Objective. To investigate the efficacy of 4 weeks of preoperative and 4 weeks of postoperative progressive resistance training (PRT), compared to 4 weeks of postoperative PRT only on functional performance, muscle strength, and patient-reported outcomes in patients undergoing total knee arthroplasty (TKA). Methods. In total, 59 patients were randomized to 4 weeks of preoperative PRT (intervention group) or to a group who lived as usual (control group). Both groups performed 4 weeks of PRT after TKA. At 6 weeks and 1 week before TKA, and at 1, 6, and 12 weeks after TKA, performance-based measures (30-second chair stand test [30sCST], timedup-and-go [TUG], and walking tests), knee extensor and flexor muscle strength (dynamometry), patient-reported functional performance, health-related quality of life, and pain scores were evaluated. Results. When comparing the changes from baseline to the primary test point 6 weeks after TKA, a significant group difference in favor of the intervention group was found for the 30sCST (2. Conclusion. Supervised preoperative PRT is an efficacious and safe intervention for improving postoperative functional performance and muscle strength, but improvements in patient-reported outcomes were not detected.

Design of the experiment is to study the crosssectional sample with retrospective information. The objective is to identify the types of physical activity associated with the decreased occurrence of low-back pain (LBP) in schoolchildren. Physical activity may be hypothesized to possess a potential for LBP prevention. The possible connection between LBP and specific sports activities is however sparsely documented. A total of 546, 15-to 16-year-old schoolchildren filled a questionnaire on current physical activities and LBP occurrence and severity. In multiple logistic regressions, the association of LBP with exposure variables was corrected for body height and weight (data from school health service files) and for anthropometric and school furniture parameters. More than half of the children reported pain or discomfort in the low-back region during the preceding 3 months, and 1/4 experienced a decreased functioning or need of care because of LBP. LBP correlated with physical inactivity, e.g. time spent on homework and hours watching TV or video, and with a series of sports activities, e.g. jogging, handball playing and gymnastics. Among sports activities, only swimming and the number of hours per week participating in soccer were associated with a decreased LBP prevalence. With the exception of swimming and soccer, the types of sport reported by this schoolchild population do not offer themselves for consideration as tools for LBP prevention. Based on the associations found with indicators of physical inactivity, attempts to motivate the children to increase their general physical activity level should be considered for trial.

PRT is safe and feasible before and/or after THA. PRT is safe, but the methodological quality of existing evidence permits no conclusion on the effectiveness of PRT before and/or after TKA.

The present study does not support the hypothesis of different types of school furniture being a causative or preventing factor for LBP. Carrying the school bag in an asymmetric manner may play a role.