There is growing evidence that physical activity (PA) is beneficial for the mental health of young people. One area that has been widely examined is the impact of PA on ‘the self’, which is a term that encompasses a range of specific and related terms (e.g. self-esteem, self-efficacy, self-perceptions). There is evidence that PA is strongly associated with ‘the self’ in childhood and beyond. However, the impact of the specific PA of resistance training (RT) is not yet clear. The purpose of this review was to advance knowledge on the potential of RT for enhancing mental health by examining the effect of RT interventions on ‘the self’ in youth. This systematic review followed the PRISMA guidelines (PROSPERO registration number CRD42016038365). Electronic literature databases were searched from the year of their inception to October 2018. The search included English language articles that examined the effect of isolated RT on the broad term of ‘the self’ in youth, with participants of school age (5–18 years). Data were extracted using an electronic form by one reviewer with 10% conducted by a second reviewer. The ‘Quality Assessment Tool for Quantitative Studies’ was used to assess the quality and risk of bias and was conducted by two reviewers. From seven peer-reviewed studies, ten data sets were included exploring seven outcomes related to ‘the self’ in participants aged between 10 and 16 years. Four of these studies (including seven data sets) were combined in a meta-analysis, with results from the remaining three studies reported separately. Significant intervention effects were identified for resistance training self-efficacy (Hedges’ g = 0.538, 95% CI 0.254 to 0.822, P < 0.001), physical strength (Hedges’ g = 0.289, 95% CI 0.067 to 0.511, P = 0.011), physical self-worth (Hedges’ g = 0.319, 95% CI 0.114 to 0.523, P = 0.002) and global self-worth (Hedges’ g = 0.409, 95% 0.149 to 0.669, P = 0.002). Although not statistically significant, the effect sizes for the remaining three outcomes were body attractiveness (Hedges’ g = 0.211, 95% CI − 0.031 to 0.454, P = 0.087), physical condition (Hedges’ g = 0.089, 95% CI − 0.238 to 0.417, P = 0.593) and sport competence (Hedges’ g = 0.004, 95% CI − 0.218 to 0.225, P = 0.974). There was variable quality of studies, with just two studies being classified as ‘strong’. This is the first review to synthesise research on the effects of isolated RT interventions on ‘the self’. The findings indicate that RT has a positive impact on some aspects of ‘the self’ in youth. More high-quality studies should be conducted to further investigate this topic. If validated, this type of intervention could have a positive impact on ‘the self’ and ultimately improve the health of individuals not only during childhood but as they progress through life.

Fundamental movement skills (FMS) are strongly related to physical activity (PA) in childhood and beyond. To develop FMS, resistance training (RT) may be a favourable intervention strategy. The purpose of this meta-analysis was to systematically examine the effect of RT interventions on FMS in youth. Meta-analysis followed the PRISMA guidelines (Prospero registration number CRD42016038365). Electronic literature databases were searched from the year of their inception up to and including June 2017. The search strategy aimed to return studies that included product and process-oriented measures as a means of assessing FMS. Studies from English language peer-reviewed published articles that examined the effect of RT on indicators of FMS in youth, with participants of school age (5–18 years) were included. Thirty-three data sets were included exploring five outcomes related to FMS. Studies included only reported product-oriented outcomes. Significant intervention effects were identified for: sprint (Hedges’ g = 0.292, 95% CI 0.017 to 0.567, P = 0.038), squat jump (Hedges’ g = 0.730, 95% CI 0.374 to 1.085, P = < 0.001), standing long jump (Hedges’ g = 0.298, 95% CI 0.096 to 0.499, P = 0.004), throw (Hedges’ g = 0.405, 95% CI 0.094 to 0.717, P = 0.011) and vertical jump (Hedges’ g = 0.407, 95% CI 0.251 to 0.564, P = < 0.001). There was variable quality of studies, with 33.3% being classified as ‘strong’. RT has a positive impact on indicators of FMS in youth but more high-quality studies should be conducted to further investigate the role RT may play in the development of FMS. Additionally, to more comprehensively evaluate the impact of RT on FMS, there is a need for FMS assessments that measure both process- and product-oriented outcomes.

There has been a rise in research into obesity prevention and treatment programmes in youth, including the effectiveness of resistance-based exercise. The purpose of this meta-analysis was to examine the effect of resistance training interventions on weight status in youth. Meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and was registered on PROSPERO (registration number CRD42016038365). Eligible studies were from English language peer-reviewed published articles. Searches were conducted in seven databases between May 2016 and June 2017. Studies were included that examined the effect of resistance training on weight status in youth, with participants of school age (5–18 years). There were 24 complete sets of data from 18 controlled trials (CTs) which explored 8 outcomes related to weight status. Significant, small effect sizes were identified for body fat% (Hedges’ g = 0.215, 95% CI 0.059 to 0.371, P = 0.007) and skinfolds (Hedges’ g = 0.274, 95% CI 0.066 to 0.483, P = 0.01). Effect sizes were not significant for: body mass (Hedges’ g = 0.043, 95% CI − 0.103 to 0.189, P = 0.564), body mass index (Hedges’ g = 0.024, 95% CI − 0.205 to 0.253, P = 0.838), fat-free mass (Hedges’ g = 0.073, 95% CI − 0.169 to 0.316, P = 0.554), fat mass (Hedges’ g = 0.180, 95% CI − 0.090 to 0.451, P = 0.192), lean mass (Hedges’ g = 0.089, 95% CI − 0.122 to 0.301, P = 0.408) or waist circumference (Hedges’ g = 0.209, 95% CI − 0.075 to 0.494, P = 0.149). The results of this meta-analysis suggest that an isolated resistance training intervention may have an effect on weight status in youth. Overall, more quality research should be undertaken to investigate the impact of resistance training in youth as it could have a role to play in the treatment and prevention of obesity.

Resistance training (RT) may have a positive impact on specific correlates of physical activity (PA) in inactive and/or obese youth, with strength as a possible underlying mechanism. The aim of this study was to investigate this. Twelve participants (aged 8.9 ± 1.0 years) were assigned to an experimental group (EG) or control group (CG). Pre and post intervention assessments for strength, physical self-perceptions (PSPs), weight status, fundamental movement skills (FMS), and PA levels were completed. The EG participated in a twice-weekly 10-week RT programme. There were significant group x time interactions for FMS (CAMSA total P = 0.016, CAMSA skill score P = 0.036) and stretch stature (P = 0.002) (EG larges changes than the CG). Large effect sizes for the differences in change scores between the EG and CG were evident for CAMSA total score (Hedges’ g = 0.830, P = 0.138), CAMSA skill score (Hedges’ g = 0.895, P = 0.112) and relative strength (Hedges’ g = 0.825, P = 0.140). This study demonstrated that a 10-week RT intervention has a positive effect on strength and FMS, and may also benefit weight status and PSPs. This study supports the development of RT interventions to develop these correlates, and increase PA levels.