Laboratory investigation of a simulated industrial task pre- and post-ergonomics intervention
- Authors: Renz, Miriam Christina
- Date: 2004
- Subjects: Human engineering , Musculoskeletal system -- Diseases , Occupational diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5162 , http://hdl.handle.net/10962/d1015806
- Description: The focus of the present study was on the investigation of the effects of an intervention strategy on an industrial task in situ and a simulation of the same task within a laboratory setting. The task of offloading crates from a truck at a local business was simulated in a laboratory setting for rigorous analysis. The effect of an ergonomically sound intervention on selected physical, physiological and perceptual variables was evaluated in a test - retest experimental set-up using 28 young, healthy male students. Each of the two experimental conditions lasted for 16 minutes. In the pre-intervention task subjects were required to transfer the crates from one point to another by sliding them along the floor. During the execution of the post-intervention task responses to reductions in the stacking height and modifications of the working method were evaluated. Results obtained for spinal kinematics during the simulated industrial task indicated a high biomechanical risk, due to large ranges of motion, high velocities and accelerations in the sagittal and transverse planes. The heavy workload of the task was also evident in elevated physiological responses (HR, RF, VT, VE, VO2, RQ, EE) and perceptual ratings (RPE, Body Discomfort). Assessment of the intervention strategy revealed that the high risk industrial task was reduced to moderate acceptable, with measurements of spinal kinematics, physiological and perceptual variables being significantly reduced. An in situ re-assessment of the workers responses to the intervention also elicited reductions in heart rates and perceptual ratings compared to the original task.
- Full Text:
- Authors: Renz, Miriam Christina
- Date: 2004
- Subjects: Human engineering , Musculoskeletal system -- Diseases , Occupational diseases
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5162 , http://hdl.handle.net/10962/d1015806
- Description: The focus of the present study was on the investigation of the effects of an intervention strategy on an industrial task in situ and a simulation of the same task within a laboratory setting. The task of offloading crates from a truck at a local business was simulated in a laboratory setting for rigorous analysis. The effect of an ergonomically sound intervention on selected physical, physiological and perceptual variables was evaluated in a test - retest experimental set-up using 28 young, healthy male students. Each of the two experimental conditions lasted for 16 minutes. In the pre-intervention task subjects were required to transfer the crates from one point to another by sliding them along the floor. During the execution of the post-intervention task responses to reductions in the stacking height and modifications of the working method were evaluated. Results obtained for spinal kinematics during the simulated industrial task indicated a high biomechanical risk, due to large ranges of motion, high velocities and accelerations in the sagittal and transverse planes. The heavy workload of the task was also evident in elevated physiological responses (HR, RF, VT, VE, VO2, RQ, EE) and perceptual ratings (RPE, Body Discomfort). Assessment of the intervention strategy revealed that the high risk industrial task was reduced to moderate acceptable, with measurements of spinal kinematics, physiological and perceptual variables being significantly reduced. An in situ re-assessment of the workers responses to the intervention also elicited reductions in heart rates and perceptual ratings compared to the original task.
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Physiological, perceptual and performance responses during cricket activity
- Authors: King, Gregory Allen
- Date: 2003
- Subjects: Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5131 , http://hdl.handle.net/10962/d1005210 , Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
- Description: The present study sought to determine the influence of environmental conditions and protective clothing on physiological, perceptual and performance responses during batting activity. The investigation examined mean skin temperature, average heart rate, estimated sweat rate, rating of perceived exertion, thermal sensation rating, average sprint time and pre-post choice reaction time. Twenty-five cricketers (18-22 yr, 73.1 ± 9.6 kg, 1768 ± 75 mm, 12.6 ± 3.1% body fat, 1.89 ± 0.16 m2) performed a work-bout consisting of a seven-Over batting period, during which time they faced deliveries from a bowling machine and performed two shuttle runs every third ball to total four sprints per Over. Trials were carried out under High-stress (23.8 ± 2.2 °C) and Low-stress (13.3 ± 1.9 °C) environmental conditions (WBGT). Within each environmental condition subjects performed the test wearing full protective batting gear and no protective gear. Thus, four specific conditions were examined; high full-gear (HFG), high no-gear (HNG), low full-gear (LFG) and low no-gear (LNG). Two-way ANOVAs were calculated to determine whether there were differences between environmental conditions and whether differences existed between the clothing conditions. One-way ANOVAs were utilised to compute differences between the four specific conditions combining clothing and environment. High environmental stress and wearing protective clothing caused batsmen to experience significant physiological strain. The environment was the greatest stressor, with the protective gear exacerbating these effects. However, when padding covered skin areas directly, this was the primary skin temperature stressor, particularly later in the activity. For skin temperature and heart rate, the strain was the most pronounced at the end of the trials. Perceptual responses indicated that the protective gear had no influence on effort sense, thermal sensation or thermal comfort. However, environmental conditions had an effect, and High-stress conditions resulted in significantly higher perceptions of effort, elevated sensations of heat and greater thermal discomfort. Effort was perceived to be greatest towards the end of the trial. There were mixed findings for performance factors. In general sprint performance was not hindered by environmental stress, but protective clothing caused a reduction in several sprint times. Choice reaction times were for the most part unaffected by either environment or clothing and few differences were observed between pre and post times. It is contended that intense short duration batting activity, likely encountered during one-day participation, imposes a stress on batsmen. The stress is greater when conditions are warmer and protective padding is worn, although it is not sufficient to impede choice reaction time. However, protective gear did have a deleterious effect on sprint performance.
