It is equally important that you not only maintain high speed, but finish each rep with a powerful glute cramp and abdominal brace. In addition to building power for knockout strikes and winning deadlifts, this exaggerated glute contraction protects the hip joints and spine. If you can no longer pinch your cheeks, the gig is up. Ditto for your abbies: Failing to tense them at the top of the swing not only robs your power, but also endangers your spine.
