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PubMed2001

Discharge of primate magnocellular red nucleus neurons during reaching to grasp in different spatial locations.

Reaching to grasp is of fundamental importance to primate motor behavior. One descending motor pathway that contributes to the control of this behavior is the rubrospinal tract. An important source of origin of the rubrospinal tract is the magnocellular red nucleus (RNm). Forelimb RNm neurons discharge vigorously during reach-to-grasp movements. RNm discharge is important for hand use, as coordinated whole-limb movements without hand use are not associated with strong discharge. Because RNm is functionally linked to muscles of the entire forelimb, RNm discharge may also contribute to use of the proximal limb that accompanies hand use. If RNm contributes to proximal limb use, we predict discharge to differ for reaches that differ in proximal limb involvement but require the same grasp. We tested this prediction by measuring discharge of individual RNm neurons while monkeys reached to grasp objects in four spatial locations in front of them. The animals reached from the waist to locations to the left, right, above, and below the shoulder of the "reaching" limb. RNm neurons of our sample were activated strongly during reach-to-grasp, and discharge of a third of the neurons tested depended on the spatial location of the object grasped. Discharge of RNm neurons and EMG activity of many of the distal and proximal forelimb muscles we tested were larger for reaching to grasp in the upper and/or right than lower and left target locations. Based on comparisons of each individual neuron's discharge patterns during reaches with and without preshaping the hand, we conclude that target location-dependent modulations in discharge rate of the majority of RNm neurons whose discharge differed for reaching to grasp in the four target locations contributed to aspects of hand preshaping that covaried with reach direction.

Action Potentials↗
PubMed2005

Deficits in grasp versus reach during acute hemiparesis.

We studied how acute hemiparesis affects the ability to perform purposeful movements of proximal versus distal upper extremity segments. Given the gradient of corticospinal input to the spinal motoneuron pools, we postulated that movement performance requiring distal segment control (grasping) should be more impaired than movement performance requiring proximal segment control (reaching) in people with hemiparesis. We tested subjects with acute hemiparesis and control subjects performing reach and reach-to-grasp movements. Three characteristics of movement performance were quantified for each movement: speed, accuracy, and efficiency. For the reach, we calculated peak wrist velocity, endpoint error, and reach path ratio. For the grasp, we calculated peak aperture rate, aperture at touch, and aperture path ratio. To evaluate the relative deficits in reaching versus grasping, performance measures were converted to z-scores using control group means and standard deviations. For both the movements, movement times were longer and performance was more variable in the hemiparetic group compared to the control group. Hemiparetic z-scores indicated that relative deficits in movement speed were small in the two movements, with deficits in grasp being slightly greater than deficits in reach. Relative deficits in accuracy showed a trend for being larger in the reach compared to the grasp, but this difference did not reach statistical significance. In contrast, relative deficits in efficiency were larger in the grasp compared to the reach, with reaching efficiency near the range of normal performance. When considering data across all three movement characteristics, the ability to perform a purposeful movement with the distal segments was not clearly more disrupted than the ability to perform a purposeful movement with the proximal segments in people with acute hemiparesis.

Acute Disease↗
PubMed2005

Neuromuscular versus behavioural influences on reaching performance in young and elderly women.

Falls are a major cause of injury in the elderly, and risk for falls depends on frequency of imbalance episodes. Improved techniques are required for determining how risk for imbalance during daily activities depends on behavioural (e.g., risk taking) versus neuromuscular factors. We developed a novel technique to determine whether differences exist between young and elderly women in tendency to approach imbalance during a forward reaching task. Eighteen young women (18-35 years) and 18 elderly community-dwelling women (70-87 years) participated in trials that required them to stand and reach forward to grasp as quickly as possible a target that moved back and forth, in and out of reach. We conducted 21 trials with each subject, varying the target distance at the time of the go cue, to measure how closely subjects would approach their maximum reach distance, beyond which imbalance would occur. On average, elderly women approached 65+/-13% (S.D.) of their maximum reach on the first trial, while young women approached 84+/-11%. Subjects became more confident over multiple trials, with the 75th percentile in voluntary reach averaging 79+/-8% of maximum reach in elderly, and 89+/-4% in young. Tendency to approach maximum reach did not associate with Activities Balance Confidence (ABC) scores, or with maximum reach itself. These results indicate that, even in the absence of fear of falling, elderly women are less likely than young to approach imbalance during forward reaching. Furthermore, physical capacity and cautiousness contribute independently to reaching behaviour in these individuals.

