# High-Intensity Interval Circuit Training Versus Moderate-Intensity Continuous Training on Cardiorespiratory Fitness in Middle-Aged and Older Women: A Randomized Controlled Trial PMID: 32164314 Journal: International Journal of Environmental Research and Public Health Published: 2020 Mar 10 Authors: Ballesta-García I, Martínez-González-Moro I, Ramos-Campo DJ, Carrasco-Poyatos M ## Question Does high-intensity interval circuit training produce greater improvements than moderate-intensity circuit training in estimated VO2max, heart rate, and blood pressure in middle-aged and older women? ## Summary In middle-aged and older women, 18 weeks of supervised high-intensity interval circuit training and moderate-intensity circuit training both improved estimated VO2max compared with a no-exercise control group. Both exercise groups also improved exercise diastolic blood pressure response, while the high-intensity circuit group showed the clearest advantage over control for exercise systolic blood pressure. The intervention used one-hour, twice-weekly circuit sessions in a day-care-center/community setting and reported no training-session adverse events. ## Population - Autonomous middle-aged and older women recruited from elderly day-care centers in Murcia, Spain. - Sample size: 54 - Age: 67.8 +/- 6.2 years; inclusion range 55-85 years. - Sex: Women only. - Fitness level: Not in a similar exercise program in the previous three months; baseline estimated VO2max about 25-27 ml/kg/min. - Health status: Generally healthy/autonomous older women; controlled hypertension allowed, cardiac/respiratory/joint disease and uncontrolled hypertension excluded. ## Methodology - Prospectively registered quasi-experimental randomized controlled trial with three parallel groups: HIICT, MICT, and non-exercise control. - 18 weeks, including a two-week familiarization period followed by four four-week progressive mesocycles. - Women were recruited from elderly day-care centers in Murcia, Spain; supervised training sessions were directed by a graduate in Physical Activity and Sport Sciences. - Randomized and controlled study design. ## Protocol - HIICT. - Modality: High-intensity interval circuit training with large-muscle-group multiplanar movements. - Intensity: High-speed exercise targeting Borg RPE 12-18. - Session duration: 60 minutes. - Frequency: 2 days per week. - Program length: 18 weeks. - Progression: Two-week familiarization and four progressive four-week mesocycles. - MICT and no-exercise control. - Modality: Moderate-intensity circuit training; control maintained normal physical activity. - Intensity: MICT targeted Borg RPE 6-14 with moderate-speed exercises. - Session duration: 60 minutes for MICT. - Frequency: 2 days per week for MICT. - Program length: 18 weeks. - Progression: Two-week familiarization and four progressive four-week mesocycles for MICT. ## Outcomes ### Estimated VO2max Status: improved HIICT increased from 26.1 to 29.5 ml/kg/min and MICT from 25.0 to 26.9 ml/kg/min; both were superior to control in ANCOVA interactions. Training x group p=0.002, F=7.36, eta2=0.224; intra-group HIICT p<0.001, Cohen d=0.58; MICT p=0.010, d=0.32. ### Exercise diastolic blood pressure Status: improved Exercise DBP increased toward a more stable response in HIICT and MICT while decreasing in control. Training x group p<0.001, F=17.4, eta2=0.405; HIICT p=0.003, MICT p=0.002, control p=0.002. ### Exercise systolic blood pressure Status: mixed Exercise SBP interaction favored HIICT compared with control, but within-group HIICT change was not significant and MICT/control decreased. Training x group p=0.038, F=3.48, eta2=0.120; HIICT within-group p=0.213. ### Heart rate peak and recovery Status: no clear change Peak HR and one-minute HR recovery did not significantly improve between groups. Heart rate peak training x group p=0.474; HR recovery training x group p=0.156. ### Maximal speed reached during treadmill test Status: improved HIICT and MICT improved maximal treadmill speed compared with control. Training x group p=0.001, F=7.68, eta2=0.231. ## Practical Insights - For screened older women, twice-weekly supervised circuit-based HIIT can be an adaptable fitness protocol, but it needs gradual familiarization and intensity monitoring. - RPE-based intensity is practical for community settings, yet the authors' fidelity limitation argues for cautious claims about exact dose-response. - HIICT did not clearly outperform MICT for estimated VO2max, so consumer guidance should not overstate high intensity as necessary for fitness improvement in this population. ## Limitations - Estimated rather than directly measured VO2max. - Small final sample and attrition. - Wide age range. - Participants and instructors not blinded. - Planned intensity achievement was difficult to control. - Borg RPE was used for day-to-day intensity control. - Exact interval and station details were not fully available in this article. ## Safety And Adherence - Five women had adverse events: four in MICT and one in control. - No adverse events occurred during training sessions. - Events included eye surgery, foot surgery, clavicle fracture, and two hip fractures after a fall. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/32164314/) (pubmed) - [DOI](https://doi.org/10.3390/ijerph17051805) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7084372/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.