J Orthop Sports Phys Ther 1980;2(1):15-19.

Study Design: Prospective, observational study. Objectives To document changes in surface electromyographic activity during sustained maximum quadriceps contractions in patients before and 5 weeks after anterior cruciate ligament (ACL) reconstruction. Background: Quadriceps weakness after injury and reconstruction of the ACL is well documented. The effect of weakness on muscle fatigue, however, is not well understood. Methods and Measures: Electromyographic signals were recorded from the vastus lateralis, vastus medialis, and rectus femoris muscles during 30-second maximum isometric contractions at 30°, in 42 patients preoperatively and 5 weeks postoperatively. Signal amplitude was quantified by integrating the rectified signal (iEMG) for the initial and final 5 seconds and comparing the involved and uninvolved sides. Median frequency (MF) was computed from 4096 point fast Fourier Transforms performed at the beginning and end of the 30-second contractions. Results: Patients had moderate preoperative quadriceps weakness (16% deficit) and gross postoperative weakness (41% deficit). Weakness was associated with deficits in both MF and iEMG (r = 0.69-0.67). During the preoperative fatigue test, torque declined similarly on the involved and uninvolved sides (significant fatigue effect). During the postoperative fatigue tests, however, torque increased on the involved side and declined on the uninvolved side (significant side by fatigue interaction). For the initial 5 seconds, MF was lower on the involved than the uninvolved side but subsequently showed a smaller decline over 30 seconds preoperatively and postoperatively (significant side by fatigue interactions). iEMG was lower on the involved side preoperatively and postoperatively. During the fatigue tests, iEMG increased similarly in the involved and uninvolved sides both preoperatively and postoperatively. Conclusion: Quadriceps endurance exercises are not indicated after ACL reconstruction. Quadriceps weakness after ACL reconstruction was associated with fatigue resistance. Lower initial MF and smaller decline in MF during sustained contraction is consistent with fast-twitch fiber atrophy and explains fatigue resistance.

J Orthop Sports Phys Ther. 2001;31(1):25-32.

Key Words: fiber type, isometric strength, median frequency

Study Design: Prospective, observational study. Objectives: To determine the association between KT-1000 measurements with an anterior translation force of 89 N and other measures of outcome (the Tegner activity score, the modified Lysholm score, subjective rating of instability, Lachman test, and pivot-shift test) 1 year following anterior cruciate ligament (ACL) reconstruction. Background: Health care professionals often use the side-to-side difference measured with the KT-1000 arthrometer to determine ACL integrity during passive motion. It has been postulated that a 5-mm or greater difference between impaired and nonimpaired knees represents a procedural failure. Methods and Measures: Ninety patients (46 men, 44 women) with a mean age of 30 ± 8 years were examined 1 year after surgery. Patients were classified in 1 of 3 groups depending on the amount of laxity between the impaired knee and the nonimpaired knee. Seventy percent of the subjects had a side-to-side difference less than or equal to 3 mm (tight), 13% had a difference of between 3 and 5 mm (moderate), and 17% had a difference greater than or equal to 5 mm (loose) on examination using the KT-1000. Results: Mean Lysholm and Tegner scores did not differ significantly among groups. Side-to-side differences in KT-1000 measurements at 89 N were not associated with the Lysholm score (r = -0.09) or Tegner score (r = 0.02). Lachman tests were related to involved-knee KT-1000 measurements (r = 0.39) but not to side-to-side differences in KT-1000 measurements (r = 0.15). Similarly, pivot-shift tests were related to involved-knee KT-1000 measurements (r = 0.26) but not to side-to-side differences (r = -0.08). Conclusions: These results suggest that side-to-side KT-1000 measurements obtained with an anterior translation force of 89 N should not be used in isolation to determine ACL reconstruction success or failure 1 year following surgery.

J Orthop Sports Phys Ther. 1999;29(9):540-545.

Key Words: anterior tibial translation, arthrometer, outcome measures

Study Design: Repeated measures of shoulder flexibility on nonimpaired subjects and intercollegiate baseball pitchers. Objectives: To present a new objective method of measuring posterior shoulder tightness, define the intratester and intertester reliability of the measurement, and assess its construct validity. Background: Posterior shoulder tightness has been linked to anterior humeral head translation and decreased internal rotation. The reliability of an objective assessment of posterior shoulder tightness has yet to be established in the literature. Methods and Measures: Five repeat measurements were made using a standardized protocol on 21 nonimpaired subjects to determine intratester reliability. To determine intertester reliability, 2 testers (blinded to their measurement) each performed 1 measurement on 49 shoulders. Twenty-two intercollegiate baseball pitchers were measured once by 1 tester to evaluate the construct validity of the measurement. Results: Measurements of posterior shoulder tightness performed by the same physical therapist had high reliability (ICC dominant = 0.92, nondominant = 0.95). lntertester measures revealed good reliability (ICC = 0.80). Pitchers had reduced dominant arm internal rotation and increased external rotation ROM compared to their other arm whereas nonimpaired subjects had less reduction in external rotation compared to the nondominant arm (pitchers: dominant, 109.7° ± 2.4°, nondominant, 98.9° ± 1.6°; nonimpaired subjects: dominant, 95.9° ± 1.5°, nondominant, 95.2° ± 1.6°) and internal rotation (pitchers: dominant, 50.0 ± 2.0°, nondominant, 69.5 ± 2.5°; nonimpaired subjects: dominant, 46.4 ± 1.3°, nondominant, 50.2 ± 1.4°). Pitchers had significantly greater posterior shoulder tightness compared to nonimpaired subjects (pitchers: dominant, 44.9 ± 0.8 cm, nondominant, 37.5 ± 0.7 cm, nonimpaired subjects; dominant, 32.9 ± 0.8 cm, nondominant, 31.4 ± 0.8 cm) and manifested a significant correlation between posterior shoulder tightness and internal rotation (r = -0.61) that was not evident in nonimpaired subjects. Conclusions: Measurement of posterior shoulder tightness using this technique is objective and reliable when done by the same physical therapist. Validity of this measurement is supported from the observation of athletes thought to have tight posterior structures. Further study is needed to determine the relationship of this measurement to patients diagnosed with shoulder impingement syndrome.

