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Ventilatory responses at the onset of passive movement and voluntary exercise with arms and legs.

This study was undertaken to elucidate whether phase I appeared at the onset of voluntary and passive arm movements and to compare these results with those of similar leg movements. Instead of the conventional cranking exercise, seven male subjects performed alternately flexion-relaxation of both arms, extension-relaxation of both legs, and combined arm and leg exercise at the rate of about 60 min-1 for four breaths in a sitting position. Similar movements were accomplished passively by the experimenters. In all experiments, minute ventilation increased rapidly within the first breath after the onset of exercise. The difference of ventilation (delta value) between the mean of the first two breaths at the onset of voluntary exercise and that of five breaths during rest was significantly (P < 0.05) greater in arm (7.75 l min-1) than in leg (5.19 l min-1). Passive movement showed a similar tendency. Arm delta ventilation correlated highly (r = 0.74-0.91) with leg delta ventilation and the slope of the regression lines was about 1.2. Heart rate increased abruptly while cardiac output did not always increase rapidly at the onset of locomotion. Oxygen uptake in the voluntary leg exercise continued for 3 min was slightly but nonsignificantly higher than in the arm exercise, indicating the equality of the exercise intensity. In conclusion, ventilatory responses at the onset of the arm exercise are larger than those of the leg in both voluntary and passive conditions regardless of the muscle mass, suggesting the different neurogenic mechanism between arm and leg.

Adult↗

Power output for wheelchair driving on a treadmill compared with arm crank ergometry.

OBJECTIVES: The limiting factors with regard to power output available for wheelchair ambulation have not been identified. The aim of the present study was to correlate power output during wheelchair driving with (i) power output and oxygen uptake during arm crank ergometry and (ii) arm muscle strength. METHODS: Eleven disabled men were examined for maximal power output (POmax) during wheelchair driving on a treadmill and during arm crank ergometry. Oxygen uptake (VO2) was recorded at submaximal and maximal arm crank ergometry in all men and during submaximal wheelchair driving on a treadmill in four men. Power output during wheelchair driving on a treadmill was measured. Static and dynamic elbow muscle strength was measured isokinetically. RESULTS: POmax was significantly lower (P < 0.001) for wheelchair driving (109 (31) W; mean (SD)) than for arm ergometry (163 (49) W). There was a significant correlation between POmax for arm crank ergometry and wheelchair driving (r = 0.73). There was no correlation between POmax and elbow strength. The mechanical efficiency was constant for the different levels on the arm crank ergometry test. The submaximal testing showed a consistently lower mechanical efficiency for wheelchair driving than for arm crank ergometry. CONCLUSIONS: It is suggested that the lower level of power output for wheelchair driving is fully explained by the lower mechanical efficiency. Any improvement in power output available for ambulation must be based on wheelchair ergonomics.

Adult↗

Distal versus proximal arm tremor in multiple sclerosis assessed by visually guided tracking tasks.

OBJECTIVES: To compare action tremor (AT) during manual tracking in normal subjects and patients with multiple sclerosis with tremor (MS-tremor group) and without tremor (MS-no tremor group), and to differentiate tremor occurring predominantly around the distal joint from that involving the proximal joints of the arm. METHODS: Subjects performed both a visually guided ramp tracking task using wrist flexion/extension and a whole arm circle tracking task using shoulder movement. Action tremor at the wrist or shoulder was computed as the SD of the tracking velocity. The ratio of wrist:arm tremor was then calculated to differentiate distal from proximal tremor in the tested arm. Frequency spectra of the records were also examined. RESULTS: During wrist tracking, AT in patients with multiple sclerosis contained a major frequency component at 4-5 Hz; the frequency was slightly lower during whole arm tracking. The ratio of wrist:arm tremor was significantly higher in the MS-tremor group. Of 12 tested arms, eight had tremor significantly weighted towards the distal joint, only one towards the proximal joint, and three had a ratio inside the control range. CONCLUSIONS: AT in the arms of patients with multiple sclerosis can be effectively differentiated into proximal or distal using these two different tracking tasks. Despite the variability of the effects of multiple sclerosis, most of the AT was distal rather than proximal in this group of patients. Possibly conduction block along the corticocerebellocortical pathways caused this distal tremor.

