Elbow Flexion Force Research Articles

Exercise, effort, and limb position sense

The importance of the sense of proprioception (literally, the perception of position) was made most forcefully in the book by Jonathon Cole about a patient who, overnight, lost his sense of where his limbs were in relation to his body ([1][1]). The title of this fascinating book, Pride and a Daily

Cancer related fatigue: Central or peripheral?

8048 Introduction: Cancer related fatigue (CRF) occurs in more than 70% of cancer patients and is a major factor in determining quality of life. Several fatigue specific symptom assessment tools have been developed but the pathophysiology and site of origin of CRF is not known. Fatigue may originate from CNS and/or from the peripheral neuromuscular system. We therefore studied the EEG and EMG signals of hand muscles and brachioradialis during a sustained contraction in advanced cancer patients. Method: Patients with advanced solid tumors, < 10% weight loss and age-, gender-, and Body Mass Index (BMI)-matched healthy controls were studied. Cancer patients and healthy controls completed a Brief Fatigue Inventory (BFI). Cancer patients were not on antidepressants, had Hgb > 10% and were at least 4 weeks from last chemotherapy or radiation treatment. The relative decline in handgrip and elbow flexion force was measured pre and post fatigue. Results: The relative decline in hand grip force, elbow flexion force, and brachioradialis m. M-wave pre and post fatigue were not significantly different. However, twitch force and fatigue demonstrated greater muscle reserve in cancer patients. Discussion: The relative decline in muscle force at the onset of fatigue was similar for cancer and normal individuals. Overall muscle strength was reduced and the time to fatigue onset is shorted with CRF. Electroencephalographic (EEG) correlates are being analyzed. CRF was associated with reduced recruitment of motor units at the onset of fatigue. This suggests that the site of origin is central. Conclusion: CRF appears to be of central origin. No significant financial relationships to disclose.

Substrate Size and Primate Forelimb Mechanics: Implications for Understanding the Evolution of Primate Locomotion

Did the anatomical and locomotor specializations of primates evolve in response to requirements of locomotion and foraging on thin branches? Laboratory studies of primates and other mammals provide data suggesting that as substrate size decreases primates will protract their arms to a greater degree, lower the center of gravity by increasing elbow flexion, and decrease forelimb substrate reaction forces. I tested these hypotheses by calculating maximum arm protraction, shoulder height, elbow flexion, and substrate reaction forces during stance phase in 5 species of Old World monkeys walking on a flat runway and raised poles of varying diameters. As substrate size decreased most subjects increased elbow flexion and lowered their shoulder height. Three of the 5 species lowered peak substrate reaction forces as substrate size decreased but, only 2 of the species increased arm protraction as substrate size decreased. These results reject the hypothesis that arm protraction is a function of branch size, but provide stronger support for the notion that branch size influences elbow flexion, shoulder height, and peak substrate reaction forces in some primates. The fact that biomechanical expectations are met in some (but not all) cases and some (but not all) species suggests that the topic is quite complex and requires further study. Nonetheless, preliminary data suggest that biomechanical accommodations to substrate size may have played a role in the early differentiation of primates from other mammals.

Distribution of muscle weakness in patients with stable chronic obstructive pulmonary disease.

The authors determined the degree of respiratory and peripheral muscle weakness in patients with moderate to severe chronic obstructive pulmonary disease (COPD). Differences in severity of muscle weakness among muscle groups may provide treatment options, such as selective muscle training, to adapt the exercise prescription in pulmonary rehabilitation programs. In addition, this information may add to the knowledge on the mechanisms of muscle weakness. Respiratory and peripheral muscle force were quantified in 22 healthy elderly subjects and 40 consecutive COPD patients (forced expiratory volume in 1 second, percent of predicted value [% pred] 41 +/- 19; transfer factor for carbon monoxide, % pred 47 +/- 26) admitted to a pulmonary rehabilitation program. Lung function, diffusing capacity, isometric force of four peripheral muscle groups (handgrip, elbow flexion, shoulder abduction, and knee extension), neck flexion force, and maximal inspiratory and expiratory pressures were measured. Patients had reduced respiratory muscle strength (mean 64% of control subjects' value [% control]) and peripheral muscle strength (mean 75% control) compared to normal subjects. Inspiratory muscle strength (59 +/- 18% control) was significantly lower than expiratory muscle strength (69 +/- 25% control) and peripheral muscle strength (P < 0.01). Neck flexion force (80 +/- 19% control) was better preserved than maximal inspiratory pressure and shoulder abduction force (70 +/- 15% control, P < 0.01). Handgrip force (78 +/- 16% control) and elbow flexion force (78 +/- 14% control) were significantly less affected than shoulder abduction force (70 +/- 15% control, P < 0.01). Finally, shoulder abduction force and knee-extension force (72 +/- 24% control) were not significantly different. Muscle weakness in stable COPD patients does not affect all muscles to a similar extent. Inspiratory muscle force is affected more than peripheral muscle force, whereas proximal upper limb muscle strength was impaired more than distal upper limb muscle strength.

