scholarly journals Force on the sacrococcygeal and ischial areas during posterior pelvic tilt in seated posture

2012 ◽  
Vol 37 (4) ◽  
pp. 282-288 ◽  
Author(s):  
Taro Kemmoku ◽  
Katsuro Furumachi ◽  
Tadashi Shimamura
Keyword(s):  
Body Weight ◽  
Repeated Measures ◽  
Pelvic Tilt ◽  
Pressure Ulcers ◽  
Ischial Tuberosity ◽  
The Body ◽  
Vertical Force ◽  
Horizontal Force ◽  
Repeated Measures Design ◽  
Seated Posture

Background: Most posture problems encountered in persons who use wheelchairs in a seated posture for extended periods are related to sacral sitting due to posterior pelvic tilt. Posterior pelvic tilt places pressure and shearing force on the sacrococcygeal area that can lead to pressure ulcers, but the relationship between pelvic tilt and force applied to the sacrococcygeal and ischial tuberosity areas has not yet been investigated. Objective: To investigate the relationships of posterior pelvic tilt in a seated posture with vertical force and horizontal force on the sacrococcygeal and ischial tuberosity areas. Study Design: Repeated measures design. Methods: Thirty male and female subjects aged ≥60 years sat in a measurement chair at varying pelvic tilt angles, and force on the sacrococcygeal and ischial tuberosity areas was measured. Results: The pressure on the sacrococcygeal area increased with pelvic tilt in all subjects, with vertical force averaging 19% of the body weight at a pelvic tilt angle of 30°. The horizontal force on the sacrococcygeal area increased in 93% of the subjects, with an average increase equal to 3% of the body weight. Conclusions: We confirmed changes in vertical and horizontal forces on the sacrococcygeal and ischial tuberosity areas with a change in seated posture (pelvic tilt). Clinical relevance: We propose guidelines for rehabilitation practitioners working with wheelchair users to suggest improved ways of sitting in wheelchairs that avoid pelvic tilt angles that might promote pressure ulcers on the buttocks.

Influence of rotational axis height of back support on horizontal force applied to buttocks in a reclining wheelchair

2014 ◽  
Vol 39 (5) ◽  
pp. 397-404 ◽  
Author(s):  
Kenichi Kobara ◽  
Hiroshi Osaka ◽  
Hisashi Takahashi ◽  
Tomotaka Ito ◽  
Daisuke Fujita ◽  
...  
Keyword(s):  
Body Weight ◽  
Repeated Measures ◽  
Shear Force ◽  
Rotational Axis ◽  
Horizontal Force ◽  
Decubitus Ulcers ◽  
Seat Height ◽  
Repeated Measures Design ◽  
Percent Body Weight ◽  
Axis Position

Background: Studies have not been conducted to investigate the influence of the height of the rotational axis of a wheelchair’s back support on the shear force applied to the buttocks during the reclining motion. Objectives: The purpose of this study was to investigate the influence of the difference in the rotational axis position of back support in the vertical direction on the horizontal force applied to buttocks for preventing decubitus ulcers. Study design: Repeated measures design. Methods: The subjects were 13 healthy adult men without leg and/or trunk diseases. The shear force was measured using a force plate. A comfortable sitting posture in the experimental chair was selected for measurement. The rotational axis was positioned 13 cm forward on the horizontal plane from the intersection between the seat and the back support. The axis positions on the vertical plane as two experimental conditions were the seat height and the 7.5-cm upward from the seat height which was nearer to the hip joint. Results: In returning the back support to an upright position, the horizontal force was 12.4 ± 1.6 (percent body weight) under the seat height-axis condition and 10.1 ± 1.8 (percent body weight) under the upward-axis condition ( p < 0.01). Conclusion: This result suggested that the wheelchair might have to be capable of adjusting the height of the rotational axis of the back support to reduce the horizontal force applied to buttocks. Clinical relevance This study shows one of the suggestions regarding seating approach for the prevention of decubitus ulcers. There is a possibility of reducing horizontal force applied to buttocks after reclined back support, by adjusting the height of the rotational axis position of wheelchair back support.

