# Effect of high-intensity interval training on cardiorespiratory fitness, physical activity and body composition in people with schizophrenia: a randomized controlled trial PMID: 32854688 Journal: BMC Psychiatry Published: 2020-08-27 Authors: Andersen E, Bang-Kittilsen G, Bigseth TT, Egeland J, Holmen TL, Martinsen EW, Stensrud T, Engh JA ## Question Does supervised treadmill HIIT improve cardiorespiratory fitness, physical activity, and body composition in people with schizophrenia compared with an active low-intensity gaming control? ## Summary In outpatients with schizophrenia, 12 weeks of supervised treadmill HIIT did not significantly improve VO2max, physical activity, sedentary time, or body composition compared with an active computer-gaming control. Adherence and valid VO2max testing were challenging. Exploratory analyses suggested staff physical-activity competence may have influenced outcomes. ## Population - Eighty-two outpatients were randomized: HIIT n=43 and comparison n=39. Participants were adults aged 18-67 with DSM-5 schizophrenia spectrum disorder, IQ at least 70, and Scandinavian language ability. Most were on antipsychotic medication; mean BMI was about 29-30. - Sample size: 82 - Age: HIIT 36 +/- 14; comparison 37 +/- 13 years - Sex: HIIT 39% female; comparison 38% female - Fitness level: Outpatients with low baseline fitness on average - Health status: Schizophrenia spectrum disorder; most on antipsychotic medication ## Methodology - Randomized controlled observer-blinded clinical trial - 12 weeks - Supervised outpatient exercise/gaming sessions - Randomized and controlled study design. ## Protocol - Supervised treadmill HIIT; details: Twelve weeks of supervised treadmill HIIT, 2 sessions/week, 45 min/session: 8-min warm-up; 4 x 4 min walking/running intervals at 85-95% maximum HR; 3-min active pauses at about 70% maximum HR; 5-min cooldown. Motivation work was informed by social cognitive theory. - Modality: Treadmill walking/running HIIT. - Work intervals: 4 min. - Recovery: 3 min. - Sets or repetitions: 4 intervals per HIIT session. - Intensity: 85-95% maximum HR during intervals; about 70% maximum HR during active pauses. - Session duration: 45 min. - Frequency: 2. - Program length: 12 weeks. - Progression: Walking/running speed and incline were adjusted to target HR. - Nintendo Wii Sports active control; details: Active control with Nintendo Wii Sports computer gaming skills sessions for the same 12-week period and session duration, intended to provide similar staff contact with lower physiological intensity, plus treatment as usual. - Modality: Treadmill walking/running HIIT. - Work intervals: 4 min. - Recovery: 3 min. - Sets or repetitions: 4 intervals per HIIT session. - Intensity: 85-95% maximum HR during intervals; about 70% maximum HR during active pauses. - Session duration: 45 min. - Frequency: 2. - Program length: 12 weeks. - Progression: Walking/running speed and incline were adjusted to target HR. ## Outcomes ### VO2max and cardiorespiratory variables Status: no clear change No significant between-group or within-group differences were found in VO2max or cardiorespiratory variables. VO2max was 32.1 +/- 11 to 30.8 +/- 11 mL/kg/min in HIIT and 31.1 +/- 11 to 31.1 +/- 11 in comparison. ### Physical activity and body composition Status: no clear change No significant changes were found in physical activity, sedentary time, or body composition. ### Valid VO2max test completion Status: mixed Only 21/43 HIIT participants and 26 comparison participants had valid VO2max tests at post-measurement. ### VO2max responder proportion Status: mixed Forty-seven percent of HIIT participants and 27% of comparison participants had at least 5% VO2max increase. ### Staff competence subgroup fitness response Status: improved Exploratory analysis suggested HIIT led by PA-competent staff increased CRF compared with non-PA-competent staff: +2.4 +/- 4.5 vs -2.2 +/- 4.7 mL/kg/min, p=.010. p=.010 ## Practical Insights - A nominal HIIT protocol may fail to improve fitness if achieved intensity, adherence, or test validity are limited. - For populations with severe mental illness, staff skill and motivational support may be part of the effective intervention. - Avoid extrapolating from prescribed HIIT dose alone; report achieved intensity. ## Limitations - Many invalid VO2max tests reduced power. - Only two sessions/week and incomplete interval intensity may have limited training stimulus. - Staff PA competence finding was exploratory/post hoc. - Clinical special population and supervised context limit generalizability. ## Safety And Adherence - No adverse events were found in the extracted text. - High-intensity adherence was incomplete: 39.9% of intervals reached at least 85% maximum HR. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/32854688/) (pubmed) - [DOI](https://doi.org/10.1186/s12888-020-02827-2) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7457274/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.