Quantifying Jump Height Using Markerless Motion Capture with a Single Smartphone.

Goal: The countermovement jump (CMJ) is commonly used to measure lower-body explosive power. This study evaluates how accurately markerless motion capture (MMC) with a single smartphone can measure bilateral and unilateral CMJ jump height. Methods: First, three repetitions each of bilateral and unilateral CMJ were performed by sixteen healthy adults (mean age: 30.87 [Formula: see text] 7.24 years; mean BMI: 23.14 [Formula: see text] 2.55 [Formula: see text]) on force plates and simultaneously captured using optical motion capture (OMC) and one smartphone camera. Next, MMC was performed on the smartphone videos using OpenPose. Then, we evaluated MMC in quantifying jump height using the force plate and OMC as ground truths. Results: MMC quantifies jump heights with ICC between 0.84 and 0.99 without manual segmentation and camera calibration. Conclusions: Our results suggest that using a single smartphone for markerless motion capture is promising.

Detecting Gait Events from Accelerations Using Reservoir Computing.

Segmenting the gait cycle into multiple phases using gait event detection (GED) is a well-researched subject with many accurate algorithms. However, the algorithms that are able to perform accurate and robust GED for real-life environments and physical diseases tend to be too complex for their implementation on simple hardware systems limited in computing power and memory, such as those used in wearable devices. This study focuses on a numerical implementation of a reservoir computing (RC) algorithm called the echo state network (ESN) that is based on simple computational steps that are easy to implement on portable hardware systems for real-time detection. RC is a neural network method that is widely used for signal processing applications and uses a fast-training method based on a ridge regression adapted to the large quantity and variety of IMU data needed to use RC in various real-life environment GED. In this study, an ESN was used to perform offline GED with gait data from IMU and ground force sensors retrieved from three databases for a total of 28 healthy adults and 15 walking conditions. Our main finding is that despite its low complexity, ESN is robust for GED, with performance comparable to other state-of-the-art algorithms. Our results show the ESN is robust enough to obtain good detection results in all conditions if the algorithm is trained with variable data that match those conditions. The distribution of the mean absolute errors (MAE) between the detection times from the ESN and the force sensors were between 40 and 120 ms for 6 defined gait events (95th percentile). We compared our ESN with four different state-of-the-art algorithms from the literature. The ESN obtained a MAE not more than 10 ms above three other reference algorithms for normal walking indoor and outdoor conditions and yielded the 2nd lowest MAE and the 2nd highest true positive rate and specificity when applied to outdoor walking and running conditions. Our work opens the door to using the ESN as a GED for applications in wearable sensors for long-term patient monitoring.

Balance control deficits in individuals with a transtibial amputation with and without visual input.

BACKGROUND: Many individuals with a transtibial amputation (TTA) exhibit balance deficits after limb loss. However, limited evidence exists on balance deficits of individuals with a TTA using hip, knee, and ankle kinematics and center of mass outcomes. OBJECTIVES: To identify balance control deficits in individuals with a TTA and determine to what extent they are accentuated without visual inputs. STUDY DESIGN: Cross-sectional. METHODS: Ten individuals with TTA and 10 healthy controls undertook a biomechanical assessment during a 30-s quiet standing task with eyes open (EO) and eyes closed (EC). The mean trunk, hip, knee, and ankle angles and center of pressure (COP) and center of mass excursions were calculated. RESULTS: More ankle dorsiflexion was observed for amputated limbs compared with intact lower limbs (mean difference: 5.8-degree, P = 0.031). Less anteroposterior (mean difference: 26.5 mm, P < 0.001) and mediolateral (ML) (mean difference: 4.2 mm, P = 0.042) COP excursions were found for amputated limbs compared with intact lower limbs and for control limbs compared with intact limbs (mean difference: 18.8 mm, P = 0.019). Greater ML COP excursion was found during EC than during EO condition (mean difference: 1.1 mm, P = 0.037). CONCLUSIONS: Individuals with a TTA presented a greater reliance on the intact lower limb, as highlighted by the greater ankle plantarflexion and anteroposterior and ML COP excursions for intact limbs compared with amputated limbs during quiet standing tasks. During EC condition, both groups exhibited greater ML COP excursions compared with EO condition, suggesting less postural stability. These differences may place them at greater risk of falling.

