Exercise adherence and intervention effects of two school-based resistance training programs for adolescents

Effectiveness of Intervention Strategies to Increase Adolescents' Physical Activity and Reduce Sedentary Time in Secondary School Settings, Including Factors Related to Implementation: A Systematic Review and Meta-Analysis

BACKGROUND

Globally, just one in five adolescents meet physical activity guidelines and three-quarters of the school day is spent sitting. It is unclear which types of school-based interventions strategies increase physical activity and reduce sedentary time among adolescents, or how these interventions are implemented influences their effectiveness.

OBJECTIVE

The three aims of our systematic review were to (a) identify intervention strategies used within secondary school settings to improve students' movement behaviours throughout school-based initiatives, delivered at or by the school; (b) determine the overall effect of the interventions (meta-analysis) on physical activity (all intensities), sedentary time, cognitive/academic, physical health and/or psychological outcomes; and (c) describe factors related to intervention implementation.

METHODS

Searches were conducted in MEDLINE complete, EMBASE, CINAHL, SPORTDiscus, APA PsycINFO, and ERIC in January 2023 for studies that (a) included high school-aged adolescents; (b) involved a school-based intervention to increase physical activity and/or decrease sedentary time; and (c) were published in English. Reported effects were pooled in meta-analyses where sufficient data were obtained.

RESULTS

Eighty-five articles, representing 61 interventions, met the inclusion criteria, with 23 unique intervention strategies used. Interventions that involved whole-school approaches (i.e., physical activity sessions, environmental modifications, teacher training, peer support and/or educational resources) were favourably associated with most of the outcomes. The meta-analyses showed: (a) non-significant effects for sedentary time (Standardized mean difference [SMD] = -0.02; 95%CI, -0.14, 0.11), physical activity at all intensities (light: SMD= -0.01; 95%CI, -0.08, 0.05; moderate: SMD = 0.06; 95%CI, -0.09, 0.22; vigorous: SMD = 0.08; 95%CI, -0.02, 0.18; moderate-to-vigorous: SMD = 0.05; 95%CI, -0.01, 0.12) and waist circumference (SMD = 0.09; 95%CI, -0.03, 0.21), and (b) a small statistically significant decrease in body mass index (SMD= -0.09, 95%CI -0.16, -0.0). Factors related to intervention implementation were reported in 51% of the articles.

CONCLUSION

While some intervention approaches demonstrated promise, small or null effects were found in meta-analyses. Future school-based interventions should utilize a whole-school approach designed to increase adolescents' activity across the day. Consistent reporting of implementation will increase understanding of how interventions are adopted, implemented and sustained.

REGISTRATION

PROSPERO (CRD42020169988).

Effects of school-based physical activity interventions on physical fitness and cardiometabolic health in children and adolescents with disabilities: a systematic review

Background: This study aimed to examine the influence of school-based physical exercise programs on physical fitness and cardiometabolic health in children and adolescents with disabilities. Methods: Web of Science, Scopus, and PubMed were thoroughly searched to identify relevant investigations. To be included in the systematic review, studies needed to fulfill the following inclusion criteria: 1) performed school-based physical exercise interventions; 2) parameters evaluated referred to health-related physical fitness (HRPF), skill-related physical fitness (SRPF), and cardiometabolic health; 3) a sample of participants consisted of children and adolescents with disabilities; 4) the mean age of respondents was less than 18 years; and 5) were written in the English language. Results: After searching the databases, a total of 474 studies have been identified, 18 of them met the eligibility criteria, and their outcomes were presented. Relating to the respondents' characteristics, the investigations involved 681 children and adolescents with disabilities, out of which 440 were male and 241 female. Regarding types of physical exercise interventions, the most commonly implemented were combined aerobic and resistance training, aerobic exercise, sports games, adapted high-intensity interval training, as well as sprint interval training. The obtained results unambiguously demonstrated that applied exercise interventions improved HRPF components such as cardiorespiratory fitness, muscular fitness, and flexibility. In terms of the SRPF, agility, balance, coordination, and power were considerably enhanced following the school-based exercise. On the other hand, the influence on indices of body composition and cardiometabolic health is quite controversial. The majority of the available studies did not find favorable effects. Additionally, no adverse events were reported in 7 of 8 research, and adherence to exercise was approximately 92%. Conclusion: School-based physical exercise programs were very efficient in improving HRPF and SRPF in children and adolescents with disabilities, while the evidence concerning the variables of body composition and cardiometabolic health is inconclusive and warrants further investigations.

