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Journal ArticleDOI

Psychophysical and psychological comparison of squat and stoop lifting by young females

01 Jan 2000-The Australian journal of physiotherapy (Elsevier)-Vol. 46, Iss: 1, pp 27-32

TL;DR: The results provide limited support for use of stoop rather than squat technique for lifting a medium sized box from floor to knuckle height.

AbstractPsychophysical and psychological criteria are accepted risk measures for manual handling task assessment, yet few reports have compared squat and stoop using these criteria. Seventeen university students participated in a within-subjects cross over design study to compare squat and stoop techniques using maximum acceptable weight (MAW), perceptions of exertion (RPE), discomfort and preference. Mean (SD) MAW for squat was lower than for stoop (7.0 (2.2) kg vs 8.5 (2.4) kg) and RPE for squat was greater than for stoop (15.2 (1.5) kg vs 13.3 (1.5) kg). More subjects reported discomfort following squat and a preference for stoop. The results provide limited support for use of stoop rather than squat technique for lifting a medium sized box from floor to knuckle height.

Topics: Squat (53%)

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Citations
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Journal ArticleDOI
Leon Straker1
Abstract: Squat lifting is widely regarded as the ‘correct’ technique for lifting low-lying objects. However what evidence is there to support this technique? Further, is the evidence sufficient to justify teaching the technique? Until the last decade there was very little evidence to support the use of squat lifting of low-lying objects. Semi-squat lifting has been the centre of renewed interest in recent years. However there is less evidence for semi-squat, either for or against, than for stoop and squat techniques. Whilst it may provide a reasonable compromise between stoop and squat, it may be a mixture of the disadvantages of stoop and squat or even create new problems. Stoop lifting is commonly understood to be ‘incorrect’. The vast majority of advice literature on lifting technique recommends against using stoop lifting. However some research results actually support the use of stoop lifting. This paper summarises the available evidence in support of using squat, semi-squat and stoop techniques to lift low-lying objects. Evidence is presented under headings of psychophysical, physiological, biomechanical, subjective, performance and clinical. No previous publication summarising this evidence could be found, and the results may be surprising to many. Relevance to industry Squat lifting technique training is one of the most common interventions made by industry in an attempt to reduce the musculoskeletal disorders associated with manual tasks. However the research literature has questioned this perception for many years. This article provides a concise summary to help industry understand the evidence.

89 citations


Journal ArticleDOI
TL;DR: This study investigated the relationship between the active cervical range of motion (ROM) and changes in the head and neck posture after continuous visual display terminal (VDT) work and measured and videotaped the craniocervical and cervicothoracic angles before and after VDT work.
Abstract: This study investigated the relationship between the active cervical range of motion (ROM) and changes in the head and neck posture after continuous visual display terminal (VDT) work. Twenty VDT workers were recruited from laboratories. The active cervical ROM of the participants was measured and videotaped to capture the craniocervical and cervicothoracic angles using a single video camera before and after VDT work. Pearson correlation coefficients were used to quantify the linear relationship between active cervical ROM measurements and the changes in the craniocervical and cervicothoracic angles after continuous VDT work. Active neck extension (r=-0.84, p<0.01) was negatively correlated with the mean craniocervical angle, and active neck flexion (r=-0.82, p<0.01) and left lateral flexion (r=-0.67, p<0.01) were negatively correlated with the mean cervicothoracic angle.

55 citations


Journal ArticleDOI
TL;DR: Changes in Craniocervical and Trunk Flexion Angles and Gluteal Pressure during VDT Work with Continuous Cross‐legged Sitting are studied.
Abstract: Objectives: This study investigated changes in craniocervical and trunk flexion angles and gluteal pressure on both sides during visual display terminal (VDT) work with continuous cross-legged sitting. Methods: The gluteal pressures of ten VDT workers, who were recruited from laboratories, were measured using a Teckscan system and videotaped using a single video camera to capture the craniocervical and trunk flexion angles during VDT work at 30 s, 10, 20 and 30 min. Results: The craniocervical angle was significantly increased at 10 and 20 min compared with the initial angle (p<0.05). The trunk flexion angle was significantly decreased at 30 s, 10, 20 and 30 min (p<0.05). The gluteal pressure of the crossed-leg side significantly increased at 30 s, 10 and 20 min (p<0.05). The gluteal pressure of the uncrossed-leg side significantly decreased at 30 s (p<0.05). Conclusion: We found that cross-legged sitting during VDT work may exert disadvantageous postural effects resulting from craniocervical and trunk flexion angles and gluteal pressure. Therefore, this posture could not be recommended during long-term VDT work.