Accidental Falls↗
PubMed2000

Skilled reaching an action pattern: stability in rat (Rattus norvegicus) grasping movements as a function of changing food pellet size.

Many animals in different mammalian orders display skilled forelimb use for prehension, but there has been little study of the rules underlying skilled forelimb use that may provide insight into its neural organization. Inflexibility of movement would imply an underlying fixed neural control characteristic of innate action pattern, whereas flexibility of movement would imply more plastic neural control. In the present study, rat reaching was examined by analyzing movements used to obtain nine different sized food pellets, weighing between 20 and 1000 mg. The prediction was that if the rats' reaching movements were flexible, then systematic modifications in reaching would occur as food pellet size changed; whereas if reaching was inflexible, disruptions should occur for extreme food pellet sizes. Reaching was filmed using normal (30 frames/s) and high-speed (60 frames/s) video-recording procedures. Behavior was scored in terms of successful reaches and, in addition, a new rating scale, derived from Eshkol-Wachman Movement Notation, was used to evaluate the qualitative aspects of movement. Reaching success was stable across smaller food pellet sizes but dropped sharply for larger food pellets sizes. Qualitative analysis of limb movements revealed that animals were unable to change their typical movement sequence to obtain the larger pellets. This result indicates that rat skilled reaching is relatively inflexible, supporting the position that it is produced by a complex, relatively fixed neural circuitry. This finding is discussed in relation to the evolution of skilled reaching, the modifications of skilled reaching that are observed after motor cortex and other nervous system injuries, and comparative differences in reaching in rats and primates.

Animals↗
PubMed2005

Impairment of gaze-centered updating of reach targets in bilateral parietal-occipital damaged patients.

Recent studies have suggested that internal updating of visuospatial targets in humans occurs in gaze-centered coordinates and takes place in the parietal and extrastriate cortices. We explored how information for reaching is updated in two patients with bilateral lesions in these areas. Subjects performed two visuomotor tasks: (i) a fixation reaching task, which began with the appearance of one of five fixation positions (varying eye positions) followed by a central reaching target. Subjects reached to the target while fixating on the presented fixation position (relative to gaze the target was always presented in the periphery); and (ii) a saccade reaching task, in which subjects foveated on the central reaching target, then made a saccade to the presented fixation position before reaching to the central target. In both tasks, subjects reached to targets after a 500 or 5000 ms delay. Gaze-centered updating predicts similarities in reaching errors between fixation and saccade trials. Control subjects showed evidence for gaze-centered updating during both 500 and 5000 ms delay conditions. In contrast, patient AT, who had extensive occipital-parietal damage, only showed signs of gaze-centered representation after 5 s. Patient IG, with a more focal lesion in the parietal cortices, showed partial updating in gaze-centered coordinates when reaching with the small memory delay but recovered a complete gaze-centered representation after the longer delay. This suggests that patients with bilateral occipital-parietal lesions may rely on non-gaze-centered frames to store immediate target locations in reaching space but, given enough time, this information may be rerouted to access other gaze-centered motor cortical mechanisms.

Adult↗
PubMed2004

Evidence for both reaching and grasping activity in the medial parieto-occipital cortex of the macaque.

In humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single-unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal cortex, is involved in both components of prehension, the hand transport towards the visual target and the grip formation to secure the grasp. In Experiment 1, neural activity was recorded in V6A while two monkeys performed two instructed-delay reaching tasks (reach-to-point and reach-to-grasp) under controlled conditions in darkness. Fourty-five of 93 tested neurons (48%) were modulated during reach-to-point and 62% (52/84) during reach-to-grasp. In 63% of cells (51/81) neural activity was significantly different between reach-to-point and reach-to-grasp tasks, suggesting that grip formation could influence neural activity. In Experiment 2, two monkeys performed natural reach-to-grasp movements in fully lit environment; V6A neural activity and arm-hand movements were recorded by a digital camcorder and analysed frame-by-frame using a digital video technique. Thirty of the 58 tested neurons (52%) were modulated during natural prehension; about 30% of these neurons (8/30) were modulated only during the last phase of prehension, i.e. during finger flexion around the object to be grasped. This is the first direct demonstration that both reaching and grasping modulate neural activity in the caudal part of the posterior parietal cortex of the macaque. Our work suggests a strict functional homology between human and monkey superior parietal lobule.

Action Potentials↗
PubMed2000

Reaching during virtual rotation: context specific compensations for expected coriolis forces.

Subjects who are in an enclosed chamber rotating at constant velocity feel physically stationary but make errors when pointing to targets. Reaching paths and endpoints are deviated in the direction of the transient inertial Coriolis forces generated by their arm movements. By contrast, reaching movements made during natural, voluntary torso rotation seem to be accurate, and subjects are unaware of the Coriolis forces generated by their movements. This pattern suggests that the motor plan for reaching movements uses a representation of body motion to prepare compensations for impending self-generated accelerative loads on the arm. If so, stationary subjects who are experiencing illusory self-rotation should make reaching errors when pointing to a target. These errors should be in the direction opposite the Coriolis accelerations their arm movements would generate if they were actually rotating. To determine whether such compensations exist, we had subjects in four experiments make visually open-loop reaches to targets while they were experiencing compelling illusory self-rotation and displacement induced by rotation of a complex, natural visual scene. The paths and endpoints of their initial reaching movements were significantly displaced leftward during counterclockwise illusory rotary displacement and rightward during clockwise illusory self-displacement. Subjects reached in a curvilinear path to the wrong place. These reaching errors were opposite in direction to the Coriolis forces that would have been generated by their arm movements during actual torso rotation. The magnitude of path curvature and endpoint errors increased as the speed of illusory self-rotation increased. In successive reaches, movement paths became straighter and endpoints more accurate despite the absence of visual error feedback or tactile feedback about target location. When subjects were again presented a stationary scene, their initial reaches were indistinguishable from pre-exposure baseline, indicating a total absence of aftereffects. These experiments demonstrate that the nervous system automatically compensates in a context-specific fashion for the Coriolis forces associated with reaching movements.

Adaptation, Physiological↗
PubMed1991

Effects of trunk support and target distance on postural adjustments prior to a rapid reaching task by seated subjects.

The purpose of this study was to determine the presence of postural adjustments before a reaching task by seated subjects. Nine seated subjects performed a rapid reaching task to a target placed at shoulder height, 45 degrees to the right of midline. Reach time, timing and magnitude of forces produced by the movement, and onset of deltoid muscle activity were analyzed under supported versus unsupported, and near versus far reach conditions. Reach time was proportional to reach distance. For all reach conditions, initial movement of the center of body mass occurred in a direction toward the target, ie, opposite in direction to reactive forces produced by the accelerating arm. Regardless of support, reactive forces were recorded approximately 30 to 50 msec before arm movement, and represented a greater percentage of body weight, for the far reach conditions. Peak acceleration to the right occurred at proportionately the same time into reach regardless of support or reach distance. Peak acceleration occurred earlier in the supported conditions. This paper provides kinetic evidence of postural adjustments before a rapid reaching task performed by seated subjects.

Acceleration↗
PubMed1999

Lateral reach: a clinical measure of medio-lateral postural stability.