Relationship between motor activity-related cortical potential and voluntary muscle activation.

The purpose of this study was to investigate the relationship between EEG-derived motor activity-related cortical potential (MRCP) and voluntary muscle activation. Eight healthy volunteers participated in two experimental sessions. In one session, subjects performed isometric elbow-flexion contractions at four intensity levels [10%, 35%, 60%, and 85% maximal voluntary contraction (MVC)]. In another session, a given elbow-flexion force (35% MVC) was generated at three different rates (slow, intermediate, and fast). Thirty to 40 contractions were performed at each force level or rate. EEG signals were recorded from the scalp overlying the supplementary motor area (SMA) and contralateral sensorimotor cortex, and EMG signals were recorded from the skin surface overlying the belly of the biceps brachii and brachioradialis muscles during all contractions. In each trial, the force was used as the triggering signal for MRCP averaging. MRCP amplitude was measured from the beginning to the peak of the negative slope. The magnitude of MRCP from both EEG recording locations (sensorimotor cortex and SMA) was highly correlated with elbow-flexion force, rate of rising of force, and muscle EMG signals. These results suggest that MRCP represents cortical motor commands that scale the level of muscle activation.

Contractile Properties, Fatigue and Recovery are not Influenced by Short‐Term Creatine Supplementation in Human Muscle

There have been several studies on the effect of short-term creatine (Cr) supplementation on exercise performance, but none have investigated both voluntary and stimulated muscle contractions in the same experiment. Fourteen moderately active young men (19-28 years) were randomly assigned, in a double blind manner, to either a creatine (Cr) or placebo (P) group. The subjects supplemented their regular diet 4 times a day for 5 days with either 5 g Cr + 5 g maltodextrin (Cr group), or 5 g maltodextrin (P group). Isometric maximal voluntary contraction (MVC), muscle activation, as assessed using the modified twitch interpolation technique, electrically stimulated contractile properties, electromyography (EMG), endurance time and recovery from fatigue were measured in the elbow flexors. The fatigue protocol involved both voluntary and stimulated contractions. Following supplementation there was a significant weight gain in the Cr group (1.0 kg), whereas the P group did not change. For each group, pre-supplementation measures were not significantly different from post-supplementation for MVC, twitch and tetanic tensions at rest, time to peak tension, half-relaxation time and contraction duration. Prior to Cr supplementation time to fatigue was 10 +/- 4 min (mean +/- S.E.M.) for both groups, and following supplementation there was a non-significant increase of 1 min in each group. MVC force, muscle activation, EMG, stimulated tensions and durations were similar for the Cr and P groups over the course of the fatigue protocol and did not change after supplementation. Furthermore, recovery of MVC, stimulated tensions and contractile speeds did not differ as a result of Cr supplementation. These results indicate that short-term Cr supplementation does not influence isometric elbow flexion force, muscle activation, stimulated contractile properties, or delay time to fatigue or improve recovery.

Visual and haptic feedback in the control of force.

The ability to control index finger and elbow flexion forces was measured while subjects used either haptic feedback or both haptic and visual feedback to control the forces exerted. Over a 120-s time period subjects were able to control the finger forces ranging from 2 to 6 N to within 1 N using only haptic feedback, and elbow flexion forces to within 4.5 N over a force range of 10-30 N. At the same force amplitude there was no significant difference between the two muscle groups in the precision or accuracy with which the force could be controlled, suggesting that there is not a proximal to distal gradient in force control as has been found for the control of limb movement and position.