Clinical Walking Tests and Gait Pattern Characterization During 6-Minute Walk Test Using Inertial Sensors: Follow-Up in Individuals With Lower Limb Amputation.

Inertial measurement units and normative values enable clinicians to quantify clinical walking tests and set rehabilitation goals. Objectives of this study were (1) to compare time- and distance-based walking tests in individuals with lower limb amputation (iLLA) and normative values following rehabilitation discharge (T1) and 6 weeks after discharge (T2) and (2) to investigate spatiotemporal and foot kinematic parameters over a 6-minute walk test using inertial measurement units. Twelve iLLA participated in this study. Distance, cadence, stance ratio, loading rate ratio, push-up ratio, path length, and minimum toe clearance were analyzed during 6-minute walk test. Nonparametric repeated-measures analysis of variance tests, Bonferroni corrections, were performed. Time of distance-based walking tests diminished at T2 (P < .02). Compared with normative values, walking performance in iLLA was reduced. Cadence at T2 increased significantly (P = .026). Stance ratio increased in both legs at T2 (P < .05). Push-up ratio tended to decrease at T2 in the amputated leg (P = .0003). Variability of path length and minimum toe clearance at T2 were less than at T1 in the nonamputated leg (P < .05). Spatiotemporal improvement at T2 could be due to prosthesis adaptation in iLLA. The lower performance of the functional walk test compared with normative values could be due to amputation and pain-related fatigue.

Assessment of biomechanical deficits in individuals with a trans-tibial amputation during level gait using one-dimensional statistical parametric mapping.

BACKGROUND: Most previous studies reported biomechanical deficits in individuals with a trans-tibial amputation (TTA) during gait using zero-dimensional analyses. However, these analyses do not allow to precisely determine during which part of the gait cycle these deficits occur. There is a need to use more appropriate methods to map the differences, such as one-dimensional statistical parametric mapping. RESEARCH QUESTION: What are the most relevant phases of the gait cycle during which the biomechanical deficits in TTA occur? METHODS: Eight TTA and 15 healthy counterparts (CON) underwent one biomechanical gait analysis. Pelvis, hip, knee and ankle kinematics, total support moment (TSM) and gastrocnemius lateralis, vastus lateralis and tibialis anterior muscle activity were compared between the amputated (AmLL), the intact (InLL) and the control (CnLL) lower limbs using one-dimensional statistical parametric mapping. RESULTS: More ankle dorsiflexion and knee flexion were observed for the AmLL compared to the InLL and CnLL (ankle only) from the end of the stance phase to the beginning of the swing phase. Less knee flexion was also found for the AmLL during early stance phase. More pelvis posterior tilt and rotation toward the contralateral limb was observed during most of the gait cycle for the AmLL compared to the InLL. TSM was smaller for the AmLL compared to the CnLL during early stance phase. SIGNIFICANCE: Using a one-dimensional statistical parametric mapping approach for TTA gait analysis, this study provides novel insights on their biomechanical gait deficits compared to CON. Greater reliance on the InLL was observed in TTA as suggested by the asymmetric kinematic and kinetic profiles.

Six-Minute Walk Test in Individuals With Unilateral Lower Limb Amputations.

