A detailed biomechanical description of baseball helps in understanding the pathomechanics of injuries sustained on the field and in developing measures to protect the player from significant loss of training time.
This stems from the fact that there is an enormous amount of energy transference that occurs from the lower to the upper extremity while playing that requires optimal muscle strength, endurance and overall flexibility.
Such physiological demands need to be in conjunction with appropriate skill and technique in order to prevent overuse injuries and to reduce any undue stress placed on the musculoskeletal system of the player.
In an effort to transfer maximal amounts of energy to the ball through the bat, a player utilises his entire kinetic chain to transfer linear and angular momentum from the ground up through the lower limbs, trunk and upper limbs.
The muscles of the proximal segment increase this momentum even further by adding their own unique momentum before passing it to the connecting distal segment, for example, the upper arm to forearm to hand, resulting in maximum bat velocity.
In one of the most extensive studies conducted on the biomechanics of the baseball swing, David Fortenbaugh, of the University of Miami, defined six phases by analysing nearly 1,300 trials from a large sample of professional batters – stance, stride, coiling, swing initiation, swing acceleration and follow-through.
During the stance phase, he observed that the upper body showed no movement at all, while the lower body slightly rocked back as the lead foot-ground reaction forces shifted bodyweight from the front foot towards the back foot, with the back knee in flexion.
The stride involved the trail foot-ground reaction forces propelling the player forward in a rather controlled manner, with the trail knee slowly extending throughout the phase; this is the phase where the pelvis, upper trunk, trail and lead shoulders, and bat counter-rotate slightly.
The coiling phase entails the body coiling in a series of countermovements which were initiated during the stride phase; this is often taught by coaches to activate the stretch-shortening cycle found during baseball batting.
It is in the swing initiation phase when most of the maximum ground reaction forces were produced as the trail and lead foot-ground reaction forces peaked to fully stabilise the lower body; the lead foot-ground reaction forces reach peak value at the end of this phase to provide the initial energy to be transmitted through the kinetic chain.
With the body moving in the direction of the swing, this is the phase when the pelvis moves much more rapidly and reaches over 95 percent of its peak velocity by the end of the phase.
The swing acceleration phase sees the most dynamic movements in swing between the time of lead foot maximum ground reaction force and bat-ball contact. The pelvis moves through a substantial range of motion while tilting anteriorly. Once the pelvis reaches its peak velocity, the upper trunk follows suit.
The follow-through phase includes all movements that occur after bat-ball contact with the body’s segments continuing to rotate forward in a decelerating manner to slow the body down as the player transitions from swinging into running towards first base.
In their comprehensive report on the long-term injury consequences of playing baseball, Rudi Meir and Robert Weatherby, from the Southern Cross University, mentioned ankle sprains and hamstring strains as some of the most common type of injuries reported by baseball players.
Based on the findings, the authors recommend injury prevention strategies that focus on areas that are most prone to injuries namely, the ankle, hamstrings and shoulder.
An orthotic intervention for improving range of motion at the ankle joint complex would require a thorough study of the patient’s gait pattern. This is because there would be an alteration of walking mechanics and an inability to distribute pressure normally across the plantar surface of the foot when foot posture faults are present.
Customised foot orthotics help improve ankle range of motion by reducing the load on the soft tissue supportive structures around the ankle, by reducing compensation and by providing a stable base of support for resistance of body sway.
MASS4D® custom foot orthotics can also be included in rehabilitative programmes involving eccentric exercises to increase the strength of the hamstring muscles in the absorption of eccentric loads whilst training and to reduce any stress on the affected muscles for a speedy recovery of the player.
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