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Reach & stretch

Reach & stretch covers the ability for one or both arms to reach out in front, above the head, or behind the back.

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The Reach & stretch section was authored by Umesh Persad and Carlos Cardoso
 

Understanding reach and stretch

Different products require the ability to reach one or both arms out from the body. This reaching can either occur in front of and above the body (to put on a hat), or out to the sides (to reach objects while sitting at a desk).

Reaching becomes more difficult as the arm moves further away from the rest position or when two arms have to reach out simultaneously.

The relative ability to position the hands compared to the head and body depends on the range of motion of the elbow and shoulder joints. The absolute position that each hand can reach to is also influenced by ergonomic factors such as body height and arm length, together with considerations such as wheelchair use.

Age-related conditions such as arthritis can cause reductions in joint mobility and stiffness leading to limited reaching ability. The distance that people can reach out to might be significantly less than the length of their arms.

Temporary injuries such as a broken or bruised arm or collarbone will also affect the distance a person can reach to.

  
Photo of the arms and diagram showing that range of movement includes both vertical and horizontal aspects.

The shape and movement of arms

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Reach and stretch functions

For product interaction, reach & stretch ability can be broken down into the ability to move one or both arms in two perpendicular directions, as shown in the figures opposite.

Most products require the ability to put one hand in front of the body to use them. Where possible, requiring both hands to be placed in front of the body simultaneously should be avoided. Using products should be possible by reaching either the left or right arm. Requiring people to reach above their heads is more demanding than requiring them to reach out in front.

Reaching out to the sides is used to access items while sitting at a desk, or to put on a jacket. The further the arm has to reach out to the side or back, the more difficult it can be to reach items.

  
A person reaches fowards, upwards and to the side.

A person's range of motion is characterised by the ability to reach out in front, above the head and to the sides

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Environmental context

Environmental factors can additionally reduce a person’s reach & stretch capability.

  • Carrying things while using a product will reduce the mobility of one or both hands, and it may not be desirable for the user to have to put down things such as tools, handbags or carrier bags
  • Clothing such as heavy jackets and multiple layers can reduce a person’s ability and comfort to reach out
  
A woman filling a kettle while holding a baby, and someone opening a door while holding carrier bags in the same hand.

The context of use may restrict the ability to move one or both arms

Someone lifting a bicycle onto a cycle rack and people making a snowman while wearing heavy coats.

The ability to reach may be restricted by heavy clothing

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Design guidance

  • Provide the option to operate a product by either reaching out the left or right arm, and try to avoid requiring both arms to be reached out at the same time
  • Ensure that products or services requiring public access are able to cope with the range of heights that people can reach to, including those in wheelchairs
  • Avoid requiring users to reach above their head, where possible, and note that the ability to exert forces will be greatly diminished when the arms are in this position
  • Consult ergonomic data sources such as Tilley (2002)

Tilley AR (2002) The Measure of Man and Woman, John Wiley & Sons, New York, USA. ISBN 0-471-09955-4

  
A photo showing two cash machines at different heights, and two adjustable chairs at different heights.

A variety of heights can account for the needs of different users

A person reaches under a desk to reach a plug socket, compared to a person reaching above the desk.

Providing plug sockets above desks makes them significantly easier to reach

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Population statistics: Prevalence data

Reach & stretch ability level (in increasing order)

R1 Cannot hold out either arm in front to shake hands
R2 Cannot put either arm up to head to put a hat on
R3 Cannot put either hand behind back to put jacket on or tuck shirt in
R4 Cannot raise either arm above head to reach for something
R5 Has difficulty holding either arm in front to shake hands with someone
R6 Has difficulty putting either arm up to head to put a hat on
R7 Has difficulty putting either hand behind back to put jacket on or tuck shirt in
R8 Has difficulty raising either arm above head to reach for something
R9 Cannot hold one arm out in front or up to head (but can with other arm)
R10 Cannot put one arm behind back to put on jacket or tuck shirt in (but can with other arm). Has difficulty putting one arm behind back to put jacket on or tuck shirt in, or putting one arm out in front or up to head (but no difficulty with other arm)
R11 Full reach & stretch ability
 
Graph showing distribution of reach & stretch ability. 3.8% (1.7 million adults) are in levels R1-R10 and therefore have less than full reach & stretch ability

Graph showing the distribution of reach & stretch ability, where those with full ability (R11) are not shown.

Important note
These reach & stretch ability levels and prevalence statistics are taken directly from the 1996/97 Disability Follow-up Survey (Grundy et al. 1999), which was commissioned by the government to plan welfare support. The GB adult population was 45.6 million people at the time of the survey. Please see the Framework section for more detail.

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Population statistics: Demand and exclusion

No demand

  • The user is not required to reach out with either arm

Low demand: The user is required to have sufficient ability to do things like:

  • Hold one arm out in front, up to the head, or behind the back (albeit with difficulty)

Moderate demand: The user is required to have sufficient ability to do things like:

  • Hold one arm out in front, up to the head, or behind the back (easily)

High demand: The user is required to have sufficient ability to do things like:

  • Hold both arms out in front, up to the head, or behind the back (easily)
  
Graph of demand levels versus percentage of GB adult population

Graph showing the number of people who would be excluded due to various levels of reach & stretch demand

Important Note
These statements refer to the level of reach & stretch ability that a product or service demands, in order to use it. For a particular demand level, the 1996/97 Disability Follow-up Survey is used to calculate the total number of people who do not have this level of ability, and will therefore be excluded. The GB adult population was 45.6 million people at the time of the survey. Please see the Framework section for more detail.

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