Body Composition Modifications Due to the “Search, Rescue and Survival Training” in Male Military Firefighter Cadets

2021 ◽  
Author(s):  
Thiago Ramos de Barros ◽  
Verônica Pinto Salerno ◽  
Thalita Ponce ◽  
Míriam Raquel Meira Mainenti
Keyword(s):  
Body Composition ◽  
Body Weight ◽  
Repeated Measures ◽  
Food Restriction ◽  
Physical Exertion ◽  
High Energy ◽  
The Body ◽  
Fat Free Mass ◽  
Sleep Restriction ◽  
Fat Percentage

ABSTRACT Introduction To train and prepare cadets for a career as firefighters in Rio de Janeiro, the second-year students of the Officers Training Course are submitted to a Search, Rescue, and Survival Training (SRST) course, which is characterized by long periods of high physical exertion and sleep restriction during a 9-day instruction module, and food restriction during a 7-day survival module. The present study investigated changes in the body composition of 39 male cadets submitted to SRST during training and 4 weeks of recovery with no restrictions in food consumption. Materials and Methods Each cadet was evaluated by anthropometric measurements at six time points: pre-SRST; after the first module; after the second module; and after 1, 2, and 4 weeks of recovery. Measurements included body girths and skinfolds, to estimate trunk (chest and waist) and limbs (arm and thigh) dimensions, as well as body composition. Repeated measures ANOVA and Friedman test were applied (depending on each data distribution). Results Statistically significant decreases in body weight (76.2; 69.8-87.2 to 63.9; 58.9-73.5 kg) and fat free mass (FFM, 69.2; 63.7-77.2 to 60.1; 56.2-68.0 kg) were observed following the second module of SRST. Following a single week of recovery, the FFM returned to pre-SRST values. Body weight returned to pre-training levels in 2 weeks. Body fat percentage and mass also significantly decreased during SRST (9.0; 7.7-12.3 to 6.5; 5.1-9.3% and 6.9; 5.6-10.0 to 6.9; 5.6-10.0 kg, respectively), which showed a slower and more gradual recovery that reached pre-SRST values after 4 weeks. The girths of arm, thigh, chest and waist significantly decreased due to SRST. The girths of the limbs (arm and thigh) returned to pre-training values after one month of recovery, while the girths of the trunk (chest and waist) did not return to pre-SRST values during the study period. Conclusions The findings suggest that men who experience periods of high energy demands and sleep restriction followed by a period of food restriction will endure unavoidable physical consequences that can be mostly reversed by a 1-month recovery.

Biology and physics of locust flight. III. The aerodynamics of locust flight

1956 ◽  
Vol 239 (667) ◽  
pp. 511-552 ◽  
Keyword(s):  
Body Weight ◽  
Posterior Part ◽  
Slow Motion ◽  
Middle Part ◽  
The Body ◽  
Vertical Force ◽  
Aerodynamic Forces ◽  
Locust Flight ◽  
Lift And Drag ◽  
Wing Stroke

