Paperwork, Physical Function Measures, Familiarization and Peak Aerobic Capacity.

Duration of roughly 2 hours

At the first visit we will begin by asking you to read this Informed Consent document and we will answer any questions you might have about any study procedures. You will then be asked to complete a medical history form, physical activity readiness questionnaire and Magnetic Resonance Safety Form.  For safety reasons it is important that you answer all questions in the forms. Next we will measure your resting blood pressure and heart rate and take your height and weight. We will also confirm that we have received a complete Physician’s Clearance Form (older adults only) prior to continuing with familiarization of study activities and aerobic testing. You will then complete two physical function tests: Advanced Short Physical Performance Battery, SPPB-A, described below) and a timed walk. You will then be shown the strength testing machine. Finally, you will be shown the treadmill and the staff will provide instruction exercise testing for Aerobic Fitness (details below). You may take as many breaks as you need through-out this visit. 

The SPPB-A test involves 3 parts:

1. Completing 10 chair raises as quickly as possible, without using your hands. 

2. Walking a straight, 6-meter path at your usual speed (you will repeat this 4 times).

3. Standing with your feet in 4 different positions, each for up to 30 seconds. The 4 foot positions are: side-by-side (shoulders-width apart), the heel of one foot next to the ball of the other foot, one foot in front of the other, and on one foot.

The Aerobic Fitness test involves walking on a treadmill while wearing a mask that collects that air that you breathe out. To start we will have you put on a heart rate monitor strap and place electrocardiogram leads on your upper chest. We will then help you put on a breathing mask that covers your nose and mouth. The mask will be connected via hoses to a machine that measures the amount of air that you breathe out and how much oxygen is in that air. We will then ask you to begin walking on the treadmill and become familiar with how it feels.  Once you are comfortable we will increase the treadmill speed so that your heart rate increases slightly. After 2 minutes we will increase the grade of the treadmill and continue to increase the grade every two minutes until you report a high effort or we reach the maximum test value. When you are walking on the treadmill we will ask you to report how hard you are exerting yourself by pointing to a number from 1 – 10 on a colored chart. During the test we will monitor also your heart rate, blood pressure and ECG. You may stop the test at anytime if you feel it may be unsafe to continue. 

Muscle Strength, Gait Analysis, and Prolonged Walk Protocol 

Duration of roughly 2.5-3 hours

At this visit, you will complete strength testing of either you calf or your thigh (which you practice at visit 1) and walk overground while measurements of how you walk and the activity of your muscles are made. Then we will ask you to walk on a treadmill for 30 minutes with three 1-minute “challenge” periods, to simulate an extended walk you might complete during daily activity. The speed of walking on the treadmill will be set based on your comfortable walking pace determined in the 400m walk at visit 1. After the treadmill walk you will repeat the gait, muscle activity and strength measures.  You can take a break whenever you would like at any time point prior to the treadmill walk. 

            For the gait analysis, you will be asked to change into a pair of shorts and provided with appropriately sized athletic walking socks and shoes. You will be outfitted with little circles of double-sided tape on your foot, calf, thigh, hip, pelvis, shoulders, and arms. These may be placed by a researcher of the opposite sex. To the other side of the double-sided tape we will stick small balls with reflective material on the outside. The markers on the pelvis (at approximately the level of the waistband) and hip will be placed over clothing; markers on the foot will be placed over the shoe; markers on the calf, thigh, shoulders, and arms will be placed directly on the skin. The position of the reflective markers will be recorded by high-speed cameras circling the data collection space. The cameras capture only the position of the reflective markers that are placed on your skin and the images do not contain any information that may be used to identify your person. We will place other double-sided stickers on your leg you’re your leg muscles to the other side we will put small rectangular sensors that measure the electrical activity of your muscles. We will then ask you to walk up and down the walkway about ~10 – 20 times while measurements are made, before and after the treadmill walk. 

            You will be asked to sit on a machine, similar to weight machines used in some gyms, which we will use to measure your thigh or calf muscle strength. Your foot, hips, and torso will be strapped securely to this machine to prevent unwanted movement. You will be asked to fold your arms across your chest and then for thigh strength straighten your leg as hard as possible while the machine measures your strength. Your leg will not move during this measurement. We will repeat this exercise a couple of times in a row.  Next, we will ask you to straighten your leg out at a medium speed and as fast possible while seated in the machine to measure your muscle power. We will ask you to repeat this twice, with 1 minute of rest between trials. For the calf muscle strength we will also secure your shank to limit unwanted movement and then ask you to point your foot as hard as possible while the machine measures your strength. The machine will not move.  Next we will ask you to point your foot as fast as possible to measure your muscle power. We will repeat this a couple of times in a row. We will ask you to repeated this twice with one minute of rest between trials 

            The prolonged walk protocol will begin on a level treadmill with the speed set at your preferred speed, determined at Visit 1. The challenge periods will occur at minutes 7, 14, and 20, where treadmill grade will be increased to 3% grade for 1 minute. This challenge is meant to mimic changes in incline that you might encounter in the real world. At the end of each challenge, the grade will be returned to level. Your walking speed will remain the same throughout the 30 minutes. Every 5 minutes during the walk, we will ask you to give us your “perceived exertion” on a scale of 1 to 10, which reflects how hard you feel you are working at that moment.

            After 30 minutes of walking on the treadmill, you will walk overground at the same speed for 2 minutes to re-acclimate your system to normal walking. Immediately following this, you will walk along the walkway in the lab while measurements of your gait are made. Finally, you will be asked to complete the muscle strength testing again.

MRI, Muscle Strength, Prolonged Treadmill Walk and SPPB Tests

Duration of roughly 3 hours

At this visit, you will complete an MRI to determine muscle size, muscle strength testing of either your calf or thigh muscles (whichever you did not complete at Visit 2), the SPPB-A (as in Visit 1) and we will measure the amount of oxygen ( same equipment as Visit 1) during a prolonged treadmill walk (same as visit 2). After the treadmill, we will ask you to repeat the strength and SPPB-A measures.  You can take a break whenever you would like up until the start of the treadmill test. 

Before entering the magnet room of the Human Magnetic Resonance Center we will review your Magnetic Resonance Safety Form, ask you to remove all jewelry and change into scrub pants.  You will then be walked through a metal detector (like at the airport) and we will use a wand metal detector to check that you are safe to enter the magnet room.  Next you will be escorted into the magnet room, where you will lay on your pack with your legs pointed towards the scanner and your arms resting at your side. We will lay a flexible mat on your dominant leg and use this mat to obtain images of your leg muscles. Headphones will be provided to you to limit the amount of noise from the scanner and to enable clear and constant communication between you and the investigators.  This will take about 60 minutes  

            Next, we will ask you to complete the strength testing for the muscle you did not complete at Visit 2 (see above) and the SPPB-A (visit 1).  We will then outfit you with the breathing mask from Visit 1 and have you stand quietly for 5 minutes while initial measurements of the oxygen you use are made. We will then asked you to complete the prolonged treadmill walk (see Visit 2 for treadmill details) this time while wear the breathing mask. During the prolonged walk we will ask you to rate how hard you are working by pointing to a number from 1- 10 on a colored chart. After the treadmill walk we will ask you repeat the SPPB-A and strength measures. We expect this part of the visit will take about 1 hour.