Final answer:
Gary Gray emphasized functional muscle training, highlighting the importance of training muscles to work together to perform daily activities and reduce injury risk.
Step-by-step explanation:
Gary Gray is known for emphasizing functional muscle training in his approach to physical therapy and exercise. Rather than focusing on isolated muscle actions, Gray pioneered the concept of functional training, which involves training muscles to work together to perform everyday tasks or specific athletic endeavors. This concept relies on the idea that muscles should be trained in a way that they function coherently during activities of daily living, sports, and work, thus potentially reducing injury risk and improving performance.