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PubMed2005

Does arm length indicate cognitive and functional reserve?

BACKGROUND: This study aimed to examine whether arm length and height were associated with cognitive and functional abilities. METHODS: Screening interviews were conducted in 235 community dwelling individuals aged 65 and over. The assessment scales included the Korean version of modified Mini-Mental State Examination (K-mMMSE) for cognition, and the Korean Instrumental Activities of Daily Living (K-IADL) for functional ability. All the participants were examined clinically and a diagnosis of dementia was ascertained. Anthropometric measurements included total arm span and height. RESULTS: Both arm length and height correlated significantly with the cognitive and functional scales. In the multivariate regression models, their associations were significant, independent of age, sex, education, and other variables. Shorter arm length was also significantly associated with dementia; while, height lost significance after an adjustment for the potential confounders. CONCLUSIONS: Arm length and height could indicate cognitive and functional ability. Arm length, which was known to be less prone to degenerative processes, might be more stable as an indicator for cognitive and functional reserve capacity than height.

Activities of Daily Living↗
PubMed1990

On the cost functions for the control of the human arm movement.

The aim of our investigation is to understand the mechanisms which control the movement of the human arm. The arm is here considered as a redundant system: the shoulder, elbow and wrist joints, which provide three degrees of freedom, combine to move the hand in a horizontal plane, i.e. a two dimensional space. Thus the system has one extra degree of freedom. Earlier investigations of the static situation led to the hypothesis that independent cost functions were attached to each of the three joints and that the configuration chosen for a given target position is that which provides the minimum total cost (Cruse 1986). The aim of the current investigation was to look for measurable values corresponding to the hypothetical cost functions. Experiments using pointers of different lengths attached to the hand showed that the strategy in choosing the joint angles are independent of the limb length. The muscle force necessary to reach a given angle is increased by a spring mounted across a joint. In this situation the angles of the loaded joint are changed for a given target point to give way to the force effect. This leads to the conclusion that the hypothetical cost functions are not independent of the physiological costs necessary to hold the joint at a given angle. The cost functions seem to depend on joint angle and on the force which is necessary to hold the joint in a given position. Cost functions are measured by psychophysical methods. The results show U-shaped curves which can be approximated by parabolas. The position of minimum cost (maximum comfort) for one joint showed no or weak dependency on the angles of the other joints. For each subject these "psychophysical" cost functions are compared with the hypothetical cost functions. The comparison showed reasonable agreement. This supports the assumption that the psychophysically measured "comfort functions" provide a measure for the hypothetical cost functions postulated to explain the targeting movements. Targeting experiments using a four joint arm which has two extra degrees of freedom showed a much larger scatter compared to the three joint arm. Nevertheless, the results still conform to the hypothesis that also in this case the minimum cost principle is applied to solve the redundancy problem. As the cost function for the whole arm shows a large minimum valley, quite a large range of arm positions is possible of about equal total costs.(ABSTRACT TRUNCATED AT 400 WORDS)

Arm↗
PubMed1995

Task dependence of primate arm postures.

We studied the relations between arm posture and hand location as monkeys performed tasks involving three-dimensional arm movements. Two specific questions were addressed: how reliable are these relations from trial to trial and from day to day, and are the arm postures dictated only by the location of the hand or are the postures also dependent on the task being performed? Based on the variable errors in linear regressions, we found that monkeys performed the tasks in a very stereotypic fashion from trial-to-trial: for a given monkey and task, knowing the position of the hand was sufficient to determine the posture of the arm. These relations did not change from day to day; the relation between hand location and posture was stable over the course of the experiments. In some of the tasks, the postures employed by the monkeys were strikingly similar to those observed in human psychophysical studies. The relations between hand location and arm posture exhibited a large degree of task dependence. Changing the required orientation of the hand resulted in changes in the arm posture.

Animals↗
PubMed1990

Neurons related to reaching-grasping arm movements in the rostral part of area 6 (area 6a beta).

