Pull ups vs. Chin ups

The pull-up and chin-up are similar, but there are noteworthy differences. With a pull-up, you have an overhand-grip. With a chin-up, you maintain an underhand-grip. How does this affect which muscles are trained? Swipe left for more.
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Let’s start with chin-ups. One of functions of your biceps is to supinate the wrists. So during chin-ups, you will notice that your biceps work harder since the wrist is in a supination position. Because your elbows are more tucked in with chin-ups, the resistance is more in line with the lower are of your lats.
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With a pull-up, you have an overhand-grip, making the biceps less dominant. Since your elbows are typically more flared, you will find that your upper back muscles engage well during pull-ups. This helps explain why research suggests the traps and infraspinatus are more involved with pull-ups compared to chin-ups [1].
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If you can’t do pull-ups or chin-ups yet, you can mimic these movement patterns via the lat pulldown. An underhand-grip pulldown mimics the chin-up, while an overhand-grip pulldown mimics the pull-up.
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Reference:
1. Youdas, James W., et al. “Surface electromyographic activation patterns and elbow joint motion during a pull-up, chin-up, or perfect-pullup™ rotational exercise.” The Journal of Strength & Conditioning Research 24.12 (2010): 3404-3414.