This time, I'd like to talk about HIIT training and lipid metabolism.
Have you ever heard of HIIT training?
Since the training boom, there has been a lot of discussion about various training methods, but there are also people who believe in the myths of training methods.
Some people believe in the myths of training methods, such as "XXX training doesn't work on muscles," "XXX training will make you lose weight dramatically," and "XXX training will improve musculoskeletal disorders.
While we should be wary of those who use such excessive language in their training methods, it is true that some training methods are designed to transform physiology.One such training method is HIIT (High Intensity Interval Training), which is popular because it allows you to apply a high load in a short period of time.
I've been practicing this training method because I've heard that it strengthens cardiopulmonary functions, but some people claim that it promotes lipid decomposition, which I've never heard of.
The study I'm going to introduce here was also investigating whether high/medium intensity interval training contributes to lipid metabolism.
Contents of the study
The purpose of this study is to compare the effects of medium intensity continuous training (MICT) and high intensity interval training (HIIT) on the lipid profile of adults.
Total Cholesterol (TC)
Triglycerides (TRG)
High-density lipoprotein cholesterol (HDL-C)
Low-density lipoprotein cholesterol (LDL-C)
The purpose of this study was to identify training or participant characteristics that may determine exercise-induced changes in
The experiment was designed as a systematic review and meta-analysis, so the quality of evidence is not low.
The evaluation criteria will be based on the following.
1) Published randomized controlled trials with group population n≥5
2) Intervention period of at least 4 weeks
3) Comparison of HIIT and MICT
4) Reporting of lipid measurements before and after the intervention.
Studies with elements of diet or pharmaceutical intervention with subjects with chronic diseases, under 18 years of age, pregnant/lactating, during elite athletic training as exclusion factors.
As a result, 29 data sets of 823 participants were pooled and analyzed.
Both HIIT and MICT were
TC (0.10 (-0.06 to 0.19), p = 0.12, I 2 = 0%)
TRG (-0.05 (-0.11 to 0.01), p = 0.10, I 2 = 0%) was not superior in reducing
LDL-C (0.05 (-0.06 to 0.17), p = 0.37, I 2 = 0%)
TC / HDL-C (-0.03 (-0.36 to 0.29), p = 0.85, I 2 = 0%)
HIIT significantly increased HDL-C compared to MICT.
In conclusion, neither HIIT nor MICT is superior in altering the ratios of TC, TRG, LDL-C, or TC-HDL-C.
Compared to MICT, HIIT appeared to significantly improve HDL-C.
These trainings may encourage participation in exercise, reduce cardiovascular risk, and raise HDL-C. HIIT may have a greater effect size than MICT.
Explanation
First of all, the difference between HIIT and MICT is the load on the cardiopulmonary function.
MICT: 55-70% of maximal heart rate, 11-13% of perceived effort on the Borg scale
HIIT: 70-90% of maximal heart rate, 14-16% of perceived effort on the Borg scale
If we are to have expectations for blood lipids, it seems that we should think only in terms of a possible increase in HDL-C levels.
Some of the studies to which this study refers include
The results of 4 to 6 weeks of MICT showed that MICT was superior to HIIT for lipid burning, but additional research was needed due to the lack of intervention period.
However, additional research is needed due to the lack of intervention period.
As for LDL-C, some data showed that both HIIT and MICT reduced LDL-C, some data showed that HIIT significantly reduced LDL-C, and some data showed that LDL-C reduction with weight loss was not confirmed.
Wood G, Murrell A, van der Touw T, Smart N. HIIT is not superior to MICT in altering blood lipids: a systematic review and meta-analysis. BMJ Open Sport Exerc. Med. 2019;5(1):e000647. published 2019 Dec 17. doi:10.1136/bmjsem-2019-000647
Conclusion
As an effect of HIIT training on blood lipids, there may be changes in HDL-C levels. That's what I thought.
The study comments that it is more likely to be the amount of physical activity than the intensity of exercise that affects blood lipids, so people who want to metabolize lipids may need to combine HIIT with other training.
Therefore, health care professionals who are in a position to manage lipids in patients should not only recommend HIIT training, but also encourage patients to consume 1,200 kcal per week (minimum threshold) through aerobic exercise.
However, please be aware that both HIIT and MICT have an effect on micro capillaries in muscles and other organs, so we do not deny these trainings.
