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PubMed2001

Postural arm control following cervical spinal cord injury.

This study used estimates of dynamic endpoint stiffness to quantify postural arm stability following cervical spinal cord injury (SCI) and to investigate how this stability was affected by functional neuromuscular stimulation (FNS). Measurements were made in the horizontal plane passing through the glenohumeral joint on three SCI-impaired arms, which ranged in functional level from a weak C5 to a strong C6. Endpoint stiffness, which characterizes the relationship between externally imposed hand displacements and the resultant forces, was estimated during the application of planar, stochastic perturbations to each arm. These estimates were used in conjunction with voluntary endpoint force measurements to quantify stability and strength during voluntary contractions and during voluntary contractions in the presence of triceps FNS. The primary findings were: 1) the differences in the force generating capabilities of these arms were due primarily to differences in shoulder strength; 2) measurements of strength alone could not be used to predict arm stability; and 3) triceps FNS improved postural arm stability for all tested conditions. These results suggest strategies for improved control of FNS systems designed to restore arm function following cervical SCI and underscore the importance of examining the effects of FNS on both strength and stability.

Algorithms↗
PubMedDate not supplied

Lymphedema of the arm and breast in irradiated breast cancer patients: risks in an era of dramatically changing axillary surgery.

The purpose of this study was to assess risk for lymphedema of the breast and arm in radiotherapy patients in an era of less extensive axillary surgery. Breast cancer patients treated for cure were reviewed, with a minimum follow-up of 1.5 years from the end of treatment. Clinical, surgical, and radiation-related variables were tested for statistical association with arm and breast lymphedema using regression analyses, t-tests, and chi-squared analyses. Between January 1998 and June 2001, 240 women received radiation for localized breast cancer in our center. The incidence of lymphedema of the ipsilateral breast, arm, and combined (breast and arm) was 9.6%, 7.6%, and 1.8%, respectively, with a median follow-up of 27 months. For breast edema, t-test and multivariate analysis showed body mass index (BMI) to be significant (p = 0.043, p = 0.0038), as was chi-squared and multivariate testing for site of tumor in the breast (p = 0.0043, p = 0.0035). For arm edema, t-test and multivariate analyses showed the number of nodes removed to be significant (p = 0.0040, p = 0.0458); the size of the tumor was also significant by multivariate analyses (p = 0.0027). Tumor size appeared significant because a number of very large cancers failed locally and caused cancer-related obstructive lymphedema. In our center, even modern, limited level 1-2 axillary dissection and tangential irradiation carries the risk of arm lymphedema that would argue in favor of sentinel node biopsy. For breast edema, disruption of draining lymphatics by surgery and radiation with boost to the upper outer quadrant increased risk, especially for the obese. Fortunately both breast and arm edema benefited from manual lymphatic drainage.

Adult↗
PubMed2005

Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.

AIM: To determine whether repetitive arm work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity. METHOD: Euglycemic clamps (2 h) were started in ten healthy individuals 15 min after 37 min periods of: (1) repetitive arm work in a simulated occupational setting; (2) dynamic concentric exercise on a cycle ergometer at 60% of VO(2max) and (3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) was recorded continuously. During the clamps, euglycemia was maintained at 5 mmol l(-1) and insulin was infused at 56 mU m(-2) min(-1) for 120 min. RESULTS: The insulin-mediated glucose disposal rate (M-value) for the steady-state period (60-120 min) of the clamp, tended to be lower following arm work than for both cycling and resting regimes. When dividing the steady-state period into 20-min intervals, the insulin sensitivity index (ISI) was significantly lower for arm work compared with the resting control situation between 60-80 min (P = 0.04) and 80-100 min (P = 0.01), respectively. Catecholamines increased significantly for arm work and cycling compared with resting regime. Data from heart rate variability (HRV) measurements indicated significant sympathetic activation during repetitive arm work. CONCLUSION: The results indicate that repetitive arm work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.

Adult↗
PubMed1999

Comparison of microvascular filtration in human arms with and without postmastectomy oedema.

