September 03, 2019
High-intensity step training that mimics real-world conditions could better promote walking ability after a patient experiences a stroke compared with traditional, low-impact training, new research suggests.
In a study of 90 patients who had weakness on one side of the body after experiencing a stroke 6 months previously, high-intensity step training was associated with greater improvements in both walking ability and gait symmetry than low-intensity training, with potentially greater improvements in balance confidence.
High-intensity variable training also resulted in improved dynamic balance while walking.
"What we found is that if you do both the high-intensity training and the variable practice, then you really get gains in both walking and balance and balance confidence," lead investigator T. George Hornby, PhD, professor of physical medicine and rehabilitation at Indiana University School of Medicine, Indianapolis, told Medscape Medical News.
The findings were published online August 22 in Stroke.
Function Over Form
The study's goal was to determine both the individual and combined contributions of intensity and variability of stepping practice to improving walking speed and distance in people who had experienced stroke.
Accumulating data suggest that traditional rehabilitation practices, which emphasize normalizing gait patterns through low-intensity exercises, produce only limited improvements in mobility. Some studies have shown that increasing exercise intensity can improve walking endurance, but this did not necessarily improve balance or the ability to perform transfers.
For the current study, researchers hypothesized that instead of training stroke patients on forward walking or with low-intensity training in stepping tasks, ramping up both the intensity and the variability of stepping practice may yield real improvement in mobility and balance.
"We need to probably simulate the tasks that people will do in the real world," said Hornby. "What we're doing in the study is essentially trying to recapitulate that in some sense, in that we do these really variable tasks that are really challenging the patient."
In this randomized, blinded, phase 2 trial, the investigators screened 152 patients aged 18 to 85 years who had experienced post-stroke hemiparesis for a period of 6 or more months.
Of those patients, 97 were randomly assigned to one of three training groups: a high variable group, which performed high-intensity, variable, difficult stepping tasks that required 70% to 80% of heart rate reserve; a high forward group, which performed high-intensity stepping but only forward walking; and a low variable group, which performed low-intensity stepping in variable contexts at 30% to 40% of heart rate reserve.
Variable tasks included walking on uneven surfaces, up inclines and stairs, over randomly placed obstacles on a treadmill, and across a balance beam.
The participants received up to 30 1-hour training sessions over 2 months, with three to five sessions per week. Assessments were conducted at baseline, post training, and at a 3-month follow-up; 90 participants completed more than 10 sessions.
All of the patients wore accelerometers on their weakened limb, which enabled the investigators to estimate the stepping amount and rate. Heart rates were documented every 3 to 5 minutes; the Borg Scale was used to rate perceived exertion.
Significant Walking Gains
Primary study outcomes included walking speeds and timed distance. Secondary outcomes included dynamic balance, transfers, and metabolic measures.
Results showed that all walking gains were significantly greater after high-intensity vs low variable training (all comparisons, P < .001). There were also significant correlations with stepping amount and rate (r = .48 – 60; P < .01).
In the high-intensity groups, 57% to 80% of participants achieved important clinical gains, whereas only 9% to 31% of participants in low-intensity training did.
The researchers observed additional gains in spatiotemporal symmetry in the high-intensity training group. In individuals with severe impairments, balance confidence increased only at the conclusion of high variable training.
"If you just practice the variable tasks without focusing on intensity, you don't get very good at walking; in fact, the gains are really small," said Hornby.
"If you practice just walking really fast, you get pretty large changes in walking, but you don't get those changes in balance and balance confidence. So you need to do both," he added.
Preventing 'Rehab Reversals'
Commenting on the study for Medscape Medical News, Steven C. Cramer, MD, professor of neurology at the University of California, Los Angeles, said that only 5% to 10% of patients with ischemic stroke receive early treatment and good therapy, and only half of them have a great response.
"The problem is that most people don't recover enough," said Cramer, who was not involved with the research. "Movement usually plateaus at about 3, sometimes 6 months — that's it. Then they have disability for the rest of their life."
He added that at around 1-year post stroke, "the spontaneous recovery of the first few months starts to reverse. People start to crumble. There's a clear trend for functional decline."
Cramer went on to note that "this is a great study" for several reasons.
"It shows us that we can take people who have serious disability and are at high risk for bad things happening and make an intervention that's rather safe and improve their walking," he said.
He added that this has major positive ramifications for many skills, including motor and social function.
"They broke down high-intensity therapy into two flavors: low cognitive demand and high cognitive demand; and that's not often considered," Cramer said.
He noted that the results suggest that "if you turn the exercise into a puzzle," there's more brain activity and "more overall voltage" dedicated to the rewiring of the brain, which leads to a better overall benefit.
However, Cramer added that the investigators could have increased the sessions of rehabilitation therapy to see more of an effect.
"I admire that they added to cognitive consideration and showed benefit from attending to that; but they could be criticized for using relatively lower doses," he said. "Some people say how fast your walk is is the sixth vital sign."
The research was funded by the US National Institute on Disability, Independent Living, and Rehabilitation Research and the National Institute of Neurological Disorders and Stroke. Hornby and Cramer have disclosed no relevant financial relationships.