Background: The ability to generate muscle strength is a pre-requisite for all human movement. Decreasedquadriceps muscle strength is frequently observed in older adults and is associated with a decreased performance and activity limitations. To quantify the quadriceps muscle strength and to monitor changes over time, instruments and procedures with a sufficient reliability are needed. The Q Force is an innovative mobile muscle strength measurement instrument suitable to measure in various degrees of extension. Measurements between 110 and 130° extension present the highest values and the most significant increase after training. The objective of this study is to determine the test-retest reliability of muscle strength measurements by the QForce in older adults in 110° extension.Methods: Forty-one healthy older adults, 13 males and 28 females were included in the study. Mean (SD) age was 81.9 (4.89) years. Isometric muscle strength of the Quadriceps muscle was assessed with the Q Force at 110° of knee extension. Participants were measured at two sessions with a three to eight day interval between sessions. To determine relative reliability, the intraclass correlation coefficient (ICC) was calculated. To determine absolute reliability, Bland and Altman Limits of Agreement (LOA) were calculated and t-tests were performed.Results: Relative reliability of the Q Force is good to excellent as all ICC coefficients are higher than 0.75. Generally a large 95 % LOA, reflecting only moderate absolute reliability, is found as exemplified for the peak torque left leg of −18.6 N to 33.8 N and the right leg of −9.2 N to 26.4 N was between 15.7 and 23.6 Newton representing 25.2 % to 39.9 % of the size of the mean. Small systematic differences in mean were found between measurement session 1 and 2.Conclusion: The present study shows that the Q Force has excellent relative test-retest reliability, but limitedabsolute test-retest reliability. Since the Q Force is relatively cheap and mobile it is suitable for application in various clinical settings, however, its capability to detect changes in muscle force over time is limited but comparable to existing instruments.
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OBJECTIVES:The purpose of the current study was to compare the results of a progressive strength training protocol for soccer players after anterior cruciate ligament reconstruction (ACLR) with healthy controls, and to investigate the effects of the strength training protocol on peak quadriceps and hamstring muscle strength. DESIGN:Between subjects design. SETTING:Outpatient physical therapy facility. PARTICIPANTS:Thirty-eight amateur male soccer players after ACLR were included. Thirty age-matched amateur male soccer players served as control group. MAIN OUTCOME MEASURES:Quadriceps and hamstring muscle strength was measured at three time points during the rehabilitation. Limb symmetry index (LSI) > 90% was used as cut-off criteria. RESULTS:Soccer players after ACLR had no significant differences in peak quadriceps and hamstring muscle strength in the injured leg at 7 months after ACLR compared to the dominant leg of the control group. Furthermore, 65.8% of soccer players after ACLR passed LSI >90% at 10 months for quadriceps muscle strength. CONCLUSION:Amateur male soccer players after ACLR can achieve similar quadriceps and hamstring muscle strength at 7 months compared to healthy controls. These findings highlight the potential of progressive strength training in rehabilitation after ACLR that may mitigate commonly reported strength deficits.
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Purpose: To determine the most effective practices for quadriceps strengthening after ACL reconstruction. Methods: An electronic search has been performed for the literature appearing from January 1990 to January 2012. Inclusion criteria were articles written in English, German or Dutch with unilateral ACL-reconstructed patients older than 13 years, RCT rehabilitation programmes containing muscle strengthening, protocol described in detail and time frame of measurements reported. Quadriceps muscle strength and patient-reported outcomes were the endpoints. Included studies were assessed on their methodological quality using the CONSORT Checklist. Results: From 645 identified studies, 10 met the inclusion criteria. Seven studies found an increase in quadriceps strength after intervention programmes regardless of type of training. An eccentric exercise programme showed significantly better values for isometric quadriceps strength compared to a concentric exercise programme. The Tegner activity scale showed a significant increase in activity level for all training programmes. The Cincinnati Knee Rating System showed significant improvements in particular for the neuromuscular training group. Conclusions: The evidence from this review indicates that eccentric training may be most effective to restore quadriceps strength, but full recovery may not be achieved with current rehabilitation practices. Neuromuscular training incorporating motor learning principles should be added to strengthening training to optimise outcome measurements. Level of evidence: II. © 2013 Springer-Verlag Berlin Heidelberg.
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The anterior cruciate ligament (ACL) is a strong rope-like tissue which connects the femur to the tibia in the knee joint. Its function is to provide structural stability to the knee while preventing unnatural forward movement of the tibia relative to the femur. Acute complete ACL ruptures during movements like knee hyperextension or sudden changes of direction (pivoting) damage two entities: the ligament itself and its nerve connections to the posterior tibial nerve (PTN). PTN innervation in the ACL is essential for: a) proprioception (e.g. perception of position and movement/acceleration experienced by the ligament), and b) stability of the knee joint. Upon ACL rupture, the orthopedic surgeon reconstructs the ACL with a graft from the hamstring, patellar or quadriceps tendon. After the surgery, the goal is to regain neuromuscular control and dynamic stabilization during rehabilitation as soon as possible for a quick return to sports and daily activities. However, surgeons are not able to reconstruct the nerve gap between the PTN and the grafted ligament due to the microscopic size of the innervation in the ACL. Not linking the PTN to the graft creates a disconnection between the knee joint and the spinal cord. To mitigate these disadvantages in ACL surgery, this study focuses on activating the growth of proprioception nerve endings using a ligament loaded with growth factors (neurotrophins). We hypothesize that neurotrophins will activate proprioceptive fibers of neurons close to the ACL. We describe graft fabrication steps and in vitro experiments to expand on the regeneration capacity of a commercially available ACL-like synthetic ligament called LARS. The results will bring the ACL regeneration field closer to having a graft that can aid patients in regaining mobility and stability during locomotion and running, confidence in the strength of the knee joint, and quick return to sports.