BACKGROUND AND PURPOSE: Medio-lateral postural instability has recently been identified as a risk factor for falls in the elderly community-dwelling population. However, few clinical tests involve challenges to stability limits in the medio-lateral direction. A lateral reach test was thus developed. Preliminary evaluation of the symmetry, accuracy, test-retest repeatability, and construct validity of the lateral reach test was undertaken to ensure its validity and repeatability prior to clinical application. METHOD: Sixty healthy older female subjects (aged 72.5 +/- 5 years) participated in this study which involved two tasks. The first was the clinical test: a maximal lateral reach to the right and left, recorded by a clinical measure (observation of hand excursion) and a laboratory measure (3D analysis of hand marker excursion). The second was the recording of centre of pressure (COP) stability limits in the lateral direction by use of a dual force platform system. Eighteen subjects returned for repeatability testing. RESULTS: No significant differences in the measures were found between the sides. Lateral reach as measured by the clinical measure was significantly (p < 0.05) correlated with both the laboratory measure of reach (r = 0.650) and with COP stability limits (r = 0.331). The clinical measure of reach was not significantly different (p > 0.01) from the laboratory measure. High test-retest repeatability (r > 0.94) was found for all measures. CONCLUSIONS: The clinical lateral reach test was found to be an accurate measure of lateral reach ability. As it was significantly correlated with COP excursion it was deemed a valid indicator of lateral stability limits. In addition, the lateral reach test had high test-retest repeatability and was symmetrical between the sides. These promising results support both it's use where a clinical indicator of medio-lateral postural stability is desired and further investigation of the lateral reach test in clinical populations.

Aged↗
PubMed2003

Adaptation of reach-to-grasp movement in response to force perturbations.

This study examined how reach-to-grasp movements are modified during adaptation to external force perturbations applied on the arm during reach. Specifically, we examined whether the organization of these movements was dependent upon the condition under which the perturbation was applied. In response to an auditory signal, all subjects were asked to reach for a vertical dowel, grasp it between the index finger and thumb, and lift it a short distance off the table. The subjects were instructed to do the task as fast as possible. The perturbation was an elastic load acting on the wrist at an angle of 105 deg lateral to the reaching direction. The condition was modified by changing the predictability with which the perturbation was applied in a given trial. After recording unperturbed control trials, perturbations were applied first on successive trials (predictable perturbations) and then were applied randomly (unpredictable perturbations). In the early predictable perturbation trials, reach path length became longer and reaching duration increased. As more predictable perturbations were applied, the reach path length gradually decreased and became similar to that of control trials. Reaching duration also decreased gradually as the subjects adapted by exerting force against the perturbation. In addition, the amplitude of peak grip aperture during arm transport initially increased in response to repeated perturbations. During the course of learning, it reached its maximum and thereafter slightly decreased. However, it did not return to the normal level. The subjects also adapted to the unpredictable perturbations through changes in both arm transport and grasping components, indicating that they can compensate even when the occurrence of the perturbation cannot be predicted during the inter-trial interval. Throughout random perturbation trials, large grip aperture values were observed, suggesting that a conservative aperture level is set regardless of whether the reaching arm is perturbed or not. In addition, the results of the predictable perturbations showed that the time from movement onset to the onset of grip aperture closure changed as adaptation occurred. However, the spatial location where the onset of finger closure occurred showed minimum changes with perturbation. These data suggest that the onset of finger closure is dependent upon distance to target rather than the temporal relationship of the grasp relative to the transport phase of the movement.

Adaptation, Physiological↗
PubMed2006

The role of kinematic redundancy in adaptation of reaching.

