Foot Dorsiflexion Velocity and Torque Variance Explained through Architectural and Electromyography Variables Comparing Elders and Stroke Survivors

Muscle activity and architecture as a predictor of hand-grip strength

BACKGROUND

Grip strength is a powerful predictor of disability as well as a good indicator of physical activity.

OBJECTIVES

This study aimed to relate ultrasound (US) and electromyography (EMG) simultaneously to maximum hand-grip strength during an isometric contraction.

APPROACH

This is a cross-sectional study. Data acquisition was done with a dynamometer, US and EMG. Outcome variables included maximum strength during the hand-grip gesture, maximum muscle activity and change in muscle thickness. A non-linear regression analysis was performed to analyse the relationship between all outcome variables.

MAIN RESULTS

A total of 38 subjects (18 men and 20 women) participated in the study. The mean results for hand-grip strength were 25.50 (SD 6.55) kg of maximum strength, a change in muscle thickness of 1.83 (SD 0.75) mm and an EMG activity of 499.29 (SD 224.20) µV. Hand-grip strength had a high correlation with muscle thickness (R ² = 0.61) and EMG activity (R ² = 0.95). The correlation between maximum muscle activity and change in muscle thickness was R ² = 0.83.

SIGNIFICANCE

The results of the present study demonstrate that this new method based on electromyographic activity and muscule architecture could be important in the development of the hand-grip test.

Measurement of Results of Functional Reach Test with Sensors: A Systematic Review

The test of physical conditions is important to treat and presents several diseases related to the movement. These diseases are mainly related to the physiotherapy and orthopedy, but it can be applied in a wide range of medical specialties. The Functional Reach Test is one of the most common physical tests used to measure the limit of stability that is highly important for older adults because their stability is reduced with aging. Thus, older adults are part of the population more exposed to stroke. This test may help in the measurement of the conditions related to post-stroke and stroke treatment. The movements related to this test may be recorded and recognized with the inertial sensors available in off-the-shelf mobile devices. This systematic review aims to determine how to determine the conditions related to this test, which can be detected, and which of the sensors are used for this purpose. The main contribution of this paper is to present the research on the state-of-the-art use of sensors available on off-the-shelf mobile devices to measure Functional Reach Test results. This research shows that the sensors that are used in the literature studies are inertial sensors and force sensors. The features extracted from the different studies are categorized as dynamic balance, quantitative, and raw statistics. These features are mainly used to recognize the different parameters of the test, and several accidents, including falling. The execution of this test may allow the early detection of different diseases.

sEMG Activation of the Flexor Muscles in the Foot during Balance Tasks by Young and Older Women: A Pilot Study

Objective: In this publication, we suggest that young adults and seniors use various defense mechanisms to counteract loss of balance. One of the hypotheses is the change in the coordination of antagonistic muscle groups, especially within the ankles. In this study, we tried to determine if there is a relationship between the condition from resilient, to pre-frail, to frail and the ability to maintain balance during free standing and balance tasks. The aim of the study was to define the importance of muscle activity in the ankle joint, dorsal flexor of the foot for the following: tibialis anterior (TA), plantar flexor of the foot gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and peroneus longus (PER), during balance tasks with eyes open (EO) and closed (EC). We hypothesized that there are differences in the activity and co-activation of the tested muscles in young and older women, which may indicate an increased risk of falls and walking disorders. Materials and methods: A group of 20 women qualified for the study. The group was divided into two subgroups, young (G1) and elderly women (G2). The aim of the study was to define the importance of muscle activity in the ankle joint, dorsal flexor of the foot for the following: tibialis anterior (TA), plantar flexor of the foot gastrocnemius medialis (GM), gastrocnemius lateralis (GL), and peroneus longus (PER), during balance tasks with eyes open (EO) and closed (EC). Results: In this study, we observed significant differences between groups in the maximum and mean values of electromyography activity (EMG) activation of the examined muscles on different types of surfaces and with open and closed eyes. Older women generated higher values of EMG activation in all muscles except the gastrocnemius medialis muscle. The results were significant for co-activation at rest for muscles as follows: tibialis anterior and gastrocnemius medialis with eyes closed (p = 0.01) and peroneus and gastrocnemius lateralis at rest with eyes open (p = 0.03), eyes closed (p = 0.04), and on a foam (p = 0.02). The sEMG amplitude of the tested muscles means that agonist muscle activity changed relative to antagonistic muscle activity. Conclusions: Activation of sEMG and coordination of ankle muscles during balance tasks change with age. It can be hypothesized that assessment of balance during free standing and equivalent tasks can predict the state of frailty, after taking into account other physiological variables that are believed to affect balance control.