you can substitute it for a 2 ounce weight. the 6 seperate muscles will still be able to perform the action longer than any single one. same thing when i'm cycling and3 hours into a ride my legs are getting fatigued, i can concentrate on using more hamstring than quads and suddenly I finish the climb, or catch back up to the group, or not fall of the back, etc. Once my hamstrings are fatigued, I can switch back to doing more work with my now rested quads.