Adult↗

Maximal oxygen uptake during exercise with various combinations of arm and leg work.

Oxygen uptake (VO2) was determined in 10 males during the following types of maximal exercise (work time: about 5 min): uphill running, bicycling, arm work (cranking), and combined arm work and bicycling (A + L). The A + L exercise was performed in four different ways, the arms doing 10%, 20%, 30%, or 40% of the same total rate of work; and also with the maximal bicycle work load plus either maximal or submaximal arm work. VO2 was the same in running as in all types of A + L exercise, except when the arm work load was 10% and 40% of the total rate of work, where VO2 was 2.5% (P less than 0.05) and 9.4% (P less than 0.001) lower, respectively. Bicycle VO2 was lower than VO2 in running but equal to A + L VO2 when arm work intensity was 40% of the total rate of work. It is concluded that VO2 during maximal exercise a) to a certain extent depends on the exercising muscle mass, b) is lower than the oxygen-consuming potential of the muscles involved in A + L exercise, and c) in A + L exercise is influenced by the ratio of arm work to total rate of work and the subject's fitness for arm work and bicycling.

Adult↗

Muscle quality. I. Age-associated differences between arm and leg muscle groups.

To determine the differences between arm and leg muscle quality (MQ) across the adult life span in men and women, concentric (Con) and eccentric (Ecc) peak torque (PT) were measured in 703 subjects (364 men and 339 women, age range 19-93 yr) and appendicular skeletal muscle mass (MM) was determined in the arm and leg in a subgroup of 502 of these subjects (224 men and 278 women). Regression analysis showed that MQ, defined as PT per unit of MM, was significantly higher in the arm ( approximately 30%) than in the leg across age in both genders (P < 0.01). Arm and leg MQ declined at a similar rate with age in men, whereas leg MQ declined approximately 20% more than arm MQ with increasing age in women (P </= 0.01 and P < 0.05 for Con and Ecc PT, respectively). Moreover, the age-associated decrease in arm MQ was steeper in men than in women whether Con or Ecc PT was used (both P < 0.05). Arm MQ as determined by Con PT showed a linear age-related decline in men and women (28 and 20%, respectively, P < 0.001), whereas arm MQ as determined by Ecc PT showed a linear age-related decline in men (25%, P < 0.001) but not in women (not significant). In contrast, both genders exhibited an age-related quadratic decline in leg MQ as determined by Con PT ( approximately 40%) and Ecc PT ( approximately 25%; both P < 0.001), and the rate of decline was similar for men and women. Thus MQ is affected by age and gender, but the magnitude of this effect depends on the muscle group studied and the type of muscle action (Con vs. Ecc) used to assess strength.

Adult↗

Nondominant arm advantages in load compensation during rapid elbow joint movements.

This study was designed to examine interlimb asymmetries in responding to unpredictable changes in inertial loads, which have implications for our understanding of the neural mechanisms underlying handedness. Subjects made repetitive single joint speed constrained 20 degrees elbow flexion movements, while the arm was supported on a horizontal, frictionless, air-jet system. On random trials, a 2-kg mass was attached to the arm splint prior to the "go" signal. Subjects were not given explicit information about the mass prior to movement nor were they able to view their limb or the mass. Accordingly, muscle activity, recorded prior to peak tangential finger acceleration, was the same for loaded and baseline trials. After this point, substantial changes in muscle activity occurred. In both limbs, the load compensation response was associated with a reduction in extensor muscle activity, resulting in a prolonged flexion phase of motion. For the nondominant arm, this resulted in effective load compensation, such that no differences in final position accuracy occurred between loaded and baseline trials. However, the dominant arm response also included a considerable increase in flexor muscle activity. This substantially prolonged the flexor acceleration phase of motion, relative to that of the nondominant arm. As a result, the dominant arm overcompensated the effects of the load, producing a large and systematic overshoot of final position. These results indicate more effective load compensation responses for the nondominant arm; supporting a specialized role of the nondominant arm/hemisphere system in sensory feedback mediated error correction mechanisms. The results also suggest that specialization of the dominant arm system for controlling limb and task dynamics is specifically related to feedforward control mechanisms.

Adult↗

Control of joint rotations in overarm throws of different speeds made by dominant and nondominant arms.

