High-Intensity Multimodal Training for Young People: It's Time to Think Inside the Box!

Abstract

Studies comparing children and adolescents from different periods have shown a decrease in physical activity and fitness in the last decades (Moliner-Urdiales et al., 2010; Runhaar et al., 2010; Cohen et al., 2011; Hardy et al., 2013; Santtila et al., 2018; Masanovic et al., 2020; Fuhner et al., 2021). Low physical fitness is associated with poor metabolic health, independent of central adiposity (Latt et al., 2018). Moreover, changes in physical fitness from childhood and adolescence to adulthood are related to metabolic health, physical activity levels, and bone mineral density (Garcia-Hermoso et al., 2019; Maestu et al., 2020), while both low cardiorespiratory fitness and muscle strength are associated with higher risk of premature death and disability (Ortega et al., 2012; Henriksson et al., 2019a,b). Obesity is another important concern (Wijnhoven et al., 2014; Ogden et al., 2016; Bentham et al., 2017), but previous studies have shown that increased physical activity might be associated with decreased adiposity (Hui et al., 2021) and can modulate the effects of genetic predisposition to obesity in young people (Todendi et al., 2021). The negative impact of a sedentary lifestyle during early life has been largely debated (Faigenbaum et al., 2011; Faigenbaum and Myer, 2012; Stracciolini et al., 2013). In the early 60s, Kraus and Raab (1961) stressed the importance of physical activity for preventing diseases and suggested that the adverse health effect of physical inactivity was comparable to lack of vitamins or contagious diseases. Based on this, Faigenbaum et al. (2013) proposed a population-wide approach for identifying inactive children, prescribing interventions and raising public awareness. Notwithstanding, some important barriers for physical activity adoption among children and adolescents might be considered, like perception of lack of safety, physical environment and lack of support (Stankov et al., 2012; Lu et al., 2014; Martins et al., 2014). It is also important to consider children and adolescents particularities (e.g., biological and behavior characteristics) when prescribing and evaluating exercise programs, since exercise programs designed for adults might be inadequate for them (Faigenbaum et al., 2013). Previous studies suggested that young people naturally engage in intermittent activities (Bailey et al., 1995) and high intensity activities might be particularly beneficial to improve cardiorespiratory fitness (Baquet et al., 2003; Costigan et al., 2015), mental health (Leahy et al., 2020), body composition (Costigan et al., 2015; D et al., 2019) cardiovascular risk and metabolic health (Cooper et al., 2016; Garcia-Hermoso et al., 2016; MA et al., 2021) in children and adolescents. The purpose of the current article is to present the benefits of high-intensity multimodal training (HIMT) programs, such as CrossFit, to the youth, with a critical discussion about its potential benefits and concerns.