Comparative effectiveness of school-based exercise interventions on physical fitness in children and adolescents: a systematic review and network meta-analysis

Background

Schools provide a favorable setting for health education, however, the most effective school-based exercise mode for improving physical fitness remains unclear. This network meta-analysis was designed to assess and rank the comparative efficacy of six exercise modalities on physical fitness indicators in a school-based setting.

Methods

An online search of the Web of Science, PubMed, SPORTDiscus, and Scopus databases was conducted. Randomized and quasi-randomized controlled trials were considered. Outcomes included measures of anthropometry and body composition, muscular fitness, and cardiorespiratory fitness. Data were pooled with a random effects model using the frequentist framework.

Results

A total of 66 studies with 8,578 participants (48% girls) were included. High-intensity interval training was the most effective intervention reducing body mass index (mean difference (MD) = -0.60 kg·m^-2, 95% confidence interval (95%CI) = -1.04 to -0.15, p = 0.009), elevating VO_2max (MD = 3.59 mL·kg^-1·min^-1, 95% CI = 2.45 to 4.74, p < 0.001), and 20-meter sprint performance (MD = -0.35 s, 95% CI = -0.55 to -0.14, p = 0.001). Aerobic training had the highest probability of reducing waist circumference (standardized mean difference (SMD) = -0.60, 95% CI = -0.88 to -0.32, p < 0.001). Active video games emerged as a promising modality for improving countermovement jump (MD = 2.43 cm, 95% CI = 0.06 to 4.80, p = 0.041) and shuttle running performance (SMD = 0.86, 95% CI = 0.29 to 1.43, p = 0.003). Strength training was the best exercise mode for improving standing long jump performance (SMD = 1.03, 95% CI = 0.07 to 1.98, p = 0.035) while combined training was rated the first for decreasing body fat percent (MD = -2.56%, 95% CI = -4.73 to -0.40, p = 0.022) and increasing push-up repetitions (SMD = 3.59, 95% CI = 0.81 to 6.37, p = 0.012).

Conclusion

School-based exercise interventions have multiple effects on physical fitness. The findings of this study will help to inform physical education teachers and coaches how best to deliver exercise programs in a school setting. Since the study was limited by the original research, the conclusions will require further verification using high-quality randomized controlled trials.

Systematic Review Registration

PROSPERO, Identifier: CRD42023401963.

Reporting of Adverse Events in Muscle Strengthening Interventions in Youth: A Systematic Review

Clear definition, identification, and reporting of adverse event (AE) monitoring during training interventions are essential for decision making regarding the safety of training and testing in youths.

PURPOSE

To document the extent to which AEs, resulting from intervention studies targeting muscle strengthening training (MST) in youth, are reported by researchers.

METHODS

Electronic databases (CINAHL, PubMed, SPORTDiscus, and Web of Science) were searched for English peer-reviewed articles published before April 2018. Inclusion criteria were: (1) average age <16 years, (2) use of MST, (3) statement(s) linked to the presence/absence of AEs, and (4) randomized controlled trials or quasi-experimental designs. Risk of reporting bias for AEs followed recommendations by the Cochrane Collaboration group.

RESULTS

One hundred and ninety-one full-text articles were screened. One hundred and thirty met all MST criteria, out of which only 44 (33.8%; n = 1278, age = 12.1 [1.1] y) included a statement as to the presence/absence of adverse events. The 86 other studies (66.2%) included no such statement. Of the reporting 44 studies, 18 (40.1%) indicated one or more adverse events. Of the 93 reported adverse events, 55 (59.1%) were linked to training or testing.

CONCLUSIONS

Most MST studies in youth do not report presence/absence of adverse events, and when reported, adverse events are not well defined.

