Correlates of knee extensor training load used in rehabilitation after knee surgery

Resistance training is one of the major components of rehabilitation after musculoskeletal injury and surgery. Despite the importance of resistance training and the frequency of its use in rehabilitation, little is known about factors that are related to training load that might be useful in devising and monitoring training in a patient and comparing training intensities between individuals and groups. We hypothesized that the following would show a statistically significant relationship to training load: injury chronicity, self-assessed knee function (Hughston Clinic questionnaire), knee swelling (injured-uninjured midpatellar knee girth), uninjured knee girth, and body mass. The purpose of this study was to evaluate whether factors such as body mass are related to the load used in training the knee extensors in rehabilitation after knee surgery. Thirty-six individuals undergoing early-phase rehabilitation after knee arthroscopic meniscectomy surgery participated in this study. Subjects were tested 5 days after surgery, just prior to commencing a 6-week outpatient rehabilitation program, and again soon after the end of this rehabilitation program. The independent variables evaluated were age, gender, body mass, meniscus injured, injury chronicity, knee function self-assessment, knee swelling (injured-uninjured midpatellar girth), uninjured knee girth, and knee flexion and extension passive range of motion (difference between injured and uninjured side). The dependent variable was the load used for training the knee extensors on the knee extension machine in the final training session prior to the posttest. The only variable exhibiting a statistically significant (p = 0.001) relationship to knee extensor final training was age (r = -0.529). This finding, that age was the only variable to have a significant relationship with training load, suggests that clinicians' expectation of training intensity should decrease with an increase in the patient's age in the range studied (20-58 years) for patients recovering from knee arthroscopic meniscectomy.