This video explores whether there is a "best" biceps exercise based on a new study and existing research, focusing on how shoulder position affects biceps growth.
New Study on Bayisian Cable Curls vs. Preacher Curls #
- 15 untrained men participated.
- One arm trained with Bayisian cable curls (shoulder extended), the other with preacher curls (shoulder flexed).
- Resistance profiles were matched, hardest at 60° of elbow flexion.
- Subjects trained twice weekly for 10 weeks, 3-5 sets, 8-12 reps to or near failure.
- Load was adjusted to maintain the 8-12 rep range.
- Biceps thickness was measured across three regions, brachialis across two.
- The study distinguished between biceps and brachialis growth measurements.
- Both exercises grew all regions.
- No statistically significant differences were found in any region.
Interpreting the New Study Results #
- Some may conclude training at longer lengths doesn't benefit biceps.
- However, the speaker suggests this might not be correct.
- Numerically, biceps growth, especially at the 55% region, was greater with Bayisian curls.
- The lowest brachialis region slightly favored preacher curls.
- Lack of statistical significance could be due to a Type II error (failing to detect a real difference) and the small sample size.
- Small sample sizes can lead to studies being underpowered to detect small to moderate real differences.
- "Not significant does not equal no difference; in many cases, it means not enough power." - Quote from a paper.
Comparing Dumbbell Incline Curls and Dumbbell Preacher Curls (Existing Literature) #
- Incline curls (shoulder extended) vs. Preacher curls (shoulder flexed).
- Unlike the new study, resistance profiles are not identical: Incline curls are hardest mid to late, Preacher curls are hardest at the start.
- Study 1 & 2: Found no differences in growth between incline and preacher curls (one even raw numbers slightly favoring preacher).
- One study was short (3 weeks) and used blood flow restriction on trained individuals.
- The other trending towards preacher had unsupervised training and unequal dropout.
- Both measured elbow flexor growth (did not distinguish biceps/brachialis).
- Study 3 (Abstract): Untrained men, one arm incline, other arm preacher.
- Separated biceps, brachialis, and brachioradialis measurement across regions.
- Overall biceps volume greater with incline curls, specifically at 20-40% of length.
- Overall brachioradialis volume greater with preacher curls, specifically at 60% of length.
- Overall brachialis volume greater with preacher curls, specifically at 70-80% of length.
- This study suggests potential for greater differences in higher biceps regions.
- Also suggests preacher curls may better develop some areas of brachialis and brachioradialis.
- Study 4: Untrained women, incline or preacher training.
- Measured elbow flexor growth across three regions.
- Growth at 50% region (mostly biceps) favored incline.
- Growth at 60% region was similar.
- Growth at 70% region (more brachialis) was greater with preacher.
- Suggests incline curls may produce greater biceps growth, while preacher may produce greater brachialis growth.
Research on Other Muscles (Quadriceps) #
- Placing hips into extension lengthens the rectus femoris (like shoulder extension for biceps).
- Leaning back leg extensions lengthen rectus femoris more than regular leg extensions.
- Evidence suggests leaning back leg extensions grew rectus femoris more, primarily at middle to upper regions.
- A study on bodybuilders showed greater rectus activity during leaning back (middle and upper regions).
- Activity measure in this paper correlates with muscle growth.
- Vastus lateralis growth (doesn't cross the hip) was similar between leaning back and regular leg extensions.
Summary of Findings So Far #
- The new study shows numerical, though not statistically significant, differences favoring Bayisian curls for biceps.
- Considering existing literature:
- Incline vs. Preacher studies show conflicting results, but some suggest incline favors biceps, especially in upper/mid regions.
- Quadriceps research supports the idea that training a multi-joint muscle at a longer length may lead to greater growth in certain regions.
- Shoulder extended curls (incline/Bayisian) could be slightly better for the biceps than shoulder flexed curls (preacher), particularly in the upper to mid regions.
Bayisian vs. Incline Curls #
- Both are shoulder extended curls.
- Incline curls are hardest mid to late in the curl.
- Bayisian curls (cable) allow adjusting the point of peak resistance.
- It's possible setting peak resistance at the start of the cable curl could lead to greater growth (though unproven).
- One study comparing free-weight preacher to cable preacher (hardest mid-late) showed similar mid-biceps growth.
- Until more evidence exists, these two variations are generally considered quite similar.
Practical Application #
- The evidence for a clear advantage of shoulder extended curls for biceps is not yet "robust or extensive."
- More data on trained individuals and comparisons with other exercises are needed.
- Including shoulder extended curls in your program or rotation is likely beneficial.
- Worst-case scenario: you build the same muscle as with other curl variations.
- Best-case scenario: evidence strengthens, leading to faster muscle growth.
- Preacher curls may be slightly better for brachialis and potentially brachioradialis, suggesting combining exercises might optimize development.
Exercise Variety for Biceps #
- Study 1: Untrained men, 8 weeks.
- One group: Standing barbell curl only isolation exercise (same exercise daily).
- Other group: Varied exercises (incline, standing barbell, cable preacher).
- Elbow flexor growth (50% region) trended better with exercise variation.
- Authors speculate incline curls contributed to this, supported by other data.
- Study 2: Small sample of well-trained individuals.
- One arm: 6 sets Bayisian curls per session.
- Other arm: 3 sets Bayisian + 3 sets Preacher curls per session.
- No clear difference in elbow flexor growth.
- Cross-sectional area and some circumference measures slightly favored the group doing only Bayisian curls.
- Could be interpreted as evidence of shoulder extended curls benefiting trained individuals.
Putting Things into Perspective #
- While there may be real growth differences between exercises, they are likely not large.
- Other factors are more important for muscle growth.
- If you dislike shoulder extended curls, other variations can still produce significant biceps growth with sufficient effort and volume.
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