Originally Posted by ripcity
1. Conserve engery. It's hard to do any thing at full force for 3:00. Try doing that X12 or even X4. Heck it's hard to keep full speed for 1:00.
2. It jars your joints.
3. By changing speed of your punches it makes it harder to be timed.
You conserve energy by throwing snappy punches, when you snap punches you rely on the recoil of the tendon to do the work for you so there is less of a metabolic cost. When you throw a snappy punch your tendons recoil and your distal muscles contract isometrically so you don't use much energy. When you're pushing your punch you're using your muscles to produce more force but you're also using less power because your power amplifiers (tendons) aren't being used as much. Your muscle shortening and lengthening has a high metabolic cost.