Enhanced athletic performance emphasizes the muscle's ability to exert maximal force output in a minimal amount of time. Exaggerated maximal muscular force develops due to athletic movements producing a repeated series of stretch-shortening cycles. The stretch-shortening cycle occurs when elastic loading, through an eccentric muscular contraction, is followed by a burst of concentric muscular contraction. A form of exercise called plyometrics employs a quick, powerful movement involving a prestretch of the muscle, followed by a shortening, concentric muscular contraction, thus utilizing the stretch-shortening muscular cycle. The literature contains numerous references to plyometric training for the lower extremity, but there is a lack of information on the upper extremity plyometric program. Overhead activities, such as throwing, necessitate elastic loading to produce maximal, explosive, concentric muscular contractions. Plyometric exercise employs the concept of the stretch-shortening muscular cycle. The rehabilitation concept of specificity of training suggests plyometric exercise drills should be performed by the throwing athlete. This paper discusses the basic neurophysiological science and theoretical basis for plyometric exercise, and it describes an upper extremity stretch-shortening exercise program for the throwing athlete.

J Orthop Sports Phys Ther 1993;17(5):225-239.

Key Words: stretch-shortening cycle, exercise, muscle spindle

Objectives: To evaluate the muscle latency times of the 3 portions of the trapezius muscle to a sudden arm movement in normal shoulders and to determine if this recruitment pattern is altered as a result of fatigue.

Background: It has been suggested that shoulder impingement may be related to altered muscle activity and muscle fatigue in the scapular stabilizers. Fatigue-induced changes in latency times of the trapezius might influence scapular stability.

Methods and Measures: Muscle latency times were investigated in 30 healthy shoulders with surface electromyography. Muscle activity was measured in all 3 sections of the trapezius and the middle deltoid muscle during a sudden downward falling movement of the arm. Subsequently the shoulder was fatigued on an isokinetic dynamometer, after which muscle latency time measurement was repeated.

Results: ANOVA for repeated measures revealed significant differences in latency times (P < 0.05) among the 4 muscles of interest. Although there were no significant differences among the 3 sections of the trapezius muscle, they all were recruited after the initialization of the deltoid muscle. The recruitment order of the shoulder muscles did not change with muscle fatigue. However, after fatigue, muscle responses were significantly slower in all muscles except for the lower trapezius (P < 0.05).

Conclusions: There is a specific recruitment sequence in the shoulder muscles in response to a sudden arm movement characterized by initial activation of the middle deltoid muscle and followed by simultaneous contraction of all 3 sections of the trapezius. This muscle activation pattern is delayed but not altered with fatigue.

J Orthop Sports Phys Ther. 2002; 32(5):221–229.

Key Words: muscle latency times, muscular balance, neuromuscular properties, scapular stabilizers

The treatment of focal full thickness articular defects in the knee has continued to present a challenge, with no traditional treatment method providing consistent acceptable long-term clinical results. Patients with significant chondral defects frequently have persistent joint line pain, swelling, and catching in the knee. In contrast to marrow stimulation treatment techniques, such as abrasion arthroplasty, drilling, or microfracture, which populate the defect with pluripotential stem cells, the use of cultured autologous chondrocytes fills the defect with cells of a committed pathway to develop hyaline-like cartilage. This hyaline-like cartilage more closely recreates the wear characteristics and durability of normal hyaline cartilage than the fibrous or fibrocartilage repair tissue formed by pluripotential stem cells. The purpose of this paper is to review the efficacy of available treatment options as well as the basic science rationale, indications, technique, postoperative rehabilitation, and clinical results of using cultured autologous chondrocytes in the treatment of focal full thickness chondral defects of the knee.

J Orthop Sports Phys Ther. 1998;28(4):241-251.

Key Words: articular cartilage surgery, knee joint disease, autologous chondrocyte, cell transplantation

Knee joint effusion has been shown to cause a reflex inhibition of the quadriceps musculature. However, the effect of effusion on knee joint proprioception has not been thoroughly investigated. This issue is further clouded by the debate surrounding the role of the muscle spindle and joint mechanoreceptors in providing afferent feedback to the central nervous system. This case study examines the effects of a chronic effusion on knee joint proprioception. Possible suggestions for the results are discussed, and areas for further study are offered.

