BACKGROUND & OBJECTIVE
Age-related muscular changes result in a significant decrease in strength and power production in older people, leading to difficulty with sit to stand transitions, stair climbing, ambulating at a faster gait speed, and reacting to a loss of balance. Such significant impact on functional mobility highlights the importance of assessing and addressing muscle power. Through valid, reliable, and feasible power assessments a clinician can prescribe appropriate exercises, resulting in increased power production and improved functional mobility. However, there are little to no clinically feasible lower extremity power tests.
To address this gap in the literature, the researchers of this study identified two objectives:
- Assess the validity of a clinically feasible muscle power calculation. A calculation that uses the five times sit to stand time, chair height, patients height, and body mass to calculate muscle power.
- Assess the association of sit to stand muscle power with physical and cognitive function, sarcopenia and quality of life.
Inclusion: older adults 70 years and older
* <4 on Short Physical Performance Battery (SPPB) * Unable to perform the five time sit to stand test (5xSTS) * <20 on Mini-mental State Examination * Uncontrolled hypertension (> 200/110 mm Hg) * Terminal illness * In the previous 6 months: neuromuscular or joint injury, stroke, myocardial infarction or bone fracture
- Participants performed 1-2 trials of the 5xSTS with 30-60 seconds of rest between them.
- The information gained from the anthropometric measurements and the results of the 5xSTS were used to calculate the participants’ muscle power. See Box 1 for the equations used to calculate muscle power.
- Mean velocity was calculated based on the equation that velocity equals distance divided by time. In this case distance is the vertical displacement by the center of mass. Because only half the body is moving during the transition the individual’s height is divided by two and since it is not starting from the ground the chair height is subtracted. The time is the average time it takes to complete the concentric portion of 1 transition during the 5xSTS and is calculated by multiplying 5xSTS time by 0.1.
- Mean Power was calculated based on the equation that power equals force times velocity. In this case the mean velocity result is taken and multiplied by body mass, 0.9, and gravity. If relative mean power is calculated the individuals body mass is not considered.
- Physical function was assessed via self-selected 3 meter gait speed
- Cognitive function was assessed via the Mini Mental Status Exam (MMSE)
- Health-related quality of life was measured via the EQ-5D-5L
- Body Composition was assessed via dual energy X-ray absorptiometry
- Power assessment via leg press
- Anthropometric measurements were assessed via height and weight measurements
Box 1: Equations for calculating the Power Assessment
Objective 1: When comparing the traditional leg press assessment and the newly proposed 5xSTS methodology it was found that they are not statistically different. This illustrates that the new method is a valid and reliable way to calculate a patient’s