A question for the uber well versed in biomechanics:
How does the hand grip type (thumbs included, no thumbs, four fingers, three fingers, two fingers, one finger) effect the muscles used in a pullup?
Dropping from four fingers to three appears to make a massive difference in the amount of power (wattage) of the pull up. I've measured this by determining heart rate differences between the two type. Converting from heart rate to power is a bit of a black magic art, but any conversion trick used does not seem to account for the increased work load. My guess is that the biomechanics of the pullup are more different than just the activation of some of the for arm muscles dependent on the hand grip position.