A proper understanding of how locusts fly must be based upon knowledge of how the wings are moved. A desert locust was suspended from a balance and placed in an air stream so that it flew under nearly the same conditions as during natural forward flight. Four stroboscopic slow-motion films were selected for measurement. The movements of the wings, i.e. their positions, velocities and accelerations, were then calculated in sufficient detail to show how these quantities vary with time during one complete wing stroke. The aerodynamic lift and drag of the entire natural wing were measured in a wind tunnel with the wing arranged in different positions relative to the flow. By placing it in the boundary layer of the tunnel, the wind speed was graded from tip to base in approximately the same way as during the actual flight. There is therefore no error due to scale effect or to the induced drag. In most respects the wings resemble ordinary, slightly cambered airfoils. Their characteristics are given as polar diagrams. The kinematic and aerodynamic analyses make it possible to calculate the forces which act upon the locust at any instant of time. It is here necessary to presuppose that the non-stationary flight situations are essentially similar to a sequence of stationary situations. For locusts, this presupposition is justified: (i) from theoretical estimates of the quantitative effect of non-stationary flow; and (ii) from control measurements of the average thrust and lift produced during flight. It was found that the calculated vertical force, when averaged over an entire wing stroke, equalled the average reduction in body weight, as measured directly on the flight balance. Similarly, the average thrust of the wings corresponded to the drag of the body. The analysis shows how the aerodynamic forces vary during the wing stroke. The hindwings are responsible for about 70 % of the total lift and thrust. About 80 % of the lift is produced during the downstroke. During flight at normal lift the angles of attack (middle part of wing) are small during the upstroke and vary between 10 and 15° during the downstroke. When the lift was larger or smaller than the body weight these figures increased or decreased respectively. The forewings are peculiar in two ways: (i) during the middle part of the downstroke a true flap (the vannus) is put into action; (ii) during the upstroke the proximal part has a Z-shaped cross-section and gives but little lift and drag. The hindwings are characteristic in that the posterior part (vannus) is flexible and becomes moulded by the wind, increasing the angle of attack at which stalling occurs to about 25°. Since both the movements of the wings relative to the body and the aerodynamic forces are known at any instant, the exchange of power with the surrounding air can be calculated. The moments of inertia of the wing mass being known, the power for accelerating the wings can also be estimated. The sum of these contributions is the power which passes the wing fulcrum; this estimate is used in a later paper (part IX) where the energetics of flight is discussed in detail. The diagrams are correct to scale. The restriction of freedom caused by the suspension is discussed, together with the possible errors of a stationary analysis.

scholarly journals Effect of cane length and swing arc width on drop-off and obstacle detection with the long cane

2017 ◽  
Vol 35 (3) ◽  
pp. 217-231 ◽  
Author(s):  
Dae Shik Kim ◽  
Robert Wall Emerson ◽  
Koorosh Naghshineh
Keyword(s):  
Standard Length ◽  
Repeated Measures ◽  
Visually Impaired ◽  
Visual Impairments ◽  
Detection Threshold ◽  
Obstacle Detection ◽  
The Body ◽  
Repeated Measures Design ◽  
Extended Length ◽  
Block Randomization

A repeated-measures design with block randomization was used for the study, in which 15 adults with visual impairments attempted to detect the drop-offs and obstacles with the canes of different lengths, swinging the cane in different widths (narrow vs wide). Participants detected the drop-offs significantly more reliably with the standard-length cane (79.5% ± 6.5% of the time) than with the extended-length cane (67.6% ± 9.1%), p < .001. The drop-off detection threshold of the standard-length cane (4.1 ± 1.1 cm) was also significantly smaller than that of the extended-length cane (6.5 ± 1.8 cm), p < .001. In addition, participants detected drop-offs at a significantly higher percentage when they swung the cane approximately 3 cm beyond the widest part of the body (78.6% ± 7.6%) than when they swung it substantially wider (30 cm; 68.5% ± 8.3%), p < .001. In contrast, neither cane length ( p = .074) nor cane swing arc width ( p = .185) had a significant effect on obstacle detection performance. The findings of the study may help orientation and mobility specialists recommend appropriate cane length and cane swing arc width to visually impaired cane users.

