It is okay to work out before dry needling treatment. The effectiveness of the treatment can even be enhanced by the increased blood flow from working out.
However, working out after dry needling is not recommended. It is important to take it easy after your visit. Acupuncture gives your body a stimulus that works towards rebalancing your system, which takes a lot of energy, blood, and other resources. If you put most of those resources to your muscles with exercise after treatment, your body will not have the power it needs to put towards rebalancing the body and addressing your primary concern that brought you in for treatment in the first place. It is essential to rest, while the body uses the increased circulation in the area from treatment to heal itself.