- Full Text:
- Authors: King, Gregory Allen
- Date: 2003
- Subjects: Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5131 , http://hdl.handle.net/10962/d1005210 , Cricket , Sports -- Psychological aspects , Sports -- Physiological aspects
- Description: The present study sought to determine the influence of environmental conditions and protective clothing on physiological, perceptual and performance responses during batting activity. The investigation examined mean skin temperature, average heart rate, estimated sweat rate, rating of perceived exertion, thermal sensation rating, average sprint time and pre-post choice reaction time. Twenty-five cricketers (18-22 yr, 73.1 ± 9.6 kg, 1768 ± 75 mm, 12.6 ± 3.1% body fat, 1.89 ± 0.16 m2) performed a work-bout consisting of a seven-Over batting period, during which time they faced deliveries from a bowling machine and performed two shuttle runs every third ball to total four sprints per Over. Trials were carried out under High-stress (23.8 ± 2.2 °C) and Low-stress (13.3 ± 1.9 °C) environmental conditions (WBGT). Within each environmental condition subjects performed the test wearing full protective batting gear and no protective gear. Thus, four specific conditions were examined; high full-gear (HFG), high no-gear (HNG), low full-gear (LFG) and low no-gear (LNG). Two-way ANOVAs were calculated to determine whether there were differences between environmental conditions and whether differences existed between the clothing conditions. One-way ANOVAs were utilised to compute differences between the four specific conditions combining clothing and environment. High environmental stress and wearing protective clothing caused batsmen to experience significant physiological strain. The environment was the greatest stressor, with the protective gear exacerbating these effects. However, when padding covered skin areas directly, this was the primary skin temperature stressor, particularly later in the activity. For skin temperature and heart rate, the strain was the most pronounced at the end of the trials. Perceptual responses indicated that the protective gear had no influence on effort sense, thermal sensation or thermal comfort. However, environmental conditions had an effect, and High-stress conditions resulted in significantly higher perceptions of effort, elevated sensations of heat and greater thermal discomfort. Effort was perceived to be greatest towards the end of the trial. There were mixed findings for performance factors. In general sprint performance was not hindered by environmental stress, but protective clothing caused a reduction in several sprint times. Choice reaction times were for the most part unaffected by either environment or clothing and few differences were observed between pre and post times. It is contended that intense short duration batting activity, likely encountered during one-day participation, imposes a stress on batsmen. The stress is greater when conditions are warmer and protective padding is worn, although it is not sufficient to impede choice reaction time. However, protective gear did have a deleterious effect on sprint performance.