The influence of selected factors and sport results of endurance horses on their saliva cortisol concentration

2013 ◽  
Vol 16 (3) ◽  
pp. 533-541 ◽  
Author(s):  
I. Janczarek ◽  
A. Bereznowski ◽  
K. Strzelec
Keyword(s):  
Air Temperature ◽  
Cortisol Level ◽  
Repeated Measures ◽  
Hormone Level ◽  
Cortisol Concentration ◽  
The Body ◽  
Clear Correlation ◽  
Mean Values ◽  
Repeated Measures Design ◽  
The Mean

Abstract The aim of the study was to define the influence of the selected factors (gender, age, transportation time, riding distance and air temperature during the ride) on the cortisol secretion and finding a correlation between the hormone level and the horses’ sport results (veterinary parameters and the ride route parameters). The research was performed on 38 Arabian pure breed horses taking part in the endurance rides. The cortisol level was measured with enzyme-immunological method in saliva samples, taken four times from each horse. In order to verify the differences between the mean results the repeated measures design was applied. The significance of the differences between the mean values was determined by the Tukey test. To evaluate the interrelations between the analysed attributes Pearson’s correlation analysis was applied. The cortisol level at rest was not affected by any of the analysed factors. In case of other results, the most significant influence (P ≤ 0.05) was related to the gender, as well as the ride distance and air temperature during the ride. Higher cortisol level was noted in mares, horses running the longest distances and at the highest temperatures. A significant increase in the cortisol level was noted when the ride distance was longer. There were no clear correlation between the adrenal cortex activity and the veterinary parameters at different riding speed. High cortisol concentration can negatively affect the heart rate (HR) by increasing it, but it can simultaneously stimulate the body to fight dehydration.

scholarly journals Glucagon and insulin responses after ingestion of different amounts of intact and hydrolysed proteins

2008 ◽  
Vol 100 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Mandy Claessens ◽  
Wim H. M. Saris ◽  
Marleen A. van Baak
Keyword(s):  
Body Weight ◽  
Whey Protein ◽  
Repeated Measures ◽  
Protein Hydrolysate ◽  
Latin Square ◽  
Glucagon Secretion ◽  
Soya Protein ◽  
Intact Protein ◽  
Glucose Determination ◽  
Repeated Measures Design

Ingestion of dietary protein is known to induce both insulin and glucagon secretion. These responses may be affected by the dose and the form (intact or hydrolysed) in which protein is ingested. The aim of the study was to investigate the effect of different amounts of intact protein and protein hydrolysate of a vegetable (soya) and animal (whey) protein on insulin and glucagon responses and to study the effect of increasing protein loads for both intact protein and protein hydrolysate in man. The study employed a repeated-measures design with Latin-square randomisation and single-blind trials. Twelve healthy non-obese males ingested three doses (0·3, 0·4 and 0·6 g/kg body weight) of intact soya protein (SPI) and soya protein hydrolysate (SPH). Another group of twelve healthy male subjects ingested three doses (0·3, 0·4 and 0·6 g/kg body weight) of intact whey protein (WPI) and whey protein hydrolysate (WPH). Blood was sampled before (t = 0) and 15, 30, 60, 90 and 120 min after protein ingestion for insulin, glucagon and glucose determination. SPI induced a higher total area under the curve for insulin and glucagon than SPH while no difference between WPI and WPH was found. Insulin and glucagon responses increased with increasing protein load for SPI, SPH, WPI and WPH, but the effect was more pronounced for glucagon. A higher dose of protein or its hydrolysate will result in a lower insulin:glucagon ratio, an important parameter for the control of postprandial substrate metabolism. In conclusion, insulin and glucagon responses were protein and hydrolysate specific.

scholarly journals The vertical force on a cylinder submerged in a uniform stream

1929 ◽  
Vol 122 (790) ◽  
pp. 387-393 ◽  
Keyword(s):  
Circular Cylinder ◽  
Wave Resistance ◽  
Point Sources ◽  
The Body ◽  
Resultant Force ◽  
Dimensional Case ◽  
Vertical Force ◽  
Horizontal Force ◽  
Two Dimensional ◽  
Sources And Sinks

