Enhancing Physical Function in Older Adults With Chronic Kidney Disease

Number of participants enrolled with a goal of 30.

Percentage of exercise sessions attended for the HVRT group (out of 36 total exercise sessions)

Percentage of participants retained at the final follow visit.

The short physical performance battery (SPPB) consists of three tests to assess lower extremity function: a balance test, a gait speed test, and a sit-to-stand test. Performance in each test will be assigned a score ranging from 0 to 4 points, and these scores will be summed to calculate the SPPB score out of 12. A higher SPPB score indicates better function, and scores of 10 or lower are indicative of high risk of disability.

For the timed up-and-go test, the time to complete this task will be measured in seconds. A lower number of seconds to complete the task is indicative of higher physical function.

Leg press peak power will be assessed at 5 relative intensities (40%, 50%, 60%, 70%, and 80% 1-repetition maximum). The highest peak power measurement among those 5 loads will be recorded as peak power. Greater peak power is indicative of greater lower body neuromuscular function.

Appendicular Lean Mass (kg/m^2) will be measured via dual-energy X-ray absorptiometry (DXA). Higher appendicular lean mass is indicative of improved body composition.

Isometric leg extension strength will be measured with a maximal isometric voluntary contraction of the dominant leg knee extensor muscles using a MicroFET2 hand-held dynamometer. Greater peak force is indicative of greater knee extensor strength.

Lower body strength will be measured as the 1-repetition maximum on the leg press, which is the maximum load (kg) that can be moved 1 time only throughout the full range of motion. Increase in leg press 1-repetition maximum is indicative of improved lower body strength.

Lower body muscle endurance will be measured on the leg press as the maximum number of repetitions completed at a load of 70% of baseline 1-repetition maximum with a fixed cadence of 60 bpm. An increase in the number of repetitions completed is indicative of an improvement in lower body muscle endurance.

Muscle activation of knee extensors (rectus femoris, vastus medialis, and vastus lateralis) will be assessed by surface electromyography (EMG) during the maximal voluntary contraction (MVC) and during the leg press exercise testing. An increase in the peak EMG root-mean-square amplitude relative to the amplitude during MVC (%MVC) is indicative of greater muscle activation.

An ActivPAL 4 triaxial accelerometer will be worn on the midline of the non-dominant thigh for 7 consecutive days prior to the start of the intervention and during the final week of the intervention. An increase in the average number of steps per day is indicative of increased physical activity level.

The average number of minutes spent in sedentary behavior per day will be measured with an ActivPAL 4 triaxial accelerometer. An decrease in the average number of minutes spent in sedentary behavior per day is indicative of a decrease in sedentary activity.

The average number of minutes spent stepping per day will be measured with an ActivPAL 4 triaxial accelerometer. An increase in the number of minutes spent stepping per day is indicative of an increase in physical activity.

The average number of minutes spent stepping above 75 steps per minute and 100 steps per minute per day will be measured with an ActivPAL 4 triaxial accelerometer. An increase in the number of minutes spent stepping above 75 steps per minute and 100 steps per minute is indicative of an increase in moderate-to-vigorous intensity physical activity.

The Symbol Digit Coding Test measures complex information processing accuracy, complex attention, visual-perceptual speed, and information processing speed. The score is the number of correct symbols drawn within a period of 120 seconds. One point is given for each correctly drawn symbol completed within the time limit. The maximum score is 133.

High scores indicate higher cognitive functioning.

The 4PCPT test is a four-part test that measures a subject's working memory and sustained attention. Higher scores indicate higher cognitive functioning.

SAT test is a measure of ability to shift from one instruction set to another quickly and accurately. Higher scores indicate higher cognitive functioning.

Stroop test has three parts. Higher scores indicate higher cognitive functioning.

The KDQOL-SF version 1.3 is a self-report measure developed for individuals with kidney disease. It includes 43 kidney-disease targeted items as well as 36 items that provide a generic core and an overall health rating item. 0-100 possible range, with higher scores always reflecting better quality of life.