The Claim

Preacher curls performed at long muscle lengths may increase muscle thickness at the distal region of the upper arm, specifically at 70% of the acromion-olecranon distance, in recreationally trained women, with an observed medium effect size (Cohen’s d = 0.623) and approximately a 9% increase in muscle thickness following 9 weeks of training.

Source: Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
47score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Quantitative
1 study reviewed
In plain English

Doing preacher curls might help women who work out regularly build more arm muscle, especially toward the lower part of the upper arm, and after about 9 weeks they could see around a 9% increase.

See the scientific wording

Preacher curls may increase muscle thickness at the distal region (70% of acromion-olecranon distance) of the upper arm in recreationally trained women, with a medium effect size (Cohen’s d = 0.623) and approximately 9% increase in muscle thickness after 9 weeks of training, suggesting this exercise performed at long muscle lengths could preferentially stimulate growth in that specific region.

What the research says

1 study
  1. Study: Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women

    The study tested preacher curls in women and found they made the lower part of the bicep thicker after 9 weeks, just like the claim says.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

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