Biomechanical Aspects of the Elbow in Sports

In many sports, large forces and torques are produced at the elbow that lead to fast movements and a full range of motion. In baseball pitching. varus torque is produced when the arm is in external rotation. This torque includes compression at the radiocapitellar joint and tension in the ulnar collateral ligament (UCL). After ball release, compressive force approaching 100% of bodyweight is produced to prevent elbow dislocation. Compared to baseball pitching, football passing produces greater elbow flexion and medial force, and less varus torque: Furthermore, elbow extension is not as rapid and arm deceleration compressive force is not as great. During the tennis serve, elbow extension is largely due to triceps contraction. During javelin throwing. the elbow extends fairly quickly, terminating well short of full extension. During underhand Softball pitching, the elbow produces compressive force and fairly rapid flexion. Elbow compressive force during pushups is equal to 45% of bodyweight. Compressive force during two-arm pushups (which are similar to falling on an arm) is 31% greater.

Maximal Isometric Muscle Strength and Socioeconomic Status, Health, and Physical Activity in 75-Year-Old Persons

This study analyzes the associations of socioeconomic status (SES), health, and physical activity with maximal isometric strength in 75-year-old men (n = 104) and women (n = 191). Maximal isometric strength was measured with dynamometers; the forces were adjusted using body weight. The maximal forces for women varied from 66% (trunk flexion) to 73% (knee extension) of those of the men. SES was not associated with muscle force. For men the trunk forces and elbow flexion force correlated negatively with the number of chronic diseases, index of musculoskeletal pain, and self-rated health. For women all the strength test results correlated with self-rated health; the other health indicators showed significant correlation with trunk extension force only. For both sexes the physically more active exhibited greater strength. The index of musculoskeletal symptoms explained the variance on trunk force factor in both sexes. It was concluded that a higher level of everyday physical activity and good values in the state-of-health indicators were the most important variables explaining greater strength among the elderly.

Force perception before and after maximal voluntary contraction.

Capacity to match a low level of elbow flexion force maintained in the control arm was measured in the experimental arm in 16 subjects before and after maximal voluntary contraction (MVC). Prior to a 1-min. MVC, the mean force exerted by the experimental arm was 3.4 +/- 1.0 kg when attempting to match the tension of a 2.3-kg weight in the control arm. After the MVC, the mean force exerted in the experimental arm was 4.4 +/- 2.6 kg. The change in perception of force after a prolonged MVC as demonstrated in this study may be due to postcontraction potentiation of contraction, which has been demonstrated by others after a brief MVC.

Elbow Flexion and Extension Force During Testing in Different Positions

Donna Capuano-Pucci, MS, PT* • Jeff A. Clifford, SPTt Matthew D. Gillan, SPTt OJ David J. Pleva, SPTt Jason S. Seiler, SPTt University of Health Sciences/Chicago Medical School . -----------------The purpose of this study was to determine the effect of different body positions on the force generated by elbow flexor and extensor muscles. The Nicholas Manual Muscle Tester, a hand-held dynamometer, was used to measure the force generated by the muscles. A random sample of 28 healthy subjects was tested by a single examiner. Each muscle group was tested with gravity eliminated and with the subjects sitting and supine. The dynamometer was positioned on the extremity and a break test was performed. The data were analyzed using the two-way analysis of variance for repeated measures. A significant difference in the force generated by the muscles was noted between positions (p < 0.05) for both elbow flexors and extensors. Alterations in body position appear to influence the amount of force generated by the elbow flexor and extensor muscles.

