High-intensity Interval Training After Stroke

Stroke is the main cause of serious, long-term disability among Americans. The effects of a stroke make it difficult to participate in routine, daily activities so people become seriously deconditioned after a stroke. This increases the chances of having another stroke and it also increases the risk of death. Even a small increase in aerobic capacity reduces these risks, making aerobic training an important component of post-stroke management.

Twenty to 60 minutes of moderate-intensity exercise on most days of the week is recommended for people with cardiovascular disease, but this is not very practical for many people after a stroke, who need to practice functional tasks like using the impaired arm and improving walking and balance. Another problem is that even when people do participate in aerobic training after a stroke, the improvements in aerobic capacity are sometimes surprisingly small. It is possible that the intensity of the training program was inadequate to improve aerobic capacity in some interventions. High-intensity interval training, in which people alternate between short, intense bouts of exercise and recovery bouts within the session, may be a way to improve aerobic capacity after a stroke with a more feasible training schedule that leaves time to practice functional skills too. High-intensity interval training on a treadmill might be appropriate to improve aerobic capacity and walking ability.

This non-randomized, non-blinded pilot study was designed to assess the feasibility of ten weeks of high-intensity interval training (HIIT) using treadmill training for adults with impaired walking who were at least 6 months post-stroke.

A secondary objective was to measure change in aerobic capacity, and a tertiary objective was to measure functional change in self-selected walking speed and leg strength as a result of the intervention.

10 participants completed HIIT intervention while 5 participants served as controls and received no intervention, but completed both baseline and post-testing sessions.

HIIT participants completed twice-weekly, 35-minute training sessions in a research laboratory for 10 consecutive weeks. At baseline and 12 weeks, all participants completed a graded exercise test, 10-meter walk test at self-selected and fastest, safe overground walking speeds, and a 30-second sit-to-stand test.

Inclusion criteria

• Male and female adults 18 years of age or older who had a unilateral stroke at least 6 months prior to enrollment
• Ability to provide informed consent and follow instructions to participate
• Medically stable
• Must be able to walk with no more than contact guard assistance on level surfaces
• Must be willing to walk on a treadmill with a support harness and handrail

Exclusion criteria

• Cerebellar stroke
• Medical instability
• Implanted pacemaker or defibrillator
• Inability to walk on a treadmill with a support harness and use of handrail for at least 5 minutes
• Absence of walking impairments
• Abnormal resting heart rate, blood pressure or ECG
• Abnormal ECG during graded exercise test