PMID 31200443

Research
All papers

Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness

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.

Methodology

  • Apparently healthy but physically inactive nonsmoking men and women aged 21-55 years, low-to-moderate ACSM risk.
  • 54 participants.
  • 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.
  • Intensity: HIIT at 100% VO2max workload; MICT prescribed from ventilatory thresholds; resistance at RPE 5-6.
  • HIIT session about 31.5-45.5 min including warm-up, intervals/recoveries, and cool-down.
  • One HIIT session/week within the personalized exercise program; resistance training 3 days/week after week 4.
  • 13 weeks.
  • Prospective randomized controlled exercise-training trial with non-exercise control, standardized MICT plus resistance training, and personalized MICT + HIIT plus resistance training arms.
  • VO2max, Metabolic syndrome z-score, Body composition and waist circumference, and Muscular fitness were tracked.

Outcomes

VO2max

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.

Improved

VO2max responder incidence

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%.

Improved

MetS z-score

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.

Improved

MetS z-score responder incidence

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.

Improved

Body fat and waist circumference

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.

Improved

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

  • No exercise-related adverse events were reported in the the paper.
  • 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.