Robert A. Panariello MS, PT, ATC, CSCS
Professional Physical Therapy
Professional Athletic Performance Center
New York, New York
Throughout my career in the related professions of Orthopedic and Sports Physical Therapy (PT) and Strength and Conditioning (S&C) of athletes my associates and I have rehabilitated literally thousands of players with various shoulder pathologies. Many of these athletes were of the opinion their shoulder pathology progressively ensued over the course of their athletic performance enhancement (weight room) training. Many (as well as their sport coaches) also expressed a concern of the possible contributing influence of overhead exercise performance to their shoulder condition. In the cases where imaging studies were performed the majority of these tests revealed the presence of overuse type pathologies i.e. impingement, tendonitis, etc. vs. a distinct rotator cuff tear. Discussions regarding their prescribed training and/or a review of the athlete’s actual training program design, frequently discloses an unwarranted prescribed number of exercises and/or specific exercise executed volumes. This commentary will place emphasis in regard to the performance training program design of athletes yet this subject matter is also appropriate to include in the sports rehabilitation setting as well.
With so much training information available via the internet, conferences, books and journals, as well as numerous training products for sale, many S&C Professionals often express the concern of how to incorporate all of this information into the training program design. The desire to include a vast number of exercises into the athlete’s program design appears to stem from the following:
a. Including a significant number of additional exercises will provide the athlete and/or team with an advantage over their opponent
b. Failure to do so will provide the opponent who incorporates these exercises with an advantage over their athlete/team
The S&C Professional should also be cognizant of not only the overall program design but of the total volume of specific exercise executed repetitions performed by the athlete during the training period as well. In recent years the “more is better” training philosophy appears to be emerging and is a fairly common practice in the development of many athletes training program design. This “more is better” viewpoint may be detrimental to the athlete as the necessary work capacity and recovery abilities to withstand such an employed program design may be lacking. Prescribing an unwarranted exercise volume of work to be executed by the athlete, over time, often results in useless neuromuscular fatigue.
Excessive neuromuscular fatigue has been recognized to give rise to the following consequences:
– A reduction in a muscle(s) force output
– A reduction in the muscle(s) rate of force production
– Negatively alter joint kinematics as well as the technical proficiency of the exercise execution
– The inability to appropriately coordinate (neuromuscular timing) with the associated muscle group(s) in a force couple
– Diminished metabolic efficiency during exercise performance
– A reduction in the athlete’s work capacity
– A decrease in a muscle group(s) “stiffness” thus reducing the ability to unload joint stress
– An increased amortization phase during plyometric activities
– A decrease in joint proprioception
With regard to the shoulder complex, these consequences initially transpire at the smaller muscles and muscle groups such as the rotator cuff. As an example a classic research study (1) demonstrated that a fatigued “normal” rotator cuff replicated the uncharacteristic gleno-humeral kinematics of a shoulder with a torn rotator cuff. A fatigued “normal” rotator cuff is unable to appropriately resist the superior directed vector forces produced by the strong deltoid muscle group, disrupting the rotator cuff- deltoid force couple (Figure 1) that occurs during arm elevation. This fatigue model resulted in an increased average resting (0 degrees of abduction) inferior directed humeral head migration of 1.2mm as well as an increased average superior humeral head migration in the glenoid fossa of 2.5mm at all angles of arm elevation tested. It should be noted that prior to implementing the condition of rotator cuff fatigue the position of the humeral head remained below the center of the glenoid fossa during all tested angles of arm elevation.
Not every exercise is appropriate for every individual however undue exercise prescription or excessive specific exercise executed volumes should also be a consideration in the athlete’s program design as this will likely result in unwarranted neuromuscular fatigue. Thus one may inquire at the time unfortunate shoulder pathology may arise if the overhead shoulder exercises executed are inappropriately blamed as it may be a poor program design that is truly at fault. Figure 2 illustrates the average increased resting inferior humeral migration as well as the superior humeral head migration patterns that are demonstrated to transpire in the glenoid fossa as a result of rotator cuff muscle fatigue.
Additionally neuromuscular fatigue will also alter scapula kinematics as the changes induced via muscle fatigue include increased scapula anterior tilt (or decreased posterior tilt), protraction, internal rotation, and upward rotation (Figure 3). It should also be noted that altered scapula kinematics and positioning is relevant for humeral head decentering in the glenoid fossa. During arm elevation the combination of irregular scapula kinematics in association with the superior migration of the humeral head in the glenoid fossa will potentially increase the incidence of rotator cuff/shoulder pathology via excessive executed exercise performance over time.
This fatigue phenomenon also occurs at other muscle groups affecting the joints which they are associated. Some examples include as a baseball pitcher fatigues not only are the shoulder and elbow joints adversely affected, but negative fluctuations also ensue in pelvic/hip height and rotation as well as lower extremity stride length. It should be noted that a pitch count is recorded for a reason. In runners and sprinters the onset of excessive neuromuscular fatigue may result in a consequential drop in hip height producing less than optimal stride lengths with associated decreased force application into the ground surface area. Wide receivers who reach a considerable state of fatigue do not institute proper foot placement during pass routes thus a disruption of the pass route ensues often leading to soft tissue injury, including documented ACL tears.
The S&C Professional is cautioned of the “more is better” mindset as this may result in the onset of neuromuscular fatigue as well as undesired and unexpected training outcomes, including but not limited to overuse type injuries (strains, sprains, tendinitis, etc.) as well as reduced physical performance. The physical quality of strength, the foundation for optimal athletic performance is enhanced via proper technically executed exercise performance in conjunction with an appropriate training program design. A lower yet sufficient number of prescribed exercises and exercise volumes are proficient as the execution of many exercises of lighter weight intensities may induce excessive neuromuscular fatigue over time. Is the incorporation of the bench press, incline bench press, push press, dumbbell presses, front- lateral- and rear dumbbell raises, and numerous rotator cuff exercises all necessary to be performed during the same training session? The focus on the quality not quantity of implemented training exercises will not only enhance the athlete’s physical quality development, but also allow for improved recovery throughout the athlete’s training period. As advanced exercises are prescribed, the elimination of the remedial exercises performed over a significant period of time is recommended. This alteration in the training program design will result in continued adaptation as well as a fairly consistent overall training volume (avoiding excessive fatigue) while enhancing the work performed i.e. the quality of the weight intensity lifted per exercise repetition.
1. Chen S, Simonian PT, Wickiewicz TL, Otis JC, and Warren RF, “Radiographic evaluation of glenohumeral kinematics: A muscle fatigue model”, J Shoulder Elbow Surg, 8:49 -52, 1999
2. Ebaugh DD, McClure PW, and Karduna AR, “Scapulothoracic and Glenohumeral Kinematics following an External Rotation Fatigue Protocol”, J Ortho Sports Phys Ther 36(8): 557 – 571, 2006
3. McQuade KJ, Shun HW, and Smidt GL, “Effects of local muscle fatigue on three-dimensional scapulohumeral rhythm”, Clinical Biomechanics 10(3): 144 – 148, 1995
4. Teyhen DS, Miller JM, Middag TR, and Kane EJ, “Rotator Cuff Fatigue and Glenohumeral Kinematics in Participants Without shoulder Dysfunction”, J Athl Train July-August 43(4): 352 – 358, 2008
5. Von Eisenhart-Rothe, Matsen FA III, Eckstein F, Vogl T, and Graichen H, “Pathomechanics in atraumatic shoulder instability: Scapula positioning correlates with humeral head centering”, Clin Orthop Relat Res (433):82 – 89, 2005