Enthesis bilateral asymmetry in humans and African apes

Changes in Activities with the Shift to Agriculture in the Southeastern United States

There are neural connections between the upper and lower limbs of humans that enable muscle activation in one limb pair (upper or lower) to modulate muscle activation in the other limb pair (lower or upper, respectively). The aims of this study were to extend previous findings regarding submaximal exercise to maximal effort exercise and determine whether there is an ipsilateral or contralateral bias to the neural coupling during a rhythmic locomotor-like task. We measured upper and lower limb muscle activity, joint kinematics, and limb forces in neurologically intact subjects (n = 16) as they performed recumbent stepping using different combinations of upper and lower limb efforts. We found increased muscle activation in passive lower limbs during active upper limb effort compared with passive upper limb effort. Likewise, increased muscle activation in passive upper limbs occurred during active lower limb effort compared with passive lower limb effort, suggesting a bidirectional effect. Maximal muscle activation in the active lower limbs was not different between conditions with active upper limb effort and conditions with passive upper limb movement. Similarly, maximal muscle activation in the active upper limbs was not different between conditions with active lower limb effort and conditions with passive lower limb movement. Further comparisons revealed that neural coupling was primarily from active upper limb muscles to passive ipsilateral lower limb muscles. These findings indicate that interlimb neural coupling affects muscle recruitment during maximal effort upper and lower limb rhythmic exercise and provides insight into the architecture of the neural coupling.

Stroke is a leading cause of long-term disability. As a consequence of stroke and associated upper motor neuron (UMN) syndrome, stroke survivors are often left with muscle over activity, including spasticity. Spasticity is characterized by over- activity in muscles after injury to the central nervous system. When left untreated, post-stroke spasticity (PSS) can lead to contractures, pain and deformity, involuntary movement, and greater functional impairments (eg, reduced mobility, self-care and dressing). Spasticity is a common symptom after stroke, arising in about 30% of patients, and usually occurs within the first few days or weeks [1]. However, the onset of spasticity is highly variable and can occur in the short- medium or long-term post-stroke period [2]. Post-stroke hemiparesis, together with abnormal muscle tone, is a major cause of morbidity and disability. Patients with poststroke spasticity often demonstrate recognizable antigravity postural patterns (Fig 1) characterized by shoulder adduction, elbow and wrist flexion in the upper limb, hip adduction, knee extension and ankle plantar flexion in the lower limb. This “hemiplegic” posture, which is thought to result from increased motor neuron activity in antigravity muscles, significantly interferes with body image, balance and gait. BoNT-A, one of the most potent biologic toxins known to man acts by blocking neuromuscular transmission via inhibiting acetylcholine release [3]. BoNT-A treatment in post-stroke upper and lower limb spasticity is a safe and effective procedure to decrease muscle tone and increase the range of motion. More recent studies are demonstrating the importance for the rehabilitation therapist intervention to work alongside the physician to create more positive and significant effects on active function [4]. Daily stretching exercise is the key for the long-lasting benefits. BoNT-A Injections, Ultrasound guided technique, performed by a Physician in combination with physiotherapy and outcomes measurements are used to improve upper and lower limb function in stroke patients with spasticity in the clinical setting [5]. We would like to share our experience on the benefit of the ultrasound guided technique to target the muscles and our results in setting up a spasticity clinic for post-stroke patients.

Limb bone bilateral asymmetry: variability and commonality among modern humans

Effect of a novel teat preparation system on upper extremity muscle activity among U.S. large-herd dairy parlor workers

An important aspect of motor control is the ability to perform tasks with the upper limbs while maintaining whole body balance. However, little is known about the coordination of upper limb voluntary and whole body postural control after mechanical disturbances that require both upper limb motor corrections to attain a behavioral goal and lower limb motor responses to maintain whole body balance. The present study identified the temporal organization of muscle responses and center of pressure (COP) changes following mechanical perturbations during reaching. Our results demonstrate that muscle responses in the upper limb are evoked first (∼50 ms), with lower limb muscle activity occurring immediately after, in as little as ∼60 ms after perturbation. Hand motion was immediately altered by the load, while COP changes occurred after ∼100 ms, when lower limb muscle activity was already present. Our secondary findings showed that both muscle activity and COP changes were influenced by behavioral context (by altering target shape, circle vs. rectangle). Voluntary and postural actions initially directed the hand toward the center of both target types, but after the perturbation upper limb and postural responses redirected the hand toward different spatial locations along the rectangle. Muscle activity was increased for both upper and lower limbs when correcting to the circle vs. the rectangle, and these differences emerged as early as the long-latency epoch (∼75-120 ms). Our results demonstrate that postural responses are rapidly and flexibly altered to consider the behavioral goal of the upper limb.NEW & NOTEWORTHY The present work establishes that, when reaching to a target while standing, perturbations applied to the upper limb elicit a rapid response in lower limb muscles. Unlike voluntary movements, postural responses do not occur before corrections of the upper limb. We show the first evidence that corrective postural adjustments are modulated by upper limb behavioral context (target shape). Importantly, this indicates that postural responses take into account upper limb feedback for online control.