J Orthop Sports Phys Ther. 1997;25(3):208-212.

Key Words: effusion, proprioception, mechanoreceptors, knee

Current concepts in postoperative anterior cruciate ligament (ACL) reconstruction management include participation in an "accelerated" rehabilitation program. There are no published reports examining the effects of accelerated or conservative rehabilitation on subjects with generalized ligamentous hyperelasticity. The purpose of this case study was to examine the effects of a conservative or "decelerated" rehabilitation program on the functional outcome of a hyperelastic female adolescent athlete following ACL reconstruction. The subject was a 15-year-old female basketball player who sustained a unilateral ACL tear and underwent subsequent ACL reconstruction using a patellar tendon autograft. The subject immediately began participation in a "decelerated" rehabilitation program in which the intensity and rate of progression was decelerated, emphasizing a prolonged period of maximum graft protection. Progress was objectively quantified with a battery of diagnosis-specific tests at scheduled intervals. Results at 52 weeks postoperative revealed normal range of motion, proprioception, balance, knee stability, quadriceps strength, hamstring strength, and subjective assessment values, and only a 4.0% deficit in functional scores. Our results suggest a "decelerated" rehabilitation program may be appropriate for the population with generalized ligamentous hyperelasticity by yielding excellent functional results without compromising the integrity of the graft and, ultimately, knee stability.

J Orthop Sports Phys Ther. 1997;26(1):29-34.

Key Words: anterior cruciate ligament reconstruction, rehabilitation, hyperelasticity

It is hypothesized that proprioceptive information plays an important role in joint stabilization and that muscle fatigue may alter proprioceptive ability. The purpose of this study was to determine what effect shoulder muscle fatigue has on glenohumeral proprioception and to examine the relationship between arm dominance and shoulder proprioception. Eighty subjects without a history of glenohumeral pathology participated. Each was seated on an isokinetic dynamometer with a randomly selected shoulder positioned in 90° of abduction and elbow flexion. With vision blinded, the arm was passively positioned in 75° of external rotation for 10 seconds, then passively returned to the neutral starting position. Three trials each of active and passive repositioning (2°/sec) were recorded. Following a fatigue protocol, both active and passive repositioning were reassessed. Testing order was randomized. A significant difference was detected between pre- and post-fatigue scores. No significant difference was detected between dominant and nondominant extremities. No relationship between arm dominance and shoulder proprioception was established. It is concluded that shoulder proprioception is diminished in the presence of shoulder muscle fatigue, suggesting clinical rehabilitation protocols must emphasize increasing muscular endurance.

J Orthop Sports Phys Ther. 1996;23(6):348-352.

Key Words: proprioception, fatigue, dominance, shoulder

Forty subjects, 13 males and 27 females, between 21 and 31 years of age (x¯ = 24.3, SD = 2.04) were tested bilaterally on the Kin-Com isokinetic dynamometer with simultaneous use of the KC-EMG electromyograph. Subjects were instructed to maximally contract their hamstring musculature in response to a sudden lever arm movement. The peak torque time (PTT) protocol quantified the time lapse between initial lever arm movement and the generation of maximum torque. The electromyograph time (EMGT) protocol measured the time lapse between initial lever arm movement and initial myoelectrical activity of the hamstring musculature. Both PTT and EMGT were found to be reliable (Cronbach alpha 0.823-0.896), with no significant difference (p<.05) between dominant and nondominant limbs. These results indicate that PTT and EMGT are effective for quantifying hamstring reaction time and that the uninvolved lower extremity may be used as a control.

J Orthop Sports Phys Ther. 1994;19(6):335-340.

Key Words: reaction time, hamstring muscles, knee rehabilitation

Knowledge applied equals a successful rehabilitation outcome and a competitive edge.

J Orthop Sports Phys Ther. 1994; 20(6):275.