JAMA study finds that high-intensity interval training improves stroke patients’ mobility more than moderate aerobic exercise
KU researcher Sandra Billinger, Ph.D., was part of a multi-site study that may change how stroke rehabilitation is conducted.
The old maxim “slow and steady wins the race” maybe isn’t the best strategy when it comes to stroke survivors still grappling with mobility issues six months or more after their strokes.
That’s the advice being shared as part of a study recently published in the prestigious JAMA Neurology journal that may change how stroke rehabilitation is conducted. Sandra Billinger, Ph.D., professor of neurology and vice chair of stroke translation research at the University of Kansas School of Medicine was part of that multi-site study.
The researchers found that participants who walked short intervals at a vigorous pace, followed by short rests, had better mobility at the three-month mark than those who walked at a moderate pace throughout the session.
“It’s very difficult when you’ve had a life-changing stroke and all of a sudden, you can’t do the things that you did before,” Billinger said. “Intervening early is an important part of recovery, but people who have been living with limited mobility are also very excited to improve, and we wanted to find the best way for them to do so.”
About the study
The clinical trial was the joint project of the University of Cincinnati in Ohio, the University of Delaware-Newark and KU Medical Center. Of the 55 enrolled study participants who were still experiencing walking problems six months to five years after their stroke, KU Medical Center studied 18 of them.
In all study locations, researchers randomly divided the number of participants into two groups. In the first group, participants in safety harnesses walked on a treadmill at a moderate pace for 45 minutes three times a week for three months. Their progress was measured by how well they walked, both on and off the treadmill, at the end of the study.
In the second group, participants also walked on a treadmill wearing a safety harness. But instead of a steady pace, these participants walked vigorously for 30 seconds, then rested for 30 to 60 seconds before repeating the process. They, too, spent 45 minutes doing the therapy three times a week for three months, and their progress was measured by how well they walked at the end of the study.
The first group practiced what researchers call moderate aerobic training (MAT), a standard method of rehabilitation. The second group practiced a new method called high-intensity interval training (HIT).
In the JAMA Neurology publication, the researchers shared what they’d discovered. At the one-month point of the study, the two groups had similar results. But after two months and again at three months, the high-intensity group did significantly better than the moderate-intensity group.
At the end of three months, the MAT group improved 90% over their pre-study mobility. The HIT group improved 184% over baseline. “So, intensity does matter,” Billinger said. “What’s important to recognize is that both groups improved. It’s just that the HIT group improved more over that 12-week period.”
Previous stroke studies conducted with high-intensity interval training had shown little difference between MAT and HIT, but those studies concluded after eight weeks, according to Billinger. The idea to lengthen the trial’s timeline was a key variable that led to this study’s groundbreaking results. “We wanted to identify the optimal duration that improved walking, and our data show three months of training is best,” she said.
The study team is “truly excited” about this research potentially being implemented into outpatient physical therapy. “I think it’s important for the stroke rehabilitation and recovery community to realize that we can implement a feasible HIT protocol that results in improved walking in people living with chronic stroke,” Billinger said.
Billinger pointed out that most physical therapy settings already have the treadmills and equipment needed to follow high-intensity interval training. “So, if we can give them the guidance on the intensity and the protocols of what we do, we hope that this will be part of physical therapy’s clinical practice guidelines.”
Future studies will need to examine why the high-interval training seems to work better than moderate continuous walking. Already the researchers are waiting to hear whether funding will be continued for the next phase of the study. In that phase, researchers plan to study whether HIT’s mobility gains measured after three months are retained three months after that.
“There are many aspects of stroke recovery that we don’t yet understand,” Billinger said. “This is just the beginning to know the effect of endurance and speed to improve walking.”