—– Machine assisted chin-ups. Combined arms and separate arms. Various sets, reps, weights and various rest minutes to tweak local muscle growth. 40-70 pound assist.
—– I think chinup muscle ability lags behind wrist and shoulder trauma.
—– The first thing thing we look for is the biceps’ ability to lift the chin over the bar. Often the wrists aren’t strong enough for one. Or the repeated muscle conditioning leaves the wrists and shoulders strained. Then we take days or weeks for the wrists and shoulders to heal, while we lose any muscular gains.
—– So do your research, and take care of the wrist joints and shoulder joints first.