1. The horizontal force on a circular cylinder immersed in a stream is familiar as an example of wave resistance. The following note supplies a similar calculation for the resultant vertical force. The problem was sug­gested in a consideration of the forces on a floating body in motion, the hori­zontal and vertical forces and the turning moment; but the case of a partially immersed body presents great difficulties. It seemed, however, of sufficient interest to compare the resultant horizontal and vertical forces for a simple case of complete immersion for which the calculations can be carried out. The horizontal force, or wave resistance, has usually been obtained indirectly from considerations of energy, but a different method is adopted here for both components of force and the turning moment. In a former paper the method of successive images was applied to the problem of the circular cylinder, taking images alternately in the surface of the cylinder and in the free surface of the stream. Using these results to the required stage of approximation, the com­plete force on the cylinder is now obtained as the resultant of forces between the sources and sinks within the cylinder and those external to it. The same method can be applied to any submerged body for which the image sytems are known, and the resultant force and couple calculated in the same manner. The proposition used in this method is that for a body in a fluid, the motion of which is due to given sources and sinks, the resultant force and couple on the body are the same as if the sources and their images attract in pairs accord­ing to a simple law of force, inverse distance for the two-dimensional case and inverse square of the distance for point sources. This fairly obvious proposition follows directly from a contour integration in the two-dimensional case; and, in view of the application, the extension is given in 2 when the flow is due to a distribution of doublets. In 3 the horizontal and vertical force on a circular cylinder are obtained by this method, the former agreeing with the usual expression for the wave resistance. The different variation of the two components with velocity is of interest, and the expressions are graphed on the same scale. The additional vertical force due to velocity changes direction at a certain speed, and is clearly associated more with the surface elevation immediately over the centre of the cylinder. In 4 reference is made to the couple on the cylinder. This should, of course, be zero for a complete solution; it is verified that the method used here gives zero moment up to the stage of approximation in terms of the ratio of the radius of the cylinder to the depth of its centre.

scholarly journals The perception of real and illusory weight differences with grasping tools

2019 ◽  
Author(s):  
Gavin Buckingham ◽  
Liam Campbell ◽  
Anna Sedda
Keyword(s):  
Tool Use ◽  
Repeated Measures ◽  
The Body ◽  
Repeated Measures Design ◽  
Prosthetic Hands ◽  
Object Properties ◽  
Action Capabilities ◽  
Growing Body

Humans routinely use tools to extend their repertoire of skilled behavior, using their action capabilities to enhance reach, dexterity, or strength. Little is known, however, about how using a tool affects our experience of object properties, such as heaviness. To better understand how using a tool to manipulate our environment affects perception, participants (n=44) lifted and reported the felt heaviness of objects which varied independently in size and mass. In a blocked repeated-measures design, they lifted with their anatomical hands and with a grasping tool. Contrary to our hypotheses, which was based on earlier work with prosthetic hands (Buckingham et al., 2018), participants experienced real and illusory weight differences just as robustly with a grasping tool as they did with their anatomical hands. These findings add to the growing body of work examining perception tool use and suggest that grasping tools may be incorporated differently into the representation of the body in action than prosthetic hands.

Accuracy and Precision of Noninvasive Temperature Measurement in Adult Intensive Care Patients

2007 ◽  
Vol 16 (5) ◽  
pp. 485-496 ◽  
Author(s):  
Lari Lawson ◽  
Elizabeth J. Bridges ◽  
Isabelle Ballou ◽  
Ruthe Eraker ◽  
Sheryl Greco ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Repeated Measures ◽  
Temporal Artery ◽  
The Body ◽  
Temperature Measurements ◽  
Confidence Limits ◽  
Axillary Temperature ◽  
Noninvasive Methods ◽  
Repeated Measures Design ◽  
Accuracy And Precision

