UP TO ten seconds. That doesn't mean that all brain activity for all actions must always start ten seconds before the body takes action.

The experiment was showing what happens when we feel like we we are making a CONSCIOUS choice. But notice closely what happens when you have to suddenly take emergency action, for example to avoid a car crash. Your body will react before you've even had time to consciously make a choice. If you notice, it doesn't even feel like a conscious choice. The body just reacts. The sensory input bypasses concious processing and makes you instinctively take action for survival.