We tested the hypothesis that dominant and nondominant overarm throws of different speeds are made by time-scaling of joint rotations, i.e., by joint rotations that have the same positions and amplitudes but that are scaled in time. Eight skilled subjects stood and made overarm throws with both their dominant and nondominant arms. Six joint rotations were computed from recordings of arm segments made with the search-coil technique. Throws made with nondominant arms were less accurate and had lower ball speeds. In contrast to the hypothesis, dominant arms showed large and consistent differences between fast and slow throws in six-dimensional angular position joint space. These same throws showed similar hand angular paths when these were time-scaled based on ball speed. Nondominant arms showed only small differences in angular position joint space in fast and slow throws. It is concluded that a joint space pattern resembling that predicted by time-scaling occurs in nondominant arm throwing when it is unskilled. However, time-scaling does not occur in dominant arm throwing, i.e., a skilled fast throw is not simply a skilled slow throw whose joint positions and amplitudes remain constant but whose joint velocities are sped-up. We hypothesize for future study that, when subjects first learn to throw at different speeds with their dominant arms, they use time-scaling of joint rotations that involves compensating for interaction torques; then as they become skilled at throwing fast, time-scaling is superseded by a more complex pattern of interjoint coordination that involves exploiting interaction torques.

Adult↗

Tactile activity in primate primary somatosensory cortex during active arm movements: correlation with receptive field properties.

1. Five hundred ninety-five single neurons with tactile receptive fields (RFs) on the contralateral arm were isolated in the primary somatosensory cortex (SI) of awake, behaving monkeys. 2. Fifty-eight percent of the tactile cells showed significantly different levels of activity during active movements of the arm in eight directions or during active maintenance of the arm over the target endpoints. 3. The discharge of many of the active tactile cells was unimodally tuned with movement direction and the pattern of the tactile population activity varied in a meaningful fashion with arm movement direction and posture. 4. The intensity of the arm-movement-induced activity was typically less than that evoked by direct tactile stimulation of the cell's RF. 5. The probability of task-related activity was correlated with certain RF properties, in particular the sensitivity of the cell to lateral stretch of the skin and to passive arm movements that avoided direct contact of the RF on any surface. 6. This suggests that task-related activity results mainly from the activation of tactile receptors by mechanical deformation of the skin as the arm changes geometry during movement. 7. These results demonstrate that tactile activity containing potential proprioceptive information is generated in SI during active arm movements that avoid direct contact of the skin with external surfaces. Whether or not this input contributes to the kinesthetic sensations evoked by the movements cannot be resolved by this study.

Adaptation, Physiological↗

Effects of image motion in the dorsal premotor cortex during planning of an arm movement.

This study examined whether neuronal activity in the dorsal premotor cortex (PMd) covaries with image motion or actual movement of the arm while planning a target-capturing task when the motor task is guided by an image of the moving arm. For this purpose, we trained a monkey to capture a target on a video screen with the part of the arm displayed on the screen. The target-capturing body part was either the right or left side of the hand image. Because the actual arm movement was invisible, the motor task was guided by the arm image, which was at times right-left inverted on the screen. We found that neuronal activity in the PMd predominantly reflected arm-image movement rather than the actual arm movement, and for half of PMd neurons, the activity differed depending on the target-capturing body-part defined in the right or left side of the arm image.

Animals↗

Dissociation of sympathetic nerve activity in arm and leg muscle during mental stress.

