Cardiorespiratory and Hematological Responses to High-Intensity Interval Training in Adolescent Girls With Overweight or Obesity: A Randomized Controlled Trial
Question
Does 10 weeks of supervised HIIT improve body composition, cardiorespiratory fitness, hematological markers, plasma volume, and muscle/metabolic strain markers in adolescent girls with overweight or obesity compared with control?
Summary
In adolescent girls with overweight or obesity, a supervised 10-week running-based HIIT program improved body mass, BMI, body fat, waist circumference, maximal aerobic speed, and estimated VO2max compared with a usual-activity control pattern. Hematological changes suggested plasma volume expansion, and creatine kinase and lactate dehydrogenase decreased within the HIIT group. The trial was small and VO2max was estimated from a field test rather than directly measured.
Methodology
- Adolescent girls with overweight or obesity.
- 28 participants.
- Running.
- Work intervals: 15 s at 90-105% MAS.
- Recovery: 15 s active recovery at 50% MAS.
- Intensity: 90% MAS weeks 1-4, 95% weeks 5-6, 100% weeks 7-8, 105% weeks 9-10.
- 10 min warm-up, interval sets, 5 min cool-down.
- 3 sessions/week.
- 10 weeks.
- Parallel randomized controlled trial.
- Body composition, Cardiorespiratory fitness, Hematological markers, and Muscle/metabolic strain markers were tracked.
Outcomes
Body composition
HIIT produced within-group reductions in body mass, BMI, body fat percentage, and waist circumference; control did not change.
Body mass p<0.001; BMI p<0.001; body fat p=0.001; waist circumference p<0.001.
Estimated aerobic fitness
HIIT increased maximal aerobic speed and estimated VO2max.
MAS p=0.007; estimated VO2max p=0.007.
Hematological profile
HIIT reduced erythrocytes, hemoglobin, and hematocrit and increased plasma volume variation; authors interpret as plasma volume expansion but hemoglobin was lower than control post-intervention.
Erythrocytes p=0.007; hemoglobin p=0.019 and lower than control p=0.004; hematocrit p=0.004; PVV higher than control p<0.001.
CK and LDH
Creatine kinase and lactate dehydrogenase decreased in the HIIT group.
CK p=0.049; LDH p=0.032.
Insights
- Short 15-s running intervals with equal active recovery are a realistic school-based HIIT structure.
- Progressing speed from 90% to 105% MAS over 10 weeks can produce estimated fitness and body composition improvements in supervised adolescent girls.
- VO2max findings should be described as estimated from a field test.
Limitations
- Small sample size.
- Single-sex adolescent sample.
- No long-term follow-up.
- VO2max estimated rather than directly measured.
- Limited reporting of achieved interval intensity.
Safety
- Participants could discontinue or modify training for musculoskeletal pain, cardiovascular overload signs, personal request, or medical advice.
- No specific adverse events were reported in the article text reviewed.
- Sessions were supervised by qualified physical education instructors.