How close to a pendulum is human upper limb movement during walking?

Effects of Gyroscope on Arm Swing and Gait in Healthy Volunteers

Background. Arm swing has a crucial role in gait. It is essential in terms of regulating gait parameters and balance during walking. In the case of bradykinesia, the arms act as a generator to maintain lower extremity movement while walking. The way gyroscopes work makes them useful in arm swings. In this study, the arm swing is facilitated by a new type of gyroscope. As a main purpose, a gyroscope was used to increase arm swing during pendulum exercise and walking. Methods. Thirty healthy volunteers were included in the study. The study covered three situations. The first evaluation was performed without the gyroscope. The second evaluation was performed while the gyroscope was installed but not activated. The final evaluation was made while the gyroscope was installed and powered up. The effect of the gyroscope on the arm swing was evaluated by the Dartfish®, and the gait was evaluated with the Zebris® force distribution measurement analysis system. Results. According to the results, the gyroscope increases the arm swing in the pendulum exercise ( $p<0.05$ ). Furthermore, using the gyroscope, the step width decreased, and the gait cycle time increased ( $p<0.05$ ). Conclusions. The gyroscope is suitable for facilitating arm swings in healthy volunteers. This study is essential to demonstrate the effect of a gyroscope on extremity movements for the first time. In the future, a medical device that has the features of a gyroscope can be designed for its use in the treatment of Parkinson’s disease and Senile Bradykinesia.

Motion Biomarkers Showing Maximum Contrast Between Healthy Subjects and Parkinson's Disease Patients Treated With Deep Brain Stimulation of the Subthalamic Nucleus. A Pilot Study

Background: Classic motion abnormalities in Parkinson's disease (PD), such as tremor, bradykinesia, or rigidity, are well-covered by standard clinical assessments such as the Unified Parkinson's Disease Rating Scale (UPDRS). However, PD includes motor abnormalities beyond the symptoms and signs as measured by UPDRS, such as the lack of anticipatory adjustments or compromised movement smoothness, which are difficult to assess clinically. Moreover, PD may entail motor abnormalities not yet known. All these abnormalities are quantifiable via motion capture and may serve as biomarkers to diagnose and monitor PD.

Objective: In this pilot study, we attempted to identify motion features revealing maximum contrast between healthy subjects and PD patients with deep brain stimulation (DBS) of the nucleus subthalamicus (STN) switched off and on as the first step to develop biomarkers for detecting and monitoring PD patients' motor symptoms.

Methods: We performed 3D gait analysis in 7 out of 26 PD patients with DBS switched off and on, and in 25 healthy control subjects. We computed feature values for each stride, related to 22 body segments, four time derivatives, left–right mean vs. difference, and mean vs. variance across stride time. We then ranked the feature values according to their distinguishing power between PD patients and healthy subjects.

Results: The foot and lower leg segments proved better in classifying motor anomalies than any other segment. Higher degrees of time derivatives were superior to lower degrees (jerk > acceleration > velocity > displacement). The averaged movements across left and right demonstrated greater distinguishing power than left–right asymmetries. The variability of motion was superior to motion's absolute values.

Conclusions: This small pilot study identified the variability of a smoothness measure, i.e., jerk of the foot, as the optimal signal to separate healthy subjects' from PD patients' gait. This biomarker is invisible to clinicians' naked eye and is therefore not included in current motor assessments such as the UPDRS. We therefore recommend that more extensive investigations be conducted to identify the most powerful biomarkers to characterize motor abnormalities in PD. Future studies may challenge the composition of traditional assessments such as the UPDRS.

The effects of arm swing amplitude and lower-limb asymmetry on gait stability

Changes to arm swing and gait symmetry are symptomatic of several pathological gaits associated with reduced stability. The purpose of this study was to examine the relative contributions of arm swing and gait symmetry towards gait stability. We theorized that actively increasing arm swing would increase gait stability, while asymmetric walking would decrease gait stability. Fifteen healthy, young adults (23.4 ± 2.8 yrs) walked on a split-belt treadmill under symmetric (1.2 m/s) and asymmetric walking (left/right, 5:4 speed ratio) with three different arm swings: held, normal, and active. Trunk local dynamic stability, inter-limb coordination, and spatiotemporal gait variability and symmetry were measured. Active arm swing resulted in improved local trunk stability, increased gait variability, and decreased inter-limb coordination (p < .013). The changes in local trunk stability and gait variability during active arm swing suggests that these metrics quantify fundamentally different aspects of stability and are not always comparable. Split-belt walking caused reduced local trunk stability, increased gait variability, and increased lower limb asymmetry (p < .003). However, the arm swing symmetry was unaffected by gait asymmetry, this suggests that the decreases in gait stability are linked to the increases in gait asymmetry rather than increases in arm swing asymmetry.

