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We investigated postural stability through the margin of stability (MoS) while reaching and grasping an object with increasing difficulty levels in younger, fallers and non-fallers. Forty-five individuals distributed into three groups participated in this study: younger adults (YA), non-fallers (OA), and fallers (FOA). They stood upright and reached and grasped a dowel. Six conditions combining the stability of the dowel's base and obstacles close to the dowel were manipulated to characterize different difficulty levels. We computed the MoS in both anterior-posterior (AP) and medial-lateral (ML) directions in the interval between reaching onset and dowel contact. From the MoS time series, we analyzed the minimum and maximum, including the time of occurrence of these events. The MoS was smaller for OA than for YA in both directions. In the ML direction, the minimum MoS was smaller for FOA than for YA. The minimum MoS took place earlier for FOA than YA in the AP direction. FOA and OA exhibited similar behavior with reduced MoS, suggesting impaired postural control during reaching-to-grasping in a standing posture. FOA used a more cautious strategy by reverting the MoS earlier than YA, allowing them to increase their MoS before YA when preparing to grasp the dowel.

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This study aimed to investigate the kinematic changes in obstacle avoidance and prehension tasks performed simultaneously by older adults with a history of falls at different levels of task difficulty. Twenty-six older adults were divided into faller and nonfaller groups. The experimental protocol was divided into two different tasks: walking with obstacle avoidance and walking with obstacle avoidance combined with a reach-to-grasp task. Two types of sensors (Kinect v2 and Leap Motion Controller, respectively) were used to analyze gait and grasp. Fallers presented kinematic changes associated with the grasping task during obstacle avoidance, such as a decrease in the velocity of the center of mass and the step length, an increase in the step width, a decrease in toe-obstacle horizontal distance, and an increase in vertical foot clearance distance, and an increase in movement time in the grasping task compared with nonfallers. To cope with the obstacle avoidance demands of both walking and grasping, fallers turned to a specific sequencing strategy. While slowing down, they attended first to the grasping task and then to crossing the obstacle on the floor.

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OBJECTIVE: To compare the levels of pain, grip strength, balance and gait in older adults with and without post-Chikungunya chronic arthralgia (PCCA). METHODS: Sixty-two older adults, 30 with and 32 without PCCA participated in the study. Pain level was assessed using a Visual Analogue Scale (VAS). Gait during a 10-m walk was assessed using inertial sensors. Semi-static balance was assessed during an eyes-closed bipedal balance test on a force platform, and grip strength was assessed using a hand dynamometer. RESULTS: Participants with PCCA presented severe levels of pain (VAS > 7.5), poorer balance, lower grip strength, walked slower, with lower cadence and stride length and higher stride time and stride length variability than participants without PCCA (P < 0.001 for all variables). CONCLUSIONS: Older adults with PCCA had high levels of pain, impaired balance and gait and lower grip strength compared to older adults without PCCA.

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The ergogenic effect of beetroot on the exercise performance of trained cyclists, runners, kayakers, and swimmers has been demonstrated. However, whether or not beetroot supplementation presents a beneficial effect on the exercise performance of jiu-jitsu athletes remains inconclusive. Therefore, the present study assessed the effect of beetroot-based gel (BG) supplementation on maximal voluntary contraction (MVC), exercise time until fatigue (ETF), muscle O2 saturation (SmO2), blood volume (tHb), and plasma nitrate and lactate in response to handgrip isotonic exercise (HIE) in jiu-jitsu athletes. In a randomized, crossover, double-blind design, 12 jiu-jitsu athletes performed 3 sets of HIE at 40% of the MVC until fatigue after 8 days (the eighth dose was offered 120 min previous exercise) of BG supplementation or a nitrate-depleted gel (PLA), and forearm SmO2 and tHb were continuously monitored by using near-infrared spectroscopy. Blood samples were taken before, immediately after exercise, and 20 min after exercise recovery in the PLA and BG conditions. MVC was evaluated at baseline and 20 min after HIE. There was a significant reduction in ΔMVC decline after HIE in the BG condition. Forearm SmO2 during exercise recovery was significantly greater only after BG supplementation. No significant difference in ETF and tHb were observed between both BG and PLA in response to HIE. Plasma nitrate increased only after BG, whereas the exercise-induced increase in plasma lactate was significantly lower in BG when compared with PLA. In conclusion, BG supplementation may be a good nutritional strategy to improve forearm SmO2 and prevent force decline in response to exercise in jiu-jitsu athletes.

