Long- and Short-Term High-Intensity Interval Training on Lipid Profile and Cardiovascular Disorders in Obese Male Adolescents

Racil G, Chelly MS, Coquart J, Padulo J, Teodor DF, Russo L

Question

How do 8 and 16 weeks of cycling HIIT affect body composition, cardiovascular variables, lipids, insulin/glucose markers, lactate, walking performance, and perceived exertion in moderately and severely obese adolescent boys?

Summary

This study followed moderately and severely obese adolescent boys through 16 weeks of supervised cycling HIIT. Both groups improved body composition, 6-minute walk distance, blood pressure, lipids, insulin, HOMA-IR, lactate, and perceived exertion. However, there was no non-exercising control group, five participants dropped out for personal reasons, and the authors cautioned that long, intense sessions may be hard for severely obese boys.

Methodology

Obese adolescent boys with BMI >=97th percentile and body fat >34%, classified as moderate or severe obesity.
35 participants.
Cycle ergometer.
Work intervals: 30 seconds at 100% peak power output at ventilatory threshold.
Recovery: 30 seconds at 50% peak power output; 5 minutes passive recovery between blocks.
Intensity: 100% PPO at ventilatory threshold; recovery 50% PPO.
35-55 minutes depending on phase, including warm-up, interval blocks, between-block rest, and cool-down.
3 sessions/week.
16 weeks.
Two-group longitudinal pre-post intervention comparing moderate and severe obesity groups; no non-exercising control group.
Body composition and walking performance, Blood pressure and heart rate, Lipids, and Glucose and insulin resistance were tracked.

Outcomes

Body composition and 6-minute walk

Both groups improved body-composition measures and 6-minute walking distance by 16 weeks.

Body mass/BMI p<0.01; body fat, LBM, RPE, and 6-min walk p<0.001; 6-min walk SOG 582 to 636 m, MOG 594 to 646 m.

Improved

Blood pressure and lipids

Both groups improved blood pressure and lipid profile, with severe obesity showing larger percentage changes in several variables.

DBP and HDL-C p<0.01; SOG SBP, resting lactate, and total cholesterol p<0.001 versus MOG p<0.05; TG/LDL-C SOG p<0.001 versus MOG p<0.01.

Improved

Glucose and insulin resistance

Insulin and HOMA-IR decreased in both groups; MOG had lower HOMA-IR post-intervention and greater glucose improvement.

Insulin and HOMA-IR p<0.001; MOG post HOMA-IR lower than SOG p<0.05.

Improved

Lactate and RPE

Lactate and RPE improved overall, but severe obesity RPE rose from week 8 to 16 as sessions lengthened.

BL5min decreased p<0.01; RPE SOG 8.8 to 7.2 to 7.3, MOG 8.5 to 6.8 to 6.7.

Mixed

Insights

Longer HIIT can improve cardiometabolic markers in obese boys but may increase perceived difficulty in severe obesity.
Shorter sessions or gradual duration increases may be more appropriate for severe obesity.
RPE should be tracked alongside objective measures.

Limitations

Boys only.
No non-training control group.
Small sample with five dropouts.
Lower baseline fitness may contribute to rapid improvements.
No detailed adverse-event reporting.

Safety

Five adolescents dropped out for personal reasons.
No adverse events or injuries were reported.
Authors caution about overexertion, joint stress, and the need for warm-up/cool-down and tailored progression.