Benefits of HIIT

  • What is High-Intensity Interval Training (HIIT)?

High-Intensity Interval Training (HIIT) is a form of exercise that incorporates brief intervals of high-intensity exercise with regular periods of lower activity or rest. HIIT principles can be applied to many different modes of exercise, including running, swimming and cycling (Ribeiro et al., 2017), which can allow an individual a degree of flexibility when exercising. One major benefit of HIIT is that it allows an individual to maintain a level of high-intensity exercise for longer periods of time than they would be able to during continuous exercise (Guiraud et al., 2012).

Many different HIIT protocols have been tried and tested for coronary heart disease (CHD) patients. These protocols can be split into 3 different categories: long interval (3 – 15 mins at 85-90% VO2 max.), medium interval (1 – 3 mins at 95-100% VO2 max.) and short interval (10 secs – 1 min at 100 – 120% VO2 max.). Each interval is followed by a period of low-intensity exercise or passive recovery (Ribeiro et al., 2017).

  • What are the benefits of HIIT?

Exercise-based cardiac rehabilitation is generally regarded as a safe and effective treatment that reduces the incidence of cardiovascular mortality and hospital admissions in CHD patients (Anderson et al., 2016).

Several studies have been published looking at the benefits of different methods of exercise training, comparing HIIT against traditional forms of exercise, such as moderate-intensity continuous exercise (MCT). The premise of HIIT is that it allows an individual to accumulate a greater volume of high intensity exercise in a single session, compared to a single session of MCT with the same energy expenditure (Ross, Porter and Durstine, 2016). This is significant because high intensity exercise (80-90% VO2 max.) is significantly more effective than medium intensity exercise (50-60% VO2 max.) at increasing VO2 max. (Rognmo et al., 2004). VO2 max. is a measure of an individuals’ maximum oxygen consumption, providing an accurate representation of aerobic and cardiovascular fitness (Snell et al., 2007) and can be considered a good predictor of mortality among CHD patients (Vanhees et al., 1994).

HIIT has been shown to elicit a significantly larger increase in VO2 max., when compared to MCT (Villelabeitia-Jaureguizar et al., 2017; Rognmo et al., 2004; Cardozo et al., 2015). HIIT is also shown to significantly reduce the post-exercise Heart Rate Recovery (HRR) time of CHD patients (Villelabeitia-Jaureguizar et al., 2017). Slow HRR can be indicative of cardiovascular dysfunction (Grad and Zdrenghea, 2014). These findings suggest that HIIT may be more effective than other forms of exercise at improving cardiovascular function and preventing early mortality for those suffering from CHD.

A meta-analysis carried out by Liou et al. (2016) looked at 10 studies comparing HIIT to MCT (n = 472), concluding that HIIT significantly improved mean VO2 max. among CHD patients. Their analysis also showed that MCT was more effective than HIIT in reducing resting heart rate and body mass among the cohort. There were no significant differences in other cardiovascular risk factors between the two groups (Liou et al., 2016).

Another benefit of HIIT is that it may provide a form of exercise that is more time efficient and better tolerated by patients. HIIT training for 20 minutes achieves the same total energy expenditure as 28.7 minutes of MCT, whilst still providing similar physiological benefits (Ribeiro et al., 2017). Additionally, HIIT was generally preferred by patients, as it was associated with lower rates of perceived exertion and a significantly lower mean ventilation rate than MCT (Guiraud et al., 2012).

  • Is HIIT safe for CHD patients?

A meta-analysis carried out by Cornish et al. (2010) looked at 7 peer-reviewed studies with a total of 213 participants. All participants had a history of cardiovascular disease and were placed onto interval training interventions that were >8 weeks in duration. No trial reported any adverse effects or health complications as a direct result of the exercise interventions. However, these studies all differed greatly in their methodology and there were variations between the training plans, so it is difficult to draw any definitive conclusions.

Generally, it appears that HIIT is a safe form of exercise for some individuals with a history of cardiovascular disease (Cornish et al., 2010). Further studies with a larger and more diverse cohort are required before making any generalized conclusions about the safety of recommending HIIT to all CHD patients.

  • Conclusion

HIIT has been shown to be significantly more effective than MCT at increasing VO2max. (Villelabeitia-Jaureguizar et al., 2017; Rognmo et al., 2004; Cardozo et al., 2015) and reducing HRR time (Villelabeitia-Jaureguizar et al., 2017). Both are considered important markers for cardiovascular risk, meaning that HIIT may be more effective than other methods of exercise at improving prognosis for CHD patients.