Oedema is caused by impaired lymphatic drainage and/or increased microvascular filtration. To assess a postulated role for the latter in postmastectomy oedema, filtration was studied in the forearms of 14 healthy subjects and 22 patients with chronic, unilateral arm oedema caused by surgical and radiological treatment for breast cancer. A new non-contact optical device (the Perometer) and a conventional mercury strain gauge were used simultaneously to record forearm swelling rates caused by microvascular filtration during applied venous congestion. Filtration rate (FR) per 100 ml tissue was measured over 10-15 min at a venous pressure of 30 cmH2O, a pressure reached in the dependent forearm (FR30), and then at 60 cmH2O (FR60). Apparent filtration capacity of 100 ml soft tissue (CFCa) was calculated from FR60 - FR30/30, after adjustment for bone volume. The Perometer and strain gauge gave similar results in normal and oedematous arms. Mean CFCa in healthy subjects was (3.8+/-0.4) x 10(-3) ml (100 ml)-1 cmH2O-1 min-1, close to literature values. In the patients, FR30 was 47 % lower in the oedematous forearm than in the opposite, unaffected forearm (P = 0.04). FR60 showed a similar trend but did not reach significance (P = 0.15). The values of CFCa of (2.2+/-0.5) x 10(-3) ml (100 ml)-1 cmH2O-1 min-1 in the oedematous arm and (2.8+/-0.5) x 10(-3) ml (100 ml)-1 cmH2O-1 min-1 in the unaffected arm were not significantly different (P = 0.47). When differences in arm volume on the two sides were taken into account, the total fluid load on the lymphatic system of the oedematous forearm was (411.0+/-82.2) x 10(-3) ml min-1 at 30 cmH2O and (1168+/-235.6) x 10(-3) ml min-1 at 60 cmH2O, similar to the normal side, namely (503.7+/-109.3) 10(-3) ml min-1 and (1063+/-152.0) x 10(-3) ml min-1, respectively (P >/= 0.50). The filtration capacity of the entire oedematous forearm (CFCa scaled up by total soft tissue volume), (25.4+/-6.2) x 10(-3) ml cmH2O-1 min-1, was not significantly greater than that of the normal forearm, (18.3+/-2.6) x 10(-3) ml cmH2O-1 min-1 (P = 0.40). The results indicate that no major change occurs in the microvascular hydraulic permeability-area product of the forearm, or in the total filtration load on the lymph drainage system during dependency, in the arm with postmastectomy oedema compared with the normal arm. This argues against a significant haemodynamic contribution to postmastectomy oedema.

Aged↗
PubMed1989

Arm and ankle blood pressure response to treadmill exercise in normal people.

Nineteen healthy volunteers, 10 men and nine women (mean age 38 and 30 years), exercised on a treadmill. The systolic blood pressure (BP) was measured at the ankle and in the arm after submaximal (8 min with a final load of 2 W kg-1 body weight) and maximal exercise. The BP was measured for 10 min after exercise, or until the elimination of a negative pressure difference between ankle and arm. The pre-study resting systolic arm and ankle pressures were 122 +/- 11 and 144 +/- 13 mmHg. One minute after submaximal exercise, arm and ankle BP were 147 +/- 18 and 159 +/- 19 mmHg (ankle-arm pressure difference 12 +/- 13 mmHg); 1 min after maximal exercise the corresponding figures were 182 +/- 26 and 153 +/- 35 mmHg (ankle-arm pressure difference -29 +/- 33 mmHg). We conclude that maximal exercise, but not an appropriately chosen submaximal exercise level, causes a negative BP difference between ankle and arm in normal people.

Adolescent↗
PubMed2005

Glucose clearance is higher in arm than leg muscle in type 2 diabetes.