Single neurons were recorded from the rostral part of the agranular frontal cortex (area 6a beta) in awake, partially restrained macaque monkeys. In the medialmost and mesial sectors of this area, rostral to the supplementary motor area, neurons were found which were activated during arm reaching-grasping movements. These neurons ("reaching-grasping neurons") did not appear to be influenced by how the objects were grasped nor, with some exceptions, by where they were located. Their activity changed largely prior to the arm movement and continued until the end of it. The premovement modulation (excitatory or inhibitory) could start with stimulus presentation, with the saccade triggered by the stimulus or after stimulus fixation. The distance of the stimulus from the monkey was an important variable for activating many neurons. About half of the recorded neurons showed a modulation of the same sign during movement and premovement period. The other half showed an increase/decrease in activity which was of the opposite sign during movement and premovement period or part of it. In this last case the discharge changes were of the same sign when the stimulus was close to the monkey and when the monkey moved its arm to reach the objects, whereas they were of opposite sign when the stimulus was outside the animal's reach. Microstimulation of area 6a beta and the reconstruction of the locations of eye movement and arm movement related cells showed that the arm field was located more medially (and mesially) than the eye field described by Schlag and Schlag-Rey (1987). It is suggested that, unlike inferior area 6, which is mostly involved in selection of effectors on the basis of the physical properties of the objects and their spatial location (Rizzolatti and Gentilucci 1988), area 6a beta plays a role in the preparation of reaching-grasping arm movements and in their release when the appropriate conditions are set.

Animals↗
PubMed1975

Effects of training on maximal working capacity and haemodynamic response during arm and leg-exercise in a group of paddlers.

Maximal oxygen uptake and circulatory adaptation to work with legs and arms were studied in a group of 5 paddlers members of the Belgian national squad and a control-group of 9 trained subjects. The results showed that the specific armtraining of paddlers induced changes in the arm-to-leg ration of physiological parameters at submaximal and maximal work. In the group of paddlers maximal oxygen intake and workload during arm-exercise averaged respectively 88.6% and 80.3% of the scores obtained with leg-exercise. In the control group the arm to leg ratio varied between 81.2% and 65.2%. At a submaximal load of 100 W the difference in heartfrequency was 21 beats/min in the canoe group and 35 beats/min in the control group. Oxygen consumption and ventilation during work with the arms was lower in the group of paddlers. The data of our study suggest that the specific training of paddlers do result in a effect on the haemodynamic adaptations to arm work.

Adaptation, Physiological↗
PubMed2000

Derivation of extracellular fluid volume fraction and equivalent dielectric constant of the cell membrane from dielectric properties of the human body. Part 1: Incorporation of fat tissue into cell suspension model in the arm.

The non-invasive characterisation of cell pathophysiology is clinically important. A cell suspension model is applied to derive the extracellular fluid (ECF) volume fraction and the equivalent dielectric constant of the cell membrane epsilon m from the dielectric properties of human arms. Frequency-dependent dielectric constants and electrical conductivities of arms are obtained from 35 surgical patients over a frequency range of 5-1000 kHz. The cell suspension model is applied to fit the data using a complex non-linear least-squares method. The arms show typical dielectric dispersions, although the cell suspension model yields a poor fitting in dielectric constants at lower frequencies and electrical conductivities at higher frequencies. In contrast, a new cell suspension model, taking into account the fat tissue component, remarkably improves the overall fitting performance, allowing estimation of the volume fractions of ECF (0.34 +/- 0.05) and fat tissue (0.16 +/- 0.04) and the equivalent epsilon m (23 +/- 9). The resulting estimates of the volume fraction of fat tissue are in good correlation with arm skinfold thickness (fat volume fraction of arm = 2.42 x 10(-3) x arm skinfold thickness (mm) + 0.099, R = 0.756, p < 0.0001). Therefore it is concluded that the newly derived cell suspension model is well suited for the description of the dielectric properties of human tissues and thus the derivation of the ECF volume fraction and equivalent epsilon m.

