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Background: Muscle stretching is widely used in sport training and in rehabilitation. Considering the important contribution of joint position sense (JPS) to knee joint stability and function, it is legitimate to question if stretching might alter the knee JPS. Objective: To evaluate if a stretch regimen consisting of three 30 s stretches alters the knee JPS. Design and setting: A blinded, randomised design with a washout time of 24 h was used. Subjects: 39 healthy students (21 women, 18 men) volunteered to participate in this study. Methods and main outcome measures: JPS was estimated by the ability to reproduce the two target positions (20˚and 45˚of flexion) in the dominant knee. The absolute angular error (AAE) was defined as the absolute difference between the target angle and the subject perceived angle of knee flexion. AAE values were measured before and immediately after the static stretch. Measurements were repeated three times. The static stretch comprised a 30 s stretch followed by a 30 s pause, three times for each muscle. Results: The AAE decreased significantly after the stretching protocols for quadriceps (3.5 (1.3) vs 0.7 (2.4); p,0.001), hamstring (3.6 (2.2) vs 1.6 (3.1); p = 0.016) and adductors (3.7 (2.8) vs 1.7 (2.4); p = 0.016) in 45˚of flexion, but no differences were found for values of the gastrocnemius and popliteus muscles in this angle and for the values of all muscles in 20˚of flexion (p.0.05). Conclusion: The accuracy of the knee JPS in 45˚of flexion is improved subsequent to a static stretch regimen of quadriceps, hamstring and adductors in healthy subjects.

Background:  Osteoarthritis (OA) is one of the most common musculoskeletal complaints worldwide. The knee is the most frequently involved joint of the lower limb in OA. Knee joint proprioception, dynamic balance and maximal quadriceps strength may be impaired in patients with knee OA. Objective:  To investigate whether females with knee OA have reduced knee joint proprioception, balance responses and quadriceps strength compared with normal controls. Methods:  We undertook a cross‐sectional study of 30 females with knee OA and 30 controls. Knee joint proprioception was measured using electrogoniometer. Dynamic balance response was determined using a step test. Quadriceps strength was measured isometrically using a modified Tornvall chair. Results:  Subjects with OA had greater mean error, poorer dynamic balance and less quadriceps strength than non‐symptomatic ones (P < 0.001). Increasing age was associated with a decline in proprioceptive acuity for both controls and patients (r = 0.40, P < 0.001). In subjects with knee OA, decreased dynamic balance was associated with increasing weight (r = 0.30, P < 0.001) and reduced quadriceps strength (r = –0.37, P = 0.002). Conclusion:  Compared with age and sex‐matched controls, females with symptomatic knee OA have reduced knee proprioception, balance responses and quadriceps strength.

Background: Stabilization exercises lead to improve muscle performance and can be used to prevent and treat of low back pain. Objectives: Aim of the present study is to evaluate and compare the level of abdominal and lumbar muscles activity during two types of stabilization exercises. Patients and Methods: Thirty healthy females aged between 20-30 years old participated in this quasi-experimental study. Muscle activity was recorded from Transversus Abdominus (TrA), Internal Oblique (IO) and multifidus on both sides with electromyography (EMG) device during the quadruped and dead bug exercises. EMG data were normalized to the percentage of maximum voluntary isometric contraction and paired t-test was used for statistical analysis. Results: The mean muscle activity in the right arm reach of quadruped and dead bug exercises showed that right IO and TrA muscles produced greater activity during quadruped exercise (P = 0.015, P = 0.001, respectively). The comparison between the mean muscles activity in the left leg reach of two exercises showed that right and left TrA muscles produced greater activity during left leg reach in quadruped exercise (P = 0.005, P = 0.046, respectively). Also, the comparison between the mean muscle activity in simultaneous movements of left leg and right arm reach in the 2 exercises showed that right TrA muscle was activated at a higher level compared to the other muscles in the quadruped exercise (P = 0.002). Conclusions: The results showed quadruped exercise can provide stability, coordination, and smoothness of the movements in healthy subjects and all considered muscles participated in this exercise.