Insulin-mediated glucose clearance (GC) is diminished in type 2 diabetes. Skeletal muscle has been estimated to account for essentially all of the impairment. Such estimations were based on leg muscle and extrapolated to whole body muscle mass. However, skeletal muscle is not a uniform tissue and insulin resistance may not be evenly distributed. We measured basal and insulin-mediated (1 pmol min-1 kg-1) GC simultaneously in the arm and leg in type 2 diabetes patients (TYPE 2) and controls (CON) (n=6 for both). During the clamp arterio-venous glucose extraction was higher in CON versus TYPE 2 in the arm (6.9+/-1.0 versus 4.7+/-0.8%; mean+/-s.e.m.; P=0.029), but not in the leg (4.2+/-0.8 versus 3.1+/-0.6%). Blood flow was not different between CON and TYPE 2 but was higher (P<0.05) in arm versus leg (CON: 74+/-8 versus 56+/-5; TYPE 2: 87+/-9 versus 43+/-6 ml min-1 kg-1 muscle, respectively). At basal, CON had 84% higher arm GC (P=0.012) and 87% higher leg GC (P=0.016) compared with TYPE 2. During clamp, the difference between CON and TYPE 2 in arm GC was diminished to 54% but maintained at 80% in the leg. In conclusion, this study shows that glucose clearance is higher in arm than leg muscles, regardless of insulin resistance, which may indicate better preserved insulin sensitivity in arm than leg muscle in type 2 diabetes.

Arm↗
PubMed2004

Modeling kinematics and dynamics of human arm movements.

A central problem in motor control relates to the coordination of the arm's many degrees of freedom. This problem concerns the many arm postures (kinematics) that correspond to the same hand position in space and the movement trajectories between begin and end position (dynamics) that result in the same arm postures. The aim of this study was to compare the predictions for arm kinematics by various models on human motor control with experimental data and to study the relation between kinematics and dynamics. Goal-directed arm movements were measured in 3-D space toward far and near targets. The results demonstrate that arm postures for a particular target depend on previous arm postures, contradicting Donders's law. The minimum-work and minimum-torque-change models, on the other hand, predict a much larger effect of initial posture than observed. These data suggest that both kinematics and dynamics affect postures and that their relative contribution might depend on instruction and task complexity.

Adult↗
PubMed1987

Arm function after stroke: measurement and recovery over the first three months.

Four short, simple measures of arm function, suitable for use with patients recovering from acute stroke, are described. These tests are: the Frenchay Arm Test, the Nine Hole Peg Test, finger tapping rate and grip strength. Good interobserver and test-retest reliability was demonstrated for all tests, and the Frenchay Arm Test was shown to be valid. Normal values for all tests were established on 63 controls. It was found that the limited sensitivity of the Frenchay Arm Test could be improved using the Nine Hole Peg Test and grip strength. Recovery of arm function has been studied in a sample of 56 patients seen regularly over the first 3 months after their stroke, using these standard measures. The results demonstrated a wide variation in recovery curves between patients. The use of the Nine Hole Peg Test enabled further recovery to be detected after patients achieved a top score on the Frenchay Arm Test. Failure to recover measureable grip strength before 24 days was associated with absence of useful arm function at three months. Measurement of finger tapping rate was not useful.

Aged↗
PubMed2004

Forward and backward arm cycling are regulated by equivalent neural mechanisms.

It was shown some time ago that cutaneous reflexes were phase-reversed when comparing forward and backward treadmill walking. Activity of central-pattern-generating networks (CPG) regulating neural activity for locomotion was suggested as a mechanism involved in this "program reversal." We have been investigating the neural control of arm movements and the role for CPG mechanisms in regulating rhythmic arm cycling. The purpose of this study was to evaluate the pattern of muscle activity and reflex modulation when comparing forward and backward arm cycling. During rhythmic arm cycling (forward and backward), cutaneous reflexes were evoked with trains (5 x 1.0 ms pulses at 300 Hz) of electrical stimulation delivered to the superficial radial (SR) nerve at the wrist. Electromyographic (EMG) recordings were made bilaterally from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted on specific sections of the movement cycle after phase-averaging contingent on the timing of stimulation in the movement cycle. EMG patterns for rhythmic arm cycling are similar during both forward and backward motion. Cutaneous reflex amplitudes were similarly modulated at both early and middle latency irrespective of arm cycling direction. That is, at similar phases in the movement cycle, responses of corresponding sign and amplitude were seen regardless of movement direction. The results are generally parallel to the observations seen in leg muscles after stimulation of cutaneous nerves in the foot during forward and backward walking and provide further evidence for CPG activity contributing to neural activation and reflex modulation during rhythmic arm movement.

