# Wearable Inertial Devices in Duchenne Muscular Dystrophy: A Scoping Review
## 3 Results
Both clinical and instrumental analysis highlighted locomotion dysfunctions in DMD patients (6 MWT mean results: 600 m control group, and 400 m DMD patients; mean total steps/day: 7000 steps for the control group, 5000 steps for DMD patients) and a strong correlation (Pearson's correlation coefficient r(16) = 0.7-0.8) was depicted between the two assessment methodologies. [PERSON] and colleagues [35] applied inertial sensors in the analysis of human movements in non-ambulatory DMD children (7 patients, mean age = 18 years). The aim of the study was to investigate any relationships between clinical and instrumental monitoring. The ActiMyo is an innovative inertial sensor (3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer) used to record linear accelerations and angular velocities over a long period of time. The ActiMyo was positioned on patients' wrist and four outcome measures were evaluated during the performance of validated tasks: the rotation rate, the ratio of the vertical component in the overall acceleration, the hand elevation rate, and the estimated power of the upper limb. Results pointed out that all the ActiMyo variables were representative of human movements and well correlated with clinical scores. The norm of the angular velocity and the mean elevation rate provided the most promising outcomes, with strong Spearman's rank correlation and good reliability (range of correlation rho(7) = 0.6-0.8). [PERSON] and colleagues [36] investigated the physical activity in 76 participants with different muscular dystrophies (MD, 15 patients with DMD, mean age = 24 years). Physical activity was measured on seven consecutive days with the GENEactiv 3-axis accelerometer. Motor activity was expressed as average daily minutes spent physically active or average daily percentage of sedentary waking hours. In addition, muscle weakness and impaired 10 m walking time were monitored. Maximum voluntary contraction during plantar flexion was significantly associated with the anatomical cross-sectional area of the gastrocnemius medialis in DMD ([PERSON]'s r(15) = 0.429, \(p\) = 0.026) and controls ([PERSON]'s r(16) = 0.553, \(p\) = 0.015). Results pointed to a significant relationship between muscle weakness and sedentary behavior in MD patients. MD groups were 14-38% more sedentary than control groups, while DMD were more sedentary than Becker MD (14%), limb-girld MD (8%), and facioscapulohumeral MD (14%). Sedentary behavior was associated with the lean body mass in DMD participants ([PERSON]'s r(15) = \(-\)0.45, \(p\) = 0.021). In January 2017, clinicians, physiotherapists, imaging experts, and patient advocacy group representatives participated in a two-day workshop discussing which outcome measures are relevant as primary and secondary endpoints in clinical trials for DMD patients. [PERSON] and [PERSON] [37] synthesized the principal concepts pointed out in the discussions and described outcome parameters that were considered for both ambulatory (6 MWT, NSAA, stride length, cadence, knee extension strength, heart rate, step activity) and non-ambulatory (PUL, respiratory function, MyoGrip, MyoPinch, MoviPlate) DMD patients. In particular, the inertial sensors were confirmed as suitable and reliable instruments for the monitoring of motion activity over a long time period, for both lower and upper limbs. In 2019, [PERSON] et al. [38] monitored the activity of seven non-ambulatory patients by means of one Silmee Bar-type Lite accelerometer, positioned on the wrist of the dominant arm. Physical activity was monitored for 8 consecutive hours. The jerk (rate of change of acceleration) was considered as an outcome measure of interest and the cumulative jerk along the 8 h of monitoring was estimated. Arm muscle strength was measured by a hand-held dynamometer during elbow flexion-extension movement. Clinical scales and subjective questionnaires were applied to the participants in the functional evaluation of the upper extremities.