Background Cardiorespiratory fitness (CRF) is recognized as an independent risk factor for cardiovascular disease (CVD) and improved CRF associates with lower risk of CVD . High-intensity interval training (HIIT) is an effective mode of exercise to increase CRF. However, HIIT is seldom utilized in physiotherapy primary care in the context of inflammatory joint disease (IJD), and the sustainable effects of HIIT have been questioned .
Objectives To investigate short- and long-term effects of twelve weeks of supervised HIIT in physiotherapy primary care on CRF, pain and fatigue in patients with IJD.
Methods In this assessor-blinded randomized controlled trial (NCT04922840), 60 patients were allocated to a control group (n=30) or a HIIT group (n=30) that received a 12-week intervention in physiotherapy primary care including two weekly supervised 4x4 minute HIIT sessions at 90-95% peak heart rate and one non-supervised exercise session at moderate intensity. Patients were assessed at baseline, 3 and 6 months. Primary outcome was change in CRF from baseline to 3 months, measured as peak oxygen uptake (VO2peak) by a cardiopulmonary exercise test. Secondary outcomes were pain and fatigue (Numeric Rating Scale 0-10, 0= no pain/fatigue). Group differences were assessed by pre-specified intention-to-treat analysis of covariance with multiple imputation of missing data for the primary outcome. Per-protocol analysis was applied for the primary outcome.
Results Median age was 59 years (IQR 52-63) and 34 participants (57%) were female. A total of 55 patients completed assessment at 3 and 6 months for the primary outcome; 27 in the HIIT group and 28 in the control group. Following HIIT, there was a significant between-group difference in VO2peak (2.5 mL/kg/min, p<0.01) in favor of the exercise group at 3 months with no corresponding differences in pain and fatigue (Table 1). At 6 months, the between-group difference in VO2peak was maintained (2.6 ml/kg/min, p<0.01) and there were no significant differences in pain and fatigue (Table 1). Per-protocol analysis at 3 months showed a between-group difference in VO2peak (3.2 mL/kg/min, p<0.001, 95% CI 1.7-4.8) in the 19 (70%) patients that adhered to ≥17/24 HIIT sessions compared to the 20 (71%) control group patients that refrained from aerobic exercise.
Conclusion CRF increased in patients with IJD following 12 weeks of supervised HIIT and the effect was maintained at 6 months. The beneficial response on CRF was not accompanied by changes in pain or fatigue and the intervention can be regarded as feasible in physiotherapy primary care. HIIT is a viable physiotherapy intervention with sustainable effects in patients with IJD.
References  Agca R et al. EULAR recommendations for cardiovascular disease risk management in patients with rheumatoid arthritis and other forms of inflammatory joint disorders: 2015/2016 update. Annals of the rheumatic diseases. 2017;76(1):17-28.
 Ross R et al. Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign: A Scientific Statement From the American Heart Association. Circulation. 2016;134(24):e653-e99.
Acknowledgments We thank the patients that participated in the ExeHeart trial, patient representatives and physiotherapists in primary care for valuable commitment and contribution to the trial.
Disclosure of Interests Kristine Nordén Speakers bureau: Lecture honoraria from UCB, Anne Grete Semb Speakers bureau: Lecture honoraria from AbbVie, Novartis, Bayer, Eli Lilly, Pfizer and Sanofi, Hanne Solveig Dagfinrud: None declared, Jonny Hisdal: None declared, Joseph Sexton: None declared, Camilla Fongen: None declared, George Metsios Speakers bureau: Lecture honoraria from Novartis, Anne Therese Tveter: None declared.
- Cardiovascular disease
- Non-pharmacological interventions
- Randomized control trial
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