Muscle Group: Biceps

Machine Curls
PreacherCurls

Machine Exercise: Machine Curls 

Free Weight: Preacher Curls

If back alignment can be maintained but the risk is the sustained upper back flexion when positioned over arm support

Sit with back aligned and supported, use two dumbbells or theraband.

UHPullup

Body Weight: Underhand Pull Up

If a client could do this (strength and control wise) then it may be OK to continue.  Watch transitions onto/off of bar. Use of gravitron to offset body weight.  Care in transitions in and out of machine.

BicepStretch

Stretch: Bicep Stretch

The typical biceps stretch shown above is more of a chest stretch and often incorporates twisting which should be avoided.