Mental stress, which increases blood pressure and heart rate, increases forearm blood flow but does not change calf blood flow. The purpose of this study was to determine if mental stress increases muscle sympathetic nerve activity in the leg and causes a dissociation of muscle sympathetic nerve activity in the arm and the leg. We recorded heart rate, blood pressure, and efferent sympathetic nerve activity during mental stress (4 minutes of mental arithmetic) in 13 healthy men. Microelectrodes were inserted percutaneously into a fascicle of the peroneal nerve (leg) and radial nerve (arm) to measure sympathetic discharge to muscle. In Study 1, leg muscle sympathetic nerve activity was recorded in seven subjects. Mental stress significantly increased heart rate and blood pressure. Despite the increased blood pressure (which would be expected reflexly to inhibit sympathetic nerve activity), leg muscle sympathetic nerve activity (in total integrated activity, bursts per 100 heart beats or bursts per minute) increased significantly during stress. Further, whereas heart rate and blood pressure returned to normal during recovery, leg muscle sympathetic nerve activity remained elevated during recovery. In Study 2, simultaneous recordings were made of arm and leg muscle sympathetic nerve activity in six subjects. Mental stress increased heart rate and arterial pressure. Leg muscle sympathetic nerve activity again increased significantly during stress and remained elevated during recovery. In contrast, arm muscle sympathetic nerve activity did not change during stress. However, arm muscle sympathetic nerve activity increased significantly during recovery after stress. These studies indicate that a sympathoexcitatory influence of mental stress overrides or inhibits baroreceptor control of leg sympathetic nerve activity and stress causes a dissociation of arm and leg muscle sympathetic nerve activity with increased outflow to the leg but not to the arm. These observations may contribute to differences in blood flow to arm and leg during mental stress.

Adult↗

Prevalence and associated features of the cold hemiplegic arm.

BACKGROUND AND PURPOSE: Some stroke patients complain of an unpleasant sensation of coldness in the hemiplegic arm. This study aimed to determine the prevalence of this symptom and any associated features. METHODS: A questionnaire about symptoms in the arms was sent to patients at least 12 months after stroke. Reflex sympathetic dystrophy (RSD) was diagnosed if four typical symptoms were present in the arm. RESULTS: One hundred patients were recruited and 75 complete replies received. The mean age of the patients was 74 years, and the mean time since the stroke was 19 months. Forty patients (53%) experienced unilateral coldness in the hemiplegic arm. In 14 this sensation was constant, and 10 rated the symptom as troublesome. The symptom developed at a median time of 1 month after stroke, but only 13 patients (32%) sought advice from a doctor. Sensory symptoms and arm and shoulder pain were common, but the only symptoms associated with coldness were numbness (P < .001) and color change (P < .05). Fifteen patients fulfilled the diagnostic criteria for RSD, 13 of whom had coldness only in the hemiplegic arm. CONCLUSIONS: A sensation of coldness in the hemiplegic arm is common and distressing. It is associated with numbness and color changes in the arm. Some cases are caused by RSD, but other patients have coldness that may be due to other causes such as a vasomotor abnormality.

Aged↗

Splanchnic and peripheral glucose and lactate metabolism during and after prolonged arm exercise.

Splanchnic and peripheral exchange of glucose and gluconeogenic substrates was examined in 12 healthy subjects during 2 h of arm or leg exercise on a bicycle ergometer and during a 40-min postexercise recovery period. The work intensity corresponded to 30% of the maximal pulmonary oxygen uptake. The regional exchange of substrates was evaluated using catheter technique and indicator dilution methods for blood flow measurements. Our findings indicate that prolonged arm exercise as compared with exercise with the legs results in a greater increase in heart rate (25-40%) and a more marked reduction in splanchnic blood flow (10-30%) as well as higher arterial concentrations of lactate, free fatty acids, and catecholamines. The respiratory exchange ratio was consistently higher with arm exercise. In addition, arm exercise results in a greater fractional extraction and utilization of glucose by exercising muscle as well as a greater hepatic gluconeogenesis from lactate and glycerol. During recovery from prolonged arm exercise, leg muscle becomes an important site of lactate release to the splanchnic bed, despite a lack of net glucose uptake by the leg. Simultaneously, arm muscle shows an increase in glucose uptake in the absence of a net release of lactate. These coincident but discordant processes in the leg and arm during recovery suggest the occurrence of a redistribution of muscle glycogen from previously resting (leg) muscle to previously exercising (arm) muscle.

Adult↗

Effect of severity of arm impairment on response to additional physiotherapy early after stroke.

