Gait velocity

Walking

Habitual gait velocity will be measured using an Ultratimer (DCPB electronics, Glasgow, Scotland). The subject is instructed to walk at a normal walking pace for 10 m to assess habitual gait velocity. The average of 2 trials will be recorded and the test re-test reliability for this measurement is excellent (ICC = .924)75.

Stair Climb: In frail elderly, a four-step stair climb has often been used; however, our experience with HIV infected men and non-frail older men has indicted higher levels of function in these subjects than seen in frail elderly. Thus, the less demanding 4 step stair climb may not discriminate as well as a more rigorous test. Stair climb time will be assessed using a standard riser of stairs76. The subject will be asked to ascend a 10 rise set of stairs as fast as they can. Subjects can ascend holding the railing or using their assistive device if necessary. The average of 2 attempts is recorded. The test-retest reliability of this measurement in our laboratory is excellent (ICC=.949)68. To improve the ability of this test to discriminate change due to the intervention, we will use a precise timing system consisting of a multi-timer and switchmats. These mats will be placed at the base of the stairs and on steps 4, 8, and 10 allowing for six different timing intervals.

Sit to Stand Transitions: Difficulty in rising from a chair is an often reported symptom of functional limitation. We will test this ability by determining the time to make repeated transitions from sitting to standing. Chair rise time will be determined on a standard, armless chair with the subject holding arms across the chest 76. Five transitions will be required. Timing for this task will be obtained through a precision timing apparatus. A bar indicating full standing height will be placed in front of the subject. The average of 2 attempts will be recorded with two minutes rest between trials. Our experience has been that the repeated (10 times) chair rise time has a higher reliability than the single chair rise (ICC =.933 vs. ICC=.124 respectively)75.

Load Carry:This task requires the carrying of a load equivalent to 10% of body weight over a distance of 50 meters as fast as possible. This task represents common activities of daily living such as carrying groceries, laundry, or objects from place to place. The load carry also adds a different element of stress compared to the other functional tests in that compensatory muscular adjustments are required in order to retain balance while walking. The test is both reliable (test-retest = 0.88) and valid in apparently healthy subjects and patients with lumbar spinal stenosis. The load will be carried in canvas bags that can be easily dropped in case of fatigue, discomfort, or loss or equilibrium. After familiarization, two trials will be given with two minutes rest between trials. The average of the two scores will be accepted as the load carry time.