STUDY DESIGN: Controlled laboratory biomechanics study using a repeated-measures, counterbalanced design. OBJECTIVES: To compare patellofemoral joint force and stress between a short- and long-step forward lunge both with and without a stride. BACKGROUND: Although weight-bearing forward-lunge exercises are frequently employed during rehabilitation for individuals with patellofemoral joint syndrome, patellofemoral joint force and stress and how they change with variations of the lunge exercise are currently unknown. METHODS AND MEASURES: Eighteen subjects used their 12-repetition maximum weight while performing a short- and long-step forward lunge both with and without a stride. Electromyography, ground reaction force, and kinematic variables were put into a biomechanical optimization model, and patellofemoral joint force and stress were calculated as a function of knee angle. RESULTS: Visual observation of the data show that during the forward lunge, patellofemoral joint force and stress increased progressively as knee flexion increased, and decreased progressively as knee flexion decreased. Between 70° and 90° of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a short step compared to a long step (P<.025). Between 10° and 40° of knee flexion, patellofemoral joint force and stress were significantly greater when performing a forward lunge with a stride compared to without a stride (P<.025). CONCLUSIONS: When the goal is to minimize patellofemoral joint force and stress during the forward lunge performed between 0° to 90° knee angles, it may be prudent to perform the lunge with a long step compared to a short step and without a stride compared to with a stride, because patellofemoral joint force and stress magnitudes were greater with a short step compared to a long step at higher knee flexion angles and were greater with a stride compared to without a stride at lower knee flexion angles.

J Orthop Sports Phys Ther. 2008; 38(11):681-690, Epub 24 October 2008. doi:10.2519/jospt.2008.2694 

KEY WORDS: knee, knee kinetics, patella, rehabilitation

The manner of acquiring strength-testing data may influence the results of an investigation. The purpose of this study was to determine if a significant difference exists between windowed and unwindowed data collection during isokinetic testing of the shoulder abductors/adductors. Fifty healthy professional baseball pitchers participated in this study. Testing was performed on a Biodex isokinetic dynamometer at 180 and 300°/sec for both the throwing and nonthrowing shoulders. Testing procedures regarding testing protocol, repetitions, positioning, and stabilization followed established guidelines for each subject. Statistical analysis was performed using a paired t-test with a p < 0.01 level of significance. Statistically significant differences were demonstrated between windowed and unwindowed mean peak torque data for both shoulders at both test speeds. The results indicated an average nonthrowing arm difference of 20.2 ft/lbs at 180°/sec and 51.7 ft/lbs at 300°/ sec for the abductors. In each instance, the unwindowed mean peak torque values were higher than the windowed values, and significant end range torque spikes were elicited during unwindowed data collection. The nonthrowing adductors exhibited an average of 39.3 and 48.3 ft/lb differences at 180 and 300°/sec, respectively. The throwing shoulder demonstrated average abductor differences of 25.6 ft/lbs at 180°/sec and 47.7 ft/lbs at 300°/sec. The average throwing adductor difference was 24.4 ft/lbs and 54.6 ft/lbs, respectively, at both test speeds. This investigation offers clinical relevance for those using isokinetic testing of the shoulder abductors/adductors in demonstrating the significant differences between windowed and unwindowed data, identifying torque spike data misinterpretation, and describing a clinical means of controlling aberrant torque production during testing.

J Orthop Sports Phys Ther 1992;15(2):107-112.

Key Words: isokinetics, shoulder testing, torque spikes, windowed data

J Orthop Sports Phys Ther 1992;15(6):279-293.

Key Words: anterior cruciate ligament reconstruction, rehabilitation, clinical outcome

The purpose of this study was to compare the effects of proximal single resistance pad placement (PSPP) and distal single pad placement (DSPP) on tibial displacement during isokinetic exercise on anterior cruciate ligament (ACL)-deficient knees. This study is important to the clinician because it documents tibial displacement during open chain isokinetic knee extension exercise at various isokinetic speeds. In addition, this study documents the range of motion where the greatest amount of anterior tibial displacement occurs. The anterior displacement of the tibia was recorded by a computerized knee laxity testing device during isokinetic exercise. Data were collected from 12 ACL-deficient knees. Each subject was tested on an OSI Knee Signature System for quantifiable tibial displacement during a Lachman's test, anterior drawer test, and active vs. passive knee extension. Following this, each subject was tested on a Biodex isokinetic dynamometer at isokinetic velocities of 60, 180, and 300°/sec with the computerized knee laxity testing device in place. Pad placement consisted of distal single pad placement, which is 1 inch proximal to the medial malleolus, and proximal single pad placement, which is 3 inches proximal to the DSPP location. The testing procedure was standardized, and peak torque was monitored to ensure consistent maximal effort throughout the study. The results indicated that PSPP resulted in less anterior tibial displacement at all three test speeds. The peak anterior tibial displacement occurred in a range from 30 to 15° of knee flexion at both pad placements and all three test speeds. Lastly, the greatest amount of anterior tibial displacement occurred at the 60°/sec isokinetic velocity, whereas less displacement occurred at 180 and 300°/sec, respectively. This study documents that high-speed isokinetics result in less anterior tibial displacement than low-speed isokinetics, and if ACL graft strength or maturation is questionable, a 30° extension block or a proximal resistance pad may be used.

J Orthop Sports Phys Ther 1993;17(1):24-30.

Key Words: anterior cruciate ligament, tibial displacement, resistive exercise

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

J Orthop Sports Phys Ther 1993;17(6):305-317.

Key Words: rehabilitation, elbow joint complex, baseball injuries

The functional anatomy of the elbow joint complex is unique in orientation and configuration. Three bones, the ulna, radius, and humerus, articulate to form four articulations: the humeroulnar, humeroradial, superior radioulnar, and inferior radioulnar joints. This unique osseous structure provides the elbow excellent static stabilization, which is enhanced by the ulnar collateral ligament, the lateral collateral ligament, and the elbow joint capsule. Twenty-three muscles are directly associated with the elbow joint and can be classified into four main groups: the elbow flexors and extensors and the flexor-pronator and extensor-supinator groups. These muscles provide dynamic stabilization to the elbow and enable the hand to perform skilled, precise motions. The purpose of this review article is to provide the clinician with an understanding of the unique anatomy at the elbow joint and to enhance the clinician's knowledge of the biomechanics, clinical examination, and rehabilitation of the elbow complex.

J Orthop Sports Phys Ther 1993;17(6):279-288.

The physical examination of the thrower's elbow presents the clinician with the clinical challenge of differentially diagnosing specific pathologies. The examination should include a thorough history and a well-organized physical examination, which relies on an extensive knowledge of the functional anatomy of the elbow. The components of an elbow examination include inspection/observation, palpation of bony and soft tissues, range of motion assessment, resisted muscle testing (both manual and mechanical), neurologic testing, and special tests. The special tests commonly performed on the thrower's elbow are the Tinel test, tennis elbow sign, ulnar collateral ligament stability testing, valgus extension overload test, and radiocapitella chondromalacia test. Other tests include radiographic examination, such as computerized tomograph arthrogram and magnetic resonance imaging testing. Information presented in this paper will provide the clinician with a systematic and thorough evaluation process for the thrower's elbow.

J Orthop Sports Phys Ther 1993;17(6):296-304.

Key Words: elbow joint complex, elbow pathologies, stability testing

J Orthop Sports Phys Ther 1993;18(1):365-378.

Key Words: shoulder joint, rehabilitation, current concepts