Doing extra arm exercises along with big compound lifts like squats and presses makes arms a little bigger, but doesn’t make you stronger than doing just the big lifts alone.
Scientific Claim
Adding single-joint exercises to a multijoint resistance training program in untrained young women is associated with a slightly greater increase in flexed arm circumference (4.39% vs. 3.50%) after 8 weeks of training, but no additional improvement in muscle strength across elbow extension, elbow flexion, or knee extension.
Original Statement
“Flexed arm circumference significantly increased in both groups; however, increases in MJ + SJ (4.39%) were significantly greater than MJ (3.50%). Increases in 10RM load in elbow extension (28.2% for MJ and 28.0% for MJ + SJ), elbow flexion (29.8% for MJ and 28.7% for MJ + SJ), and knee extension (26.92% for MJ and 23.86% for MJ + SJ) were all significant and not different between groups.”
Evidence Quality Assessment
Claim Status
overstated
Study Design Support
Design cannot support claim
Appropriate Language Strength
association
Can only show association/correlation
Assessment Explanation
The abstract describes group comparisons but does not confirm randomization or control for confounders, so causal language like 'results showed that adding... resulted in no additional benefits' is inappropriate. Only association can be claimed.
Evidence from Studies
Supporting (1)
Influence of Adding Single-Joint Exercise to a Multijoint Resistance Training Program in Untrained Young Women.
Adding arm-specific exercises to a full-body workout made arms slightly bigger in young women, but didn’t make them stronger than just doing the big compound exercises alone.