26 citations


Journal ArticleDOI
TL;DR: Avoiding rounding the back while lifting is a common belief in PTs and MHAs, despite the lack of evidence that any specific spinal posture is a risk factor for low back pain.
Abstract: Background It is commonly believed lifting is dangerous and the back should be straight during lifting. These beliefs may arise from healthcare professionals, yet no study has evaluated the lifting and back beliefs of manual handling advisors (MHAs) and physiotherapists (PTs). Objectives To evaluate (i) what lifting technique MHAs and PTs perceive as safest, and why, and (ii) the back pain beliefs of MHAs and PTs. Design Data was collected via an electronic survey. Method Participants selected the safest lifting posture from four options: two with a straight back and two with a more rounded back, with justification. Back beliefs were collected via the Back-Pain Attitudes Questionnaire (Back-PAQ). Relationships were investigated using multiple linear and logistic regression models. Results 400 PTs and MHAs completed the survey. 75% of PTs and 91% of MHAs chose a straight lifting posture as safest, mostly on the basis that it avoided rounding of the back. MHAs scored significantly higher than PTs on the Back-PAQ instrument (mean difference = 33.9), indicating more negative back beliefs. Those who chose the straight back position had significantly more negative back beliefs (mean 81.9, SD 22.7) than those who chose a round back lift (mean 61.7, SD 21.1). Conclusion Avoiding rounding the back while lifting is a common belief in PTs and MHAs, despite the lack of evidence that any specific spinal posture is a risk factor for low back pain. MHAs, and those who perceived a straight back position as safest, had significantly more negative back beliefs.

22 citations


Cites background from "Psychophysical and psychological co..."

  • ...In contrast, when not instructed, pain-free individuals use a more rounded style of lifting (Straker and Duncan, 2000), which has been shown to be more efficient (Holder, 2013)....

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Journal ArticleDOI
Abstract: The majority of lifting research uses male subjects, and thus it is necessary to investigate if gender differences exist in lifting technique that may limit extrapolation of these studies. Three-dimensional kinematics of the ankle, knee, hip and lumbar and thoracic spine were collected for 30 subjects (15 males and 15 females) during lifting trials under two load conditions: 0% and 10% of maximum isometric back strength. Applying a principal component analysis (PCA) to the lifting waveforms, 30 principal components (PCs) were retained using a 90% trace criterion. There was a significant effect of load on PC2 of lumbar spine flexion and PC2 of hip rotation, but no effect of gender on any of the PCs. Therefore, independent of gender, under loaded conditions individuals demonstrated a semi-squat lifting technique. By employing a sophisticated statistical method such as PCA and standardising load to the individual's strength characteristics, there was no significant effect of gender on lifting technique.

20 citations


Cites background from "Psychophysical and psychological co..."

  • ...This notion can be supported by the knowledge that studies have shown that participants tolerate 10–20% greater maximal acceptable weight when performing a stoop rather than a squat lift (Straker and Duncan 2000)....

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References
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Journal ArticleDOI
TL;DR: The results of four new manual handling experiments were integrated with the results of seven similar experiments published previously by this laboratory and used to revise maximum acceptable weights and forces originally published in 1978.
Abstract: Four new manual handling experiments are reviewed. The experiment used male and female subjects to study lifting, lowering, pushing, pulling, and carrying tasks. Each experiment used a psychophysical methodology with measurements of oxygen consumption, heart rate, and anthropometric characteristics. Independent variables included task frequency, distance, height and duration; object size and handles; extended horizontal reach; and combination tasks. The results of the four experiments were integrated with the results of seven similar experiments published previously by this laboratory. The integrated data were used to revise maximum acceptable weights and forces originally published in 1978. The revised tables are presented and compared with the original tables.

