Effect of 4 Weeks of Foot Orthosis Intervention on Ambulatory Capacities and Posture in Normal-Weight and Obese Patients.

BACKGROUND: Several works have shown the benefits of foot orthosis intervention on postural stability in healthy individuals and patients with foot malalignment. However, the effects of foot orthoses on the daily ambulatory activities explored by the Six-Minute Walk Test (6MWT) were never examined. We hypothesized that foot orthoses could increase the gait distance and attenuate the post-6MWT posture alterations already reported in healthy individuals. METHODS: In ten normal-weight (NW) and ten obese patients with foot malalignment and/or abnormal foot arch, we examined the benefits of 4 weeks of custom-molded orthosis intervention (D30) on 6MWT gait distance, fatigue sensation scores, ankle plantarflexion force, and post-6MWT sway of the center of pressure (COP) measured by a pedobarographic platform. Data were compared with those measured in two control-matched groups of ten NW and ten obese individuals, explored at study inclusion and at D30. RESULTS: At study inclusion, the post-6MWT changes in COP surface and the medial and lateral COP deviations were significantly higher in obese participants who needed to wear the foot orthoses compared with obese control subjects. The foot orthosis intervention significantly improved the ambulatory performances of NW and obese individuals during the 6MWT, attenuated the bodily fatigue sensation after the 6MWT, and reduced the post-6MWT COP deviations, with the benefits of insoles being significantly accentuated in obese participants. CONCLUSIONS: Four weeks of foot orthosis intervention significantly increases gait distance and is an effective means to reduce postural sway after walking.

Effect of the 6-minute walk test on plantar loading and capability to produce ankle plantar flexion forces.

The six-minute walk test (6MWT) is used to evaluate the ambulatory capacity of patients suffering from respiratory disorders, obesity or neuromuscular diseases. Our primary aim was to evaluate the effects of the 6MWT on the postural sway and the ankle plantar flexion forces in healthy subjects. We measured the ankle plantar flexion forces and the plantar contact area before and after a 6MWT in normal weight and overweight subjects with no history of respiratory, cardiac, and neuromuscular disorders. A post-6MWT sensation of bodily fatigue was evaluated by Multidimensional Fatigue Inventory (MFI) and Pichot fatigue scales. A computerized pedobarographic platform was used to collect the mean plantar contact area, the changes of the center of pressure (CoP) surface and its medial and lateral deviations. In a limited number of subjects, the reproducibility of all the measurements was explored. In both groups, the 6MWT elicited a sensation of bodily fatigue. It also significantly reduced the ankle plantar flexion forces, and increased both the mean plantar contact area and the CoP surface, the changes being not apparent after 10min. The post-6MWT lateral CoP deviations were accentuated in normal weight subjects, while an increase in medial CoP deviations occurred in overweight ones. The 6MWT-induced changes in the plantar flexion force and pedobarographic variables were reproducible. Because this study clearly showed some post-6MWT alterations of the subjects' posture sway of our subjects, we questioned the possible mechanisms occurring that could explain the altered muscle force and the transient destabilization of posture after the 6MWT.

Psychophysical estimate of plantar vibration sensitivity brings additional information to the detection threshold in young and elderly subjects.

OBJECTIVE: Vibration detection threshold of the foot sole was compared to the psychophysical estimate of vibration in a wide range of amplitudes in young (20-34 years old) and elderly subjects (53-67 years old). METHODS: The vibration detection threshold was determined on the hallux, 5th metatarsal head, and heel at frequencies of 25, 50 and 150 Hz. For vibrations of higher amplitude (reaching 360 µm), the Stevens power function (Ψ = k * Φn ) allowed to obtain regression equations between the vibration estimate (Ψ) and its physical magnitude (Φ), the n coefficient giving the subjective intensity in vibration perception. We searched for age-related changes in the vibration perception by the foot sole. RESULTS: In all participants, higher n values were measured at vibration frequencies of 150 Hz and, compared to the young adults the elderly had lower n values measured at this frequency. Only in the young participants, the vibration detection threshold was lowered at 150 Hz. CONCLUSION: The psychophysical estimate brings further information than the vibration detection threshold which is less affected by age. SIGNIFICANCE: The clinical interest of psychophysical vibration estimate was assessed in a patient with a unilateral alteration of foot sensitivity.