Chin-Up

Move · Resistance Training · Movement, Typed Supps

Turning your palms towards you lets the biceps pull from the position it is strongest in, which is why most people manage a few more chin-ups than pull-ups.

Stage by stage

Set-up (Forearm supinated): Palms towards you at roughly shoulder width; a wider supinated grip loads the wrist and elbow awkwardly for little gain.
During the set (Elbow flexor leverage improves): Biceps brachii operates at its best advantage as an elbow flexor, which is the whole of the difference from a pull-up.
Through the pull (Lat remains prime mover): Humeral extension and adduction are unchanged, so latissimus dorsi still produces most of the force.
Weeks later (Rep capacity rises): Better elbow leverage raises reps at bodyweight, so a set delivers more volume even with the same muscles involved.

Muscles trained

Primary: lats
Secondary: abs, biceps, rotator cuff, traps, upper back

Intensity

8 METs (Calisthenics (e.g., push ups, sit ups, pull-ups, jumping jacks), vigorous effort).

Time to effect

Weeks: Extra reps come quickly at first as your biceps and lats coordinate better and your grip stops being the limiting factor.
Months: Both your back and your arms visibly fill out, and the exercise starts to feel like a back movement with bicep help rather than the other way around.

Related supplements

Creatine Monohydrate

Common myth

"Chin-ups only work your biceps, not your back." In reality: The supinated grip increases biceps involvement compared with a pull-up, but it doesn't replace the lats as the prime mover — EMG data shows the back still does most of the pulling in a chin-up too.