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Physiological and perceptual responses of SANDF personnel to varying combinations of marching speed and backpack load
- Authors: Christie, Candice Jo-Anne
- Date: 2002
- Subjects: Marching -- Physiological aspects , Walking -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5128 , http://hdl.handle.net/10962/d1005207 , Marching -- Physiological aspects , Walking -- Physiological aspects
- Description: The objective of the present study was to establish effective combinations of marching speed and backpack load in order to meet specific military requirements. Thirty infantrymen from the South African National Defence Force (SANDF) comprised the sample and experimental procedures were conducted in a laboratory setting using a Cybex Trotter treadmill. Sixteen conditions were set up which included combinations of four speeds (3.5, 4.5, 5.5, and 6.5 km.h⁻¹) and four backpack loads (20, 35, 50, and 65kg). Each subject was required to complete 8 of the sixteen conditions, each consisting of a six-minute treadmill march. Physiological data (heart rate, ventilation and metabolic responses), kinematic gait responses (step-rate and stride length) and perceptions of exertion (“Central” and “Local” RPE) were collected during the third and sixth minutes of the treadmill march and areas of body discomfort were identified post-march. Responses revealed five distinct categories of exertional strain. Three marches constituted “nominal” (below 40% VO₂max) and three “excessive” strain (above 75% VO₂ max). These represent combinations of extreme military demands and are highly unlikely to be utilised by the military. Three “tolerable” levels of required effort were recommended and these 10 combinations were further divided into three sub-categories. The “moderate” stress marches were identified as “ideal” for prolonged marches and had statistically similar responses of working heart rates (range of 118 bt.min⁻¹ to 127 bt.min⁻¹), energy expenditure (26 kJ.min⁻¹ and 27 kJ.min⁻¹) and ratings of perceived exertion (“Central” ratings of 10 and 11). Thus, marching at 5.5 km.h⁻¹with 20kg, 4.5 km.h⁻¹ with 35kg or 3.5 km.h⁻¹ with 50kg all require a similar energy cost. Four “heavy” category marches were identified for possible use when the duration of the march is reduced. During these marches responses were statistically similar with heart rates ranging from 127 bt.min⁻¹ to 137 bt.min⁻¹, energy expenditure from 32 kJ.min⁻¹ to 37 kJ.min⁻¹ and “Central” ratings of perceived exertion were 12 and 13. When short, high intensity marches are necessary, then combinations from the “very heavy” category may be utilised but with caution. During these marches, soldiers were taxed between 65% and 75% of VO2 max. The results of this study clearly demonstrate that the interplay between speed and load needs to be adjusted when determining “ideal” combinations for specific military demands. Essentially, if speed is of the essence then load must be reduced, and if heavy loads need to be transported then speed must be reduced.
- Full Text:
- Authors: Christie, Candice Jo-Anne
- Date: 2002
- Subjects: Marching -- Physiological aspects , Walking -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5128 , http://hdl.handle.net/10962/d1005207 , Marching -- Physiological aspects , Walking -- Physiological aspects
- Description: The objective of the present study was to establish effective combinations of marching speed and backpack load in order to meet specific military requirements. Thirty infantrymen from the South African National Defence Force (SANDF) comprised the sample and experimental procedures were conducted in a laboratory setting using a Cybex Trotter treadmill. Sixteen conditions were set up which included combinations of four speeds (3.5, 4.5, 5.5, and 6.5 km.h⁻¹) and four backpack loads (20, 35, 50, and 65kg). Each subject was required to complete 8 of the sixteen conditions, each consisting of a six-minute treadmill march. Physiological data (heart rate, ventilation and metabolic responses), kinematic gait responses (step-rate and stride length) and perceptions of exertion (“Central” and “Local” RPE) were collected during the third and sixth minutes of the treadmill march and areas of body discomfort were identified post-march. Responses revealed five distinct categories of exertional strain. Three marches constituted “nominal” (below 40% VO₂max) and three “excessive” strain (above 75% VO₂ max). These represent combinations of extreme military demands and are highly unlikely to be utilised by the military. Three “tolerable” levels of required effort were recommended and these 10 combinations were further divided into three sub-categories. The “moderate” stress marches were identified as “ideal” for prolonged marches and had statistically similar responses of working heart rates (range of 118 bt.min⁻¹ to 127 bt.min⁻¹), energy expenditure (26 kJ.min⁻¹ and 27 kJ.min⁻¹) and ratings of perceived exertion (“Central” ratings of 10 and 11). Thus, marching at 5.5 km.h⁻¹with 20kg, 4.5 km.h⁻¹ with 35kg or 3.5 km.h⁻¹ with 50kg all require a similar energy cost. Four “heavy” category marches were identified for possible use when the duration of the march is reduced. During these marches responses were statistically similar with heart rates ranging from 127 bt.min⁻¹ to 137 bt.min⁻¹, energy expenditure from 32 kJ.min⁻¹ to 37 kJ.min⁻¹ and “Central” ratings of perceived exertion were 12 and 13. When short, high intensity marches are necessary, then combinations from the “very heavy” category may be utilised but with caution. During these marches, soldiers were taxed between 65% and 75% of VO2 max. The results of this study clearly demonstrate that the interplay between speed and load needs to be adjusted when determining “ideal” combinations for specific military demands. Essentially, if speed is of the essence then load must be reduced, and if heavy loads need to be transported then speed must be reduced.
- Full Text:
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