Biomedical subjects

Andris Freivalds

Publications and source records attributed to Andris Freivalds.

4 recordsLinked to original sources

PubMed2006

Laboratory evaluation of belt usage with apple buckets.

BACKGROUND: Migrant and seasonal orchard harvest workers experience musculoskeletal strain caused by carrying heavy loads and holding awkward postures. An ergonomic hip belt designed to redistribute weight from the upper back, neck, and shoulders to the hips was evaluated. METHODS: A comparison of muscle exertion (using electromyography [EMG]) of four key back and shoulder muscles and shoulder surface pressure (using a surface pressure sensor [PS]) was made among 10 laboratory volunteers under intervention and control conditions, in two postures (standing erect [0 degrees ]) and flexed [45 degrees ]). RESULTS: All but one measure showed a significant reduction in the flexed posture with the intervention. Two of eight measures showed a significant reduction in the erect posture. Correlations with shoulder discomfort were found for deep shoulder EMG (r=0.71, P=0.021) and shoulder surface pressure (r=0.58, P=0.082). CONCLUSIONS: The hip belt intervention produces significant reductions in muscle activity while in a posture commonly assumed during orchard work.

Adult↗

PubMed2005

Evaluation of hook handles in a pulling task.

To evaluate the effect of handle design characteristics on subjective ratings and pulling forces, meat-hook handles with various handle shapes, sizes, and hook positions were tested in a pulling task. Finger and phalange force data measured by force sensitive resistors and subjective ratings of discomfort were also evaluated. Generally subjects preferred 37-mm double frustum, 30-mm oval handles followed by 30-mm double frustum handles, 37-mm oval, and 45-mm double frustum handles. In the analyses of total pulling force, 37- and 45-mm double frustum handles showed less required pulling force than the others. The averages of finger force contributions to the total pulling force were 27.2, 28.1, 23.9, and 20.8% in order from index to little fingers. The average of phalange force contributions were 28.8, 33.6, and 37.6% for the distal, middle, and proximal phalanges, respectively. The findings illustrate that the pulling finger forces and subjective discomfort ratings were related to the handle shape as well as handle size.

Adult↗

PubMed2004

Evaluation of handles in a maximum gripping task.

Various hook handles were tested to evaluate the effect of handle design characteristics on subjective discomfort ratings and phalange forces in a maximum gripping task. A force glove system with 12 thin force sensitive resistor (FSR) sensors was used to measure phalange forces on the hook handles. Thirty subjects (15 males and 15 females) were tested, and generally subjects preferred 30 or 37 mm (the latter for large handed males) double frustrum handles followed by 30 mm oval handles, whereas overall they showed less preference for 37 mm oval handles and 45 mm double frustrum handles. The phalange force was more related to handle shape than to handle size in this study, i.e. the individual phalange forces on oval handles were about 8% higher than those on double frustum handles. The force distributions in the maximum gripping task showed significant differences in finger and phalange forces, in the order of middle, index, ring, and little fingers and distal, middle, and proximal phalanges from the highest to the lowest forces. The findings of this study may provide guidelines for designing double frustum handles for satisfying user's preference and oval handles for obtaining high phalange forces in a maximum gripping task.

Adolescent↗

PubMed2004

The development of risk assessment models for carpal tunnel syndrome: a case-referent study.

The present study developed risk assessment models for carpal tunnel syndrome (CTS) which can provide information of the likelihood of developing CTS for an individual having certain personal characteristics and occupational risks. A case-referent study was conducted consisting of two case groups and one referent group: (1) 22 work-related CTS patients (W-CTS), (2) 25 non-work related CTS patients (NW-CTS), and (3) 50 healthy workers (HEALTHY) having had no CTS history. The classification of CTS patients into one of the case groups was determined according to the type of insurance covering their medical costs. Personal characteristics, psychosocial stresses at work, and physical work conditions were surveyed by using a questionnaire tailor-designed to CTS (reliability of each scale > or = 0.7). By contrasting the risk information of each case group to that of the referent group, three logistic regression models were developed: W-CTS/HEALTHY, NW-CTS/HEALTHY, and C-CTS/HEALTHY (C-CTS, the combined group of W-CTS and NW-CTS). ROC analysis indicated that the models have satisfactory discriminability (d' = 1.91 to 2.51) and high classification accuracy (overall accuracy = 83-89%). Both W-CTS/HEALTHY and C-CTS/HEALTHY include personal and physical factors, while NW-CTS/HEALTHY involves only personal factors. This suggests that the injury causation of NW-CTS patients should be attributable mainly to their 'high' personal susceptibility to the disorder rather than exposure to adverse work conditions, while that of W-CTS patients be attributable to improper work conditions and CTS-prone personal characteristics in combination.

Carpal Tunnel Syndrome↗