Collection Editors: Dr Flavio Cadegiani (Federal University of São Paulo, Brazil), and Dr Fred DiMenna (Icahn School of Medicine at Mount Sinai, USA).
High-intensity training: It’s not just for athletes anymore - by Fred DiMenna
In 1930, Swedish coach Gustaf Holmér decided that for his cross-country runners to improve their race pace, they would have to train at a pace that was faster; albeit, necessarily, for a shorter period of time. Known at the time as Fartlek, which means ‘speed time’ in Swedish, Holmér’s runners performed periods of fast running interspersed with slower runs that were required for recovery. Athletes embraced the concept (after all, no pain, no gain) and what we now call high-intensity interval training (HIIT) was born. However, training at intensities that exceed the maximal sustainable pace has undergone more than a name change during the 90 years that followed.
There is now growing acceptance for the contention that recreationally-active individuals, previously-sedentary novices and even certain patient populations can benefit from high-intensity exercise if prescribed with research-based precision. The 11 articles we have published for this Article Collection will help to inform such a process. For example, with respect to patient populations, Nytrøen et al. found that young heart-transplant recipients benefited more from HIIT compared to moderate-intensity continuous exercise, while the feasibility of HIIT in cardiac rehabilitation and as an intervention to improve prognosis for African American women at risk for metabolic syndrome were explored in retrospective analyses of data by Way et al. and Arad et al., respectively. In contrast, planning for the future, Frimpong et al. detailed a randomized controlled trial designed to determine the effectiveness and feasibility of home-based HIIT for women with overweight/obesity. As for patients with chronic pulmonary disease, Sawyer et al. provide a narrative review of the literature and conclude that more research is required to determine the effects of HIIT compared to moderate-intensity continuous exercise, while Reuveny et al. provide preliminary findings to guide such research for cystic fibrosis patients who demonstrated faster oxygen-uptake kinetics and increased exercise tolerance after eight weeks of HIIT. The feasibility nature of some of these studies still demonstrates the early stages of this exciting exercise-based medicine, and we expect more concrete evidence to appear.
High-intensity resistance training is also accounted for in this series as Tjøsvoll et al. present preliminary evidence which suggests that a program comprising weekly undulating periodization is feasible for individuals with persistent non-specific lower back pain, and Saeterbakken et al. found that daily bouts of resistance training at the workplace reduced neck and shoulder pain and improved quality of life for office workers. Interestingly, in the latter study, one 10-min bout was equally as effective as two, which confirms that the training effect attributable to high-intensity exercise is not necessarily amplified by increased volume. This coheres with observations by Reuveny et al. that oxygen supplementation, which allowed more high-intensity work to be performed by one group of patients in their study did not enhance the training effect derived from HIIT. Finally, Cockcroft et al. observed an inverse relationship between baseline insulin sensitivity and the change in insulin sensitivity that occurred for healthy adolescent boys after two weeks of HIIT. This means that youngsters with the greatest risk of falling victim to progression to type-2 diabetes stand to benefit the most from this type of training. Consequently, the usefulness of high-intensity exercise in the clinical setting might actually predate and, therefore, delay or prevent the onset of disease.
Collectively, these studies and the others in this thematic review are representative of a large and growing body of research which indicates that properly-prescribed high-intensity training is appropriate for man and woman, young and old, conditioned and deconditioned and healthy and diseased alike. In short, it’s not just for athletes anymore.