Examinations of factors influencing toe grip strength.

[Purpose] This study examined the relationship between toe grip strength and its associated factors by focusing on factors that were suggested to have a relationship with toe grip strength in previous studies, aiming to clarify the factors influencing the toe grip strength of healthy women. [Subjects and Methods] Twelve healthy young women were selected for this study. Their toe grip strength, angular changes in their ankle joint during toe grip, maximum voluntary contraction activities of the rectus femoris, biceps femoris, and tibialis anterior muscles, and the medial head of the gastrocnemius muscles were measured using electromyography. Their toe curl ability, foot-arch height ratio, and weight were also measured. [Results] Multiple regression analysis demonstrated that the predictors of toe grip strength in the resulting model were foot-arch height ratio and the percentage of integrated electromyography (%IEMG) of the tibialis anterior muscle, as the dependent variables. This reveals that women whose tibialis anterior muscle %IEMG values and foot-arch height ratio are high have greater %IEMG values have greater toe grip strength. [Conclusion] These findings suggest a significant relationship between foot-arch height ratio and toe grip strength, with a reciprocal interaction. These findings further indicate that the risk of falls by the elderly could be decreased if toe grip strength were enhanced, by increasing the height of a low foot-arch with the help of an inserted insole.

Strength and muscle activities during the toe-gripping action: comparison of ankle angle in the horizontal plane between the sitting upright and standing positions.

[Purpose] The aim of this study was to investigate whether toe grip strength and muscle activities are affected by the ankle angle in the horizontal plane in the sitting upright and standing positions. [Subjects] The subjects were 16 healthy young women. [Methods] We measured toe grip strength and the maximum voluntary contraction activities of the rectus femoris, biceps femoris, anterior tibialis, and medial head of the gastrocnemius. In addition, we calculated the percent integrated electromyography during foot gripping in 3 different ankle joint positions between the long axis of the foot and the line of progression on the horizontal plane, namely 10° of internal rotation, 0°, and 10° of external rotation. [Results] Two-way analysis of variance revealed significant differences. A significant main effect was observed in the measurement conditions for the percent integrated electromyography of the rectus femoris muscle and long head of the biceps femoris. However, two-way analysis of variance did not reveal any significant difference, and a significant main effect was not observed in toe grip strength. [Conclusion] These findings suggest that exerted toe grip strength is only slightly affected by the ankle angle in the horizontal plane in the sitting upright and standing positions. Therefore, the current measurement positions were shown to be optimal for measurement.

Structure-Based Design and Synthesis of 3-Amino-1,5-dihydro-4H-pyrazolopyridin-4-one Derivatives as Tyrosine Kinase 2 Inhibitors.

We report herein the discovery and optimization of 3-amino-1,5-dihydro-4H-pyrazolopyridin-4-one TYK2 inhibitors. High-throughput screening against TYK2 and JAK1-3 provided aminoindazole derivative 1 as a hit compound. Scaffold hopping of the aminoindazole core led to the discovery of 3-amino-1,5-dihydro-4H-pyrazolopyridin-4-one derivative 3 as a novel chemotype of TYK2 inhibitors. Interestingly, initial SAR study suggested that this scaffold could have a vertically flipped binding mode, which prompted us to introduce a substituent at the 7-position as a moiety directed toward the solvent-exposed region. Introduction of a 1-methyl-3-pyrazolyl moiety at the 7-position resulted in a dramatic increase in TYK2 inhibitory activity, and further optimization led to the discovery of 20. Compound 20 inhibited IL-23-induced IL-22 production in a rat PD assay, as well as inhibited IL-23 signaling in human PBMC. Furthermore, 20 showed selectivity for IL-23 signaling inhibition against GM-CSF, demonstrating the unique cytokine selectivity of the novel TYK2 inhibitor.

Comparison of toe grip strength and muscle activities during maximal toe grip strength exertion according to the presence/absence of an ankle immobilization belt.

