THE STUDY OF POSTURE & PRESSURE ON THE HUMAN FORM ON COMPARATIVE BED TYPES
The following information comprises excerpts from the full study. Enquiries for more information pertaining to these studies should be directed to Ergonomic Life International.
Introduction
Since the inception of the ‘innerspring mattress’ there has not been a major improvement in a mattress’s supportive capabilities of the human body.
By 1998, Mario Piraino, a Structural Engineer, tested thousands of people on various beds. He soon suspected, then formed the belief, that in fact:
1. Modern mattresses’ supportive capabilities are not much better than those of 50 years ago.
2. The terms ‘soft, medium and firm’ are (relative only to the feel of the mattress, not support as often claimed) simplistic and basically meaningless.
3. The words ‘comfort’ and ‘support’ are often misused and intermixed, and…
4. Many claims and bed descriptions made by manufacturers and retailers about their bed’s ‘supportive’ and ‘pressure reducing’ qualities are often misleading and sometimes plainly untrue. The most common situation is where a manufacturer will illustrate a person lying on a mattress with a straight spine and yet the observations of the time suggest this was not achievable.
On the 8th of December 2005, the first truly comparative testing of a wide range of mattress types from the best known industry brands was carried out openly in the Bio Mechanics Research Laboratory of one of Melbourne’s Public Universities.
It was conducted using proven scientific research protocols i.e. testing each subject with the same measuring equipment, on the same day, by the same research staff, etc. the only variable in each case being the different types of beds being tested.
The testing involved measuring the body surface pressure and the skeletal alignment of 2 subjects (1 female and 1 male) of average weight and shape on each of the 12 different bed systems.
Hypothesis
In a standing position a neutral posture is achieved where the spine is naturally straight in the vertical plane and the hips and shoulders are straight in the horizontal plane. Of course, this assumes the body is symmetrical where there are no underlying pathologies such as scoliosis.
It is assumed that a neutral posture imposes the least amount of stress on the vertebral column. That is, asymmetrical loading of the spine does not occur (zero stress)
When the human form, with variations in weight and shape along the body, is supine on a support surface such as a mattress, areas with more mass will sink lower than other lighter areas. Wider areas that are lighter, such as hips and shoulders will not sink as required and act as bridging points. The vertebral column, therefore, is no longer in a neutral position and is loaded asymmetrically.
Testing Protocols
The testing procedures were conducted in an independent Biomechanics Laboratory by Senior Researcher Noel Lythgo (PhD).
A representative male (mass = 79.6kg, height = 172.5cm) and female adult (mass = 62.8kg, height = 165.5cm) participated in this project. The alignment of the vertebral column, hips and shoulders was recorded for 12 bed types manufactured by major companies of varying construction types. Subjects lay on their side in the same relative position for each bed type.
Bed Models Testbed
1. Sleepmaker Classic Miracoil 5 zone Mattress/Platform Base
2. Sealy Posturepedic Prestige/Platform Base
3. 7 Turn Coilflex Standard Mattress/Platform Base
4. 7 Turn Coilflex Standard Mattress Variable Zone/Platform Base *
5. Endorsed Medium Firm 3 Zone/Platform Base
6. 5 Zone Pocket Spring/PlatformBase
7. Simmons Beauty Rest Physio Supreme Comfort/Platform Base
8. Pocket Spring Variable Zone/Platform Base
9. Tempur-pedic (20cm) VE /Platform Base
10. Tempur-pedic (20cm) VE /Variable Support Base **
11. Latex Mattress (17cm)/Platform Base
12. Latex Mattress (17cm)/Variable Support Base ***
*Denotes Mattress Type C. Variable Support In Mattress Ergolife Active
**Denotes Mattress Type I. with Variable Support “Under Mattress” Ergolife Zero Stress
***Denotes Mattress Type K. with Variable Support “Under Mattress” Ergolife Zero Stress
Equipment
A Vicon (Oxford Metrics) 460 Motion Measurement System was used to record the 3D spatial coordinate position of spherical (9mm diameter) passive reflective markers placed on the following known anatomical landmarks: (1) shoulder region – right and left scapula (mid-spine region of the scapulae); (2) vertebral column – spinous processes of C7, T8, T12, L3, L5; (3) sacrum (median sacral crest); and, hip region – right and left posterior superior iliac spines.
Bed Testbed
Test Component 1: Posture Profiles
The subject was placed in a standing position.
This Control Benchmark was captured and is represented by the yellow dots on each of the data sheets as shown on the example below.
The subject was then progressively placed on each of the bed types tested and captured. This posture profile is represented by the blue marks on each of the data sheets as shown on the example in Section 2, ‘How to Read the Test Results.’
This component of the testing procedures was used to identify the degree of variation in posture including spinal alignment and relationship of shoulders and hips to the plane of the spine.
Test Component 2: Pressure Mapping
Each bed was fitted with a Pressure Mapping Unit to record the variations of pressure along the human form.
The pressure imaging was captured coinciding with the capture of the Posture Profile.
This image identifies peak pressure regions (highest level is red region) and no pressure regions (lowest level is white). Refer to the Pressure Mapping Image in Section 2, ‘How to Read the Test Results.”
This component of the testing procedures was used to identify the distribution of pressure along the human form and variations in pressure on different bed types.
Test Results
How to Read the Test Results
Pressure Point Image Posture Comparison
Comparative Analysis (Summary)
By comparing imaging recorded on different bed types it is apparent that both posture and pressure change on each of the mattress types. This assists in determining which mattress types are most effective at:
The reader of this report is invited to draw their own conclusions from the following profiles
Individual Bed Test Reports
Illustrations of Posture and Pressure with and without Variable Support:
L8 Simmons Pocket Spring Physio Endorsed compared to L4 Spinal Support Pocket Spring.
The above offers only a sample of the Test Results obtained in measuring Comparative Pressure and Posture Plots for each mattress model using 1 x male & 1 x female.
