Biomedical subjects

Michael Voigt

Publications and source records attributed to Michael Voigt.

6 recordsLinked to original sources

PubMed2003

Standardized low-load repetitive work: evidence of different motor control strategies between experienced workers and a reference group.

The purpose of this laboratory study was to evaluate the possible differences in motor strategies to a new standardized low-load repetitive work task in between healthy experienced workers and a reference group. Work task event duration, i.e. working rhythm, cutting forces, surface electromyographic (EMG) activity from four shoulder muscles, postural activity, and arm and trunk movements in 3D were recorded during low-load repetitive work simulation. The experienced group showed lower EMG activity and frequency contents (P<0.05), more abducted position of the upper arm and forward flexion of the trunk prior to work simulation (P<0.05), and increased arm and trunk range of motion (P<0.05) compared with the reference group. The results highlight that experienced butchers have a different motor strategy compared with a reference group, i.e. more variable form of coordination pattern. Furthermore, the initial implementation of a possible protective motor strategy by experienced workers might be a very important prognostic factor.

Adult↗

PubMed2003

Albumin versus crystalloid therapy in the management of hepatorenal syndrome: a model for using meta analysis in cost effectiveness studies and the design of clinical trials.

We applied traditional methods of gathering, integrating and summarizing findings of current literature, with new approaches for assessing the cost effectiveness of two treatments for hepatorenal syndrome (HRS). Findings of this cost effectiveness study are used to form a proposal for a multi-center prospective clinical trial, to assess the economic and clinical benefits of albumen versus crystalloid therapy in the care of these patients. Our initial findings suggest that albumin therapy is superior to standard crystalloid therapy, in the treatment of HRS patients. The number of survival days appears to increase with this form of therapy per dollar cost, while patients await liver transplantation.

Albumins↗

PubMed2002

The effects of neck-shoulder pain development on sensory-motor interactions among female workers in the poultry and fish industries. A prospective study.

OBJECTIVES: The purpose of this prospective laboratory study was to follow newly employed workers in the fish or poultry industry for 6 months and investigate possible changes in sensory manifestations and motor performance during low load, repetitive work simulation. It was investigated whether the changes were an effect of employment duration and of development of neck-shoulder complaints. METHODS: Twelve newly employed female filleting employees without any sign of neck-shoulder tenderness/pain at the time of employment of 0 months took part in two laboratory recording sessions planned within 1 month of employment and after 6 months of employment at the plant. After 6 months, six workers out of 12 had developed pain and/or tenderness in the neck-shoulder region. The recording sessions evaluated sensory-motor aspects by measuring pressure pain threshold, work-task timing, cutting forces, surface electromyographic activity of four shoulder muscles, displacement of the centre of pressure, and 3D movements of the arm and trunk during simulation of low load, repetitive filleting. RESULTS: Effects due to the duration of employment were observed in both groups, i.e. decreased sensibility to pressure, decrease in the duration of the work cycle, increased arm starting position with respect to the upright position, and decreased range of motion of the arm and trunk (P<0.05) after 6 months. Among the workers with neck-shoulder complaints, increased sensibility to pressure, lower force level, higher electromyographic activity, decreased amplitude of arm movement, and increased trunk posture and movement amplitude (P<0.05) were observed, compared with workers without complaints. CONCLUSIONS: Differences in terms of sensory manifestations and motor control strategy were seen after 6 months of employment with or without neck-shoulder complaints. In general, changes in sensory manifestations and motor control strategy after 6 months work were most likely of importance, as they underlined a learning process as employment duration increased. Moreover, the present sensory-motor changes observed among workers with neck-shoulder complaints highlighted the potential physical risk factors associated with low load, repetitive work.

Adult↗

PubMed2002

Shoulder reflexes.