Although important differences exist between learning a new motor skill and adapting a well-learned skill to new environmental constraints, studies of force field adaptation have been used frequently in recent years to identify processes underlying learning. Most of these studies have been of reaching tasks that were each hand position was specified by a unique combination of joint angles. At the same time, evidence has been provided from a variety of tasks that the central nervous system takes advantage of the redundancy available to it when planning and executing functional movements. The current study attempted to determine whether a change in the use of joint motion redundancy is associated with the adaptation process. Both experimental and control subjects performed 160 trials of reaching in each of four adaptation phases, while holding the handle of a robot manipulandum. During the first and last adaptation phases, the robot motors were turned off. During phases 2 and 3 the motors produced a velocity-dependent force field to which experimental subjects had to adapt to regain relatively straight line hand movements during reaching to a target, while the motors remained off for the control group. The uncontrolled manifold (UCM) method was used to partition the variance of planar clavicle-scapular, shoulder, elbow and wrist joint movements into two orthogonal components, one (V(UCM)) that reflected combinations of joint angles that were equivalent with respect to achieving the average hand path and another (V(ORT)) that took the hand away from its average path. There was no change in either variance component for the control group performing 640 non-perturbed reaches across four 'pseudo-adaptation' phases. The experimental group showed adaptation to reaching in the force field that was accompanied initially by an increase in both components of variance, followed by a smaller decrease of V(UCM) than V(ORT) during 320 practice reaches in the force field. After initial re-adaptation to reaching to the null field, V(UCM) was higher in experimental than in control subjects after performing a comparable number of reaches. V(UCM) was also larger in the experimental group after re-adaptation when compared to the 160 null field reaching trials performed prior to initial force field introduction. The results suggest that the central nervous system makes use of kinematic redundancy, or flexibility of motor patterns, to adapt reaching performance to unusual force fields, a fact that has implications for the hypothesis that motor adaptation requires learning of formal models of limb and environmental dynamics.

Adaptation, Physiological↗
PubMed2007

The reach-to-grasp-food task for rats: a rare case of modularity in animal behavior?

Humans and non-human animals make use of sensory hierarchies in "selecting" strategies for solving many cognitive and behavioral tasks. Often, if a preferred type of sensory information is unavailable or is not useful for solving a given task, the animal can switch to a lower-priority strategy, making use of a different class of sensory information. In the case of rats performing a classic reach-to-grasp-food task, however, prior studies indicate that the reaching maneuver may be a fixed action pattern that is guided exclusively by the food's odor plume until the point of contact with the food morsel [Whishaw IQ, Tomie JA. Olfaction directs skilled forelimb reaching in the rat. Behav Brain Res 1989;32(1):11-21; Metz GA, Whishaw IQ. Skilled reaching an action pattern: stability in rat (Rattus norvegicus) grasping movements as a function of changing food pellet size. Behav Brain Res 2000;116(2):111-22; Whishaw IQ. Did a change in sensory control of skilled movements stimulate the evolution of the primate frontal cortex? Behav Brain Res 2003;146(1/2):31-41]. We sought to confirm and extend these findings in several ways. In Experiment 1, using a GO/NO-GO variant of the classic task, we demonstrated that rats used the GO target's odor both to trigger and guide their reaches. In Experiment 2, we showed that rats deprived of (a) vision, (b) object-recognizing rostral whiskers and forearm sinus hairs, or (c) both, displayed no deficits in triggering and guiding their reaches. Finally, in a third experiment in which the GO target's location varied randomly across trials and only olfactory cues were available, we demonstrated that rats could determine the spatial endpoint of their reach without any loss of accuracy. Combined with results from a prior study in which bulbectomized rats never developed a new, successful reaching strategy despite extensive post-operative training [Whishaw IQ, Tomie JA. Olfaction directs skilled forelimb reaching in the rat. Behav Brain Res 1989;32(1):11-21], these results indicate that rats do not have a sensory hierarchy for solving the reach-to-grasp-food task, but rather, are guided by olfaction alone until their paw contacts the food morsel.

Animals↗
PubMed2005

Frontal cortical areas of the monkey brain engaged in reaching behavior: a (14)C-deoxyglucose imaging study.

