Strength
Systematic Review
2015
Effect of adding single-joint exercises to a multi-joint exercise resistance-training program on strength and hypertrophy in untrained subjects
By Paulo Gentil, Saulo R.S. Soares and Martim Bottaro
Applied Physiology, Nutrition, and Metabolism, 40(10), pp. 1130-1134
Abstract
<h2>Abstract</h2> <p>This study investigated whether the addition of single-joint (SJ) isolation exercises to a multi-joint (MJ) resistance-training program confers additional benefits in terms of muscular strength and <a href="/terms/muscle-hypertrophy/" class="term-link" data-slug="muscle-hypertrophy" title="hypertrophy">hypertrophy</a> in untrained individuals. Forty young men were randomly assigned to either a multi-joint-only group (MJ) or a combined multi-joint plus single-joint group (MJ+SJ). Both groups trained three times per week for 10 weeks. Muscle <a href="/terms/cross-sectional-area/" class="term-link" data-slug="cross-sectional-area" title="cross-sectional area">cross-sectional area</a> (CSA) of the elbow flexors and extensors was assessed via ultrasound, and maximal dynamic strength was evaluated through <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="one-<a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="repetition maximum">repetition maximum</a>">one-repetition maximum</a> (1RM) testing in the lat pulldown and triceps pushdown. Results demonstrated that both groups exhibited significant increases in muscle CSA and 1RM strength over the training period. Crucially, no statistically significant differences were observed between groups for either hypertrophy or strength outcomes. These findings suggest that, for untrained individuals, multi-joint exercises alone provide sufficient mechanical and metabolic stimuli to drive arm muscle growth and strength gains equivalent to those achieved with additional isolation work. The practical implication is that program designers and coaches working with beginners can achieve comparable results using time-efficient, <a href="/terms/compound-exercise/" class="term-link" data-slug="compound-exercise" title="compound movement">compound movement</a>-based protocols without the need to incorporate supplementary single-joint exercises [1].</p>Introduction
Introduction
Resistance training programs are routinely designed around two fundamental categories of exercise: multi-joint (MJ) compound movements, which recruit multiple muscle groups and joints simultaneously, and single-joint (SJ) isolation movements, which target specific muscles with limited synergist involvement. Classic examples of MJ exercises include the bench press, squat, and barbell row, while SJ movements encompass the bicep curl, triceps extension, and leg extension. In practice, the vast majority of resistance training programs — whether designed for general fitness, bodybuilding, or athletic performance — incorporate both categories.
The prevailing rationale for including SJ exercises is the assumption that MJ movements fail to provide adequate direct stimulation to smaller synergist muscles, such as the elbow flexors and extensors, that assist during compound lifts. It is commonly believed that the lat pulldown, for instance, does not sufficiently challenge the biceps brachii in isolation and that dedicated curling exercises are necessary to fully develop arm musculature. However, the empirical basis for this assumption has not been rigorously tested in controlled experimental settings [1].
From a practical standpoint, the question carries meaningful implications for program design. Adding SJ exercises increases session volume, duration, and potential fatigue accumulation. For time-limited populations — recreational gym-goers, older adults, or individuals in rehabilitation settings — understanding whether isolation exercises offer measurable benefits beyond compound movements is essential for evidence-based programming. Similarly, for strength and conditioning coaches seeking to maximize training efficiency, the cost-benefit ratio of including SJ movements must be justified by demonstrable physiological outcomes [2].
This investigation aimed to address this gap by directly comparing MJ-only training to a combined MJ+SJ protocol in untrained men across a standardized 10-week program, measuring both hypertrophic and strength outcomes.