The Use of a Finger-Worn Accelerometer for Monitoring of Hand Use in Ambulatory Settings

Objective assessment of stroke survivors' upper limb movements in ambulatory settings can provide clinicians with important information regarding the real impact of rehabilitation outside the clinic and help to establish individually-tailored therapeutic programs. This paper explores a novel approach to monitor the amount of hand use, which is relevant to the purposeful, goal-directed use of the limbs, based on a body networked sensor system composed of miniaturized finger- and wrist-worn accelerometers. The main contributions of this paper are twofold. First, this paper introduces and validates a new benchmark measurement of the amount of hand use based on data recorded by a motion capture system, the gold standard for human movement analysis. Second, this paper introduces a machine learning-based analytic pipeline that estimates the amount of hand use using data obtained from the wearable sensors and validates its estimation performance against the aforementioned benchmark measurement. Based on data collected from 18 neurologically intact individuals performing 11 motor tasks resembling various activities of daily living, the analytic results presented herein show that our new benchmark measure is reliable and responsive, and that the proposed wearable system can yield an accurate estimation of the amount of hand use (normalized root mean square error of 0.11 and average Pearson correlation of 0.78). This study has the potential to open up new research and clinical opportunities for monitoring hand function in ambulatory settings, ultimately enabling evidence-based, patient-centered rehabilitation and healthcare.

Changes in gait kinematics and muscle activity in stroke patients wearing various arm slings

Stroke patients often use various arm slings, but the effects of different slings on the joint kinematics and muscle activity of the arm in the gait have not been investigated. The effects of joint kinematics and muscle activity in the gait were investigated to provide suggestions for gait training for stroke patients. In all, 10 chronic stroke patients were voluntarily recruited. An eight-camera three-dimensional motion analysis system was used to measure joint kinematics while walking; simultaneously, electromyography data were collected for the anterior and posterior deltoids and latissimus dorsi. The amplitude of pelvic rotation on the less-affected side differed significantly among the different arm slings (P<0.05). Changes in the knee kinematics of the less-affected side also differed significantly (P<0.05), while there were no significant differences in the muscle activity of the affected arm. In stroke patients, an extended arm sling is more useful than no sling or a flexed arm sling in terms of the amplitude of the rotation of the less-affected pelvic side in the stance phase while walking. The less-affected knee joint is flexed more without a sling than with any sling. All arm slings support the extension of the contralateral knee.

Arm swing in human walking: what is their drive?

Although previous research has studied arm swing during walking, to date, it remains unclear what the contribution of passive dynamics versus active muscle control to arm swing is. In this study, we measured arm swing kinematics with 3D-motion analysis. We used a musculoskeletal model in OpenSim and generated dynamic simulations of walking with and without upper limb muscle excitations. We then compared arm swing amplitude and relative phase during both simulations to verify the extent to which passive dynamics contribute to arm swing. The results confirm that passive dynamics are partly responsible for arm swing during walking. However, without muscle activity, passive swing amplitude and relative phase decrease significantly (both p<0.05), the latter inducing a more in-phase swing pattern of the arms. Therefore, we conclude that muscle activity is needed to increase arm swing amplitude and modify relative phase during human walking to obtain an out-phase movement relative to the legs.

The how and why of arm swing during human walking

Humans walk bipedally, and thus, it is unclear why they swing their arms. In this paper, we will review the mechanisms and functions of arm swinging in human gait. First, we discuss the potential advantages of having swinging arms. Second, we go into the detail on the debate whether arm swing is arising actively or passively, where we will conclude that while a large part of arm swinging is mechanically passive, there is an active contribution of muscles (i.e. an activity that is not merely caused by stretch reflexes). Third, we describe the possible function of the active muscular contribution to arm swinging in normal gait, and discuss the possibility that a Central Pattern Generator (CPG) generates this activity. Fourth, we discuss examples from pathological cases, in which arm swinging is affected. Moreover, using the ideas presented, we suggest ways in which arm swing may be used as a therapeutic aid. We conclude that (1) arm swing should be seen as an integral part of human bipedal gait, arising mostly from passive movements, which are stabilized by active muscle control, which mostly originates from locomotor circuits in the central nervous system (2) arm swinging during normal bipedal gait most likely serves to reduce energy expenditure and (3) arm swinging may be of therapeutic value.