Voluntary and electromyostimulation forces in trained and untrained men

Electromyostimulation (EMS) evoked responses of lower extremity muscles of sedentary or disabled subjects have been extensively studied to improve muscular strength and delay atrophy. However, it is not apparent whether EMS can serve a similar function in upper extremity muscles and in athletes. We compared the forces of maximal voluntary isometric contraction (MVC), percutaneous EMS-evoked tetanus, and EMS superimposed on MVC of the elbow flexors in six strength-trained and six untrained healthy men. Stimulation consisted of a 2.5-kHz alternating current sine wave modulated at 50 bursts.s-1 with a 50% duty cycle. Reliability of the criterion measures was assessed over 4 d and ranged from R = 0.746 to R = 0.948. Strength-trained men had 29% higher MVC than untrained controls (P less than 0.001). Untrained men tolerated 21.9 mA and trained men 31.3 mA of EMS current (P less than 0.021), yet tetanic forces were similar: 92.5 N vs 96.0 N (P greater than 0.196). These tetanic forces corresponded to 32% (untrained) and 24% (trained) of MVC (P less than 0.047). When EMS was superimposed on MVC, compared with MVC alone, force was significantly (P less than 0.048) lower by 10% (31 N, untrained) and 13% (55 N, trained). These data suggest that, independent of training status, percutaneous EMS reduces maximal voluntary elbow flexion forces and that tetanic forces may not be sufficiently high for purposes of muscular strength development or prevention of atrophy.

Relationship between active range of motion deficits and muscle strength and tone at the elbow in patients with hemiparesis

The purpose of this study was to describe the relationship between deficits in active range of motion (ROM) at the elbow and both agonist muscle strength and antagonist muscle tone in patients with stroke. Twenty-three patients with non-flaccid hemiparesis participated. Active elbow flexion and extension ROM were measured gravity eliminated bilaterally and ROM deficits were calculated for the paretic side. Isometric elbow flexion and extension strength were measured on the paretic side using a hand-held dynamometer. Elbow flexor and extensor muscle tone were graded manually using the Modified Ashworth Scale. The Spearman correlations between active elbow flexion ROM deficits and elbow flexion force, and between active elbow extension ROM deficits and elbow extension force were -.929 and -.772 respectively. The correlations between the elbow flexion ROM deficits and elbow extensor muscle tone, and between the elbow extension ROM deficits and elbow flexor muscle tone were .287 and .480 respectively. Regression analysis revealed a curvilinear relationship between active elbow flexion ROM deficits and elbow flexion force (R =.881), and a linear relationship between active elbow extension ROM deficits and elbow extension force (R = .771). In patients like those tested, agonist muscle force (strength) may be more important than passive antagonist restraint (tone) as a determinant of ROM deficits. Because a limited amount of muscle force is required for full active ROM, increases in muscle strength beyond some threshold will not be accompanied by further improvements in active ROM.

Influence of Shoulder Position on Maximum Voluntary Elbow Flexion Force in Stroke Patients

This study was designed to investigate the effect of shoulder position on elbow flexion force in 24 hemiparetic stroke patients. The patients' elbow flexion forces were measured bilaterally with a hand-held dynamometer while their shoulders were in adducted and abducted (90°) positions. Elbow flexion force was not significantly different between positions on either side. Therefore, any tendency that stroke patients have to flex their elbows in “synergy” with shoulder abduction cannot be explained on the basis of a positionally dependent difference in elbow flexion force production.

Trajectory control in targeted force impulses

We have previously shown that when aiming impulses of force to unpredictable flexion and extension targets, subjects prepare themselves to respond by preselecting a default amplitude and direction. In our preceding study, where flexion and extension target ranges were symmetrical, subjects prepared a single default amplitude near the center of each of the two ranges and selected a default direction arbitrarily (Favilla, Hening et al. 1989). Following target presentation, amplitude and direction were specified gradually and in parallel. By using an experimental paradigm in which target amplitudes had unequal probabilities in only one of the two directions, we no sought to determine to what extent the default amplitude prepared by subjects is dependent on the default direction that is selected for a given trial. Five normal subjects produced isometric elbow flexion and extension force impulses to match four targets requiring responses of two amplitudes in each direction. Flexion and extension targets were of the same size. In all biased probability conditions, targets were presented in unpredictable order and, in one direction, the probability of occurrence of the targets was biased (80% versus 20%). In the other direction, the two targets were equiprobable. To maximize the effect of the default settings on response parameters, we required subjects to initiate their response in synchrony with a predictable tone occuring less than a reaction time subsequent to the presentation of the visual target. Such a short interval was chosen to disclose the default parameters selected by limiting the influence of the target just presented on the amplitude and direction of the subjects' responses.(ABSTRACT TRUNCATED AT 250 WORDS)

Restoration of elbow flexion and wrist extension in brachial plexus paralyses by means of free muscle transplantation innervated by intercostal nerve

