Exercise
11 Mar 2023
High-Intensity Training: benefits and potential injury risk — Part I
High-intensity training, in its various forms, can be used by exercise and physical activity professionals to improve the performance, health markers and body composition of the people they work with. Since high-intensity training is by definition shorter in duration than moderate-intensity continuous training, while potentially delivering similar benefits in performance and body composition, it presents itself as a potentially more effective and more efficient way of reaching those goals.
Lack of time is often cited as an obstacle to maintaining an adequate level of physical activity, which feeds the perception that high-intensity training may make behaviour change easier and raise activity levels. The possible benefits in aerobic capacity, lipid metabolism, vascular function and balance, as well as improved bone density in older populations, may also contribute to greater uptake of this kind of training. Another decisive factor may be the relationship between high-intensity training and weight loss: this type of training can produce a similar or greater reduction in fat mass than moderate-intensity continuous training. Given that high-intensity training does not appear to increase lipolysis or fatty acid oxidation but rather to increase glycogen expenditure, its apparent benefits in reducing fat mass may be related to the post-exercise period. After training, metabolism remains slightly elevated for a period that can range from one to fourteen hours, depending on the intensity of the session. This effect alone does not appear capable of inducing a significant reduction in fat mass, however, and should be weighed alongside other factors associated with high-intensity training, such as its apparent positive effect on appetite regulation.
Given these apparent advantages over moderate-intensity continuous training, it is to be expected that interest in high-intensity training has grown, as has its adoption by an increasing number of people and institutions — it has consistently ranked in the top five of the ACSM fitness trends list in recent years. That being so, we believe it is worth understanding whether high-intensity training is as safe as moderate-intensity continuous training, or whether, because the intensity is greater, the prevalence and incidence of injury is greater too.
…continued in Part II
References:
Keating, S. E., Johnson, N. A., Mielke, G. I., & Coombes, J. S. (2017). A systematic review and meta-analysis of interval training versus moderate-intensity continuous training on body adiposity. Obes Rev, 18(8), 943-964. https://doi.org/10.1111/obr.12536
Viana, R. B., Naves, J. P. A., Coswig, V. S., de Lira, C. A. B., Steele, J., Fisher, J. P., & Gentil, P. (2019). Is interval training the magic bullet for fat loss? A systematic review and meta-analysis comparing moderate-intensity continuous training with high-intensity interval training (HIIT). Br J Sports Med, 53(10), 655-664. https://doi.org/10.1136/bjsports-2018-099928