Posturally induced leg vasoconstrictive responses: relationship to standing duration, impedance and volume changes

[Does a Physical Education lesson affect the foot morphology in school-aged children?]

BACKGROUND

To analyze the changes in foot morphology in school-age children, after a Physical Education lesson.

METHODS

A total of 10 school-age children (5 girls and 5 boys) were recruited with a mean age of 9.3 ± 0.5 years that voluntary participated in this study. Measurements of both feet were obtained using a 3D foot digitizer model IFU-S-01 (Japan) in two different moments, before and after a physical education lesson (per-exercise and post-exercise), where different activities involving displacements, jumps and landings were performed.

RESULTS

By comparing foot morphology before and after exercise, significant differences in the arch height were found, which increased after exercise (p<0.05). The ball width shows greater changes after exercise but without significant differences (p= 0.07; effect size [ES] = 0.2). Furthermore, a positive correlation between the ball width and the arch height (p<0.05) and negative correlation between the distance from the heel to the first metatarsal and the ball width (r = - 0.7; p<0.05), were observed.

CONCLUSIONS

The type of activities undertaken during physical education lesson (displacements, jumps and landings) increased the pressure on the forefoot, which would lead to a lager arch height. Development of children's sport footwear systems should take into account the foot lengths, widths and heights, for a better fit, preventing future musculoskeletal injuries.

Comparison of changes in heart rate variability and sacral skin perfusion in response to postural changes in people with spinal cord injury

The current clinical practice has established guidelines to assess influences of severity of autonomic injury on the control of heart and blood pressure following spinal cord injury (SCI). However, the influences of SCI-induced autonomic impairment on microvascular dysfunction have not yet been established. Heart rate variability (HRV) has been shown to be a potential tool for quantifying residual sympathovagal regulation of the cardiovascular system following SCI and may be used to assess the effect of autonomic injury on skin microvascular dysfunction. A total of 26 people were recruited into the study, including 12 people with SCI and 14 nondisabled controls. HRV and sacral skin intervals and sacral skin perfusion were continually recorded during 10 min upright and 10 min prone postures. The sympathovagal balance was defined as the ratio of the power of the low frequency to the high frequency of HRV. The results showed that postural changes of nondisabled people produced significant changes in the sympathovagal balance; lower sympathovagal balance was associated with higher skin perfusion (p < 0.05). People with SCI did not show a significant change of HRV and skin perfusion in response to postural changes. In this study, we have demonstrated that the sympathovagal balance assessed by HRV was associated with the skin vasoconstrictive response to postural changes.