KITE Research Spotlight: High-intensity interval training could drastically improve cardiorespiratory health for stroke patients

This paper, for the first time, identifies the benefits of a novel type of exercise training that more than doubles the improvement in cardiorespiratory fitness level

TORONTO–New research from the KITE Research Institute at UHN suggests that high-intensity interval training (HIIT) could be the key to improving cardiorespiratory health for stroke patients.

A recent trial led by KITE scientist Dr. Susan Marzolini found that use of HIIT can more than double the improvement of a patient’s cardiorespiratory fitness level compared to conventional exercise training for those with walking dysfunction following a stroke.  

Each year over 100 000 Canadians suffer from a stroke, which makes it the third leading cause of death and the leading cause of adult disability.

Dr. Marzolini is the co-creator and lead of Toronto Rehabilitation Institute/UHN’s Exercise and Risk Factor Modification Program for People following Stroke.

The results of this trial, which were published in the Journal of the American Heart Association, will help optimize recovery for stroke patients and decrease their chances of recurrent strokes.

The KITE Research Institute connected with Dr. Marzolini to learn more about her findings.

 Which patient groups are most affected by this? 

Individuals who have suffered a stroke.

After a stroke, people become inactive leading to marked cardiorespiratory deconditioning that is approximately half of age- and sex-predicted normative values for sedentary adults, falling below the necessary criterion for independent living. 

In addition, while most stroke survivors regain the ability to walk, they will lack sufficient walking speed and endurance to resume regular day-to-day activities. 

What did you find? 

We found that six months of a novel HIIT protocol using shorter (30 seconds) and longer (120 seconds) high-intensity intervals resulted in more than a two-fold significant and clinically important greater change in cardiorespiratory fitness compared to conventional moderate-intensity continuous training at the ventilatory anaerobic threshold. In addition, both groups had similar and marked increases in six-minute walk distance (>70 meters). This was almost three times the minimal clinically important difference of 25 meters and exceeded what is considered a large improvement (50 meters). Moreover, HIIT was safe, and 96 per cent of the patients completed the study.

Why does this matter?

Determining strategies to optimize cardiorespiratory fitness is important as low fitness is associated with higher stroke risk, and is a strong independent predictor of cardiovascular and all-cause mortality. In addition, both poor cardiorespiratory fitness and walking dysfunction are significant barriers to returning to regular activities-of-daily-living. 

Furthermore, our previous research demonstrated that 72 per cent of patients with post-stroke walking dysfunction were unable to reach a walking intensity at or above the recommended intensity for improving cardiorespiratory fitness during a six-minute walk test (i.e., walking as fast as possible in six minutes). This limitation restricts a patient’s potential for recovery. However, we now have evidence that we can overcome this limitation by using an exercise strategy called HIIT. 

What is the potential impact? 

These findings show proof of concept that HIIT yields greater improvement in cardiorespiratory fitness than conventional training in appropriately screened individuals.  The results of this research will have a global societal benefit in helping future patients optimize their recovery, as other rehabilitation programs around the globe will begin to offer high-intensity interval training for eliciting greater improvement in cardiorespiratory fitness.


Research Spotlight: 
The HIT-Stroke trial

Assistant Professor in the Faculty of Kinesiology and Physical Education, University of Toronto, Co-creator and lead of Toronto Rehabilitation Institute/University Health Network's Exercise and Risk Factor Modification Program for People following Stroke, Registered Kinesiologist 

Name of Publication:
Effect of High‐Intensity Interval Training and Moderate‐Intensity Continuous Training in People With Poststroke Gait Dysfunction: A Randomized Clinical Trial.

Name of Journal:
Journal of the American Heart Association