines may not promote symmetrical force generation across the upper extremities. If balanced force production is a training objective, practitioners should consider unilateral resistance exercises, such as single-arm machine presses or free-weight dumbbell presses, to enhance neuromuscular balance and address limb asymmetry. Future research should compare dual-independent-arm resistance machines and barbell chest press modalities to quantify symmetry and evaluate the role of visual feedback or real-time force monitoring. Incorporating force-sensor technology may reduce asymmetry-related performance deficits.