While each impact is driven with their hip flexor and front neck muscles, biologists have learned that there is a more breathy force at play here. Like tennis stars grunting to sync and stabilize their core and whack a ball, woodpeckers also synchronize their breathing with their movement when they strike wood. This helped them track the birds’ breathing before returning to the wild. The team found that their hip flexor and front neck muscles are essential. Some can strike even faster than the downy woodpeckers in this study.