The participant in this case study was a 58-year-old Caucasian female who was recruited to participate in a larger research study (data not published) observing the effects of an 8-week exercise intervention on CR fitness and a physical function test (six-minute walk test). Prior to the onset of stroke, the participant reported incorporating regular exercise 45 minutes per day, 4-5 days per week. Her risk factors for stroke included: hyperlipidemia, hypertension and pre-diabetes. The participant was admitted to the hospital with right sided weakness and word finding difficulties. Diagnosis by the neurologist who read the MRI scan revealed an ischemic stroke in the left basal ganglia affecting the globus pallidus and posterior limb of the internal capsule. Primary deficits post-stroke included aphasia, difficulty writing with the right hand, and difficulty performing activities of daily living (ADL's). The participant's hospital stay was 4 days in length and included physical, occupational, and speech therapies.
In order to be enrolled into the study, the participant had to meet the following criteria: (1) Between 45-70 years of age; (2) Admission to hospital with diagnosis of a first-time, unilateral stroke; (3) Ability to walk with stand-by-assist; (4) Ability to travel or have transportation to participate in all testing and exercise sessions. The subject did not demonstrate the following exclusion criteria: (1) Acute renal failure; (2) Acute ischemic cardiovascular event or coronary artery bypass surgery less than 3 months ago; (3) Severe peripheral artery disease (Ankle-Brachial Index (ABI) < 0.40); (4) Diagnosis of congestive heart failure; (5) Current smoker; (6) Either unable to physically perform the exercise test using the recumbent stepper or demonstrate absolute indications for terminating exercise testing that follows the American College of Sports Medicine's (ACSM) guidelines; (7) Uncontrolled blood pressure with medication in the hospital (BP > 190/110mmHg).
The participant in this case study was enrolled in a larger exercise trial. The parent study was approved by the Institutional Review Board at the University of Kansas Medical Center. After initial screening, institutionally approved written informed consent was obtained. The participant's Ankle-Brachial Index (ABI) was 1.12, indicating normal or negligible obstruction in the periphery, and had a total Fugl Meyer score of 124 out of 124 possible points. Physician clearance was obtained for participation in the study.
At 15 days post-stroke the participant completed baseline testing. Baseline measures for all tests were repeated at the end of the 8-week exercise intervention and again at a 4-week follow-up visit. Day 1 included anthropometric measures, and a 6 Minute Walk Test (6-MWT).On Day 2 she returned for a graded exercise test (GXT) using an exercise protocol specifically developed for post-stroke patients. Prior to exercise testing we gathered anthropometric data. The participant was 154.9 cm tall with a body weight was 64.0 kg and a body mass index (BMI) of 24.75 kg*m2-1. At baseline her resting heart rate (HR) was 79 bpm and blood pressure (BP) was 121/86 mmHg.
The 6 Minute Walk Test (6-MWT) is an outcome measure used in the stroke population to quantify an individual's functional capacity and endurance. The 6-MWT was used in this study to assess walking endurance. The 6-MWT was performed in a tiled hallway measuring 22.2 meters in length between each marker cone. The subject was told to walk as quickly as possible between the two cones for six minutes and was given standard encouragement. The participant's baseline was 476.7m, which is below the normal mean value of 538 m for a female between 60-69 years of age.
A total body recumbent stepper (TBRS) (NuStep T5XR, Ann Arbor, MI) was used as the exercise modality for the graded exercise test (mTBRS-XT). The mTBRS-XT begins at 25 Watts and increases 15 Watts every 2 minutes until fatigue or test termination criteria are met. A metabolic cart (ParvoMedics, Sandy, UT) was used to assess gas exchange during the exercise test and determine VO2 peak. Due to the fact that a stroke diagnosis is considered a high cardiac risk, a physician supervised the exercise test. Borg's Rate of Perceived Exertion (RPE) Scale of 6-20 was used to assess exertion and HR was continuously monitored using a 12-lead EKG. BP and VO2 were recorded every 2 minutes along with RPE and HR. Standard guidelines of the American College of Sports Medicine (ACSM) were used to determine exercise test endpoints. Absolute indications for terminating an exercise test include; drop in systolic BP of > 10 mmHg from baseline BP, moderately severe angina, increasing nervous system symptoms (ataxia, dizziness, etc), signs of poor perfusion, technical difficulties monitoring the ECG or systolic BP, subject's desire to stop, sustained ventricular tachycardia, ST elevation (+1.0 mm) in leads without diagnostic Q-waves. The participant's exercise test lasted 14 minutes, her VO2 peak was 20 mL*kg-1*min-1, her peak HR was 158 bpm, and her peak BP was 158/88 mmHg. The subject reported a RPE of 20 indicating her maximal effort. The participant stopped the exercise due to volitional fatigue.
A progressive aerobic exercise intervention using the TBRS was designed based on the values obtained from the exercise test. The peak HR achieved during the exercise test was used to determine a target HR training zone using the Karvonen formula. The intensity was set to maintain HR between 50-59% of HR reserve for weeks 1-4 and during weeks 5-8 the intensity was increased to 60-69% of HR reserve. Exercise duration began at 20 minutes with the goal of reaching 30 minutes of continuous exercise at a specified workload. The TBRS was programmed to maintain a constant workload based on target HR with a rate of 100-105 steps per minute. HR was monitored using a Polar T31 coded chest strap (Polar USA, Kempele, Finland). HR and BP were measured at rest, at peak exercise, and at post-exercise during rest. The RPE scale was used to rate the level of intensity of the exercise session. The intervention was three times per week for eight weeks.
Since cardiac medications can affect HR and BP response during exercise, the participant was asked at each visit whether any changes in medications occurred. She was taking medications for high BP, specifically an angiotensin-converting enzyme, calcium channel blocker and a diuretic. There were no medication changes during the intervention period or at the follow-up.
The results illustrate an improvement in outcome measures after 8 weeks of a moderate to high intensity aerobic exercise intervention. See table 1 for a summary of outcome measures. This individual started the exercise intervention just 15 days post-stroke and did not have any adverse events during the peak exercise tests or exercise intervention.
This individual had notable improvements in the 6-MWT, improving from a distance of 476.74 meters at baseline to 500.71 meters post-intervention and then 551.4 meters at the 4-week follow-up. Normal ranges for the 6-MWT that have been reported in the literature include a walking distance calculated between 538 +- 95m and 576 +- 87m for women between 20 and80 years of age . Compared to normative data, the participant walked 61.26 m less at baseline, which demonstrates decreased functional endurance. After the exercise intervention she increased walking distance but was still considered below normative values. At the 4-week follow-up the participant was within the normal range. This is an important measure for endurance and ability to perform ADL's and functional activities such as walking in the community.
The subject's initial VO2 peak of 20 mL*kg-1*min-1 is between the 1stand 5th percentiles when compared to healthy, age and gender-matched peers, indicating her CR fitness to be very poor. After the exercise intervention, she improved her peak capacity by 21% to 24.2 mL kg-1 min-1 and then continued to improve to 27.4 mL kg-1 min-1 at the 4-week follow-up. Improvements in other exercise testing measures are reported in Table 1.