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As a complex movement, Tai Chi (TC) could be challenging for knee control, and the compensatory changes in TC biomechanics of knee pain patients are unknown. The Brush Knee and Twist Step (BKTS) is a typical TC movement that involves basic leg motion repeated in the whole TC. This pilot study examined electromyography and retro-reflective marker trajectory data to investigate neuromuscular control strategies of the lower extremity during BKTS in TC practitioners with and without knee pain. Twelve experienced TC practitioners with (n = 6) and without knee pain (n = 6) participated. Our results revealed that knee pain practitioners presented muscle imbalance in the vastus medialis-vastus lateralis and vastus lateralis-biceps femoris, and poor alignment of the knee with the toes in TC lunge. Additionally, they adaptively developed rigid coordination strategies, showing higher levels of lower limb muscle co-contraction and activity compared to controls. Training programs for TC practitioners with knee pain should be designed to modify both abnormal muscle synergy patterns and incorrect lunge during TC, which may improve exercise safety. [ABSTRACT FROM AUTHOR]

This study assessed the associations of maximal isometric strength and movement economy in 126 recreationally active men and women. Oxygen consumption was assessed through a graded treadmill test with 4-minute increments (4–12 km∙h−1). Maximal isometric leg extensor, leg flexor and handgrip strength were assessed by isometric dynamometry. Models of best fit for gross oxygen cost and gross caloric unit cost were observed across the majority of velocities when the leg extensor/flexor strength ratio and handgrip strength were combined (R2 = 0.207–0.525 and R2 = 0.152–0.475, respectively). Additionally, the oxygen cost differed statistically for the majority of velocities when participants were split by the median of leg extensor strength (12.3–26.3 ml∙kg−1∙km−1, p < 0.05) and the average of all strength variables (13.9–30.3 ml∙kg−1∙km−1, p < 0.05). Our data underline the importance of maintaining maximal strength in order to perform activities with low to moderate oxygen demands. [ABSTRACT FROM AUTHOR]

To study the relationship between daily activity level and cognitive function in community-dwelling elderly. We collected demographic features, cognitive function, activity level and self-rating depression scale scores in 53 community-dwelling olderly aged 60 years or above. The activity level and moderate-to-vigorous physical activity (MVPA) time were assessed by using the accelerometer for 7 consecutive days. We compared activity level, MVPA time and depression scores between cognitive impaired and normal groups. Cognitive functions were compared in groups with different MVPA level, and the correlation between cognitive function and MVPA time was analysed. Of the 53 subjects, 27 had varying degrees of cognitive impairment. Individuals with cognitive impairment shown significantly shorter MVPA time and higher depression score compared to the cognitive normal group (P < 0.05). After controlling for confounding factors (age, BMI), MVPA time was associated with cognitive function (r = 0.358, P = 0.009). The memory factor score correlated with MVPA time (r = 0.357, P = 0.012) and mean activity level (r = 0.287, P = 0.046). Moderate-to-vigorous physical activity in the elderly was positively related to their cognitive function. Strengthening daily activities may beneficial for the elderly to maintain better cognitive function. [ABSTRACT FROM AUTHOR]