Work-related musculoskeletal disorders and risk factors among weavers: A cross-sectional study.

Background: Work-related musculoskeletal disorders (WRMSDs) are a major health issue for low-income countries because of their high prevalence among workers and on account of the scarcity of ergonomic preventative measures in the workplace.

Objectives: To determine the prevalence of WRMSDs among weavers, assess their consequences, and analyse the associated occupational risk factors.

Method: A cross-sectional survey was carried out among 257 handloom weavers using the Nordic questionnaireand the working conditions were assessed through a descriptive analysis using the key indicator method.

Biomechanical behavior of the lower limbs and of the joints when landing from different heights.

Landing from a jump is a challenging task as the energy accumulated during the aerial phase of the jump must be fully dissipated by the lower limbs during landing; the higher the jump height, the greater the amount of energy to be dissipated. In the present study, we aim to understand (1) how the biomechanical behavior is tuned as a function of the mechanical demand, and (2) the relationship between the self-selected landing strategy and the behavior of the joints. Fourteen subjects were asked to drop off a box of 10 to 60 cm height and land on the ground.

Effect of age and speed on the step-to-step transition strategies in children.

The development and acquisition of mature walking in children is multifactorial, depending among others on foot interaction with the ground, body dynamics and the knowledge of the 'rules' stemming from the gravity field. Indeed, each step the velocity of the centre of mass must be redirected upwards. This redirection may be initiated by the trailing leg, propulsing forward and upward the body before foot contact, or later by the loading limb after the contact with the ground.

Nonspecific chronic low back pain conditions and therapeutic practices in Burkina Faso.

Background: The management of nonspecific chronic low back pain (NCLBP) is complex because of its multifactorial origin.

Objectives: To investigate NCLBP care by evaluating patients' condition and therapeutic management of health practitioners.

Method: A cross-sectional survey was carried out among 92 patients with NCLBP, 30 medical practitioners (MP) and 20 physiotherapists (PT) from four public health institutions in Burkina Faso.

Control of landing under conditions of height-induced threat.

Purpose: Landing involves a tuned anticipatory control to allow for soft and safe contact with the ground. Fearful situations are known to affect postural control strategies during standing, but it is still unclear how fear interferes with the control of a voluntary dynamic task requiring coordination between posture and movement.

Methods: Ground reaction forces, limb movements, physiological arousal, and perceived levels of confidence and fear of falling were recorded when hopping off a box to a platform situated 0.

The Timed Up and Go Test in Children: Does Protocol Choice Matter? A Systematic Review.

Purpose: Results on reliability and normative data for the Timed Up and Go test (TUG) in children who are developing typically are systematically reviewed.

Summary Of Key Points: Six different TUG protocols are presented for which normative data are available for ages 3 to 18 years. TUG time is consistent within and between raters and sessions and is influenced by age.

Effect of age and speed on the step-to-step transition phase during walking.

Gait is a powerful measurement tool to evaluate the functional decline throughout ageing. Falls in elderly adults happen mainly during the redirection of the center of mass of the body (CoM) in the transition between steps. In young adults, this step-to-step transition begins before the double contact phase (DC) with a simultaneous forward and upward acceleration of the CoM.

Determination of the vertical ground reaction forces acting upon individual limbs during healthy and clinical gait.

In gait lab, the quantification of the ground reaction forces (GRFs) acting upon individual limbs is required for dynamic analysis. However, using a single force plate, only the resultant GRF acting on both limbs is available. The aims of this study are (a) to develop an algorithm allowing a reliable detection of the front foot contact (FC) and the back foot off (FO) time events when walking on a single plate, (b) to reconstruct the vertical GRFs acting upon each limb during the double contact phase (DC) and (c) to evaluate this reconstruction on healthy and clinical gait trials.

Motor Control of Landing from a Jump in Simulated Hypergravity.

On Earth, when landing from a counter-movement jump, muscles contract before touchdown to anticipate imminent collision with the ground and place the limbs in a proper position. This study assesses how the control of landing is modified when gravity is increased above 1 g. Hypergravity was simulated in two different ways: (1) by generating centrifugal forces during turns of an aircraft (A300) and (2) by pulling the subject downwards in the laboratory with a Subject Loading System (SLS).