786 citations


"Psychophysical and psychological co..." refers methods in this paper

  • ...Following established psychophysical methodology (Snook and Ciriello 1991), subjects were instructed to determine a suitable load that they perceived they could lift working as hard as they could without straining, becoming unusually tired, overheated, weakened or out of breath for an 8h day (Straker et al 1996)....

    [...]

  • ...Following established psychophysical methodology (Snook and Ciriello 1991), subjects were instructed to determine a suitable load that they perceived they could lift working as hard as they could without straining, becoming unusually tired, overheated, weakened or out of breath for an 8h day…...

    [...]



Journal ArticleDOI
TL;DR: RPE was higher for a given level of oxygen uptake during arm work than during leg work, as well as during bicycling compared to running or swimming, and a better correlation was found in these experiments between RPE and blood lactate concentration.
Abstract: The relationship between the subjective rating of perceived exertion (RPE) and different physiological variables during work were investigated in 19 healthy subjects under the following conditions: 1) after heart rate (HR) has been experimentally changed during work by the use of autonomic nervous system blocking agents. 2) during different types of physical work and 3) before and after an 8 week period of physical training, respectively. In most work situations, HR mirrors the physical strain subjectively experienced. However, this good correlation between HR and RPE was altered during the experiments with blocking agents. Therefore, a tachycardia as such is not the primary factor in the setting of HR during exercise — RPE was higher for a given level of oxygen uptake during arm work than during leg work, as well as during bicycling compared to running or swimming. A better correlation was found in these experiments between RPE and blood lactate concentration. After training, and in parallel to the decrease in HR at submaximal work loads, RPE was lower for a given level of oxygen uptake, but was the same when related to the “relative” (per cent of maximum) oxygen uptake.

326 citations


"Psychophysical and psychological co..." refers background in this paper

  • ...Discomfort and exertion have been found to be related to biomechanical loading and physiological stress (Bonney et al 1990, Bousenna et al 1982; Cafarelli et al 1977, Ekblom and Goldbarg 1971) thus providing indirect evidence of their validity as a risk measure....

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Journal ArticleDOI
TL;DR: It was determined that a worker is three times more susceptible to low back injury if exposed to excessive manual handling tasks, and the ergonomic redesign of these tasks to reduce the manual handling exposure represents a partial control for low back injuries.
Abstract: The prevention of low back injuries in industry has traditionally been attempted by (1) careful selection of workers, (2) good training in safe lifting, and (3) designing the job to fit the worker (ergonomics). One hundred ninety-one low back injuries were analyzed to determine the effectiveness of each preventive approach. The results indicate that the common selection techniques, as they are being used today, are not an effective control for low back injuries. Similarly, training on safe lifting procedures, as it is being administered today, is not an effective control for low back injuries. It was determined that a worker is three times more susceptible to low back injury if exposed to excessive manual handling tasks. The ergonomic redesign of these tasks to reduce the manual handling exposure represents a partial control for low back injuries.

308 citations


Journal ArticleDOI
TL;DR: The results show that each of the models can be used to predict both the incidence and severity of certain overexertion types of injuries such as contact, musculoskeletal and back injuries.
Abstract: This paper summarizes a three year epidemiological study conducted in five large industrial plants in order to evaluate the validity of two alternative modeling approaches to overexertion injury prediction. Detailed biomechanical and psychophysical job evaluations were performed for 55 industrial jobs comprised of 2934 potentially stressful manual materials handling tasks. The medical experiences of 6912 incumbent workers were monitored retrospectively for two years and prospectively for one year to establish a data base for comparison of the different models. The results show that each of the models can be used to predict both the incidence and severity of certain overexertion types of injuries such as contact, musculoskeletal and back injuries. The application of these models to identify or design administrative and engineering controls, however, may be limited as a result of the inherent correlation between the available indices and multifaceted jobs.

157 citations


"Psychophysical and psychological co..." refers background in this paper

  • ...Similarly, Herrin et al (1986) found injury incidence and severity was weakly correlated with psychophysical acceptability....

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