[Purpose] The aim of this study was to compare toe grip strength and muscle activity during toe grip strength exertion according to the presence/absence of an ankle immobilization belt and to examine the relationship between the differences in muscle activity and toe grip strength. [Subjects] The Subjects were 13 healthy young women. [Methods] We measured toe grip strength and muscle activity during toe grip strength exertion in the presence and absence of an ankle immobilization belt using electromyography. Activity in the following leg muscles was recorded: rectus femoris, biceps femoris, medial head of the gastrocnemius, and tibialis anterior. We then calculated the percent integrated electromyography during toe gripping. [Results] Toe grip strength and percent integrated electromyography of the medial head of the gastrocnemius muscle were significantly higher with ankle belt immobilization compared with without ankle belt immobilization. In addition, in the presence of ankle belt immobilization, the percent integrated electromyography of the tibialis anterior muscle and medial head of the gastrocnemius muscle demonstrated a positive correlation with toe grip strength (r = 0.75 and r = 0.65, respectively). [Conclusion] These findings suggest that greater toe grip strength could be exerted in the presence of ankle belt immobilization. The measured values reflect the percent integrated electromyography of the crural muscles. Therefore, it was shown that toe grip strength should be measured in the presence of an immobilization belt.

Kinematic analysis during toe-gripping strength exertion: angular changes in the ankle joint and leg muscle activities.

[Purposes] To investigate angular changes in the ankle joint and leg muscle activities during toe-gripping, and to examine the relationship between these changes and toe-gripping strength. [Subjects] Eleven healthy young women were selected. [Methods] We measured the toe-gripping strength, angular changes in the ankle joint, and leg muscle activities of all patients during toe-gripping. [Results] The mean change in the ankle angle in dorsiflexion from a neutral position was 3°, and a positive correlation was observed between this angle and toe-gripping strength (r = 0.61). Thus, toe-gripping strength increased with the angle of dorsiflexion. Regarding the leg muscle activities, activities of the tibialis anterior muscle and medial head of the gastrocnemius muscle demonstrated positive correlations with toe-gripping strength (r = 0.75 and r = 0.72, respectively). [Conclusion] These findings suggest that the ankle dorsiflexes in order to exert great toe-gripping strength, and the crural muscles contract simultaneously because of ankle fixation.

An Examination of Limb Position for Measuring Toe-grip Strength.

[Purpose] The purpose of the present study was to investigate the limb position at which the maximum toe-grip strength could be exerted as well as measurement reproducibility. [Subjects] Twenty healthy young women were selected. [Methods] We measured toe-grip strength under three conditions: 90° hip and knee flexion while sitting, 90° hip flexion and knee extension while sitting, and a standing position. [Results] We found that toe-grip strength was significantly lower in the 90° hip flexion and knee extension sitting position than in the 90° hip and knee flexion sitting position and standing position. Moreover, the 90° hip and knee flexion sitting position produced the best intraclass correlation coefficient (r = 0.813). [Conclusion] The results suggest that 90° hip and knee flexion while sitting is the most suitable limb position for measuring toe-grip strength, as this position allows maximum strength to be exerted and allows measurements to be repeated.

Activity of the Femoral Muscles during Toe-gripping Action.

[Purpose] In the present study, we investigated femoral muscle activity during toe-gripping, and the role of the femoral muscles in toe-gripping strength. [Subjects] Fourteen healthy young women were selected. [Methods] We measured the maximum voluntary contraction of the rectus femoris and long head of the biceps femoris muscles. We then calculated the percent integrated EMG (%IEMG) during the toe-gripping action. [Results] We found that the %IEMG of the biceps femoris was significantly higher than that of the rectus femoris. Moreover, a significant positive correlation was found between the %IEMG of the rectus femoris and that of the biceps femoris. [Conclusion] These results suggest that femoral muscles co-contract during the toe-gripping action, and thus possibly contribute to knee joint stability.