Triceps surae stretch reflex modulation after a mechanically evoked ankle dorsiflexion during the swing phase of human running.

The purpose of this study was to mechanically evoke a triceps surae stretch reflex during the swing phase of running, to study its within-the-step phase dependency. Seven participants ran on a treadmill at 2.8 m·s-1 wearing an exoskeleton capable of evoking a sudden ankle dorsiflexion.

Running humans attain optimal elastic bounce in their teens.

In an ideal elastic bounce of the body, the time during which mechanical energy is released during the push equals the time during which mechanical energy is absorbed during the brake, and the maximal upward velocity attained by the center of mass equals the maximal downward velocity. Deviations from this ideal model, prolonged push duration and lower upward velocity, have found to be greater in older than in younger adult humans. However it is not known how similarity to the elastic bounce changes during growth and whether an optimal elastic bounce is attained at some age.

Calculation of the external work done during walking in very young children.

During walking, muscles must perform positive work to replace the energy lost from the body at each step, even if the average speed is constant and the terrain level. Young children have immature and irregular walk, but little is known about the effect of this walking pattern on the muscular external work done. Our objective was to measure using force platforms and the method of Cavagna (J Appl Physiol 39:174-179, 1975) the amount of muscular external work done by 1-year-old-, 4-year-old children and adults during walking.

Neurons in the pontomedullary reticular formation signal posture and movement both as an integrated behavior and independently.

We have previously suggested that the discharge characteristics of some neurons in the pontomedullary reticular formation (PMRF) are contingent on the simultaneous requirement for activity in both ipsilateral flexor muscles and contralateral extensors. To test this hypothesis we trained cats to stand on four force platforms and to perform a task in which they were required to reach forward with one forelimb or the other and depress a lever. As such the task required the cat to make a flexion movement followed by an extension in the reaching limb while maintaining postural support by increasing extensor muscle tonus in the supporting limbs.

Descending signals from the pontomedullary reticular formation are bilateral, asymmetric, and gated during reaching movements in the cat.

We examined the contribution of neurons within the pontomedullary reticular formation (PMRF) to the control of reaching movements in the cat. We recorded the activity of 127 reticular neurons, including 56 reticulospinal neurons, during movements of each forelimb; 67/127 of these neurons discharged prior to the onset of activity in the prime flexor muscles during the reach of the ipsilateral limb and form the focus of this report. Most neurons (63/67) showed similar patterns and levels of discharge activity during reaches of either limb, although activity was slightly greater during reach of the ipsilateral limb.

Energetics of load carrying in Nepalese porters.

Nepalese porters routinely carry head-supported loads equal to 100 to 200% of their body weight (Mb) for many days up and down steep mountain footpaths at high altitudes. Previous studies have shown that African women carry head-supported loads of up to 60% of their Mb far more economically than army recruits carrying equivalent loads in backpacks. Here we show that Nepalese porters carry heavier loads even more economically than African women.

Independent and convergent signals from the pontomedullary reticular formation contribute to the control of posture and movement during reaching in the cat.

We have addressed the nature of the postural control signals contained within the discharge activity of neurons in the pontomedullary reticular formation, including reticulospinal neurons, during a reaching task in the cat. We recorded the activity of 142 neurons during ipsilateral reaching movements that required anticipatory postural adjustments (APAs) in the supporting limbs to maintain equilibrium. Discharge activity in 82/142 (58%) neurons was significantly increased before the onset of the reach.

Cortical and brainstem control of locomotion.

While a basic locomotor rhythm is centrally generated by spinal circuits, descending pathways are critical for ensuring appropriate anticipatory modifications of gait to accommodate uneven terrain. Neurons in the motor cortex command the changes in muscle activity required to modify limb trajectory when stepping over obstacles. Simultaneously, neurons in the brainstem reticular formation ensure that these modifications are superimposed on an appropriate base of postural support.

Strategies for the integration of posture and movement during reaching in the cat.

We have examined the relationship between the movement and the anticipatory postural adjustments (APAs) that precede that movement during a reaching task in the cat. We recorded ground reaction forces in all 3 planes from all 4 limbs as well as electromyographic (EMG) activity from limb and axial muscles. The reaching movement was always preceded by an APA that was characterized by a loading of the reaching forelimb and an unloading of the support forelimb.