Activity Cycles↗
PubMed2002

Handedness: dominant arm advantages in control of limb dynamics.

Recent findings from our laboratory suggest that a major factor distinguishing dominant from nondominant arm performance is the ability by which the effects of intersegmental dynamics are controlled by the CNS. These studies indicated that the dominant arm reliably used more torque-efficient patterns for movements made with similar speeds and accuracy than nondominant arm movements. Whereas, nondominant hand-path curvatures systematically varied with the amplitude of the interaction torques transferred between the segments of the moving limb, dominant hand-path curvatures did not. However, our previous studies did not distinguish whether dominant arm coordination advantages emerged from more effective control of dynamic factors or were simply a secondary effect of planning different kinematics. The purpose of this study was to further investigate interlimb differences in coordination through analysis of inverse dynamics and electromyography recorded during the performance of reaching movements. By controlling the amplitude of intersegmental dynamics in the current study, we were able to assess whether systematic differences in torque-efficiency exist, even when differences in hand-path shape were minimal. Subject's arms were supported in the horizontal plane by a frictionless air-jet system and were constrained to movements about the shoulder and elbow joints. Two targets were designed, such that the interaction torques elicited at the elbow were either large or small. Our results showed that the former produced large differences in hand-path curvature, whereas the latter did not. Additionally, the movements with small differences in hand-path kinematics showed substantial differences in torque patterns and corresponding EMG profiles which implied a more torque-efficient strategy for the dominant arm. In view of these findings we propose that distinct neural control mechanisms are employed for dominant and nondominant arm movements.

Adult↗
PubMed1979

Characteristics of motor programs underlying arm movements in monkeys.

1. The experiments described here are addressed at identifying some of the processes underlying arm movements in monkeys. 2. We used three adult monkeys that were trained to point to a target light with the forearm and hold at that position for about 1 s in order to obtain a reward. During the experimental sessions the monkey was seated in a primate chair and its forearm was fastened to an apparatus that permitted flexion and extension of the forearm about the elbow in the horizontal plane. 3. We tested their performance prior to and after bilateral dorsal rhizotomy (C2--T3). Forearm movements were performed without the sight of the arm both before and after the surgical intervention. In intact animals we unexpectedly displaced the arm prior to movement initiation (150--200 ms) and observed the outcome of this displacement on movement termination. Our results indicated that the arm moved accurately to the target. The same procedure was used in the deafferented monkeys, yielding qualitatively the same results; i.e., a displacement of the initial position did not affect the attainment of the intended final position. 4. These results are relevant to the question of what is being controlled by motor commands. It appears that the controlled variable is an equilibrium point resulting from the interaction of agonist and antagonist muscles. Consequently, a change in the equilibrium leads to movement and the attainment of a new posture. The fact that both intact and deafferent monkeys display essentially similar motor behavior in our highly practiced task should not obliterate the dramatic difference in motor performance that exists between intact and rhizotomized animals. In fact, the successful execution of the learned motor performance in the deafferented animal is contingent on the animal's body being in a fixed relation to the arm apparatus. Whenever we changed the usual spatial relationship between the monkey's body and the arm apparatus, the animal's pointing response to the target was inaccurate. All of our intact monkeys, in contrast, were able to compensate quickly for any variations in their accustomed position with respect to the arm apparatus. The dramatic inability of the deafferented monkey to execute accurate pointing responses in an unusual postural setting underscores the great importance of the afferent monkey to execute accurate pointing responses in an unusual postural settiing underscores the great importance of the afferent feedback. These findings suggest that, in the performance of visually evoked learned movements, one of the major functions of the afferent feedback is in the adaptive modifications of learned motor programs.