Background Research on the accuracy and precision of noninvasive methods of measuring body temperature is equivocal. Objectives To determine accuracy and precision of oral, ear-based, temporal artery, and axillary temperature measurements compared with pulmonary artery temperature. Methods Repeated-measures design conducted for 6 months. Sequential temperature measurements on the same side of the body were obtained within 1 minute, with measurements repeated 3 times at 20-minute intervals. Accuracy, precision, and confidence limits were analyzed. Results In 60 adults with cardiopulmonary disease and a pulmonary artery catheter, mean pulmonary artery temperature was 37.1°C (SD 0.6°C, range 35.3°C–39.4°C). Mean (SD) offset from pulmonary artery temperature (with the mean reflecting accuracy and SD reflecting precision) and confidence limits were 0.09°C (0.43°C) and −0.75°C to 0.93°C for oral measurements, −0.36°C (0.56°C) and −1.46°C to 0.74°C for ear measurements, −0.02°C (0.47°C) and −0.92°C to 0.88°C for temporal artery measurements, and 0.23°C (0.44°C) and −0.64°C to 1.12°C for axillary measurements. Percentage of pairs with differences greater than ±0.5°C was 19% for oral, 49% for ear, 20% for temporal artery, and 27% for axillary measurements. Intubation increased oral measurements compared with pulmonary artery temperatures (mean difference 0.3°C, SD 0.3°C, P = .001). Conclusions Oral and temporal artery measurements were most accurate and precise. Axillary measurements underestimated pulmonary artery temperature. Ear measurements were least accurate and precise. Intubation affected the accuracy of oral measurements; diaphoresis and airflow across the face may affect temporal artery measurements.

7. Frontal Plane Knee Loading during Bodyweight Squat Performance: Effects of Stance Width and Foot Rotation

2016 ◽  
Author(s):  
David Kingston
Keyword(s):  
Body Weight ◽  
Knee Joint ◽  
Repeated Measures ◽  
Inverse Dynamics ◽  
Exercise Prescription ◽  
Reaction Force ◽  
Frontal Plane ◽  
The Body ◽  
Knee Adduction Moment ◽  
Squat Exercise

The bodyweight squat is routinely used for conditioning of the knee musculature. In the performance of this exercise, modifications in the initial standing position may result in altered frontal plane kneel loading, and hence may potentially be used for targeted exercise prescription. The purpose of this study is to quantify the frontal plane mechanical loading on the knee joint whilst performing the bodyweight squat exercise, and to examine the effects of varying stance width and foot rotation angle. Twenty-four participants (14 males) performed 4 randomized sets of 8 repetitions of the body weight resistant squat exercise in the following conditions: 1) Shoulder width (SW) stance with parallel feet; 2) SW stance with feet externally rotated 30°; 3) 140% SW stance with parallel feet, and; 4) 140% SW stance with the feet externally rotated by 30°. The adduction/abduction knee joint moment experienced across conditions was calculated using inverse dynamics procedures. Moment waveforms were subjected to Principal Component (PC) analysis, with 3 PC’s retained based on a 90% trace criteria. Following, a 1-way repeated measures ANOVA and pair wise comparisons were used to discern differences between conditions. Omnibus test results indicate significant differences across conditions for PC1 and PC2 (p<0.01), Post hoc comparisons and waveform interpretation of PC1 extreme scores showed that the magnitude of the adduction moment was higher throughout the movement in the foot rotated conditions vs. the parallel feet conditions in both stance widths (mean Z scores .69 & .65 vs. -.88 & -.45, p<0.01, respectively). For PC2, significant differences were found between the 2 parallel feet conditions and the 2 foot rotated conditions, as well as between the foot conditions in the wide stance squats. PC2 differences were interpreted as phase shift operators. We found that modification of foot rotation slightly alters the magnitude and timing of knee adduction moment component during performance of the body weight squat. The observed magnitude differences are presumably a consequence of alteration in the location of the point of application of the ground reaction force during the initial standing posture. The findings may assist clinicians in exercise prescription decision making.

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