**Background:** Poor cardiorespiratory fitness and insufficient physical activity are risk factors for adverse health outcomes and compromised work performance. Workplace exercise interventions have shown benefits, but lack of time is a major barrier to participation. High-intensity interval training (HIT) is time-efficient and may overcome this barrier, but its feasibility in real-world workplace settings has been debated due to concerns about negative affective responses, especially in sedentary populations. This systematic review aimed to summarize evidence on the feasibility and effectiveness of HIT interventions in the workplace.
**Methods:** A systematic literature search was conducted in PubMed and SPORTDiscus (September–October 2021). Inclusion criteria were: intervention studies conducted in the workplace setting, including HIT protocols (brief bursts of high-intensity exercise >85% HRmax or all-out, interspersed with recovery), measuring physical, psychological, or work-related outcomes. The search identified 496 articles; after screening, 7 studies (317 participants) met inclusion criteria. Methodological quality was assessed using the PEDro scale (0–10). Due to heterogeneity in interventions and outcomes, a narrative synthesis was conducted rather than meta-analysis. Within-group and between-group Cohen's d effect sizes were calculated.
**Key Results:** HIT interventions lasted 6–12 weeks, with 2–4 sessions/week and 8–30 min per session (median 10 min). Feasibility: Five studies reported adherence rates >80% (range 83–90%), except Eather et al. (60% attendance, 4% dropout). Dropout rates ranged from 4% to 65%, with reasons typically unrelated to the intervention (personal or work-related). Four studies collected qualitative data on participant perceptions; positive aspects included time efficiency, flexible scheduling, sense of competence from individualized intensity, enjoyment, and socialization. Negative aspects included discomfort during strenuous efforts and reluctance to continue in some cases. Intervention fidelity was evaluated in 3 studies, with heart rate responses averaging 86–87% HRmax. Physical fitness: Cardiorespiratory fitness improved in 5 of 6 studies measuring it, with mean VO2max improvements of approximately 10% (range 7.4% to higher). Between-group effect sizes ranged from trivial (d=0.09) to large (d=1.4). Muscular fitness showed large effects in 2 of 3 studies (upper limb d=0.95–0.96; lower limb d=0.80–1.12). Body composition showed trivial-to-small effects across all 7 studies. Cardiometabolic health: Blood pressure effects were heterogeneous; systolic pressure reductions were larger in participants with higher baseline values (~129 mmHg). Lipid profile changes were trivial-to-small. Psychological outcomes: Health-related quality of life showed small-to-medium improvements (vitality d=0.51, pain reduction d=0.67). Autonomous motivation to exercise showed medium-to-large effects (d=0.76–0.88), and self-efficacy showed a large effect (d=1.57) in one study. Only one study examined work-related outcomes, reporting a small effect for productivity (d=0.47) and trivial effect for job satisfaction (d=0.05). Methodological quality: Median PEDro score was 5 (range 2–6); only 2 studies scored ≥6 (high quality), 2 scored ≤3 (low quality).
**Clinical Implications:** HIT appears feasible in workplace settings, primarily due to time efficiency and positive psychosocial responses including increased self-efficacy and motivation to exercise. The mean VO2max improvement of ~10% (2.8–4.7 ml/kg/min) is clinically meaningful, as each 1 ml/kg/min increase in VO2max is associated with 45 additional days of longevity, and a 3–4 ml/kg/min improvement corresponds to a 19% reduction in cardiovascular mortality. However, the evidence base is limited by small sample sizes, short intervention durations, heterogeneity in protocols and outcomes, and lack of rigorous study designs. Only 2 of 7 studies were RCTs. The authors note that most studies were conducted in university settings (highly controlled environments), and all focused on white-collar workers, limiting generalizability. Future research requires well-designed RCTs comparing different HIT protocols, investigating effects in blue-collar workers and those with musculoskeletal or metabolic disorders, and including economic analyses to quantify the return on investment for employers.