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Typically, falls in older adults occur when 2 tasks are performed simultaneously, due to the increased motor demand required to maintain stability and attention to perform the other task. The authors' purpose was to investigate walking while grasping, transporting, and placing a dowel on a predetermined target while manipulating difficulty levels of the manual task. Faller and nonfaller older adults performed a walking block (manual tasks combined with gait) and a stationary block (upright stance combined with manual tasks). The manual task involved grasping, transporting, and placing the dowel over a target. The results showed that fallers underperformed when compared with nonfallers in the task of placing the dowel over the target. The main difference observed between the groups was found in the condition that required allocation of attention between tasks and greater accuracy in the final placement of the object. Fallers showed gait stability similar to the nonfallers, but fallers were less accurate than nonfallers in the object placement task, especially for the highest level of difficulty. Thus, fallers seem to use a stability-first strategy. Fallers had problems in executing the manual tasks, which suggests a more global change in motor behavior rather than specific changes to balance control.

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Typically, prehension and gait behaviors are studied separately. However, little is known about what changes occur in these motor skills when they are combined. We investigated and characterized motor performance during combined walking and prehension at different levels of difficulty of the prehension task. Fifteen right-handed young adults were invited to walk at their self-selected pace and grasp a dowel as they walked. They also grasped the dowel in a stationary condition (upright stance). We combined conditions with/without obstacles and stable/unstable base for dowel prehension. Modifications in gait and prehension were identified when they were combined, especially for the most difficult prehension conditions. The grasping task caused an adaptation in gait because the participants preferred to adopt a more conservative strategy of increasing their dynamic stability during the approach phase and when grasping the dowel. Walking changed the prehension movement by reducing the reaching movement time, peak wrist velocity, and peak grip aperture velocity. In addition, the peak grip aperture was affected by the presence of obstacles close to the dowel. The participants adjusted their gait during the approach phase to facilitate dowel prehension, and they controlled the hand position online to adjust its configuration based on the prehension conditions.

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We have shown before that grasping movements from a given starting position to a given object differ substantially when performed as a typical laboratory task (L) and when they are embedded in an everyday-like context (E). The present study investigates whether this context-dependence is related to the subjects' motivation focus. We manipulated subjects' motivation focus and observed significant effects of Context on performance, as in previous work, but also significant effects of Motivation and Context x Motivation on performance. The interaction term could not be interpreted as generally higher or lower motivation sensitivity in L than in E, and therefore it doesn't support the hypothesis that context-dependence of grasping can be reduced to motivation-dependence. We conclude that some brain areas contribute differently to L and to E, thus producing context-dependence, and that those areas are differently sensitive to motivation...

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Como podemos falar de objetos, duração e estabilidade em um mundo feito de vertigem e puro fluxo? Este artigo propõe a problematização do conceito de objeto na prática cartográfica para pensar a formação do cartógrafo. Para tanto, necessitamos ultrapassar o dualismo entre estável e instável. Por meio de conceitos como os de tensão e complexidade podemos produzir uma ontologia metaestável. Para produzir esta ontologia relacional, criativa e complexa, vamos usar uma caixa de ferramentas conceitual advinda de dois autores. De Henri Bergson tomaremos os conceitos de duração, intuição, seleção e sentido. De A. N. Whitehead tomaremos os conceitos de preensão, sentires e criação. A partir desses conceitos produziremos um conceito de objeto adequado ao empirismo transcendental e suas virtualidades, um conceito de objeto que ultrapasse os dualismos entre os fluidos e os sólidos: objeto-acontecimento, objeto-problema.

