Force applied to a grab bar during bathtub transfers

Area of Science:

• Biomechanics
• Human Factors Engineering
• Rehabilitation Engineering

Background:

• Grab bars are crucial for fall prevention in bathrooms.
• Limited biomechanical data exist to guide grab bar selection and installation.
• This study addresses the need for quantitative force data during bathtub transfers.

Purpose of the Study:

• To measure the force magnitude and duration applied to grab bars during bathtub transfers.
• To evaluate the influence of different grab bar configurations and slippery surfaces on applied forces.
• To provide data for evidence-based recommendations on grab bar strength.

Main Methods:

• A repeated measures design was employed in an experimental bathroom setup.
• Seven healthy adults performed bathtub transfers with/without a slippery surface, using four grab bar types.
• Forces were measured using 6-degrees of freedom load cells.

Main Results:

• Average force applied was 23.2% ± 6.4% of body weight.
• Grab bar configuration and surface slipperiness did not significantly affect maximum force, except for vertical bars without slipperiness.
• Slippery surfaces increased the duration of force application on grab bars.

Conclusions:

• Grab bars must withstand a minimum of 23.2% of body weight, plus a safety factor of 1.5.
• This recommendation applies regardless of grab bar configuration.
• Consideration of increased force application time on slippery surfaces is important for safety.