Afferent Pathways↗
PubMed1992

Effects of reversible blockade of basal ganglia on a voluntary arm movement.

1. The effects of a reversible blockade of basal ganglia were examined in two monkeys trained to perform a visually guided, step-tracking arm movement around the elbow joint. To block glutamatergic excitation, kynurenate (a glutamate antagonist) was locally injected into the putamen and the external segment (GPe) and the internal segment (GPi) of the globus pallidus contralateral to the arm tested. Muscimol [a gamma-aminobutyric acid (GABA) agonist] was also used to suppress neuronal activity in these structures. The drugs were injected in the arm area of the putamen, which was identified by microstimulation or by recording neural activity. For the GPe and GPi, injections were made into the area medioventral to the arm area of the putamen. 2. The blockade of the putamen caused abnormal braking of the arm movements. The first step of the movement became hypometric, and multiple steps were necessary to reach the target. The electromyographic (EMG) analysis revealed an increase of burst activity in the antagonist muscles and a decrease of that in the agonist muscles at the fast movements. The tonic activity increased in the extensor muscles during a holding period. 3. The blockade of the GPi caused dysmetric movements. Amplitude and peak velocity of the first step of movement largely fluctuated among trials. It became difficult for the animal to brake and adjust its arm onto the target. 4. The blockade of the GPe caused a flexion posture at the elbow joint of the contralateral arm. The tonic activity of the flexor muscles increased. Cocontraction of the agonist and antagonist muscles was also observed. 5. These results suggest that the putaminopallidal system of the basal ganglia contributes to both of two motor functions: 1) static control to maintain the posture with tonic muscle activity, and 2) dynamic control to enable fast movements.

Animals↗
PubMed1997

Reaching movements with similar hand paths but different arm orientations. II. Activity of individual cells in dorsal premotor cortex and parietal area 5.

Reaching movements with similar hand paths but different arm orientations. II. Activity of individual cells in dorsal premotor cortex and parietal area 5. J. Neurophysiol. 78: 2413-2426, 1997. Neuronal activity in primary motor cortex (MI) is altered when monkeys make reaching movements along similar handpaths at shoulder level with two different arm orientations, either in the natural orientation with the elbow positioned below the level of the shoulder and hand or in an abducted orientation with the elbow abducted nearly to shoulder level. The present study examines to what degree two other cortical areas, the dorsal premotor (PMd) and parietal area 5, also show modulation of cell activity related to arm geometry during reaching. The activity of most (89%) of the 207 cells in PMd recorded while monkeys made reaching movements showed a statistically significant change in activity between orientations [analysis of variation (ANOVA), P < 0.01]. A common effect of arm orientation on cell activity was a change in the overall level of discharge either before, during, and/or after movement (67%, ANOVA, task main effect, P < 0.01). Many cells (76%) showed a statistical change in their response to movement direction (ANOVA, task x direction interaction term, P < 0.01), including changes in dynamic range and changes in the preferred direction of cells that were directionally tuned in both arm orientations. Overall, these effects were similar qualitatively but not as strong quantitatively as those observed in MI. A sample of cells was recorded in area 5 of one monkey. Most (95%) of the 79 area 5 cells showed a change in activity when reaching movements were performed using different arm orientations (ANOVA, P < 0.01). As in PMd and MI, many area 5 cells (56, 71%) showed changes in their tonic discharge before, during, and/or after movement, and 70 cells (89%) showed changes in their response to movement direction (ANOVA, task x direction interaction term, P < 0.01). The observed changes in neuronal activity related to posture and movement in MI, PMd and area 5 demonstrate that single-cell activity in these cortical areas is not simply related to the spatial attributes of hand trajectory but is also strongly influenced by attributes of movement related to arm geometry.

Analysis of Variance↗
PubMed2005

Task-specific training with trunk restraint on arm recovery in stroke: randomized control trial.

