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Background and Purpose: Although total knee arthroplasty (TKA) is a common treatment for severe osteoarthritis, high risks of fall and balance loss are the main complications of this procedure. While multiple rehabilitation protocols have been suggested for TKA, efficacy of early resistive exercise therapy aimed at improving balance has not yet been thoroughly investigated. Methods: In this double-blind randomized controlled trial study, 40 patients with severe osteoarthritis, sampled by a simple convenient method, were randomly assigned into either “control” group or “early resistive exercise” group. After TKA surgery, both groups attended a routine rehabilitation program while the experimental group received extra early resistive exercises. Static, semidynamic, and dynamic balance were assessed by the Sharpened Romberg (SRBT), Star Excursion (SEBT), and Berg (BBT) balance tests prior to surgery, after the rehabilitation process (seventh week), and at a 2-week later follow-up time (ninth week). Results: At the end of the seventh and ninth weeks, in both groups all 3 balance scores were significantly enhanced comparing the baseline scores (P < .001). The experimental group had significantly higher scores than the control group in SRBT, SEBT, and BBT after the intervention and at the follow-up time (P < .001). Discussion and Conclusions: The findings of this study showed that rehabilitation following TKA is accompanied by balance (static, semidynamic, and dynamic) improvement, and this improvement is greater among patients participating in an early resistive exercise regimen. Early progressive resistive exercise in addition to routine physical therapy may lead to better balance performance than routine physical therapy and might be incorporated into the postoperative physical therapy of these patients. Further studies with longer follow-up periods are needed to confirm these results.

Purpose: Frequent and powerful jumps and landings in volleyball exert significant stresses on lower extremities which can be determinant of injury prevalence. This study aimed to investigate the possible correlation between Maximum Jump (MJ) performance and force-time variables of volleyball block landing. Methods: Thirty elite junior volleyball players (Mean±SD of age: 18.140±1.125 y, sports background: 4.390±0.957 y, and height: 197.100±3.161 cm) performed three block jumps, and best of trials was considered for further analysis. The study data were collected by the KISTLER force platform (1000 Hz). Force-time, velocity-time, and displacement-time were obtained using the Excel program. The Kolmogorov-Smirnov and Pearson correlation coefficient were used for assessing data normality and possible correlations between variables using SPSS v. 21 (P<0.05). Results: Peak vertical impact forces were reported in a range of 1.8-3.5 BW (F1, F2) during 27 to 83 ms of peak times (T1, T2). Significant positive correlations were obtained between temporal variables of time of peaks (T1, T2), the time elapsed between peaks (TP), and end of landing time (Tf). A significant negative correlation was found between F2 and T2 and a significant positive correlation between MJ performance with peak vertical forces (F1, F2). Conclusion: According to the findings, T1 has little impact on shock absorption. Coaches and volleyball players should consider the importance of soft landing through increasing T2, which decreases F2, not only for performance improvement but also for reducing injuries.

The present study examined selected kinematic characteristics analysis of knee and ankle joints during block jump in elite junior volleyball players. Methods: Thirty male junior elite volleyball players (Mean±SD age: 18.14±1.12 y, height: 197.10±3.16 cm, sports history: 4.39±0.95 y, & weight: 771.20±59.83 N) participated in this study. A time-synchronized 5-camera sampling at 100 Hz was used to determine the Three Dimensional (3D) coordinates of markers. Kolmogorov-Smirnov test, linear regression, and magnitude of coefficient were used in SPSS to analyze the obtained data (P<0.05). Results: The Mean±SD height of block jump was 45.5±2.06 cm, and the Mean±SD angles of knee and ankle flexion were 93.37±4.75 and 21.25±2.98 cm, respectively. Moreover, there was a negative relationship between knee and ankle flexion angle and block jump height (-0.051,-0.054, respectively) (P<0.05). However, smaller knee flexion angles had more negative effect on block jump height (0.741) (P<0.05). Conclusion: The study results could be used by coaches as a simple tool in jumping performance among junior volleyball players. The obtained data could also be beneficial in the efficient control of applied training procedures.