Dynamic shoulder stability is dependent on muscular coordination and sensory inputs. In the shoulder, mechanoreceptors are found in the coracoacromial ligament, the rotator cuff tendons, the musculotendinous junctions of the rotator cuff and in the capsule. The number of receptors in the capsule is small compared to the number in the other shoulder structures. Proprioceptive information from numerous receptors in muscles and tendons is mediated via fast conducting nervefibers and probably contribute more to kinaestethic sensation than information from capsule and ligaments. Therefore it seems likely that the joint receptors have a more distinct role for the kinaestethic sense than muscle receptors. In cats a direct reflex from the afferents innervating the shoulder to the muscles around the shoulder has been presented. The reflex had an extremely short latency (2.7-3.1 ms). In man, a very long latency (300 ms) excitatory reflex has been found when nerves in the capsule were stimulated electrically during shoulder surgery. In addition, when the anterior-inferior capsule was excited in conscious humans with modest amplitude electrical stimuli during muscle activity, a strong inhibition was found with an average latency of 33 ms. Stimulation of the sensory nerves in the coracoacromial ligament has also been found to modify muscle activity strongly. Even though our understanding of the control of shoulder motion is incomplete, it is clear that sensory inputs can strongly modify muscle activity around the shoulder. This has implications for rehabilitation and shoulder surgery.

Electric Stimulation↗

PubMed2002

Inversion injury biomechanics in functional ankle instability: a cadaver study of simulated gait.

The purpose of this study was to test pathogenetic models for the "unprovoked" ankle inversion injuries seen in functional ankle unstable subjects. The consequence of spatial mal-alignment of the ankle/foot complex on the risk of producing an ankle inversion torque at heel-strike and during swing-phase follow through was analyzed in cadaver simulations. Heel-strike was simulated using a 5 degrees of freedom rig in a material testing machine. A set-up capable of accelerating lower limb specimens towards a support surface simulated swing-phase follow through. Joint excursions were monitored with flexible wire goniometers. The unloaded ankle/foot complex was placed in increasing positions of talar and subtalar joint excursions. The consequences of these settings on the behavior of the ankle/foot complex at heel-strike and when the lateral part of the foot "caught" the ground during swing-phase follow through were monitored. An inversion torque at heel-strike was first seen when the unloaded foot was set in positions exceeding 30 degrees of inversion combined with full plantar flexion and 10 degrees of internal tibial rotation. A collision between the lateral border of a 20 degrees inverted, but otherwise neutral ankle/foot complex and the ground surface during swing-phase follow through forced the foot into the full limit of inversion, plantar flexion and internal tibial rotation measurable in this set-up. Clinical consequence: The study showed that the foot/ankle complex exhibits a high degree of intrinsic stability at heel-strike. The foot will thus stabilize itself and move into normal eversion at the beginning of the stance-phase even though it is set to the ground in a substantial degree of mal-alignment. In contrast, the swing-phase collision model provides a link that can connect the small deficits in inversion angle awareness measured in chronic functional ankle unstable subjects with an increased risk in this group of sustaining ankle inversion injuries.

Aged↗

PubMed2002

Assessment of functional series elastic stiffness of human dorsiflexors with fast controlled releases.

The series elastic stiffness (SES) of the human dorsiflexors was investigated in vivo with the fast controlled release method in 8 subjects. The maximum moment of a voluntary contraction (66 +/- 17 Nm) was significantly higher than the maximum moment with electrical stimulation of tibialis anterior (34 +/- 16 Nm). At an ankle moment of 34 Nm produced with either voluntary or electrical stimulation, we found a significantly different SES of 219 +/- 54 and 149 +/- 54 Nm. rad(-1), respectively. It is proposed that this is due to the fact that, during voluntary contraction, more elastic tissue parallel with each other is involved, because of coactivation of the extensor hallucis longus, extensor digitorum longus, and tibialis anterior. This shows that, for a functional assessment of the SES of the dorsiflexors, one has to include the toe extensors, which is possible with the fast controlled release method. Additionally, our results demonstrated that the SES of the human dorsiflexors at moment levels up to about isometric maximum did not reach an asymptote at which the stiffness is independent of moment, i.e., the series elastic component of the dorsiflexors is during daily activities loaded for the greatest part in the nonlinear part of the stress-strain function.

Adult↗