Adipose Tissue↗
PubMed1998

Are arm span measurements useful in the prediction of osteoporosis in postmenopausal women?

A consensus report on osteoporosis in The Netherlands recommends general practitioners to use an arm span-height difference of at least 3 cm as one of the criteria for suspecting osteoporosis. In this study it was investigated how well this criterion discriminates between patients with established osteoporosis and controls in a group of postmenopausal women. When the Dutch general practitioners criterion of arm span-height difference exceeding 3 cm was applied in a logistic regression analysis to predict the probability of having osteoporosis, a resultant sensitivity of 58% and a specificity of 56% were found. In order to improve the predicted probability of osteoporosis, two more predictors in addition to the arm span-height difference were introduced in the logistic regression model. The first additional predictor related to information whether subject's age was below or above 70 years, and the second whether the arm span was below or above 160 cm. All three predictors appeared to be highly significant. It was shown that the predicted probability of osteoporosis by this model could be considerably improved when the age category and the arm span category were also taken into account, leading to a sensitivity of 81% while the specificity amounts to 64%. This seems quite satisfactory for such a simple method and clearly improves on the original single criterion of arm span-height difference.

Age Factors↗
PubMed2001

Functional status of the paretic arm affects the loss of bone mineral in the proximal humerus after stroke: a 1-year prospective study.

The aim of this study was to evaluate the effect of decreased arm function after stroke on bone mineral density (BMD) in the proximal humerus. Twenty-five patients were evaluated 1 week after acute stroke and reevaluated 2 months, 7 months, and 1 year after the stroke. BMD of the proximal humerus was measured and the functional status of the paretic arm was assessed. Within 1 year the BMD decreased significantly in the proximal humerus at the paretic side. No significant BMD change was found at the nonparetic side. Patients with an initial completely paralyzed arm lost 27% (P <0.001), those with severe to moderate paresis lost 11% (P <0.001), and patients with minor or no paresis had no significant bone loss in the proximal humerus at the paretic side after 1 year. A statistically significant trend with initial arm function was found both 7 months and 1 year after the stroke at the paretic side (P <0.01). Patients who were paralyzed or had severe to moderate paresis both at inclusion and after 1 year had a larger 1-year bone loss in the proximal humerus than the patients who recovered and these who had only minor impairment throughout the study, 25%, 8%, and 5%, respectively (P-value for linear trend <0.001). We conclude that during the first year after stroke bone mineral is lost in the proximal humerus of the paretic arm, but that the loss depends on the initial degree of paresis. The loss may be prevented if arm function is regained.

Aged↗
PubMed2003

Body segment lengths and arm span in healthy men and women and patients with vertebral fractures.

We studied 112 healthy men and 261 healthy women aged 18-92 years, and 34 men and 73 postmenopausal women with vertebral fractures aged 45-90 years to determine (i) whether patients with vertebral fractures have shorter stature before fracture, and (ii) whether the difference between arm span and standing or sitting height can be used to identify patients with fractures. Arm span was measured by using a calibrated extended ruler. Standing height, sitting height and leg length were measured by using a Holtain stadiometer. The results were expressed in absolute term and standard deviation (SD) or Z-scores (mean+/-SEM). Advancing age was associated with decreased sitting height (r=-0.37 to -0.41, both P<0.01) and a trend towards decreased arm span (r=-0.12 to -0.17, P=0.06 and 0.07) in healthy men and women; leg length was independent of age in both sexes (r=-0.09 to -0.12, NS). In patients with vertebral fractures, sitting height was reduced in women (Z=-0.83+/-0.14 SD, P<0.01) and men (Z=-1.37+/-0.21 SD, P<0.01) but only the women had reduced leg length (Z=-0.46+/-0.15 SD, P<0.01) and arm span (Z=-0.76+/-0.15 SD, P<0.01). Univariate and multivariate analyses suggest that the predictive ability of the difference between arm span and standing or sitting height to identify patients with vertebral fractures is limited. We concluded that women, not men, with vertebral fractures may come from a population with short stature. The difference between arm span and standing or sitting height cannot be used to predict vertebral fracture risk.

