Effects of HIIT on HRV in Sub-acute Post-stroke Patients

Objective. To assess the effect of innovative "High-Intensity Interval Training" (HIIT) on Heart Rate Variability, a strong biomarker of positive outcome after stroke.

Design. A randomized controlled study with blinded assessment of the main criteria.

Population. NIHSS\<20 post-stroke patients, hospitalized in secondary care stroke-units within the first 3 months (sub-acute phase).

Selection. Eligibility test on a semi-recumbent cycloergometer Intervention. In addition to a standard neurorehabilitation program (3±1 sessions daily, including cognitive and occupational therapy, physiotherapy with strengthening-stretching exercises), the aerobic group will benefit from a HIIT procedure (HIIT group) with a semi-recumbent cycloergometer, for 6 weeks representing 16 sessions; while the non-aerobic group will undertake a "Low-Intensity Group-Gymnastic Training" (Control or LIGT Group) (=segmental strengthening-stretching and proprioceptive exercises mainly), with the same training volume and frequency for both groups.

Main outcome measure. Standard Deviation of Normal-to-Normal RR intervals (SDNN) from 24h Holter-ECG recordings at W4, W8 and M6.

Modifications in patients' medical management are expected, as generalization of AT in moderate to severe stroke patients at the sub-acute phase, with "Low volume HIIT" and simple devices.

A randomized controlled 2-arms parallel study, comparing HRV in two groups of stroke patients.

Post-acute stroke patients hospitalized in rehabilitation stroke¬-units, within secondary care hospitals, are screened for eligibility.

* Inclusion criteria:

  * first-ever hemispheric stroke, with consistent clinical and neuroimaging signs
  * \<3 month
  * NIHSS \<20 in acute care
  * age\>18
* Non-inclusion criteria:

  * complicated diabetes mellitus with objective neuropathy and/or autonomic dysfunction
  * other concomitant cardiac or pulmonary diseases possibly affecting HRV recordings, ie: acute myocardial infarction (\<6 month), myocardial dysfunction as severe dilated or hypertrophic cardiomyopathy, class 3 and 4 heart failure, arrhythmias including chronic atrial fibrillation, conduction abnormalities.
  * beta-blockers with no alternative options
  * severe cognitive impairment inconsistent with free, informed and written consent or questionnaire filling
* Patients will benefit beforehand from a symptom-limited Graded Exercise Test (GXT), with ECG monitoring and using a semi recumbent cycle ergometer (Ergoline, Optibike MED600), mainly to exclude a CV risk and to accurately assess their exercise capacities for better individualized programs. Peak oxygen uptake, Peak Power , Peak Heart Rate, Respiratory Exchange Ratio (VO2peak, Power peak, HRpeak, RER respectively) will be measured, Ventilatory Threshold 1 (VT1) will be estimated, and oxygen uptake, power and heart rate at VT1 will be recorded (VO2vt1, Pvt1, HRvt1).
* The global rehabilitation program will consist daily in a mean of 3 sessions (2 to 4), five days a week: physiotherapy (with, among others, Strengthening-Stretching activity), occupational therapy, cognitive therapy (orthophonist or neuro-psychologist), and either aerobic training (HIIT) or non-aerobic training (Control Group-CG by Low Intensity Group Training-LIGT).
* HIIT and LIGT training volume and duration will be the same (16 sessions, 6 weeks).
* The intervention-group (HIIT Group) will realize a 6-weeks Aerobic Training as follows:

Among the FITT principle:

* Frequency: 3 times a week
* Intensity: long-HIIT: 4 to 5 four-minutes intervals at Pvt1 interspersed with two- minutes interval at 50% Pvt1=(4-5 x (4':2')/(Pvt1 :50%Psv1))

  * short-HIIT: 8 to 10 forty-five seconds intervals at Pmax, interspersed with forty-five seconds intervals rest = 8-10x(45":45")/Pmax :Rest)
* Time: 12' to 30' per session (8 short-sessions of 12 to 15', 8 long-sessions of 24 to 30')
* Type: cycling on a semirecumbent ergometer

In the CG group, HIIT will be replaced by "LIGT" sessions, as follows:

Among the FITT principle:

* Frequency: 3 times a week
* Intensity: Low HR controlled by HR monitoring (\<60% HRpeak or 30%HRR)
* Time: 12' to 30' per session (8 short-sessions of 12 to 15', 8 long-sessions of 24 to 30')
* Type: Static and Segmental strengthening and stretching mainly

Novelty

1. To use a new and strong risk marker of stroke relapse and post-stroke complications (mortality, morbidity, and poor functional outcomes), which is improved by physical activity, to strengthen the use of Aerobic Training (AT) in secondary prevention.
2. To allow generalization of conclusions:

   * by studying AT with a shorter intervention-design, limiting competition with neuro-rehabilitation (fatigue, time spent) and via a simple intervention-device (semi recumbent ergometer).

(Indeed, most of non-ambulatory participants (82% ) in RCTs benefited from AT through assistive walking devices, using Weight Bearing Support Treadmill, which are difficult to set up (accessibility, personnel and equipment costs...)).

° by studying AT effects in a more disabled population and at an early stage. (Indeed, in Randomized Controlled Studies having assessed AT in chronic (\>6months) post-stroke patients, NIHSS ≤ 5/42 was most often chosen for inclusion criterion, with a median NIHSS around 3 at study start.

Eligibility Criteria:
Inclusion Criteria:

* first-ever hemispheric stroke, with consistent clinical and neuroimaging signs
* \<3 month
* NIHSS \<20 in acute care

Exclusion Criteria:

* age\<18 years-old
* diabetes mellitus complicated by neuropathy or autonomic dysfunction; or any other concomitant nervous system, cardiac or pulmonary disease possibly affecting the autonomic nervous system ie:
* myocardial infarction\< 6 months,
* myocardial dysfunction as severe dilated or hypertrophic cardiomyopathy, class 3 and 4 heart failure,
* severe conduction abnormalities and arrhythmias, including chronic atrial fibrillation,
* mechanical ventilation,
* beta-blockers with no alternative options, pharmacological mandatory treatment possibly affecting the autonomic nervous system and HRV.
* severe cognitive impairment inconsistent with free, informed and written consent or questionnaire filling