Does reduced hamstring flexibility affect trunk and pelvic movement strategies during manual handling?

Department of Physical Therapy, Laboratory of Preventive Physical Therapy and Ergonomics, Federal University of São Carlos (UFSCar), Via Washington Luiz, Km 235, CEP 13565-905, São Carlos, SP, Brazil
International Journal of Industrial Ergonomics (Impact Factor: 1.21). 02/2013; 39(1):115-120. DOI: 10.1016/j.ergon.2008.05.004

ABSTRACT ObjectiveTo evaluate the influence of reduced hamstring flexibility on trunk and pelvic movement strategies adopted by healthy males during manual handling tasks.MethodsSeventeen subjects performed a sagittally symmetrical handling task involving a 15 kg box, and hamstring flexibility was measured by means of the Straight Leg Raise Test. The task was filmed with a 2D acquisition system at a sampling rate of 50 frames/s. The images were digitized and a MatLab® routine was implemented to analyze the trunk and pelvis movement patterns. Kinematic data from trunk movements were plotted against the data from pelvic movements in order to provide coordination analysis.ResultsSubjects with reduced flexibility presented higher trunk movement amplitudes and a restriction on pelvis movements during handling tasks. Movement coordination was also influenced by the reduced flexibility.ConclusionThe results suggest that reduced hamstring flexibility is related to increased trunk angles, which can overload the spine during manual materials handling.Relevance to industryHamstring shortness can influence pelvic dynamics and, consequently, affects trunk movements adopted by subjects during occupational activities. As movement restrictions can reduce the capacity to obtain appropriate postural responses, this should be accounted for in order to provide better comprehension on how to prevent low back injuries in the occupational setting.

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    ABSTRACT: The purpose of this study was to examine the effects of a 1-minute stretching programme and 5 weeks of detraining on sit-and-reach score among schoolchildren aged 5–6 years in a physical education setting. Forty-five schoolchildren 5–6 years old from two classes were clustered randomly assigned to an experimental group (n ¼ 23) or a control group (n ¼ 22). During the physical education classes, the students of the experimental group performed a 1-minute stretching programme twice a week for 8 weeks. Subsequently, these participants underwent a 5-week detraining period. The classic sit-and-reach test was performed at the beginning and at the end of the development programme, as well as at the end of the detraining period. The results of the two-way ANOVA showed that the intervention programme increased significantly the students’ sit-and-reach scores ( p < 0.001). However, after 5 weeks of detraining, children’s flexibility reverted back to the baseline levels ( p > 0.05). Although an only 1-minute stretching programme seems to develop the schoolchildren’s flexibility, after the 5-week detraining period students’ score reverts back to its initial level. This knowledge could help physical education teachers to design programmes that permit students to increase and maintain flexibility levels along the entire academic year.
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May 21, 2014