The ((14)C)-deoxyglucose method was employed to study whether different areas of the primate frontal lobe are involved in different aspects of reaching behavior. To this end, we mapped the functional activity of the frontal motor cortical areas in three monkeys performing reaching movements with one forelimb. The first monkey had to capture a peripheral visual target with a saccade and a forelimb-reach together, the second monkey had to reach a peripheral visual target with one forelimb while fixating a central target, and the third one had to reach a peripheral memorized target with one forelimb in complete darkness while the eyes maintained a straight ahead direction. The extent and intensity of activations were compared to those of three respective control monkeys: a saccade-control, a fixation-control, and a dark-control. The primary somatosensory (S1) and motor (F1) forelimb representation, the S1- and F1-trunk representation, the F2-dimple region, areas F3-forelimb, F4, F5-bank of arcuate sulcus, F7-ridge, the dorsal bank of cingulate sulcus, and 24 c were activated in all reaching monkeys regardless of accompanying visual stimulation and oculomotor behavior. Interestingly, the S1-forelimb activation in the monkey reaching to memorized targets in complete darkness was more pronounced than that in the monkeys reaching to visual targets in the light, indicating that increased somatosensory processing compensates for the absence of visual feedback. On the other hand, areas F2-periarcuate, F5-convexity, F6, and 23 were preferentially activated by reaching to visual targets and remained unaffected during reaching to memorized targets when no visual feedback was available.

Animals↗
PubMed2002

Impairment of pronation, supination, and body co-ordination in reach-to-grasp tasks in human Parkinson's disease (PD) reveals homology to deficits in animal models.

Animal (monkey, rat, mouse) models are widely used to investigate degenerative processes and potential therapeutic treatments for human Parkinson's disease (PD). One task that has proved useful in these investigations is a reach-to-grasp task (skilled reaching) in which an animal reaches for a piece of food that it then consumes. Rats with extensive unilateral Dopamine depletions are impaired in using the contralateral limb. The qualitative features of posture, lifting and advancing the limb, pronating the paw to grasp food, and in withdrawing and supinating the paw to place the food in the mouth are impaired, as is reaching success. Humans with PD are often described as having poor manual dexterity that worsens as the disease progresses. As there have been no detailed comparisons of reaching movements in the animal models and in PD subjects, the following descriptive analysis was performed. Ten subjects with PD, eight age matched controls and 14 young normal subjects were studied as they used a natural movement of reaching for a small piece of food that they then placed in the mouth to eat. The reaching movements were described using Eshkol-Wachman Movement Notation (EWMN), supplemented with kinematic analyses. From this description, a 21-point rating scale was devised to describe the component movements of the reach. Movements included: orienting the head and eyes to the target, adjusting posture, lifting the hand, shaping and aiming the digits to the target, pronating the hand to grasping the food with a pincer grip, lifting and supinating the hand to transporting the food to the mouth, and further supinating the hand and opening the digits to place food in the mouth, and finally returning the hand to the starting position. Analysis indicated that most aspects of the reaching movements of the PD subjects were significantly different relative to both young control subjects and old control subjects. As compared to the control groups, postural and reaching components of the movements were fragmented, movements were achieved using more proximal segments of the body, and rotatory movements of the hand were limited. The PD subjects did use a pincer grasp to obtain the food, but the grasp was less independent of other digit movements than was observed in the control subjects. These results are discussed in terms of a homology to impairments displayed animal models of PD.

Adult↗
PubMed2001

Dissociable contributions of the orbitofrontal and lateral prefrontal cortex of the marmoset to performance on a detour reaching task.

To gain insight into the nature and neural specificity of the relationship between simple problem solving, inhibitory control and prefrontal cortex, comparison of the effects of excitotoxic lesions of the orbitofrontal and lateral prefrontal cortex were examined on the performance of common marmosets on a detour reaching task. Monkeys were required to inhibit reaching directly for food reward in a transparent box and instead make a detour reach around to the side of the box either having had (i) no prior experience on the task (experiment 1) or (ii) previous experience in reaching around the sides of an opaque box (experiment 2). Whilst monkeys with orbitofrontal lesions had difficulty in inhibiting direct reaches to visible food reward (experiment 1), they could resist this prepotent response tendency following extensive prior experience of detour reaching with an opaque box (experiment 2). In marked contrast, monkeys with lateral prefrontal lesions exhibited no difficulty in inhibiting reaching to visible food reward or acquiring detour reaching per se (experiment 1). However, having been given the opportunity to acquire an efficient detour reaching strategy to hidden food reward these lateral prefrontal lesioned monkeys were impaired at transferring this strategy to the new context in which the food reward was made visible (experiment 2). This double dissociation between the effects of orbitofrontal and lateral prefrontal lesions on detour reaching provides evidence for a clear distinction in the level of control over responding exerted by the orbitofrontal and lateral prefrontal cortex, consistent with hierarchical ordering of response control processes within prefrontal cortex.