Control and function of arm swing in human walking and running

We investigated the control and function of arm swing in human walking and running to test the hypothesis that the arms act as passive mass dampers powered by movement of the lower body, rather than being actively driven by the shoulder muscles. We measured locomotor cost, deltoid muscle activity and kinematics in 10 healthy adult subjects while walking and running on a treadmill in three experimental conditions: control; no arms (arms folded across the chest); and arm weights (weights worn at the elbow). Decreasing and increasing the moment of inertia of the upper body in no arms and arm weights conditions, respectively, had corresponding effects on head yaw and on the phase differences between shoulder and pelvis rotation, consistent with the view of arms as mass dampers. Angular acceleration of the shoulders and arm increased with torsion of the trunk and shoulder, respectively, but angular acceleration of the shoulders was not inversely related to angular acceleration of the pelvis or arm. Restricting arm swing in no arms trials had no effect on locomotor cost. Anterior and posterior portions of the deltoid contracted simultaneously rather than firing alternately to drive the arm. These results support a passive arm swing hypothesis for upper body movement during human walking and running, in which the trunk and shoulders act primarily as elastic linkages between the pelvis, shoulder girdle and arms,the arms act as passive mass dampers which reduce torso and head rotation, and upper body movement is primarily powered by lower body movement.

The influence of rifle carriage on the kinetics of human gait

The influence that rifle carriage has on human gait has received little attention in the published literature. Rifle carriage has two main effects, to add load to the anterior of the body and to restrict natural arm swing patterns. Kinetic data were collected from 15 male participants, with 10 trials in each of four experimental conditions. The conditions were: walking without a load (used as a control condition); carrying a lightweight rifle simulator, which restricted arm movements but applied no additional load; wearing a 4.4 kg diving belt, which allowed arms to move freely; carrying a weighted (4.4 kg) replica SA80 rifle. Walking speed was fixed at 1.5 m/s (+/-5%) and data were sampled at 400 Hz. Results showed that rifle carriage significantly alters the ground reaction forces produced during walking, the most important effects being an increase in the impact peak and mediolateral forces. This study suggests that these effects are due to the increased range of motion of the body's centre of mass caused by the impeding of natural arm swing patterns. The subsequent effect on the potential development of injuries in rifle carriers is unknown.

Acquisition of the lateral inconsistency in involuntary behaviour of upper limbs in 12-year-old children during walking at moderate speed

The aim of this work was to investigate possible lateralisation in the behaviour of periodic motion of the human upper limb, during normal walking at a comfortable speed of locomotion. Ten healthy pre-adolescent, strongly right-handed, 12-year-old males participated in the experiment. Participants were walking on a treadmill with a standardised velocity of 1.1m/s (comfortable speed for all of them). A video analysis system with Silicon software was used to synchronically measure various angles of arms and forearms. The initial, final and interim angular positions of both arms and forearms in 10 cycles of each participant were compared in terms of variations (cycle to cycle) between both upper extremities at corresponding phases of each cycle for distal and proximal segments, respectively. We compared the coefficients of variation in relation to the spatial and temporal data of both limbs and their angular velocities. In addition we investigated the level of cycle-to-cycle regularity (constancy) of behaviour in relation to various positions, periods and velocities of movement of upper extremities (specifically arms and forearms) using the Eta non-linear method of correlation. All participants exhibited a lower level of regularity for the distal segments. The spatial and temporal variations in the dominant limb were also greater than the non-dominant limb for all participants. This may be due to a larger contribution from the right-sided muscles that are considered to be the main contributing factor to the motion of the dominant upper limb during walking, rather than simply gravity force acting alone. A possible practical application of this information may be useful in the objective clinical identification of the level of dominance of the upper extremity (arm plus forearm), in addition to 'traditional' handedness.