Adolescent↗
PubMed2002

Adaptations in arm movements for added mass to wrist or ankle during walking.

The aim of the present study was to answer the question whether adaptations to local perturbations are restricted to the perturbed limb or whether they induce a reorganization of all co-moving limbs. Specifically, we studied the adaptations in arm movements to mass perturbations in seven healthy adults during walking on a treadmill. Four different perturbation conditions were employed in random order (no perturbation, mass added to both wrists, to the right wrist, and to the right ankle). During each experimental condition ten different belt speeds (0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0 km/h) were successively offered, while the arm movements and the electromyographic activity of the musculus deltoid posterior and anterior were measured. The results indicated that cadence was not affected by adding mass to the wrist or ankle. However, adding mass to a wrist not only resulted in an increase in muscle activity and a decrease of movement amplitude of the perturbed arm, but also in alterations in the non-perturbed arm. Notably, adding mass to one ankle induced adaptive changes in both arms, in that both muscle activity and arm movement increased. The present results indicate that during walking the loading of one of the limbs induces a general reorganization, involving all participating bodily segments, presumably to maintain balance while providing rhythm constancy.

Adaptation, Physiological↗
PubMed2003

Hemiparetic stroke impairs anticipatory control of arm movement.

Internal models are sensory motor mappings used by the nervous system to anticipate the force requirements of movement tasks. The ability to use internal models likely underlies the development of skillful control of the arm throughout life. It is currently unknown to what extent individuals with hemiparetic stroke can form and implement such internal models. To examine this issue, we measured whether such individuals could learn to anticipate forces applied to their arms by a lightweight robotic device as they practiced reaching to a target. Thirteen subjects with post-stroke hemiparesis were tested. Forces were applied to the arm, which curved the hand path in either the medial or lateral direction, as the subjects reached repeatedly towards a target located in front of them at their workspace boundary. The subjects exhibited a decreased ability to adapt to the perturbing forces with their hemiparetic arms. That is, they did not straighten their reaching path as well, compared to their ipsilesional arms, and they exhibited smaller aftereffects when the perturbing force was unexpectedly removed. The ability to adapt to the force improved significantly with decreasing impairment severity, as quantified using both clinical scales and quantitative strength measurements. Some subjects with strength reductions as severe as 60% were able to adapt to the fields, generating significant aftereffects. We conclude that hemiparetic stroke impairs the ability to implement internal models used for anticipatory control of arm movement, although even some severely weakened subjects retain at least a partial ability to form and use internal models. Finding ways to fully restore this adaptive ability, or to make use of what adaptive ability remains during rehabilitation, is an important goal for improving functional motor recovery.

Adult↗
PubMed2003

Vestibular contribution to combined arm and trunk motion.

Recent studies have shown that the hand-pointing movements within arm's reach remain invariant whether the trunk is recruited or not or its motion is unexpectedly prevented. This suggests the presence of compensatory arm-trunk coordination minimizing the deflections of the hand from the intended trajectory. It has been postulated that vestibular signals elicited by the trunk motion and transmitted to the arm motor system play a major role in the compensation. One prediction of this hypothesis is that vestibular stimulation should influence arm posture and movement during reaching. It has been demonstrated that galvanic vestibular stimulation (GVS) can influence the direction of pointing movements when body motion is restrained. In the present study, we analyzed the effects of GVS on trunk-assisted pointing movements. Subjects either moved the hand to a target or maintained a steady-state posture near the target, while moving the trunk forward with the eyes closed. When GVS was applied, the final position of the hand was deviated in the lateral and sagittal direction in both tasks. This was the result of two independent effects: a deviation of the trunk trajectory and a modification of the arm position relative to the trunk. Thus, the vestibular system might be directly involved not only in the control of trunk motion but also in the arm-trunk coordination during trunk-assisted reaching movements.