Animals↗
PubMed2002

Alterations in reaching after stroke and their relation to movement direction and impairment severity.

OBJECTIVES: To examine the effects of stroke severity and target location on reaching (1) to identify regions in space that are difficult to reach, (2) to determine whether specific alterations in reaching are associated with particular clinical impairment levels, and (3) to characterize relationships between reaching alterations. DESIGN: Participants reached toward a screen of 75 targets spanning an approximate range from +/-90 degrees side to side and from waist to head. SETTING: Rehabilitation research center. PARTICIPANTS: Sixteen chronic stroke patients with a wide range in residual arm function and 4 control subjects. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Chedoke-McMaster Stroke Arm Assessment, distance, velocity, smoothness, straightness, and direction of the hand path during each reach. Hand position trajectories were recorded with an electromagnetic sensor. RESULTS: Reaches performed with the impaired arms showed significant degradation in all performance measures. Although only modestly dependent on the target location, these features correlated strongly with impairment level, as well as with each other. Reaching distance showed the strongest correlations with the other parameters. CONCLUSIONS: Stroke alters a broad array of features of reaching, yet largely the same degree of movement control is preserved across a range of target locations. The only consistently problematic task is to reach far out from the torso, independent of the movement direction. Thus, active range of motion (AROM), rather than control over a specific subset of movement directions, is a logical focus for therapy. In addition, measuring AROM is a simple clinical measure that yields much information.

Adult↗
PubMedDate not supplied

Reach profiles of men and women 65 to 89 years of age.

Reach and anthropometric data were collected on a heterogeneous group of subjects 65 to 89 years of age. The purpose of this pilot study was to determine whether the process of aging has an effect on the ability to reach. Analysis of the data collected showed that age-related changes had an effect on reaching in the vertical plane, especially for the male subjects. The vertical reach fingertip and grip (VRT and VRG) measurements for men 85 to 89 years old were significantly lower than those for all other age groups, indicating that reaching abilities decrease between the ages of 80 and 85 years. The results for women were not as conclusive, but additional analysis showed a decline in VRT and VRG in terms of stature. Horizontal reach measurements showed no age-related effect in the analysis. An attempt was made to compare reach data collected here with those collected in previous studies. However, comparisons of the reach data were limited as a result of differences in reaching activities and measuring techniques in other studies. Anthropometric measurements of this older cohort were compared with those of a younger population. It was noted that older subjects had smaller anthropometric measurements than their younger cohorts. Differences in body size and reach, whether statistically significant or not, need to be considered when designing living environments and appliances for the aged.

Aged↗
PubMed1992

Functional reach: predictive validity in a sample of elderly male veterans.

A new measure of balance, functional reach, has been recently developed. Functional reach is the maximal distance one can reach forward beyond arm's length while maintaining a fixed base of support in the standing position. Reliability, criterion, and concurrent construct validity of functional reach have been established. The purpose of this study was to assess the predictive validity of functional reach in identifying elderly subjects at risk for recurrent falls. Two hundred and seventeen elderly, community-dwelling male veterans (aged 70-104) underwent baseline screening and were followed for 6 months to monitor falls. Subjects with two or more falls during the 6-month follow-up were classified as recurrent fallers. Logistic regression reveals that if individuals were unable to reach, the adjusted odds ratio (OR) of having two falls was 8.07 (2.8-23.71); if their reach was less than or equal to 6 inches the OR was 4.02 (1.84-8.77); and if reach was greater than 6 inches but less than 10 inches the OR was 2.00 (1.35-2.98). The association between functional reach and recurrent falls was not confounded by age, depression, or cognition. We conclude that functional reach is a simple and easy-to-use clinical measure that has predictive validity in identifying recurrent falls.

Accidental Falls↗