BACKGROUND AND PURPOSE: Task-specific training improves functional outcomes after stroke. However, gains may be accompanied by increases in movements compensating for motor impairments. We hypothesized that restriction of compensatory trunk movements may encourage recovery of premorbid movement patterns leading to better functional outcomes. The goal was to determine whether task-specific training with trunk-restraint (TR) produces greater improvements in arm impairment and function than training without TR in patients with chronic hemiparesis. METHODS: Double-blind randomized control trial of a therapist-supervised home program (3 times per week, 5 weeks) in 30 patients with chronic hemiparesis stratified by arm impairment level (Fugl-Meyer) was performed. Intervention group (TR group) received progressive object-related reach-to-grasp training with prevention of trunk movements. Control group (C) practiced tasks without TR. Main outcome measures were upper limb impairment (Fugl-Meyer Arm Section) and function (TEMPA) and movement kinematics (trunk displacement, elbow extension; Optotrak, 10 trials) of a reach-to-grasp movement. Evaluations were repeated before, immediately after, and 1 month postintervention by blind evaluators. RESULTS: TR training led to greater improvements in impairment and function compared with C. Improvements were accompanied by increased active joint range and were greater in initially more severe patients. In these patients, TR decreased trunk movement and increased elbow extension, whereas C had opposite effects (increased compensatory movements). In TR, changes in arm function were correlated with changes in arm and trunk kinematics. CONCLUSIONS: Treatment should be tailored to arm impairment severity with particular attention to controlling excessive trunk movements if the goal is to improve arm movement quality and function.

Aged↗
PubMed1999

Randomized, controlled trial to evaluate increased intensity of physiotherapy treatment of arm function after stroke.

BACKGROUND AND PURPOSE: Many patients have impaired arm function after stroke, for which they receive physiotherapy. The aim of the study was to determine whether increasing the amount of physiotherapy early after stroke improved the recovery of arm function and to compare the effects of this therapy when administered by a qualified therapist or a trained, supervised assistant. The physiotherapy followed a typical British approach, which is Bobath derived. Ten hours of additional therapy were given over a 5-week period. METHODS: The study design was a single-blind, randomized, controlled trial. Stroke patients were recruited from those admitted to the hospital in the 5 weeks after stroke. They were randomly allocated to routine physiotherapy, additional treatment by a qualified physiotherapist, or additional treatment by a physiotherapy assistant. Outcome was assessed after 5 weeks of treatment and at 3 and 6 months after stroke on measures of arm function and of independence in activities of daily living. RESULTS: There were 282 patients recruited to the study. The median initial Barthel score was 6.5, and the median age of the patients was 73 years. The median initial Rivermead Motor Assessment Arm score was 1. There were no significant differences between the groups at randomization or on any of the outcome measures. Only half of the patients allocated to the 2 additional-therapy groups completed the program. CONCLUSIONS: This increase in the amount of physiotherapy for arm impairment with a typical British approach given early after stroke did not significantly improve the recovery of arm function in the patients studied. A number of other studies of interventions aimed at rehabilitation of arm function have reported positive results. Such findings may have been due to the content of these interventions, to the greater intensity of the interventions, or to the selection of patients to whom the treatments were applied.

Aged↗
PubMed2000

Repetitive bilateral arm training with rhythmic auditory cueing improves motor function in chronic hemiparetic stroke.

BACKGROUND AND PURPOSE: Chronic upper extremity hemiparesis is a leading cause of functional disability after stroke. We investigated the hypothesis that bilateral arm training with rhythmic auditory cueing (BATRAC) will improve motor function in the hemiparetic arm of stroke patients. METHODS: In this single group pilot study we determined the effects of 6 weeks of BATRAC on 14 patients with chronic hemiparetic stroke (median time after stroke, 30 months) immediately after training and at 2 months after training. Four 5-minute periods per session (3 times per week) of BATRAC were performed with the use of a custom-designed arm training machine. RESULTS: The patients showed significant and potentially durable increases in the following: Fugl-Meyer Upper Extremity Motor Performance Test of impairment (P<0.0004), Wolf Motor Function Test (performance time measure, P<0.02), and University of Maryland Arm Questionnaire for Stroke measuring daily use of the hemiparetic arm (P<0.002). Isometric strength improved in elbow flexion (P<0.05) and wrist flexion (P<0.02) for the paretic arm and in elbow flexion (P<0.02) and wrist extension (P<0.02) for the nonparetic arm. Active range of motion improved for paretic-side shoulder extension (P<0.01), wrist flexion (P<0.004), and thumb opposition (P<0.002), and passive range of motion improved for paretic wrist flexion (P<0.03). CONCLUSIONS: -Six weeks of BATRAC improves functional motor performance of the paretic upper extremity as well as a few changes in isometric strength and range of motion. These benefits are largely sustained at 8 weeks after training cessation.

