Accelerometry-based method for assessing energy expenditure in patients with diabetes during walking.

BACKGROUND: Monitoring activity-related energy expenditure (EE) is essential in the management of daily activity and the dietary programme in patients with type 2 diabetes (T2D) and must be estimated accurately. Accelerometry-based equations have frequently used to estimate EE, although the validity of these methods has not been confirmed in patients with T2D. The present study aimed to test the validity of an accelerometry-based method (Bouten's method) to assess EE during walking in patients with T2D. METHODS: The study included 20 patients with controlled T2D [mean (SD) duration: 10.6 (6.1) years; age: 57.5 (8.4) years; body mass index: 26.4 (2.6) kg m- ²]. All participants performed five 6-min periods of walking at different speeds (0.5-1.5 m s-1 ) on a treadmill. Mechanical data were recorded using an inertial measurement unit placed on the lower back with gas exchange being simultaneously monitored. RESULTS: Values of EE during walking estimated by the accelerometer method did not differ significantly from those measured by indirect calorimetry. Bias and root mean square error were -1.17 and 2.93 kJ min-1 , respectively, on average across speeds. CONCLUSIONS: Our results suggest that EE during walking may be accurately estimated in patients with diabetes mellitus using an accelerometer.

Ground-reactive forces after hallux valgus surgery: comparison of Scarf osteotomy and arthrodesis of the first metatarsophalangeal joint.

AIMS: The purpose of this study was to analyse the biomechanics of walking, through the ground reaction forces (GRF) measured, after first metatarsal osteotomy or metatarsophalangeal joint (MTP) arthrodesis. PATIENTS AND METHODS: A total of 19 patients underwent a Scarf osteotomy (50.3 years, standard deviation (sd) 12.3) and 18 underwent an arthrodesis (56.2 years, sd 6.5). Clinical and radiographical data as well as the American Orthopaedic Foot and Ankle Society (AOFAS) scores were determined. GRF were measured using an instrumented treadmill. A two-way model of analysis of variance (ANOVA) was used to determine the effects of surgery on biomechanical parameters of walking, particularly propulsion. RESULTS: Epidemiological, radiographical and clinical data were comparable in the two groups and better restoration of propulsive function was found after osteotomy as shown by ANOVA (two way: surgery × foot) with a surgery effect on vertical forces (p < 0.01) and a foot effect on anteroposterior impulse (p = 0.01). CONCLUSION: Patients who underwent Scarf osteotomy had a gait pattern similar to that of their non-operated foot, whereas those who underwent arthrodesis of the first (metatarsophalangeal) MTP joint did not totally recover the propulsive forces of the forefoot. TAKE HOME MESSAGE: The main findings of this study were that after surgical correction for hallux valgus, patients who underwent scarf osteotomy had a gait pattern similar to that of their non-operated foot in terms of forefoot propulsive forces (Fz3, Iy2), whereas those who underwent arthrodesis of the first MTP joint had not. Cite this article: Bone Joint J 2016;98-B:641-6.

A simple method for measuring power, force, velocity properties, and mechanical effectiveness in sprint running.

This study aimed to validate a simple field method for determining force- and power-velocity relationships and mechanical effectiveness of force application during sprint running. The proposed method, based on an inverse dynamic approach applied to the body center of mass, estimates the step-averaged ground reaction forces in runner's sagittal plane of motion during overground sprint acceleration from only anthropometric and spatiotemporal data. Force- and power-velocity relationships, the associated variables, and mechanical effectiveness were determined (a) on nine sprinters using both the proposed method and force plate measurements and (b) on six other sprinters using the proposed method during several consecutive trials to assess the inter-trial reliability. The low bias (<5%) and narrow limits of agreement between both methods for maximal horizontal force (638 ± 84 N), velocity (10.5 ± 0.74 m/s), and power output (1680 ± 280 W); for the slope of the force-velocity relationships; and for the mechanical effectiveness of force application showed high concurrent validity of the proposed method. The low standard errors of measurements between trials (<5%) highlighted the high reliability of the method. These findings support the validity of the proposed simple method, convenient for field use, to determine power, force, velocity properties, and mechanical effectiveness in sprint running.

Detection of swing heel-off event in gait initiation using force-plate data.

This study investigated the accuracy and reliability of four methods using force-plate data for detecting the swing heel-off (HO) time in gait initiation. Results of these methods were compared to those obtained by means of a reference method using a footswitch. Ten young healthy adults performed 18 forward gait initiation trials at self-selected speed and at maximal speed. Results showed that the method based on vertical impulse was the most accurate and reliable in determining HO in both speed conditions. The mean error obtained with this method was -8±10ms in the self-selected speed condition (-7±10ms in the maximal speed condition), with no significant effect of gait speed (P>0.05). These findings suggest that this method based on force-plate data is valid and reliable for detecting HO in forward gait initiation in the absence of additional hardware.