George J. Davies

Concentric versus eccentric isokinetic strengthening of the rotator cuff Objective data versus functional test

Twenty-two male and female college varsity tennis players trained for 6 weeks, one group using eccentric isokinetic internal and external shoulder rotation, and the second group using concentric isokinetic internal and external shoulder rotation. Subjects pretested and posttested both concentrically and eccentrically, so that training overflow and specificity could be examined. Three maximally hit tennis serves made before and after training, which were analyzed by high speed cin ematography to obtain ball velocity, served as a func tional performance measurement. Statistical analysis of peak torque (newton meters) and peak torque to body weight ratio have revealed significant concentric strength gains (P < 0.005) in the concentric as well as the eccentric training groups. Eccentric strength gains were demonstrated by the concentric training group at selected speeds (P < 0.05 and P < 0.005) but were not generated in the eccentric group at the P < 0.05 significance level. Functional test analysis shows an increase in maximal serve velocity at a significance level of P < 0.005 in the concentric training group, with no significant (P > 0.01) increases in the eccentric group.

Loading response following anterior cruciate ligament reconstruction during the parallel squat exercise

OBJECTIVEnTo determine if individuals 1.5-15 months post-anterior cruciate ligament reconstruction demonstrated an equal loading response on their involved and uninvolved lower extremity during a parallel squat exercise versus a control group.nnnDESIGNnFour-group repeated measures design with one between-subject factor (time post-anterior cruciate ligament reconstruction) and two within-subject factors (knee angle and added weight).nnnBACKGROUNDnIt has been a clinical observation that post-anterior cruciate ligament reconstruction, individuals do not place equal amounts of weight upon each lower extremity during double-leg exercises.nnnMETHODSnTwenty-four subjects were in each of the experimental groups, 1.5-4 months, 6-7 months, and 12-15 months post-anterior cruciate ligament reconstruction, while 24 subjects without history of lower extremity pathology/injury served as the control group. Pedar in-shoe sensors were placed inside the subjects shoes to record loading response patterns during the exercises. All performed 3 sets of 9 randomized squats to each of the three knee flexion angles (30 degrees, 60 degrees, and 90 degrees ) with the three different weights (20.45 kg bar only, 35%, and 50% body mass) using a Smith squat rack. A three-way repeated measures ANOVA (P < 0.050) was used to compare the differences between groups in loading response statically between the uninvolved and involved lower extremity for each of the different weights at each knee flexion angle during the squat exercise.nnnRESULTSnThe three-way repeated measures ANOVA revealed that there was a significant group effect (P < 0.001). Thus, the amount of time post-anterior cruciate ligament reconstruction affected the difference in the subjects loading response for the uninvolved and involved lower extremities. There was also a three-way interaction, indicating that the difference in loading response was dependent on the group, amount of knee flexion, and amount of added weight (P = 0.010).nnnCONCLUSIONnThese data suggest that subjects significantly load their uninvolved lower extremity until 12-15 months post-anterior cruciate ligament reconstruction.nnnRELEVANCEnBased on the results of this study, caution may be warranted when adding resistance during the parallel squat for an individuals first year post-anterior cruciate ligament reconstruction, particularly with less knee flexion to avoid compensation and injury.

Muscular control of the patella.

Patellofemoral patients are among the most common yet most challenging individuals presenting for orthopedic care. The key word in the previous sentence is individual. A single protocol of care is not sufficient for these special individuals. Many concepts have been evaluated through review of the peer-reviewed literature with the following highlights: (1) the concept of VMO isolation through specific exercise should no longer be part of our lexicon; (2) patellofemoral patients improve when they are able to enhance quadriceps functional patterns by way of pain-free exercise; (3) patellofemoral patients do not fit into a single box but rather require an evaluation-based classification and specific interventional pattern. Many of the special techniques used by clinicians in treating these patients have not been well defined through research and also are lacking in evidence of clinical efficacy. We also must recognize, however, that good clinical observations can be the first step in defining what questions should be asked and how they can be answered. It is vital that we answer the questions without allowing bad science through dogma and anecdote to prevail. Likewise, we need to be diligent in determining our successes and failures through well designed and implemented clinical and research studies.

Comparison of Quadriceps Isokinetic Eccentric and Isokinetic Concentric Data Using a Standard Fatigue Protocol

. The purpose of the study was to compare fatigue development in concentric vs. eccentric muscular activation in the quadriceps of 15 healthy human subjects, controlling as many of the dynamic variables as possible. An isokinetic testing protocol was used, with knee joint angular velocity limited to 180 deg/sec, and with 40 repetitions through a range of motion of 75 deg constituting the fatigue-developing exercise. Quadriceps torque was measured via a robotic dynamometer, IEMG of the rectus femoris muscle was recorded, and a subjective pain rating scale was used to assess delayed muscle soreness following fatiguing exercise for concentric and eccentric tests. Eccentric peak torque to body weight ratio was greater than the concentric ratio (1.25 vs. 0.66, p < .001), significant torque fatigue developed in both eccentric and concentric tests (30.3% and 13.7%), and significant decline in IEMG occurred in both eccentric and concentric tests (17.0% and 15.1 %). The eccentric declines in torque and IEMG were not significantly different than the concentric declines. There was no clear difference in the pain reports associated with the two different exercise modes. Delayed onset muscle soreness was rated as mild (3 on scale of 10) at most during the 72-h surveillance period. It is concluded that the development of fatigue through eccentric muscular activation may stress the contractile mechanism less than that associated with concentric muscular contraction, and that standard clinical