Effects of milking unit design on upper extremity muscle activity during attachment among U.S. large-herd parlor workers

Galc ablation in Schwann cells produces a demyelinating peripheral neuropathy characterized by psychosine formation but lacking globoid cells

Active and passive contributions to arm swing: Implications of the restriction of pelvis motion during human locomotion

Objective:The study aimed to assess the electrophysiological parameters (Hofmann reflex [H-reflex] and motor nerve conduction velocity [MNCV]) on children’s upper and lower limbs with lumbosacral meningomyelocele (MMC) and age-matched control to see the effect of the MMC on the cervical segment of the spinal cord.Materials and Methods:The present study was performed on infants with lumbosacral MMC. Twenty-five infants were examined with a mean age of 50 days of either sex. Out of them, 13 infants were in control and the remaining 12 were diagnosed with MMC. The H-reflex parameter and MNCV were recorded in these children’s right upper and lower limbs.Results:H-reflex was elicited in all the control group babies. In MMC, the H-reflex was elicited in the upper limbs. However, H-reflex was not elicited in the lower limbs of a few MMC babies. The upper limb’s H-reflex parameters and conduction velocity were significantly higher than those corresponding lower limbs in control babies. In MMC, where the H-reflex was elicited, such differences in the lower and upper limbs were not observed. However, the values of MNCV in the upper limb (right median nerve) were significantly less, and the values of Hmax in the lower limb (soleus muscle) were significantly more in MMC babies than in the control group.Conclusions:The values of electrophysiological parameters were higher in the upper limbs as compared to the corresponding lower limbs in control. These values were not altered in the upper limbs than those corresponding lower limbs of MMC, suggesting that motor function development was impaired/delayed in the spinal segment cranial to MMC lesion, and motor impairment in MMC children is mostly a result of upper motor neuron dysfunction.

Humans spontaneously alternate between walking and running with a change in locomotion speed, which is termed gait transition. It has been suggested that sensory information in the muscle is a factor that triggers the gait transition; however, direct evidence for this has not been presented. In addition, it has been suggested that upper limb movement during human gait facilitates leg muscle activity due to the neural coupling between the upper and lower limbs. We hypothesized that a disturbance of afferent inputs in the neural coupling between the upper and lower limbs suppressively act on the gait transition. Here, we aimed to deepen the understanding of contribution of the afferent inputs in neural coupling between the upper and lower limbs to the gait transition. Eight participants performed spontaneous walk-to-run and run-to-walk transitions under two different conditions: Normal (arms swinging normally); and TIS (partial blocking of afferent inputs from the arms by inducing tourniquet ischemia). We compared the preferred gait transition speeds (PTS), joint angles, muscle activities, and muscle synergies between the two conditions. Control of coordinated muscle activities can be investigated by analyzing muscle synergies, which are groups of muscles that activate together. The PTS, joint angle profiles, muscle activity profiles, and muscle synergies were nearly identical between conditions (walk-to-run PTS at Normal and TIS: 6.9 ± 0.4 and 6.9 ± 0.4 km/h; run-to-walk PTS at Normal and TIS: 6.6 ± 0.4 and 6.5 ± 0.4 km/h; p = 0.869 and p = 0.402, respectively). Therefore, we conclude that the control of gait transition is little affected by disturbing the neural coupling between the upper and lower limbs by reducing afferent inputs from the forearms and distal upper arms. Our findings might reflect robustness of the neural coupling between the upper and lower limbs during locomotion against neural perturbations or disturbances.

During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient's lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes (P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.