J Orthop Sports Phys Ther. 1999;29(5):262-274.

Key Words: reproducibility, posterior capsule, flexibility

Changes in running economy, or the oxygen cost of running at a given submaximal speed (ml/m/kg), during prolonged exercise have been well described in men but not in women. Lower extremity strength changes associated with prolonged exercise have never been addressed. We examined changes in running economy and strength following a 2-hour run in 8 men and 8 women. Knee and hip strength were measured pre- and post-running. Peak oxygen consumption (VO2peak) and oxygen consumption at ventilatory threshold were determined. Subjects then ran for 2 hours at an intensity that elicited ventilatory threshold (68.7% vs. 66.6% of VO2peak for men and women, p = 0.5). Water was ingested at a rate of 0.5% of body weight each half hour. Oxygen uptake (VO2) and respiratory exchange ratio were measured initially and at 1 and 2 hours. Body weight declined in the men (p = 0.001) but not in the women (p = 0.12). Running economy decreased in the men (p < 0.001) but not in the women (p = 0.084). At 2 hours of running, knee flexion and extension strength declined significantly in the men only (effect of gender x time, p < 0.014), but hip flexion, abduction, and adduction strength declined in both genders. Decreased knee extensor/flexor strength was evident in men only, while decreased hip strength was independent of gender. We conclude that 2 hours of running produced changes in knee strength and running economy in men only.

J Orthop Sports Phys Ther. 1998;27(3):189-196.

Key Words: running, economy, fatigue, gender

Loss of motion and knee extension weakness are recognized as significant complications following anterior cruciate ligament (ACL) reconstruction. The purpose of this study was to determine 1) what degree of preoperative motion loss represents a risk for postoperative motion problems and 2) if preoperative weakness (deficit = 20%) affects return of strength following surgery. Measurements of range of motion and strength were made on 102 patients (56 men, 46 women; age = 31 ± 1 years) within 2 weeks prior to ACL reconstruction (preop) and repeated 6 months following surgery (postop). Thirteen of 40 patients (33%) lacking =5° preop, 8 of 20 patients (40%) lacking 1-4° preop, and 3 of 42 (7%) patients with full extension preop had =5° loss 6 months postop (p < 0.001). Thirty-two of 39 (82%) patients with normal strength preop had weakness 6 months postop. Forty of 51 (78%) patients with preop knee extension weakness still had weakness 6 months postop. Preop strength was not a good predictor of residual weakness following ACL reconstruction. The magnitude of the preop extension loss appears not to be a risk factor. It is the presence or absence of full extension equal to the contralateral leg that identifies risk for postop problems regaining extension.

J Orthop Sports Phys Ther. 1998;27(6):407-411.

Key Words: dynamic strength, arthrofibrosis, anterior cruciate ligament, rehabilitation

Professional ice hockey players often sustain hip and low back strains. We hypothesized that playing the sport of ice hockey may result in the shortening of the iliopsoas muscles, increasing the likelihood of lumbosacral strains and hip injuries. The purpose of this study was to identify whether ice hockey players demonstrate a decrease in hip extension range of motion when compared with age-matched controls. Objective data were obtained using the Thomas test with an electrical circuit device to determine pelvic tilt motion. Obtaining X-rays in 6 subjects during the Thomas test validated the device. The study then examined 25 professional hockey players and 25 age-matched controls. A 2-way analysis of variance was applied for statistical analysis to examine the effect of sport and side. The results demonstrated that ice hockey players have a reduced mean hip extension range of motion (p < .0001) by comparison with age-matched controls. There was no difference between right and left sides, nor was there any interaction of the sport with the side of the body. Therefore, hockey players demonstrated a decreased extensibility of the iliopsoas muscles. Future research may be directed toward establishing a link between prophylactic stretching and injury rate in professional ice hockey players.

J Orthop Sports Phys Ther. 1996;24(5):303-308.

Key Words: iliopsoas, muscle extensibility, pelvic tilt