Traumatic lesions of the brachial plexus with nerve root avulsion pose extremely complex therapeutic problems. Since 1965, the authors have performed neurotization of the musculocutaneous nerve by intercostal nerves in order to restore elbow flexion. The results of this operation are considerably poorer when the interval between the trauma and the neurotization exceeds 6 months. In these late cases, the authors have used, since 1978, a free muscle transfer reinnervated by a transposed intercostal nerve. 17 patients have been operated by means of this technique; 8 of the 11 patients with a follow-up exceeding one year recovered elbow flexion force evaluated to be M3 or more. Encouraged by these results, the authors have extended this procedure to restoration of wrist extension by free musculocutaneous transfer of the gracilis muscle innervated by intercostal nerves. 17 of the 29 patients operated have a follow-up of more than one year and 9 these cases have regained wrist extension with a score of M3 or more.

A perceptual analysis of stiffness

The perception of stiffness was studied in ten human subject using two servo-controlled electromagnetic linear motors with computer-controlled stiffness, one motor coupled to each wrist of the subject. Using the contralateral limb-matching procedure in which subjects adjusted the stiffness of the motor connected to one (matching) arm until it was perceived to be the same as that connected to the other (reference) arm, a psychophysical function for stiffness was calculated. Eight different stiffness intensities were matched by subjects with five repetitions at each stimulus amplitude. The relation between the stiffness of the reference and matching motors was linear, and the accuracy with which subjects could match stiffness paralleled that reported previously for force and displacement. The Weber fraction for stiffness was 0.23 which is three times that reported for elbow flexion forces and forearm displacement. These findings were interpreted as indicating that subjects can perceive changes in the stiffness of mechanical devices used to effect action in the environment and that these perceptions are based on sensory signals conveying force and movement information.

How accurately can elbow flexion force be estimated?

The purpose of this study was to determine how accurately healthy young subjects could produce a muscular force that was 50% of their maximum and to determine the influence of several independent variables on the accuracy. On each of three nonconsecutive days, 14 men and 19 women (18 to 46 yr. old) performed three maximal elbow-flexion efforts and three efforts that they estimated to be 50% of their maximum. Isometric force was measured with a hand-held dynamometer. The estimated forces ranged from 18.3 to 81.7% of maximum. The error in force from 50% was related to whether the dominant or nondominant extremity was tested, but it was unrelated to whether maximal or submaximal efforts were performed first and to the day of testing. When the accurate generation of a submaximal force is required, naive subjects may require feedback.

Influence of head-neck rotation on static elbow flexion force of paretic side in patients with hemiparesis.

The purpose of this investigation was to examine the influence of bead and neck (HN) position in the transverse plane on the static production of elbow flexion force in the involved (paretic) upper extremity of patients with hemiparesis. Thirty-one patients who had experienced a cerebrovascular accident a mean of 44 days before testing participated in the study. Static elbow flexion force was tested with a hand-held dynamometer, twice with the HN rotated toward the paretic side and twice with the HN rotated toward the nonparetic side. Elbow flexion force did not differ with the HN in the two positions (F = 0.008, p = 931). Results of this study support the conclusion that HN position in the transverse plane does not influence the production of static elbow flexion force on the paretic side in patients with stroke. Clinicians, therefore, may wish to reexamine any emphasis they place on HN position for facilitating elbow flexion force production on the paretic side of patients with hemiparesis.

Magnitude and reliability of hand-held dynamometer measurements within and between days

The purpose of this study was to compare the magnitude and describe the reliability of repeated measurements of elbow flexion force obtained within and between days with a hand-held dynamometer (HHD). A total of 33 healthy subjects (14 men and 19 women with a mean age of 29.9 years) performed three maximal elbow flexion trials on each of three non-consecutive days. A digital HHD registered the peak force of each trial. Analysis of variance revealed that the measured forces did not differ significantly between trials, but that the forces did differ significantly between days (F= 4.541, P= 0.014). Across days, the force decreased linearly (F= 8.038, P= 0.008). The measurements were reliable within days [intra class correlation coefficient (ICC) = 0.98–0.99] and between days (ICC = 0.987). Although clinicians can be confident that consistent measurements of relatively high muscle forces can be obtained with a HHD, they should establish their own capacity to obtain reliable measurements with the HHD.