Archive for February 15th, 2010

EMG of Football Throw

Posted 15 Feb 2010 — by Brandon
Category Uncategorized

Studies of the overhead throw are most commonly performed for the sport of baseball because every athlete in baseball must have the ability to throw well to participate in the sport.  However, in the game of football the quarterback displays the same overhead throw techniques as in baseball.  According to Kelly, Backus, Warren, & Williams (2002), state, “Although the football throw is similar in some respects to other overhead throwing motions, the increase weight of the football (0.42 kg versus 0.14 kg for the baseball) appears to affect shoulder position and stresses throughout the throwing motion”(837).  The increase weight and shape of the football may allow for different firing patterns of the muscles that accompany the shoulder.  In this study, an electromyographic (EMG) analysis was done on the overhead football throw to give quarterbacks, coaches, strength coaches, athletic trainers, and physical therapist a better understanding on how to strengthen, prevent injuries, and treat injuries of the overhead football throw.

            For instance, in 2002 a study was performed using videos of quarterbacks in the National Football League (NFL) and fourteen male participants who’s skilled levels ranged from recreational athletes to collegiate level athletes who all had experience of throwing a football.  First, researchers analyzed the videos of the NFL quarterbacks to break down the phases of the football throw.  The phases consisted of early cocking, late cocking, acceleration, and follow-through.  According to Kelly et al. (2002) state,

Early cocking was initiated at rear foot plant and continued to maximal shoulder abduction and internal rotation.  Late cocking started at maximal shoulder abduction and internal rotation and ended with maximal shoulder external rotation.  The acceleration phase began with maximal shoulder external rotation and ended with ball release.  Finally, the follow-through was defined as the phase from ball release to maximal horizontal adduction (838).

After the phase analysis was complete, an EMG was performed on the fourteen male participants using fine-wire and surface electrodes.  Each participant was allowed a total of twenty throws into a net that was approximately ten yards away.  After the data was collected from the EMG analysis, researchers separated the muscles into two groups.  Group I muscles which consisted of the supraspinatus, infraspinatus, anterior deltoid, and middle deltoid showed static levels of activity throughout the throwing motion.  These muscles in group I stabilize the shoulder during the entire throwing motion.  In addition, group II muscles consisted of the subscapularis, pectoralis major, and latisimus dorsi showed more activity during the acceleration and follow-through phases.  The muscles in group II are responsible for throwing velocity and deceleration of the arm during the throw. 

            In my opinion, I believe that this study done on the overhead football throw was well done because it broke down the football throw into four simple phases which consisted of early cocking, late cocking, acceleration, and follow-through.  From the each phase, you could easily break down the movements to understand what muscles are being active through that specific phase of the throw.  However, the study itself was very simplistic because it only examined what went on in the glenohumeral joint and not any other joints such at the elbow, wrist, trunk and especially the legs.  I believe that the legs are the most important factor for a quarterback because the legs generated the most power in the throw and also important for balance.  Just with any total body moment, it must involve the whole kinetic chain the build-up of momentum and power.  Another thing that I thought was odd  was that the subjects only threw from ten yards into a net.  During a football game, a quarterback must throw a variety of passes which might consist of different lengths and velocities. 

            For instance, if I were to perform this study I would have the same idea but involve more passes of different varieties and not just throwing into a net from ten yards away.  I would have the quarterback throw to an actual receive rather than a net because the study would come out to more of a realistic outcome. The receiver could run different patterns and have different displacements such as ten, twenty, and thirty yards away while the quarterback throws to him.  I would also gather an EMG reading of the legs because and other joints in the body.  Since, overhead throws are more associated with baseball; I believe that this study did a good job of opening up the doors to other researchers who want to explore more about the overhead football throw.   

References

Kelly, B.T., Backus, S.I., Warren, R.F., & Williams, R.J. (2002). Electromyographic analysis                  and phase definition of the overhead football throw. American Journal of Sports   Medicine, 30: 837-844.  Retrieved November 9, 2008 from PubMed database.

Lit Review: ACL Injuries

Posted 15 Feb 2010 — by Brandon
Category Uncategorized

The anterior cruciate ligament (ACL) is the most important stabilizing ligaments in the knee and is composed of three fibrous bands twisted together.  These bands are composed of anteromedial, intermediate, and posterolateral bands that prevent posterior movement of the femur and anterior movement of the tibia, as well as assisting with resisting internal rotation of the knee.  The ACL receives the most attention out of the all the stabilizers in the lower leg because it is the most vulnerable to injury.  According to the National Academy of Sports Medicine, “An estimated 80,000 to 100,000 anterior crucaite ligaments (ACL) injuries occur annually in the general U.S. population.  Approximately 70% of these are noncontact of these are noncontact injuries” (Clark, Luccett, Corn, 2008, p. 5).  In addition, females are more likely to suffer ACL injuries than males because of several intrinsic and extrinsic factors.  Researchers are exploring new surgical, nonsurgical, and rehabilitation techniques to help restore stability of the ACL, while preventing reoccurring injuries and help limit arthritis of the knee joint.

            Injuries of the ACL are most likely to occur when the tibia is externally rotated and the knee is in a valgus or “knock knee” position.  Injury of the ACL is mostly likely to happen in any sport or activity that involves cutting, jumping, running, and direct contact.  Whether or not to perform surgery on an ACL injury depends on many factors.  According to Prentice (2009), he states:

Therefore, a decision for or against surgery must be based on the patient’s age, the type of stress applied to the knee, and the amount of instability present, as well as the techniques available to the surgeon.  A simple surgical repair of the ligament may not establish the desired joint stability (p.676).