Objective: The aim of this study is to evaluate a novel composite measure of active range of motion (XA) and determine whether this measure correlates with active function. Design: Post hoc analysis of two randomized, placebo-controlled, double-blind studies with open-label extensions exploring changes in active function with abobotulinumtoxinA. Setting: Tertiary rehabilitation centers in Australia, Europe, and the United States. Subjects: Adults with upper (n = 254) or lower (n = 345) limb spastic paresis following stroke or brain trauma. Interventions: AbobotulinumtoxinA (⩽5 treatment cycles) in the upper or lower limb. Main measures: XA was used to calculate a novel composite measure (CXA), defined as the sum of XA against elbow, wrist, and extrinsic finger flexors (upper limb) or soleus and gastrocnemius muscles (lower limb). Active function was assessed by the Modified Frenchay Scale and 10-m comfortable barefoot walking speed in the upper limb and lower limb, respectively. Correlations between CXA and active function at Weeks 4 and 12 of open-label cycles were explored. Results: CXA and active function were moderately correlated in the upper limb (P < 0.0001–0.0004, r = 0.476–0.636) and weakly correlated in the lower limb (P < 0.0001–0.0284, r = 0.186–0.285) at Weeks 4 and 12 of each open-label cycle. Changes in CXA and active function were weakly correlated only in the upper limb (Cycle 2 Week 12, P = 0.0160, r = 0.213; Cycle 3 Week 4, P = 0.0031, r = 0.296). Across cycles, CXA improvements peaked at Week 4, while functional improvements peaked at Week 12. Conclusion: CXA is a valid measure for functional impairments in spastic paresis. CXA improvements following abobotulinumtoxinA injection correlated with and preceded active functional improvements.

The purpose of this study was to verify the effect on the general mood scale and upper and lower limb muscle activity according to participation in the HealSwing exercise. The subjects of the study randomly selected 8 middle school students and compared the difference in mood and muscle activity when performing the HealSwing exercise(HSE) and bicycle exercise(CE). The exercise protocol consisted of warm-up, this exercise, and the cool-down, and this exercise was carried out in three stages in both HSE and CE. The general mood scale factor in the measurement items was measured before and after the exercise with a sevenstep score that increased from one point to seven points from positive emotion to negative emotion. The upper and lower limb activity factors measured the upper and lower limb muscle activity factors: biceps brachii caput longus, flexor caput radialis, rectus femoris, gastrocnemius medialis muscles. The results showed a significant difference between the main effects(p.001) and the interaction effects(p.01) in the analysis between the exercise form and the measurement period. In muscle activity variables, the upper limbs were significantly higher in area, mean, and peak during the HealSwing exercise than in the bicycle exercise at all stages of exercise. The rectus femoris muscles of the lower limbs were significantly higher in area, mean, and peak during the HealSwing exercise than in the bicycle exercises in all stages of exercise, but the gastrocnemius medialis muscles were not different. In conclusion, the HealSwing exercise applied to this study showed significant effects in mood, and in upper and lower muscle activity, the upper and lower muscle activity showed significant effects on the biceps brachii caput longus muscles, the flexor caput radialis muscles and the rectus femoris muscles, but the gastrocnemius medialis muscles showed no significant difference. Therefore, it is expected that the application of the HealSwing exercise program in the sports field will contribute to the health management and promotion of the people and the quality of life.

Pedaling is a physical exercise practiced with either the upper or the lower limbs. Muscle coordination during these exercises has been previously studied using electromyography and synergy analysis, and three to four synergies have been identified for the lower and upper limbs. The question of synergy adaptabilities has not been investigated during pedaling with the upper limbs, and the impact of various modalities is yet not known. This study investigates the effect of pedal type (either clipped/gripped or flat) on the torque performance and the synergy in both upper and lower limbs. Torques applied by six participants while pedaling at 30% of their maximal power have been recorded for both upper and lower limbs. Electromyographic data of 11 muscles on the upper limbs and 11 muscles on the lower limbs have been recorded and synergies extracted and compared between pedal types. Results showed that the torques were not modified by the pedal types for the lower limbs while a deep adaptation is observable for the upper limbs. Participants indeed used the additional holding possibility by pulling the pedals on top of the pushing action. Synergies were accordingly modified for upper limbs while they remain stable for the lower limbs. In both limbs, the synergies showed a good reproducibility even if larger variabilities were observed for the upper limbs. This pilot study highlights the adaptability of muscle synergies according to the condition of movement execution, especially observed for the upper limbs, and can bring some new insights for the rehabilitation exercises.