Effects of High-Intensity Interval Training After Stroke (The HIIT Stroke Study) on Physical and Cognitive Function: A Multicenter Randomized Controlled Trial.

OBJECTIVE: To assess the effects of high-intensity interval training (HIIT) on physical, mental, and cognitive functioning after stroke. DESIGN: The HIIT Stroke Study was a single-blind, multicenter, parallel-group randomized controlled trial. SETTING: Specialized rehabilitation units at 3 Norwegian hospitals. PARTICIPANTS: Adult stroke survivors (N=70) 3 months to 5 years after a first-ever stroke. Mean age was 57.6±9.2 years and 58.7±9.2 years in the intervention and control groups, respectively. INTERVENTIONS: Participants were randomized to standard care in combination with 4×4 minutes of treadmill HIIT at 85%-95% of peak heart rate or standard care only. OUTCOMES: Outcomes were measured using physical, mental, and cognitive tests and the FIM and Stroke Impact Scale. Linear mixed models were used to analyze differences between groups at posttest and 12-month follow-up. RESULTS: The intervention group showed a significant treatment effect (95% confidence interval [CI]) from baseline to posttest on a 6-minute walk test of 28.3 (CI, 2.80-53.77) meters (P=.030); Berg Balance Scale 1.27 (CI, 0.17-2.28) points (P=.025); and Trail Making Test Part B (TMT-B; -24.16 [CI, -46.35 to -1.98] s, P=.033). The intervention group showed significantly greater improvement on TMT-B at the 12-month follow-up (25.44 [CI, -49.01 to -1.87] s, P=.035). The control group showed significantly greater improvement in total Functional Independence Measure score with a treatment effect of -2.37 (CI, -4.30 to -0.44) points (P=.016) at 12-month follow-up. No significant differences were identified between groups on other outcomes at any time point. CONCLUSIONS: HIIT combined with standard care improved walking distance, balance, and executive function immediately after the intervention compared with standard care only. However, only TMT-B remained significant at the 12-month follow-up.

Effects of High-Intensity Interval Training After Stroke (the HIIT-Stroke Study): A Multicenter Randomized Controlled Trial.

OBJECTIVE: To examine if 8 weeks of high-intensity interval training (HIIT) in addition to standard care would increase and maintain peak oxygen uptake (Vo2peak) more than standard care alone in patients with stroke. DESIGN: This was a single-blind, multicenter, parallel group, randomized controlled trial. SETTING: Specialized rehabilitation units at 3 Norwegian hospitals. PARTICIPANTS: Participants (N=70), 3 months to 5 years after first-ever stroke, were randomly assigned to the intervention group (n=36) or the control group (n=34); 42% were women, mean age was 57.6±9.3 years, mean time post stroke was 26.4±14.5 months. INTERVENTION: The intervention was 8 weeks: 3 times a week with HIIT treadmill training with work periods of 4 × 4 minutes at 85%-95% of peak heart rate interspersed with 3 minutes of active recovery at 50%-70% of peak heart rate. The control group received standard care according to national guidelines. OUTCOMES: The primary outcome, analyzed by intention-to-treat, was Vo2peak measured as liters per minute 12 months after inclusion. Secondary outcome measures were blood pressure and blood profile. RESULTS: Mean baseline Vo2peak was 2.63±1.08 L·min-1 vs 2.87±0.71 L·min-1, while at 12 months Vo2peak was 2.70±1.00 L·min-1 vs 2.67±0.76 L·min-1 (P=.068) in the intervention and control groups, respectively. There was a significant and greater improvement in the intervention group compared with the control group at 12 months in 3 of 6 secondary outcomes from the peak test but no significant differences for blood pressure or blood profile. CONCLUSIONS: The HIIT intervention, which was well-tolerated in this sample of well-functioning survivors of stroke, was not superior to standard care in improving and maintaining Vo2peak at the 12-month follow-up. However, secondary results from the peak test showed a significant improvement from before to immediately after the intervention.

Oxygen uptake during functional activities after stroke-Reliability and validity of a portable ergospirometry system.

BACKGROUND: People with stroke have a low peak aerobic capacity and experience increased effort during performance of daily activities. The purpose of this study was to examine test-retest reliability of a portable ergospirometry system in people with stroke during performance of functional activities in a field-test. Secondary aims were to examine the proportion of oxygen consumed during the field-test in relation to the peak-test and to analyse the correlation between the oxygen uptake during the field-test and peak-test in order to support the validity of the field-test. METHODS: With simultaneous measurement of oxygen consumption, participants performed a standardized field-test consisting of five activities; walking over ground, stair walking, stepping over obstacles, walking slalom between cones and from a standing position lifting objects from one height to another. All activities were performed in self-selected speed. Prior to the field-test, a peak aerobic capacity test was performed. The field-test was repeated minimum 2 and maximum 14 days between the tests. ICC2,1 and Bland Altman tests (Limits of Agreement, LoA) were used to analyse test-retest reliability. RESULTS: In total 31 participants (39% women, mean (SD) age 54.5 (12.7) years and 21.1 (14.3) months' post-stroke) were included. The ICC2,1 was ≥ 0.80 for absolute V̇O2, relative V̇O2, minute ventilation, CO2, respiratory exchange ratio, heart rate and Borgs rating of perceived exertion. ICC2,1 for total time to complete the field-test was 0.99. Mean difference in steady state V̇O2 during Test 1 and Test 2 was -0.40 (2.12) The LoAs were -3.75 and 4.51. Participants spent 60.7% of their V̇O2peak performing functional activities. Correlation between field-test and peak-test was 0.689, p = 0.001 for absolute and 0.733, p = 0.001 for relative V̇O2. CONCLUSIONS: This study presents first evidence on reliability of oxygen uptake during performance of functional activities after stroke, showing very good test-retest reliability. The secondary analysis showed that the amount of energy spent during the field-test relative to the peak-test was high and the correlation between the two test was good, supporting the validity of this method.