Adult↗
PubMed2004

Feedforward activity of the cervical flexor muscles during voluntary arm movements is delayed in chronic neck pain.

The objective of this study was to compare onset of deep and superficial cervical flexor muscle activity during rapid, unilateral arm movements between ten patients with chronic neck pain and 12 control subjects. Deep cervical flexor (DCF) electromyographic activity (EMG) was recorded with custom electrodes inserted via the nose and fixed by suction to the posterior mucosa of the oropharynx. Surface electrodes were placed over the sternocleidomastoid (SCM) and anterior scalene (AS) muscles. While standing, subjects flexed and extended the right arm in response to a visual stimulus. For the control group, activation of DCF, SCM and AS muscles occurred less than 50 ms after the onset of deltoid activity, which is consistent with feedforward control of the neck during arm flexion and extension. When subjects with a history of neck pain flexed the arm, the onsets of DCF and contralateral SCM and AS muscles were significantly delayed ( p<0.05). It is concluded that the delay in neck muscle activity associated with movement of the arm in patients with neck pain indicates a significant deficit in the automatic feedforward control of the cervical spine. As the deep cervical muscles are fundamentally important for support of the cervical lordosis and the cervical joints, change in the feedforward response may leave the cervical spine vulnerable to reactive forces from arm movement.

Adult↗
PubMed1999

The oculomanual coordination control center takes into account the mechanical properties of the arm.

When the eyes and arm are involved in a tracking task, the characteristics of each system differ from those observed when they act alone: smooth pursuit (SP) latency decreases from 130 ms in external target tracking tasks to 0 ms in self-moved target tracking tasks. Two models have been proposed to explain this coordination. The common command model suggests that the same command be addressed to the two sensorimotor systems, which are otherwise organized in parallel, while the coordination control model proposes that coordination is due to a mutual exchange of information between the motor systems. In both cases, the interaction should take into account the dynamic differences between the two systems. However, the nature of the adaptation depends on the model. During self-moved target tracking a perturbation was applied to the arm through the use of an electromagnetic brake. A randomized perturbation of the arm increased the arm motor reaction time without affecting SP. In contrast, a constant perturbation produced an adaptation of the coordination control characterized by a decrease in arm latency and an increase in SP latency relative to motor command. This brought the arm-to-SP latency back to 0 ms. These results support the coordination control model.

Adaptation, Physiological↗
PubMed2004

The middle collateral artery: anatomic basis for the "extreme" lateral arm flap.

The vascularization of the posterolateral area of the arm is supplied by the terminal branches of the deep brachial artery [middle collateral artery (MCA) and posterior radial collateral artery]. Their anatomy has been a field of confusion for a long time. An extended lateral arm flap, named the "extreme" lateral arm flap, supplied by these branches and dissected as a retrograde island flap has been proposed as an alternative for large compound defects of the distal forearm. We carried out an extensive anatomic study of the "extreme" lateral arm flap on 69 upper limbs: 54 fresh injected with colored latex, 10 embalmed and 5 radiographed after Micropaque injection. Two origin levels of the MCA were found: a proximal one (37%) above the radial groove, and a distal one (63%) at the level of the groove. The deep brachial artery always bifurcated after the origin of the MCA into a posterior radial collateral artery (PRCA) and anterior radial collateral artery (ARCA). Indeed in our dissections, after the origin of the MCA from the deep brachial artery, there was always a common trunk named the radial collateral artery (RCA) which bifurcated into the ARCA and PRCA. In all dissected arms we always found the MCA anastomosed in a transverse pattern with the inferior ulnar collateral artery (IUCA), contributing to the anastomotic circle of the elbow. This circle represents the unique vascularization source of the reverse "extreme" lateral arm flap.

Aged↗
PubMed2002

Oxygen uptake and heart rate kinetics during heavy exercise: a comparison between arm cranking and leg cycling.

