Overhead athletes are your baseball, football, tennis, and volleyball players, and many others. We are familiar with the fundamental mechanics of various overhead skills – throwing, pitching, spiking, serving. Although the general kinematics of these overhead skills have many similarities, the demands on the body and various joints are quite different.
The biggest factor separating these skills is the relationship to the ball: are they holding and releasing the ball, or are they contacting it via their hand or a racket? Both are required to use a proper kinematic sequence (from the ground up through their body) to develop peak velocity at their throwing/hitting hand. However, at the time of ball release or contact, the muscle activation and joint stability demands are very different.
Throwers vs. Hitters
Throwers hit peak velocity (hopefully) at the time of release. At this time, their most proximal segment in the kinematic sequence (throwing arm) is fairly loose moving through release. This is immediately followed by controlled deceleration.
Hitters and servers are also moving at peak velocity at the time of contact with one crucial difference: muscle activation and body movement at the time of contact…they need to be stiff! This moment of stiffness is important for two main reasons:
- By making their body a solid object, they maximize the force and power on the ball. It’s like hitting the ball with a body made of steel instead of rubber. The more relaxed they are at the time of contact, the more forces are absorbed at the moving joints and soft tissues instead of being transferred to the ball.
- Although the ball is typically very lightweight, it is still applying an opposing force back onto the body that the athlete must overcome (Newton’s third law). The repetitive force absorption could result in overuse injuries. Athletes could face chronic joint pain through muscle imbalance, joint instability, tissue microtears, shoulder impingements, etc.
Consider This When Training
When it comes to skill development, particularly early in training where the focus is on coordination, it is important to keep this difference in mind. Many coaches incorporate throwing practice to help develop hitting/serving skills (we see this a lot in volleyball). The general sequence of the skill is similar, yes, but by indirectly training the athlete to have loose movement (mainly through the upper body) through the time of ball contact, performance will suffer and overuse injuries can occur. Ensure stiff and stable joints for optimal health and performance!
Hitters: Is Your Body Stiff?
With an athlete moving at full speed, it is impossible to see with the naked eye how stiff they really are. With Gears 3D Motion Capture, we can detect the smallest changes in joint position and velocity. This can show if an athlete is more stiff at the time of contact, or if they are too loose – allowing the forces to be dissipated in their body. With sensor markers that we can put anywhere, Gears reveals every “invisible” movement occurring at the major joints and segments.