Change in Achilles Tendon Length after Walking on Treadmill with Gradient.

Objectives: Improving ankle joint contracture is important because stiffness in ankle dorsiflexion can lead to pain, especially when weight-bearing during walking, which tends to concentrate on the forefoot. We hypothesized that the contraction of the gastrocnemius muscle in ankle dorsiflexion would increase the Achilles tendon length and improve the dorsiflexion range of motion. We evaluated the effects of walking with and without a gradient on Achilles tendon length. Methods: This study included 23 men who underwent ultrasound imaging to measure the Achilles tendon length while they stood on an inclined table adjusted according to the dorsiflexion angle. Treadmill walking was performed for 10 min with a 10° incline (gradient condition) or without gradient (level condition). The measurements were compared using a paired t-test. Results: In the gradient condition, the range of motion for ankle dorsiflexion was significantly increased after the intervention. In the gradient condition, the Achilles tendon length while standing on an inclined surface was significantly increased after the intervention. Conclusions: Walking under gradient conditions led to the extension of the Achilles tendon in the ankle dorsiflexion position. This was accompanied by contraction of the gastrocnemius muscle, resulting in lengthening of the Achilles tendon. This finding suggests that such interventions may have clinical applications.

Examination of gait characteristics and related factors in elderly subjects with and without hallux valgus.

OBJECTIVE: Elderly people with hallux valgus have decreased gait speed, which can result in reduced capacity to perform the activities of daily living. Therefore, this study examined the gait ability and related factors of patients with hallux valgus. METHODS: The study participants were 10 patients with hallux valgus and 10 without. Ground reaction forces were measured as front-rear (X), lateral (Y), and vertical (Z) components from the early to late stance phases. Three-dimensional motion analysis was used to measure gait speed; touchdown distance; release distance; the angles of the limb joints and trunk at heel contact, toe-off, and peak ground reaction force; and the center of mass (COM) displacement in the sagittal plane. The height of the COM was calculated as a percentage of the body height. The hallux valgus and control groups were compared using the Mann-Whitney U-test. RESULTS: In the hallux valgus group, the ground reaction force showed a significant increase in the Y component in each stance phase and in the Z component in the late stance phase. The lowest COM position in the hallux valgus group was significantly higher than that in the control group, resulting in a smaller difference in COM height over a gait cycle. CONCLUSIONS: The hallux valgus group was found to have reduced gait speed because of a shortened touchdown distance. Moreover, the continued high COM position in the hallux valgus group meant that potential energy could not efficiently be converted to kinetic energy.

Function of the Distal Part of the Vastus Medialis Muscle as a Generator of Knee Extension Twitch Torque.

The distal part of the vastus medialis (VM) (VM obliquus: VMO) muscle acts as the medial stabilizer of the patella. However, it has been known to facilitate VMO contraction during training of the quadriceps femoris muscle in knee joint rehabilitation. This study aimed to examine the contribution degree of VMO as a knee joint extension torque generator. Sixteen healthy male volunteers participated in this study. Electrical muscle stimulation (EMS) was performed on VMO at 60° knee angle for 20 min to induce muscle fatigue. Knee extension twitch torques (TT) at 90° and 30° knee angle evoked by femoral nerve stimulation were measured before and after EMS. Although each TT at 90° and 30° knee angle significantly decreased after EMS, the decreased TT rate in both joint angles showed no significant difference. Our results show that VMO might contribute to the generation of the knee joint torque at the same level in the range from flexion to extension. Therefore, it was suggested that the facilitating the neural drive for VMO is important during the quadriceps femoris muscle strengthening exercise.

Lower trunk muscle activity-induced alignment and cop position during single-leg standing.

[Purpose] The purpose of this study was to clarify fundamental changes induced by lower trunk muscle contraction during single-leg standing. [Subjects and Methods] Ten healthy normal males participated in this study. All subjects could accurately perform lower trunk muscle contraction-type Abdominal Expansion (AE), Abdominal Bracing (AB), and Abdominal Cave-in (AC). The alignment and position of the center of foot pressure (COP) during single-leg standing with SLR and step position after rotating the body from single-leg standing with maximum SLR were measured in each lower trunk muscle contraction type. [Results] When AC was performed during single-leg standing with SLR, the SLR angle increased, COP shifted backward, and the posterior tilt angle of the trunk and cross step distance decreased. [Conclusion] It was assumed that AC during wind-up increases the angle of lower limb elevation and decreases the posterior tilt angle of the trunk and cross step distance.