This study examined the oxygen uptake (VO(2)) and heart rate (HR) kinetics during arm cranking and leg cycling at work rates above the anaerobic threshold (AT). Ten untrained male subjects [21.6 (1.3) years] completed two 7 min 15 s constant-load arm cranking and two leg cycling tests at a power output halfway between the mode-specific AT and peak VO(2). The time constants for phase II VO(2) (tau) and HR (tau) kinetics were determined by fitting a monoexponential curve from the end of phase I until 3 min of exercise. VO(2) tau and HR tau values were significantly (P < 0.001) slower in arm cranking [VO(2) tau = 66.4 (3.0) s; HR tau = 74.7 (4.4) s] than in leg cycling [VO(2) tau = 42.0 (1.9) s; HR tau = 55.6 (3.5) s]. The VO(2) slow component (VO(2SC)) accounted for a significantly (P < 0.001) greater percentage of the total exercise response during arm cranking [23.8 (1.6)%] than during leg cycling [14.2 (1.5)%]. The greater relative VO(2SC) and the slower VO(2) tau with arm exercise are consistent with a greater recruitment of metabolically inefficient type II muscle fibres during arm cranking than during leg cycling.

Adult↗
PubMed2003

Limitation of muscle deoxygenation in the triceps during incremental arm cranking in women.

The present study investigated the difference in oxygen kinetics in the exercising muscle between arm cranking and leg cycling in women. Twenty-seven females completed incremental arm cranking and leg cycling tests on separate days. During each exercise, spatially resolved near-infrared spectroscopy was used to measure changes in the tissue oxygen saturation ( SO(2)), oxygenated (oxy-) hemoglobin and/or myoglobin (Hb/Mb), deoxygenated (deoxy-) Hb/Mb, and total Hb/Mb in the triceps during arm cranking and in the vastus lateralis during leg cycling. During arm cranking, there was a rapid increase in the respiratory exchange ratio and a lower ventilatory threshold compared to leg cycling, which confirmed accelerated anaerobic glycolysis in this mode of exercise. During leg cycling, SO(2) remained decreased near to or until approaching peak oxygen uptake (VO(2peak)). During arm cranking, however, the decrease in oxy-Hb/Mb and increase in deoxy-Hb/Mb stopped at the middle of VO(2peak) (mean 51.4%), consequently resulting in a leveling off in the SO(2 )decrease, although total Hb/Mb continued to increase. These results might suggest that the oxygen demand in the triceps attained the maximum at that intensity, despite an adequate oxygen supply during arm cranking.

Adolescent↗
PubMed1997

Cardiorespiratory and subjective responses to prolonged arm and leg exercise in healthy young and older men.

Ten young (aged 23-30 years) and nine older (aged 54-59 years) healthy men with a similar size of limb muscle mass performed arm crank and leg cycle exercise for 30 min at relative exercise intensities of 50% and 75% of maximal oxygen uptake for the corresponding muscle group. In the tests, heart rate, blood pressure, gas exchange variables, rating of perceived exertion and blood lactate concentration were measured. The limb muscle mass was determined by anthropometric measurements. At the 75% target exercise level, four of the older men and two of the young men could not complete the arm-cranking test, and one of the older men and two of the young men could not complete the leg-cycle test. During arm-cranking the absolute exercise intensity was similar for the young and older men because of similar maximal values during arm-cranking. But during leg-cycling the absolute exercise intensity was higher for the young men than for the older men due to the difference in corresponding maximal values. During arm-cranking there were no significant differences in the physiological responses between the age groups except that a higher ventilatory response was noted among the older compared to the young men. During leg-cycling the heart rate values were higher among the young compared to the older men. But, when the heart rate values were expressed as a percentage of maximal heart rate in the corresponding maximal tests, no significant differences between the age groups were found. The results indicated that 30-min of arm or leg exercise at the same relative submaximal exercise intensity produces a similar degree of physiological strain in healthy older compared to young men. During armcranking, the young and the older men exercised at the same external intensity, indicating a similar ability to perform prolonged excercise using smaller muscle groups expressed both in absolute and relative terms.

Adult↗