This study examined the relationship between hip joint flexor and extensor strength and jump performance. [Subjects] The subjects were 16 healthy adults with no significant current medical problems. [Methods] Hip joint extensor / flexor muscle testing was undertaken at joint angular velocities of 60ÅE180ÅE300 deg/sec using an isokinetic sthenometer to establish peak torque to body weight ratio. Jump performance measurements were made of vertical jump, broad jump, triple jump, and 6m hop. The relationship between muscular strength and jump performance was analyzed using Pearson's correlation coefficient. The significance level was p<.05. [Results] Significant correlations were found between all jump conditions at angular velocities of 180, 300 deg/sec and hip joint flexor strength. Hip joint flexor strength at the angular velocity of 60 deg/sec was correlated with performance of vertical jump only. There was no significant correlation between extensor muscle strength and jump performance. [Conclusion] The results suggest that the hip joint flexor group of muscles plays a significant role in controlling stability of posture before jumping, control of pre-jump posture for output direction, and control of landing.

[Purpose] The objective of this research was to investigate the relationship between jump actions involving changes in direction and hip and knee muscle strength.[Subjects] The subjects were 32 healthy adults (average age, 21.05 years) with no medical history of orthopedic problems of the lower limbs. The subjects were given an explanation of the study protocol prior to the experiment and their consent to participation was obtained.[Method] Using the BIODEX isokinetic muscle strength measuring device, we measured hip and knee joint extension and flexion strengths 3 times. Three types of jump action were performed, 6 m hopping on one leg, figure of 8 jumping, and slalom jumping, and the times taken to reach the goal were recorded. Correlations between muscle strengths and jump times were investigated using Pearson's correlation coefficient. [Results] We found significant correlations between each of the muscles strengths and each of the jump actions.[Conclusion] Jump actions involving changes in direction were more strongly related to muscle strength than jump action in a straight line, and the relationship was especially strong for knee flexion strength.

Resident microglia are important to maintain homeostasis in the central nervous system, which includes the retina. The retinal microglia become activated in numerous pathological conditions, but the molecular signatures of these changes are poorly understood. Here, using an approach based on FACS and RNA‐seq, we show that microglial gene expression patterns gradually change during RGC degeneration induced by optic nerve injury. Most importantly, we found that the microglial cells strongly expressed Tnf and Il1α, both of which are known to induce neurotoxic reactive astrocytes, and were characterized by Gpr84high‐expressing cells in a particular subpopulation. Moreover, ripasudil, a Rho kinase inhibitor, significantly blunted Gpr84 expression and cytokine induction in vitro and in vivo. Finally, GPR84‐deficient mice prevented RGC loss in optic nerve‐injured retina. These results reveal that Rho kinase‐mediated GPR84 alteration strongly contribute to microglial activation and promote neurotoxicity, suggesting that Rho‐ROCK and GPR84 signaling may be potential therapeutic targets to prevent the neurotoxic microglial phenotype induced by optic nerve damage, such as occurs in traumatic optic neuropathy and glaucoma.