OBJECTIVE: To investigate effect of initial severity of arm impairment on response to additional physiotherapy for the arm after stroke. DESIGN: In this controlled trial, patients were randomized into one of three groups: routine physiotherapy (RPT) patients received no additional physiotherapy; qualified physiotherapy (QPT) patients received additional treatment from a qualified physiotherapist; assistant physiotherapy (APT) patients received additional treatment from a trained supervised assistant. Comparisons between the whole groups found no significant differences and have been reported elsewhere. In a post hoc analysis, the groups were subdivided according to severity of initial arm impairment. The subgroups were then compared. SETTING: A general hospital with acute and rehabilitation facilities for stroke patients. SUBJECTS: Patients (n = 282) between one and five weeks after stroke. INTERVENTIONS: Ten hours additional physiotherapy were given over a five-week period. The treatment approach reflected current usual British practice. 'Blind' outcome assessment was performed after intervention, and at three and six months after stroke. MAIN OUTCOME MEASURES: Rivermead Motor Assessment Arm Scale, Action Research Arm Test. RESULTS: In more severe patients, no benefits of additional treatment were detected. In less severe patients, significant benefits were found in those who completed treatment with the trained assistant. However, a considerable number of patients did not complete the additional treatment. The content of treatment differed between the QPT and APT groups. Treatment of less severe APT patients emphasized repetitive supervised practice of movements and functional tasks. No significant effects of additional treatment were found in terms of shoulder pain or spasticity. CONCLUSIONS: Regardless of whether additional physiotherapy was given or not, patients with severe arm impairment improved very little in arm function. Enabling adaptation to loss of arm function may be an appropriate rehabilitation strategy for some patients. Trends in the data confirm findings of some previous studies that intensive treatment for patients with some motor recovery of the upper limb is effective. Following patient assessment and treatment planning by a qualified physiotherapist, it may be appropriate for guidance of repetitive practice of motor and functional tasks to be delegated to trained and closely supervised assistant staff.

Activities of Daily Living↗

Sport-dependent variations in arm position during single-limb landing influence knee loading: implications for anterior cruciate ligament injury.

BACKGROUND: Increased valgus loading at the knee has been previously identified as a possible risk factor for noncontact anterior cruciate ligament injuries, which are common in sports. Arm position variation may affect risk of injury by altering valgus knee loading. HYPOTHESIS: Sport-dependent variations in arm position increase valgus loading of the knee during run-to-cut maneuvers. STUDY DESIGN: Controlled laboratory study. METHODS: Eleven subjects performed a sidestep cutting maneuver, first with no arm constraints and then with 3 sports-related arm positions in random order (holding a lacrosse stick, holding a football on the plant side, and holding a football on the cut side). The analysis focused on the knee valgus moment relative to the arm positions during the landing phase of the activity. RESULTS: Arm position significantly influenced the valgus moment with an increase in the lacrosse trials and in the plant-side football trials but not in the cut-side football trials (alpha = .05). CONCLUSIONS: Constraining the plant-side arm results in increased valgus loading at the knee during run-to-cut maneuvers, which suggests the possibility of greater risk of anterior cruciate ligament injury during these conditions. CLINICAL RELEVANCE: These results suggest that training methods that consider arm position as a risk factor could help reduce the risk of anterior cruciate ligament noncontact injury.

Adult↗

Chronic arm morbidity after curative breast cancer treatment: prevalence and impact on quality of life.

PURPOSE: To determine the prevalence of and contributing factors for chronic arm morbidity including lymphedema in breast cancer patients after treatment and to assess the impact of arm morbidity on quality of life (QOL). PATIENTS AND METHODS: A four-question screening questionnaire was developed and mailed to a random sample of 744 breast cancer patients treated curatively in two cancer centers from 1993 to 1997. Patients were without recurrence and at least 2 years from diagnosis. Respondents were classified as with or without arm-related symptoms on the basis of the survey. Stratified random samples from each group were then invited for a detailed assessment of their symptoms and signs, including the presence of lymphedema. Their QOL was assessed by the European Organization for Research and Treatment of Cancer QOL Questionnaire C-30 and by a detailed arm problem questionnaire that assessed various aspects of daily arm functioning. RESULTS: Approximately half of all screened patients were symptomatic and 12.5% of all assessed patients had lymphedema. Axillary dissection (AD) and axillary radiotherapy (RT) after dissection were statistically significantly related to the occurrence of arm symptoms (odds ratio for AD = 3.3, P <.001; odds ratio for RT = 3.1, P <.001). Symptomatic patients and patients with lymphedema both had impaired QOL compared with asymptomatic patients. CONCLUSION: Treatment for breast cancer is associated with considerable arm morbidity, which has a negative impact on QOL. Arm morbidity should be carefully monitored in future studies involving local treatment modalities for breast cancer.

