# Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness PMID: 31200443 Journal: International journal of environmental research and public health Published: 2019 Jun 13 Authors: Byrd BR, Keith J, Keeling SM, Weatherwax RM, Nolan PB, Ramos JS, Dalleck LC ## Question Does personalized moderate-intensity continuous training combined with HIIT improve cardiorespiratory and cardiometabolic training responsiveness more than standardized MICT alone when both exercise programs include resistance training? ## Summary In physically inactive but apparently healthy adults, a 13-week personalized program combining threshold-guided moderate continuous training, one weekly treadmill HIIT session, and resistance training produced larger improvements in VO2max and metabolic syndrome severity than a standardized moderate continuous plus resistance training program or no exercise. All 16 completers in the personalized MICT + HIIT group met the paper's responder criteria for both VO2max and MetS z-score, whereas the standardized MICT group had non-responders. ## Population - Apparently healthy but physically inactive nonsmoking men and women aged 21-55 years, low-to-moderate ACSM risk. - Sample size: 54 - Age: 21 to 55 years; group means among completers about 32-34 years. - Sex: Men and women; completer groups reported as control 8 women/7 men, standardized MICT 9 women/7 men, personalized MICT + HIIT 8 women/8 men. - Fitness level: Physically inactive; baseline VO2max group means about 28.6-31.8 mL/kg/min. - Health status: Apparently healthy, low-to-moderate cardiovascular risk. ## Methodology - Prospective randomized controlled exercise-training trial with non-exercise control, standardized MICT plus resistance training, and personalized MICT + HIIT plus resistance training arms. - 13 weeks - University/community exercise-training research setting with supervised sessions and laboratory testing. - Randomized and controlled study design. ## Protocol - Personalized MICT + HIIT plus resistance training. - Modality: Treadmill HIIT; MICT on cycle/rower/elliptical/treadmill; resistance training. - Work intervals: 60 s at workload corresponding to 100% VO2max. - Recovery: 150 s active recovery at 30-<40% HRR. - Sets or repetitions: 8 intervals in weeks 1-4, 10 in weeks 5-8, 12 in weeks 8-13. - Intensity: HIIT at 100% VO2max workload; MICT prescribed from ventilatory thresholds; resistance at RPE 5-6. - Session duration: HIIT session about 31.5-45.5 min including warm-up, intervals/recoveries, and cool-down. - Frequency: One HIIT session/week within the personalized exercise program; resistance training 3 days/week after week 4. - Program length: 13 weeks. - Progression: Interval count increased from 8 to 10 to 12 while recovery duration stayed constant. - Standardized MICT plus resistance training and non-exercise control. - Modality: MICT on aerobic machines plus machine-based resistance training; control continued usual lifestyle habits. - Sets or repetitions: Resistance training two sets of 12 repetitions on machine exercises. - Intensity: MICT by percentage of HRR; resistance training at modified Borg RPE 5-6. - Session duration: Similar frequency and duration of exercise training to the personalized group; exact session duration not stated in extracted text. - Frequency: Resistance training 3 days/week from week 4; MICT frequency not stated in extracted text. - Program length: 13 weeks. - Progression: Resistance progressed every 2 weeks by about 3-5% upper-body load and 6-10% lower-body load to maintain RPE 5-6. ## Outcomes ### VO2max Status: improved Personalized MICT + HIIT improved VO2max from 31.8 +/- 4.8 to 36.3 +/- 5.5 mL/kg/min and was significantly more favorable than both standardized MICT and control. Within-group p < 0.05; change significantly different from control and standardized MICT, p < 0.05. ### VO2max responder incidence Status: improved 100% (16/16) in personalized MICT + HIIT were VO2max responders compared with 68.75% (11/16) in standardized MICT. Responder incidence significantly greater than standardized MICT, p < 0.05; responder threshold delta > 4.9%. ### MetS z-score Status: improved Personalized MICT + HIIT improved MetS z-score from -3.35 +/- 2.87 to -5.15 +/- 2.34, with more favorable change than standardized MICT and control. Within-group p < 0.05; change significantly different from control and standardized MICT, p < 0.05. ### MetS z-score responder incidence Status: improved 100% (16/16) in personalized MICT + HIIT were MetS z-score responders compared with 56.25% (9/16) in standardized MICT. Responder incidence significantly greater than standardized MICT, p < 0.05. ### Body fat and waist circumference Status: improved Both exercise groups reduced body fat and waist circumference more than control; personalized MICT + HIIT body fat changed from 24.5 +/- 8.5% to 22.1 +/- 7.3% and waist from 80.5 +/- 11.9 to 78.8 +/- 11.5 cm. Within-group p < 0.05; change different than control, p < 0.05. ## Practical Insights - A small weekly HIIT dose can be embedded into a broader personalized moderate-training and resistance program rather than prescribed as a standalone all-HIIT plan. - One-minute hard intervals with longer active recovery and progression by bout count are a practical structure for supervised inactive adults. - This paper supports personalization and mixed training for reducing response variability more than it supports HIIT-only programming. ## Limitations - Dietary intake was not strictly controlled or quantified. - Activities of daily living and sedentary behavior outside the intervention were not monitored. - The intervention combined personalized MICT, HIIT, and a different resistance-training prescription, so the independent effect of HIIT cannot be isolated. - Equipment and testing requirements reduce direct translation to unsupervised app workouts. ## Safety And Adherence - No exercise-related adverse events were reported in the extracted text. - Four exercise-treatment participants did not complete the study: illness (n=2) and personal reasons (n=2). - The introduction notes HIIT may briefly elevate cardiac-event risk in persons with undiagnosed cardiovascular disease and may require initial supervision in untrained and high-risk individuals. ## Original Sources - [PubMed](https://pubmed.ncbi.nlm.nih.gov/31200443/) (pubmed) - [DOI](https://doi.org/10.3390/ijerph16122088) (doi) - [PMC full text](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6616602/) (full text) ## Agent Guidance Preserve the paper-level scope of this note. Do not generalize beyond the population, protocol, measured outcomes, and limitations above.