Effect of high aerobic intensity interval treadmill walking in people with chronic stroke: a pilot study with one year follow-up.

OBJECTIVE: To determine the physiological and functional responses from high aerobic intensity treadmill walking in 4 x 4-minute intervals in people with chronic stroke and to evaluate the feasibility of this mode of training. METHOD: This was a baseline control trial with 1 year follow-up in an outpatient rehabilitation setting at a university hospital. Eight people with chronic stroke participated in and completed the study. Their mean age was 48.9 (± 10.6) years. We tested uphill treadmill walking in 4 x 4-minute work periods at an intensity between 85% and 95% of peak heart rate from initial maximal treadmill testing. There were 3-minute active breaks between the intervals. The main outcome measures were peak oxygen uptake (VO2peak) and walking economy (Cw). Overall compliance and adverse events determine the feasibility. RESULTS: VO2peak increased from 2.32 (± 0.44) to 2.60 (± 0.55) L • min-1 post training (P = .003). Walking economy (Cw) improved from 1.12 (± 0.15) to 1.04 (± 0.18) L • min-1 (P = .043). At 1 year follow-up, VO2peak was 2.59 (±0.58) L • min -1 and was not significantly different from posttraining measurement (P = 1.00). Cw was 1.19 (± 0.15) L • min-1 at 1 year follow-up and thus was worse than post training (P = .023). Functional improvements were found in the 6-minute walk test (6MWT) (P = .020), 10-meter walk test (10MWT) (P = .032), and Timed Up and Go test (TUG) (P = .002) at post tests. CONCLUSIONS: High aerobic intensity interval treadmill walking significantly increased VO2peak and improved Cw in these subjects. The training was feasible and may have important implications for cardiovascular health and future rehabilitation programs in this population.

Maximal strength training enhances strength and functional performance in chronic stroke survivors.

OBJECTIVE: This study aimed to demonstrate that maximal strength training improves muscle strength and to assess the effect of training on function, aerobic status, and quality-of-life among chronic stroke survivors. DESIGN: Ten patients acted as their own controls for 4 wks, before an 8-week training intervention. Patients trained 3 days/wk, with four sets of four repetitions at 85%-95% one repetition maximum in unilateral leg press and plantarflexion with an emphasis on maximal mobilization of force in the concentric phase. RESULTS: After training, leg press strength improved by 30.6 kg (75%) and 17.8 kg (86%); plantarflexion strength improved by 35.5 kg (89%) and 28.5 kg (223%) for the unaffected and affected limbs, respectively, significantly different from the control period (all P < 0.01). The 6-min walk test improved by 13.9 m (within training period; P = 0.01), and the Timed Up and Go test time improved by 0.6 secs (within training period; P < 0.05). There were no significant changes in walking economy, peak aerobic capacity, Four-Square Step Test, or health-related quality-of-life after training. CONCLUSIONS: Maximal strength training improved muscle strength in the most affected as well as in the nonaffected leg and improved Timed-Up-And-Go time and 6-min walk distance but did not alter Four-Step Square Test time, aerobic status, or quality-of-life among chronic stroke survivors.

Neuromuscular performance of paretic versus non-paretic plantar flexors after stroke.

The objective of this study was to compare the neuromuscular function of the paretic and non-paretic plantar flexors (i.e. soleus, gastrocnemius medialis, lateralis) in chronic stroke patients. It was hypothesized that the contractile rate of force development (RFD) and neural activation, assessed by electromyogram (EMG) and V-waves normalized to the M-wave, and voluntary activation (twitch interpolation) would be reduced during plantar flexor maximum voluntary isometric contraction and that the evoked muscle twitch properties would be reduced in the paretic limb. Ten chronic stroke survivors completed the study. The main findings were that the paretic side showed deteriorated function compared to the non-paretic leg in terms of (1) RFD in all analyzed time windows from force onset to 250 ms, although relative RFD (i.e. normalized to maximum voluntary force) was similar; (2) fast neural activation (for most analyzed time windows), assessed by EMG activity in time windows from EMG onset to 250 ms; (3) V-wave responses (except for gastrocnemius medialis); (4) voluntary activation; (5) the evoked peak twitch force, although there was no evidence of intrinsic muscle slowing; (6) EMG activity obtained at maximal voluntary force. In conclusion, this study demonstrates considerable neuromuscular asymmetry of the plantar flexors in chronic stroke survivors. Effective rehabilitation regimes should be investigated.