Arm↗

Are the arms and legs in competition for cardiac output?

Oxygen transport to working skeletal muscles is challenged during whole-body exercise. In general, arm-cranking exercise elicits a maximal oxygen uptake (VO2max) corresponding to approximately 70% of the value reached during leg exercise. However, in arm-trained subjects such as rowers, cross-country skiers, and swimmers, the arm VO2max approaches or surpasses the leg value. Despite this similarity between arm and leg VO2max, when arm exercise is added to leg exercise, VO2max is not markedly elevated, which suggests a central or cardiac limitation. In fact, when intense arm exercise is added to leg exercise, leg blood flow at a given work rate is approximately 10% less than during leg exercise alone. Similarly, when intense leg exercise is added to arm exercise, arm blood flow and muscle oxygenation are reduced by approximately 10%. Such reductions in regional blood flow are mainly attributed to peripheral vasoconstriction induced by the arterial baroreflex to support the prevailing blood pressure. This putative mechanism is also demonstrated when the ability to increase cardiac output is compromised; during exercise, the prevailing blood pressure is established primarily by an increase in cardiac output, but if the contribution of the cardiac output is not sufficient to maintain the preset blood pressure, the arterial baroreflex increases peripheral resistance by augmenting sympathetic activity and restricting blood flow to working skeletal muscles.

Arm↗

Lateral difference in the reproduction of arm positioning movement: an examination of the hypothesis on the levels of psychological processes.

The purpose of this study was to determine whether the hypothesis on the levels of psychological processes (Hatta, 1977, 1978) accounts for lateral differences in arm positioning movement (a spatial localization task). Fifteen right-handed male subjects were asked to perform a constrained criterion movement, 12 cm in length, with the left or right arm. Then, after a 10-sec retention interval, they were asked to perform the movement with the same arm, estimating lengths of 6, 12 or 24 cm. Different levels of psychological processes were assumed to be involved in estimating these various movement lengths--half, the same, or double that of the original. All possible combinations of the arm (left/right) and three movement length were tested. The CE scores were lower (more accurate) for the left arm (half; 1.5 +/- 8.1 mm, same; 4.3 +/- 6.2mm, double; 5.9 +/- 20.3 mm) than those for the right arm (half; 5.9 +/- 7.6 mm, same; 10.6 +/- 10.6 mm, double; 11.8 +/- 23.6 mm) in all conditions, indicating a lateral difference (the right hemisphere dominance) in arm positioning tasks. This typical lateral difference, which displayed no significant difference among conditions, is supposed to be mediated by complex or high-level psychological processes. These psychological processes are required by the subjects in the estimation of the various movement lengths. This study suggests that the level of psychological processes is a crucial factor in the manifestation of lateral differences in the performance of arm positioning movements.

Adult↗

Lateralized regular spatial patterns in oscillating drawing arm movements of right-handed young women.

There is a lacuna in literature with reference to the spatial lateral difference in fast rhythmical movements produced by the whole dominant and nondominant whole arm, where spinal regulation has a significant role. Based on a fast oscillating zigzag drawing task, this study focused on (a) creation of a specific model of the task based on the intermittencies of coupled vectors of the fast motion, (b) identification of the spatial patterns that triggered these vectors, and (c) identification of quantified lateral differences between the spatial rhythmical patterns. 12 strongly right-handed young women performed 9 to 11 trials drawing zigzag lines. Each participant was required to extend her arm and perform this task using the left and right arm selectively on a frontally positioned graphic design system. The spatial patterns produced on each trial were identified in terms of five constant combinations of horizontal (X) and vertical (Y) projections of each line on the zigzag drawings. The dominant arm differed from the nondominant arm in preferred patterns. Because the duration of each line in the zigzag was highly restricted in time, the appearance of the patterns with different block schemes of movement could be explained as being associated with lower levels of the central nervous system. Initiation of fast movement of the total upper arm is probably associated with selection of the block scheme of motor control appropriate to each arm. Each block scheme is grounded on the coupled vectors of motion organised with particular muscle groups. Some block schemes seemed linked specifically to the dominant arm.

Adult↗