could heavy deadlifts and pulls be considered isometrics for the biceps because of the extreme amount of tension required to hold the weight at an extreme angle.
In have spoken to people who really believe in supine grip DL as the ultimate biceps tension inducer. Obviously the fact there is little ROM about the elbow joint means the strength transfer is limited to roughly about the ROM used during the lift (see the Russian ‘functionaly isometrics’ theory’). Understanding that the load lifted will be less and potential to increase low back strain can rise (posture/grip relation) if not perfomed spot-on.