Restoring knee stability and joint proprioception is the most important factor while maintaining a healthy kinetic chain for a patient suffering with an ACL injury.  Since the ACL is the most vulnerable ligament of the knee, many studies have reported findings of new operative and non-operative treatments of the ACL injury.

            For example, a study in 2007 compared an autograft and allograft of the hamstring tendon for an ACL reconstruction.  Most ACL reconstructions are mostly performed using autograft tissue taken from the middle third of the patellar tendon.  The disadvantages of the autografts are harvest-site morbidity, longer operative time, and nerve damage (Edgar, Zimmer, Kakar, Jones, Schepsis, 2007).  Furthermore, using allograft tissue reduces operative time, lacks donor-site morbidity, and exhibits less pain and stiffness compared to the autograph.  Eighty-four patients participated in the study and out of the eighty-four patients, thirty-seven had autografts and forty-seven were treated with allografts.  According to Edgar et al. (2007) he states,

We asked whether (1) hamstring tendon allograft tissue stretches with time leading to increased laxity or an increased rate of failures, and (2) hamstring allograft constructs have similar clinical performance in primary ACL reconstruction based on accepted clinical outcome scores as compared with traditional hamstring autograft constructs (p. 2239).

The outcome of the study showed that an allograft hamstring construct showed similar scores to that of the autograft.  There was no significant difference in the outcome of the Knee Documentation Committee scores, Lysholm scores, Tegner activity scales, and KT-1000 arthromeres measurements.  Even though the autografts are more popular with surgeons, further studies must be done to determine what techniques work best for the reconstruction of the ACL.

            Furthermore, another study explored the long-term results after primary repair and non-surgical treatment of the ACL.  In this study, one-hundred patients participated in a 15 year follow up to explore the long term affects after primary repair or non-surgical treatment.  The main focus of the study was to see if there was a presence of radiological osteoarthritis (OA).  According to Meunier, Osdensten, & Good (2007) state, “Our hypothesis was that surgical repair of the ACL reduces the risk of OA and improves the subjective outcome and function compared with non-surgical treatment”(230).  They found that a number of patients that undergone non-surgical treatment had more meniscus injuries and one-third of the non-surgical group underwent a second treatment because of instability problems.  The condition of the menisci is found to be the most important factor of developing OA (Meunier, Osdensten, Good 2007).  In conclusion, OA is more contributed to injuries of the menisci.  Early surgical repair of the ACL can reduce secondary meniscus tears, while inhibiting OA from occurring.

            In addition, whether or not surgery is administered to a patient with an ACL injury must rely on a good rehabilitation program.  For instance, an athlete that has suffered from an ACL injury goes through a physical and psychological regression which might prolong the rehabilitation process.  Recovery and getting back to play is absolutely the most important thing to an athlete who has suffered any injury.  According to Prentice (2009) he states, “A detailed rehabilitation program for an ACL reconstruction is provided in the accompanying management plan.  It has been suggested that it may take up to two years for a patient to regain normal quadriceps muscle function following ACL reconstruction”(676).  Traditional ACL rehabilitation process is broken down into four phase that consist of acute, subacute, functional progression, and return to activity (Myer, Paterno, Ford, Hewett 2008).  However, a recent study out of the Journal of Strength and Conditioning Research developed a new and improve progressive way to make the ACL rehabilitation process better for all athletes returning to sport.  This new criteria is broken down into four phases that include core stabilization, functional strengthening, power development, and sports performance symmetry.  According to Myer, Paterno, Ford, & Hewett (2008) each phase is designed to treat common deficits after ACL reconstruction and address any risk factors that the athlete might have been contributing to before the athlete’s injury.

            In conclusion, I believe that there is not enough evidence out there to establish an actual protocol on how to treat ACL injuries.  All of the studies, reports, and books that I have read, focus only on establishing knee stability after an ACL injury and rarely focusing on the importance of the kinetic chain.  Whether or not surgery is required, proper functional movements of sports or activities of daily living should be the main concern for therapist, trainers, and doctors.  The ACL is the most common knee ligament that is injured and I believe that the main problem is that professionals in the sports medicine field, need to practice a holistic approach to not only fixing and repairing ACL injuries but, fixing and repairing the kinetic chain and the body as a whole. 

 

 

References

Clark, M.A., Corn, R.J., & Lucett, S.C. (2008). Nasm essentials of: Personal fitness training.

            Baltimore, MD: Lippincott Williams & Wilkins.

Edgar, C.M., Zimmer, S., Kakar, S., Jones, H., Schepsis, A.A. (2008). Clinical Orthopaedic

            Related Research, 466, 230-237. Retrieved November 10, 2008, from Pubmed database.

Meunier, A., Odensten, M., Good, L. (2007). Long-term results after primary repair or non-

            surgical treatment of anterior cruciate ligament rupture: a randomized study with a 15-

            year follow-up. Scandinavian Journal of Medicine & Science in Sports, 17, 230-237.

            Retrieved November 10, 2008, from Pubmed database.

Myer, G.D., Paterno, M.V., Ford, K.R., & Hewett, T.E. (2008). Neuromuscular training

            Techniques to target deficits before return to sport after anterior cruciate ligament

            Reconstruction, 23(3), 987-1014. Retrieved November 15, 2008, NSCA database.

Prentice, W.E., (2009). Arnheim’s principles of athletic training: A competency-based approach.

            Boston, MA: McGraw-Hill