BACKGROUND: The 6-minute walk test (6MWT) is one of the common clinical tests to assess rehabilitation progress and needs in individuals with lower-limb amputation (iLLAs). However, the analysis of this test is mostly limited to the distance parameter. The first aim was to investigate effort intensity and spatiotemporal parameters of 6MWT in iLLAs using inertial measurement units (IMUs) and heart rate (HR) monitor, and second, to assess physical, physiological, and pain-related aspects of fatigue over 6MWT. METHODS: Eleven unilateral iLLAs (57.91±15.63 years old) participated in this study. To evaluate HR and spatiotemporal parameters over 6MWT, data were classified using 6 intervals of 1 minute each (I1-I6). The pain level of participants was estimated using the visual analog scale (VAS). RESULTS: Our results showed that the means of normalized HR gradually increased over 6MWT (I1: 61.59±10.73 HRmax%, I6: 70.15±12.26 HRmax%, P = .003). Variability of HR during the first interval of 6MWT was higher than the others (P < .05). The stance ratio of the gait cycle increased over 6MWT (P < .05). Cadence and speed decreased over 6MWT (P < .05). VAS score after 6MWT was significantly higher than before 6MWT (P = .016). CONCLUSION: In this preliminary study, effort intensity over 6MWT gradually increased because of enhancement of HR. Deterioration of speed and cadence and enhancement of stance ratio over 6MWT imply potential physical aspects of fatigue and instability. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Standing Balance Performance and Knee Extensors' Strength in Diabetic Patients with Neuropathy.

Diabetes peripheral neuropathy (DPN) leads to balance impairment among diabetes mellitus (DM). The aims of this study were to (1) distinguish between DM patients who have/do not have DPN and to (2) compare quadriceps' strength and balance performance of DM, DPN, and healthy groups. Fifteen healthy females and 33 females with type 2 diabetic patients participated. The electrodiagnostic method was used to classify diabetic patients into DM and DPN. A dynamometer was used to measure quadriceps' strength. Single-leg standing on a force plate was also used to quantify participants' balance. Smaller conduction velocity and amplitude and greater distal latency of all nerves were observed in the DPN compared with the DM in particular for sensory nerve. In DPN, conduction velocity was asymmetrical. The quadriceps' strength of both legs in DPN and the right leg in DM was smaller than in the control group. The root mean square of the center of pressure was similar between DM and DPN. But it was larger in DPN than in the control group. DPN is associated with asymmetrical conduction velocity, smaller quadriceps' strength, and weaker balance performance that is suggestive of higher risk of falling. Balance training is recommended for the DPN group during their rehabilitation to reduce their falling risk.

Electromyographic activity of erector spinae and external oblique muscles during trunk lateral bending and axial rotation in patients with adolescent idiopathic scoliosis and healthy subjects.

BACKGROUND: The aim of this study was to analyze electrical activity of trunk muscles in adolescent idiopathic scoliosis patients and healthy subjects during trunk lateral bending and rotation movements. METHODS: Ten patients with right thoracic scoliosis [Cobb angle: 29.1° (10.4°)] and 10 control adolescents were studied. Electrical activities of erector spinae muscle at 6th and 10th thoracic and 3rd lumbar vertebral level, and external oblique muscles were measured bilaterally during the right and left bending from standing and prone positions, and trunk rotation in sitting position. FINDINGS: In trunk rotation to the right, the right-side external oblique (antagonist) muscle in scoliosis group was greater than that in control group (p<0.05). In left bending from standing position, in scoliosis group, the antagonistic activity of EST6 muscle was greater than its agonistic activity (p<0.05). Also, in the right bending motion, the agonistic activity of external oblique of scoliosis group was higher than that of control group (p=0.02). During the left bending from prone position, right-side EST6 and right-side ESL3 muscles of scoliosis group were greater than that of control group (p<0.05). INTERPRETATION: In left bending from standing position, in scoliosis group, the greater antagonistic activity of erector spinae muscle at 6th thoracic vertebral level than its agonistic activity, indicates that scoliosis is associated with asymmetrical muscle activity. Lateral bending from standing position is appropriate test to distinguish between scoliosis and control subjects. In scoliosis, the asymmetrical muscle activity is not an inherent characteristic since it was not displayed in all back motions.