Acoustic Stimulation↗
PubMed1991

Respiratory response to arm elevation in patients with chronic airflow obstruction.

We have shown that patients with chronic airflow obstruction (CAO) complain of disabling dyspnea when performing seemingly trivial tasks with unsupported arms. Surprisingly little is known about the metabolic and ventilatory responses to unsupported upper extremity activity even though some of the muscles of the upper torso and shoulder girdle are used to perform simple and complex everyday tasks as well as partake in ventilation. To determine the effect of simple arm elevation in 20 patients with CAO we studied their lung function, VO2, VCO2, and VE, with arms down at the side (AD), during 2 min with arms extended forward up to shoulder level (AE), and during recovery. To determine the pattern of ventilatory muscle recruitment we also measured endoesophageal (Ppl), gastric (Pg), and transdiaphragmatic (Pdl) pressures. In five of the patients the electromyographic signal (EMG) of the sternocleidomastoid (Sm) muscle was recorded and analyzed in its time domain (amplitude) and power spectrum density (median frequency). Within 30 s of arm elevation VO2, VCO2, and VE rose and remained elevated for 1 min after the arms were lowered. The increase in VE resulted from increases in respiratory rate and minimal rise in tidal volume (VT). With AE, FEV1 decreased by 5% (p less than 0.02) but FRC increased by 2% (p less than 0.05). Peak inspiratory pressure (Pimax) dropped from 54 +/- 4 to 48 +/- 4 cm H2O (p less than 0.005); Pdimax remained unchanged. Immediately after raising the arms Pgi, inspiratory swing in Pdi (delta Pdi), end-expiratory Ppl, and end-expiratory Pg increased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2006

Gender differences in anaerobic power of the arms and legs--a scaling issue.

PURPOSE: Physiological variables must be scaled for body size differences to permit meaningful comparisons between groups. Using allometric scaling, this study compared the anaerobic performance, using both arms and legs, of men and women. Ten active male and 10 active female subjects performed the leg cycling and arm cranking in a 30-s all-out Wingate test (WAnT). Regional measurements of the legs, gluteal area, arms, and torso taken using dual-energy x-ray absorptiometry (DXA) served as indicators of lower body active musculature (LBAMM) and upper body (UBAMM) active musculature. RESULTS: Body mass (BM) was the best predictor (i.e., r = 0.93-0.96) for peak power (PP) and mean power (MP) generated from sprint cycling and arm cranking. Sex differences for leg and arm power (i.e., PP and MP) were identified in absolute terms and then expressed in ratio to BM(1.0). When the same data were allometrically scaled to BM and expressed as power function ratios (Power;BM(b)), the sex differences in PP and MP for sprint cycling were nullified (female:male ratio x 100: 100-103%), but remained for arm cranking (female:male power ratio x 100: 69-84%). CONCLUSIONS: These results confirmed that anaerobic power of the upper body and lower body were best normalized to BM and, when statistically appropriate methods were used to take into account differences in BM, PP, and MP generated from sprint cycling were similar for both men and women. In contrast, after allometric scaling for BM, men remained more powerful than women for the supramaximal arm cranking task. Qualitative differences in the upper body musculature between men and women are speculated to account for the more powerful performance of men, but confirmatory evidence using noninvasive techniques is warranted.

Adult↗