How can you talk about objects, during and stability and a world made of vertigo and pure fluxes? This article proposes a question about the concept of object in the cartography, to work the formation of the researcher. We need to go beyond the dualism between stable and instable. With concepts like tension and complexity we can produce a metastable ontology. To elaborate this relational, complex and creativity ontology we will use some concepts that can be very useful like a tool box. From Henri Bergson we will catch the following concepts: duration, intuition, selection and felt. From Alfred North Whitehead, we will catch the concepts of prehension, feelings, creation. Working a complexity and relational ontology with this concepts, we will be producing an object without form and substance, beyond the dualism and the necessary essential. An object with a virtual dimension, on a transcendental empiricism: the event-object, the problem-object.

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Como podemos falar de objetos, duração e estabilidade em um mundo feito de vertigem e puro fluxo? Este artigo propõe a problematização do conceito de objeto na prática cartográfica para pensar a formação do cartógrafo. Para tanto, necessitamos ultrapassar o dualismo entre estável e instável. Por meio de conceitos como os de tensão e complexidade podemos produzir uma ontologia metaestável. Para produzir esta ontologia relacional, criativa e complexa, vamos usar uma caixa de ferramentas conceitual advinda de dois autores. De Henri Bergson tomaremos os conceitos de duração, intuição, seleção e sentido. De A. N. Whitehead tomaremos os conceitos de preensão, sentires e criação. A partir desses conceitos produziremos um conceito de objeto adequado ao empirismo transcendental e suas virtualidades, um conceito de objeto que ultrapasse os dualismos entre os fluidos e os sólidos: objeto-acontecimento, objeto-problema.(AU)

How can you talk about objects, during and stability and a world made of vertigo and pure fluxes? This article proposes a question about the concept of object in the cartography, to work the formation of the researcher. We need to go beyond the dualism between stable and instable. With concepts like tension and complexity we can produce a metastable ontology. To elaborate this relational, complex and creativity ontology we will use some concepts that can be very useful like a tool box. From Henri Bergson we will catch the following concepts: duration, intuition, selection and felt. From Alfred North Whitehead, we will catch the concepts of prehension, feelings, creation. Working a complexity and relational ontology with this concepts, we will be producing an object without form and substance, beyond the dualism and the necessary essential. An object with a virtual dimension, on a transcendental empiricism: the event-object, the problem-object.(AU)

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STUDY DESIGN: Repeated measures experiment. INTRODUCTION: Traumatic injuries and certain other diseases of the hand typically affect mobility of the finger joints. Decreased mobility may alter grip force control while one is grasping and lifting objects. However, the effect of finger joint hypomobility on grip force control has not yet been systematically investigated. PURPOSE OF THE STUDY: The aim of this study was to investigate the effects of limited finger joint mobility, without other associated symptoms like pain, or sensory/proprioceptive deficits, on precision grip force control. METHODS: Fifteen healthy subjects performed a pinching and lifting task of an object equipped with a force sensor and an accelerometer, via opposition of the thumb and index finger, in the following experimental conditions: unrestricted finger joint movement (UJM), restricted finger flexion (RFF), restricted finger extension (RFE), mock restricted flexion (MRF), mock restricted extension (MRE). The following pinch force variables were measured and analyzed: grip force at lift off, grip force peak, load force peak, latency, and static force. RESULTS: A significant increase in latency (F = 4.41, p < 0.01) was noted during RFE relative to UJM and MRF conditions. There were no statistically-significant differences between the conditions among the other variables of precision grip force control. CONCLUSIONS: Limited joint mobility of the thumb and index finger may cause temporal changes in precision grip force control, which can lead to reduced manual dexterity. Restoring range of motion might be an important priority to improve thumb-index pinch force control during manipulative tasks.

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We have shown before that grasping movements from a given starting position to a given object differ substantially when performed as a typical laboratory task (L) and when they are embedded in an everyday-like context (E). The present study investigates whether this context-dependence is related to the subjects' motivation focus. We manipulated subjects' motivation focus and observed significant effects of Context on performance, as in previous work, but also significant effects of Motivation and Context x Motivation on performance. The interaction term could not be interpreted as generally higher or lower motivation sensitivity in L than in E, and therefore it doesn't support the hypothesis that context-dependence of grasping can be reduced to motivation-dependence. We conclude that some brain areas contribute differently to L and to E, thus producing context-dependence, and that those areas are differently sensitive to motivation.(AU)

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