HIIT is generally preferred by patients when compared to MCT (Guiraud et al., 2012). This preference for HIIT over MCT may lead to higher rates of long-term compliance, resulting in improved patient outcome. HIIT may be particularly useful for individuals who have tried a traditional MCT training program and found it too challenging or difficult to adhere to. It should also be noted that a session of HIIT can achieve the same physiological benefits as a session of MCT, albeit in a shorter period of time (Ribeiro et al., 2017). This opens the possibility for HIIT to be used for those who have a busy schedule and are struggling to find the time to exercise.

Exercise training is safe, improves prognosis for CHD patients, confers improvements in cardiovascular, pulmonary and skeletal muscle function, as well as increasing quality of life and reducing symptoms of depression and stress (Ribeiro et al., 2017). HIIT provides a time-effective and well tolerated method of exercise, whilst still providing significant physiological benefits for CHD patients. It should be noted that studies applied a range of different HIIT protocols, so more research should be conducted to identify the optimum protocol and to determine if HIIT should be used alongside or in place of MCT to improve the overall well-being and prognosis of CHD patients.

 

  • References

    Anderson, L., Thompson, D., Oldridge, N., Zwisler, A., Rees, K., Martin, N. and Taylor, R. (2016). Exercise-based cardiac rehabilitation for coronary heart disease. Cochrane Database of Systematic Reviews, 67(1).

    Cardozo, G., Oliveira, R. and Farinatti, P. (2015). Effects of High Intensity Interval versus Moderate Continuous Training on Markers of Ventilatory and Cardiac Efficiency in Coronary Heart Disease Patients. The Scientific World Journal, 2015(1), pp.1-8.

    Cornish, A., Broadbent, S. and Cheema, B. (2010). Interval training for patients with coronary artery disease: a systematic review. European Journal of Applied Physiology, 111(4), pp.579-589.

    Grad, C. and Zdrenghea, D. (2014). Heart rate recovery in patients with ischemic heart disease – risk factors. Medicine and Pharmacy Reports, 87(4), pp.220-225.

    Guiraud, T., Nigam, A., Gremeaux, V., Meyer, P., Juneau, M. and Bosquet, L. (2012). High-Intensity Interval Training in Cardiac Rehabilitation. Sports Medicine, 42(7), pp.587-605.

    Liou, K., Ho, S., Fildes, J. and Ooi, S. (2016). High Intensity Interval versus Moderate Intensity Continuous Training in Patients with Coronary Artery Disease: A Meta-analysis of Physiological and Clinical Parameters. Heart, Lung and Circulation, 25(2), pp.166-174.

    Ribeiro, P., Boidin, M., Juneau, M., Nigam, A. and Gayda, M. (2017). High-intensity interval training in patients with coronary heart disease: Prescription models and perspectives. Annals of Physical and Rehabilitation Medicine, 60(1), pp.50-57.

    Rognmo, Ø., Hetland, E., Helgerud, J., Hoff, J. and Slørdahl, S. (2004). High intensity aerobic interval exercise is superior to moderate intensity exercise for increasing aerobic capacity in patients with coronary artery disease. European Journal of Cardiovascular Prevention & Rehabilitation, 11(3), pp.216-222.

    Ross, L., Porter, R. and Durstine, J. (2016). High-intensity interval training (HIIT) for patients with chronic diseases. Journal of Sport and Health Science, 5(2), pp.139-144.

    Snell, P., Stray-Gunderson, J., Levine, B., Hawkins, M. and Raven, P. (2007). Maximal Oxygen Uptake as a Parametric Measure of Cardiorespiratory Capacity. Medicine & Science in Sports & Exercise, 39(1), pp.103-107.

    Vanhees, L., Fagard, R., Thijs, L., Staessen, J. and Amery, A. (1994). Prognostic significance of peak exercise capacity in patients with coronary artery disease. Journal of the American College of Cardiology, 23(2), pp.358-363.

    Villelabeitia-Jaureguizar, K., Vicente-Campos, D., Senen, A., Jiménez, V., Garrido-Lestache, M. and Chicharro, J. (2017). Effects of high-intensity interval versus continuous exercise training on post-exercise heart rate recovery in coronary heart-disease patients. International Journal of Cardiology, 244(1), pp.17-23.

Print Friendly, PDF & Email