Exercise as it relates to Disease/Effect of treadmill rehabilitation on ambulation and CV fitness in chronic stroke patients

1.What is the background to this research?
Increasing overall fitness in any given population is essential to reduce fatigue & increase quality of life on a daily basis. In disease populations, exercising regularly is often hampered due to underlying determinants of a condition. According to Duncan et al. (1992), majority of stroke survivors experience at least some form of neurological recovery; in which the optimal timeframe for recovery plateaus within 11 weeks for 95% of patients. Recent evidence suggests that after a stroke, 50% of patients initially are unable to walk, 12% can walk with assistance, and 37% can walk independently. At the end of 11 weeks of intensive rehabilitation, 18% of patients still are unable to walk, 11% can walk with assistance, and 50% can walk independently. Studies have concluded that there are minor differences between treadmill & over ground walking; except that treadmill training is concluded to be much more beneficial for replication over a given time period. Several of the literature to date, has assessed acute and sub-acute rehabilitation for stroke patients, but there is minimal evidence supporting the effect of detraining and physiological adaptations in the chronic phase. The major purpose of this article is to address physical inactivity in chronic stroke patients; in order to determine whether treadmill training is more effective than conventional rehabilitation on ambulation and cardiovascular fitness.

2. Where is the research from?
This study was conducted in the U.S by Macko, R and colleagues; with both male and female participants (45 yrs and older) recruited from either Baltimore VA or University of Maryland's Hospital.

3.What kind of research was this?
The study performed was a randomized control trial in which 61 patients with chronic (defined as >6 months) hemi-paretic gait (one-side affected) following an ischemic stroke, were randomized to either a control group (stretching plus low-intensity walking program) or an aerobic treadmill exercise program (T-AEX); 3 times per week. After initial exercise testing; participants were randomly stratified via a computer generating system. Questionnaires, survey's and functional gait measures were assessed by blinded physicians at a separate location then the training location; in order to minimize bias. Due to safety regulations; the same supervisors that performed the treadmill training re-assessed treadmill gait measures.

4.What did the research involve?
Initially, a treadmill tolerance test was performed to assess gait safety; participants whom could sustain greater than or equal to 0.22 m/sec for 3 minutes or longer were considered suitable for the study. The T-AEX group began training at 40-50% Heart Rate Reserve (HRR) for 10–20 minutes, progressing by a desired 5% HRR & 5 minutes each proceeding week; in order to reach the goal of 3 x 40 minute sessions at 60-70% HRR weekly. The control group in contrast, performed 13 stretching exercises for 35 minutes and 5 minutes of low intensity walking at 30-40% HRR. Both groups received 48 hours of training across 6 months. Vo2 (volume of oxygen consumed per minute) peak was assessed to determine the effect of both modes of training on cardiovascular fitness. Outcome measures utilized were a 30 ft timed walking test to stimulate a 'home-based ambulatory setting' and a 6 min walking test to assess functional aerobic capacity. Two questionairres were also utilized to assess changes in perceived ambulatory capability; the Rivermead Mobility Index (RMI) and the Walking Impairment Questionnaire (WIQ).

5.What were the basic results?
25 patients (78%) finished the TEX program and 20 patients (69%) the control program, at cessation of the 6 month period. Participants failed to continue as a result of un-related medical issues or non-compliance; with no major difference in baseline measures as a result of drop-outs. After the 6 months, the T-AEX group had clinically significant changes in aerobic intensity, training duration and training intensity, as seen in ''Table 1. When comparing results between both groups, there was a statistically significant change in VO2 peak levels between the T-AEX and control groups (''Table 1). Gait economy was similar in both groups, but both were more economical. When comparing objective outcome measures there was a clinically significant change in 6 minute walking distance between both groups (Table 1); but no significant change in 30 ft timed walk. Finally, there was a self-reported four fold increase in functional mobility scores using the WIQ questionnaire in the T-AEX group as opposed to the control group. Researchers proposed that an increase in training duration correlated to an increase in overall 6 minute walking capacity in the T-AEX group; whereas an increase in training intensity positively predicted an increase in overall Vo2 peak capacity.

Table 1: Demonstrates the major variables measured across both groups at baseline and after 6 months, as a result of the interventions.

6.What conclusions can we take from this research?
According to the results, aerobic exercise training can improve cardiovascular fitness, overall walking distance and functional mobility measures. Results less favor the impact of the intervention on gait parameters and walking speed over a short distance. This challenges assumptions proposed by previous research suggesting that physiological exercise benefits begin to plateau after 11 weeks; in the stroke population, with all significant changes maintained after 6 months. These potential long-term benefits have a major impact on quality of life and activities of daily living. Also worth noting is the effect of increasing either training duration or intensity, to aid ambulatory function or cardiovascular fitness, respectively. This gives physicians the ability to manipulate aspects of training principles in chronic stroke patients to achieve a desired outcome; based primarily on patient goals, and given potential for functional progression.

7.Practical advice
This study has numerous effects for clinical practice in chronic stroke patients. Firstly, the large effect of aerobic treadmill training on cardiovascular fitness is vital, with the implication of 3 sessions a week of graded-aerobic training to be considered for stroke patients with goals of improving overall fitness. Standard principles of gradually increasing intensity and duration, should also be implemented for both fitness & function benefits. This particular study had a low sample size and in order to increase the reliability and reduce bias of results; similar prognostic indicators should be measured with a larger population. Furthermore, training benefits didn't plateau after 11 weeks, suggesting that the application of exercise programs in this population should be progressed beyond the sub-acute phase. As stroke patients often have deficits in other functional activities such as upper limb activities or functional transfers; further research could assess the benefit of prolonged graded-exercise training in other physical domains. This will assist to determine functional recovery over a greater time period in chronic stroke patients.

8. Further information/resources
Further resources regarding clinical guidelines for rehabilitation, aerobic exercise & treadmill training in stroke patients can be found at:

1. Clinical Guidelines for Stroke Rehabilitation and Recovery (National Stroke Foundation): https://www.nhmrc.gov.au/guidelines-publications/cp105

2. Effect of Treadmill Aerobic Exercise Training in control of Blood Pressure following Stoke: http://www.academia.edu/17811734/Effectiveness_of_Treadmill_Aerobic_Exercise_Training_in_Control_of_Blood_Pressure_Following_Stroke_-_A_Review_of_Evidences

3. Effect of task-orientated treadmill-walking training on walking ability of stroke patients: http://www.ncbi.nlm.nih.gov/pubmed/25920503

4. Physical Fitness Training for Stroke Patients (Cochrane review): https://www.essa.org.au/wp-content/uploads/2015/06/Stroke_Cochrane-Review.pdf

5. Stroke Rehabilitation: https://www.researchgate.net/profile/Julie_Bernhardt/publication/51125705_Stroke_Care_2_Stroke_rehabilitation/links/0912f50c95c8d0556e000000.pdf