School-Based Comprehensive Strength Training Interventions to Improve Muscular Fitness and Perceived Physical Competence in Chinese Male Adolescents

Purpose. This research was to see how effective and feasible school-based comprehensive strength training programs are in improving muscular fitness and perceived physical competence in Chinese male adolescents. Methods. A total of 123 participants ( $13.46\pm 0.60$ years) were randomized to comprehensive strength training intervention group (CST) ( $n=62$ ) and the control group (CON) ( $n=61$ ). The training sessions were performed three times a week for ten weeks in CST. Muscular fitness (i.e., muscular strength, power, and muscular endurance) and perceived physical competence were assessed at initial testing and final testing. Results.The subjects in the CST significantly improved their mean performance in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min push-ups ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) after the intervention. Moreover, the CST were greater in standing long jump ( $p<0.05$ ), vertical jump ( $p<0.05$ ), 1 min sit-ups ( $p<0.05$ ), handgrip strength ( $p<0.05$ ), and perceived physical competence ( $p<0.05$ ) compared to the CON, but no in 1 min push-ups ( $p>0.05$ ). Conclusions. The comprehensive strength training interventions designed in this study can significantly increase male adolescents’ muscular fitness, especially in the lower extremity muscle power and abdominal core endurance, and can enhance their perceived physical competence.

The Benefits of Resistance Training in Obese Adolescents: A Systematic Review and Meta-analysis

BACKGROUND

Physical activity is essential in acquiring healthy lifestyle behaviors in the early years of maturational development and preventing various diseases. Resistance training (RT) is fundamental for improving body composition and is increasingly recommended for obese adolescents. A systematic review and meta-analysis were performed to synthesize and analyze data on the effects of RT programs in this population, seeking to develop useful recommendations for health and sports professionals.

METHODS

A search was performed using four databases (Web of Science, Scopus, PubMed, and ScienceDirect). According to specific inclusion criteria, twenty-one studies were selected to evaluate the impact of RT on body mass index (BMI), body fat, waist circumference, muscle strength, insulin sensitivity, lean mass and cardiorespiratory fitness.

RESULTS

After the RT programs, the adolescents improved their muscle strength (SMD, 1.44; 95% CI: 0.76-2.12), cardiorespiratory fitness (SMD, 1.09; 95% CI: 0.15-2.04), BMI (SMD, 0.21; 95% CI: 0.07-0.35), waist circumference (SMD, 0.27; 95% CI: 0.06-0.47) and body fat (SMD, 0.20; 95% CI: 0.05-0.34). However, insulin sensitivity (SMD, 0.32; 95% CI: - 0.47 to 1.10) and lean mass (SMD, 0.12; 95% CI: - 0.06 to 0.31) did not reveal any changes. Different RT programs were used but it seems that 2-3 times/week ∼60 min/session of RT for 12 weeks should be recommended for positive changes.

CONCLUSIONS

RT seems to be effective when the objective is to improve muscle strength, cardiorespiratory fitness and can be an efficient strategy to reduce obesity in adolescents by reducing body fat, waist circumference and body mass index. PROSPERO Registration number: CRD42022333411.

The Effect of Intensity, Frequency, Duration and Volume of Physical Activity in Children and Adolescents on Skeletal Muscle Fitness: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Physical activity could improve the muscle fitness of youth, but the systematic analysis of physical activity elements and muscle fitness was limited. This systematic review and meta-analysis aim to explore the influence of physical activity elements on muscle fitness in children and adolescents. We analyzed literature in Embase, EBSCO, Web of Science, and PubMed databases from January 2000 to September 2020. Only randomized controlled studies with an active control group, which examined at least 1 muscle fitness evaluation index in individuals aged 5–18 years were included. Articles were evaluated using the Jaded scale. Weighted-mean standardized mean differences (SMDs) were calculated using random-effects models. Twenty-one studies and 2267 subjects were included. Physical activity had moderate effects on improving muscle fitness (SMD: 0.58–0.96, p < 0.05). Physical activity element subgroup analysis showed that high-intensity (SMD 0.68–0.99, p < 0.05) physical activity <3 times/week (SMD 0.68–0.99, p < 0.05), and <60 min/session (SMD 0.66–0.76, p < 0.01) effectively improved muscle fitness. Resistance training of ≥3 sets/session (SMD 0.93–2.90, p < 0.01) and <10 repetitions/set (SMD 0.93–1.29, p < 0.05) significantly improved muscle fitness. Low-frequency, high-intensity, and short-duration physical activity more effectively improves muscle fitness in children and adolescents. The major limitation of this meta-analysis was the low quality of included studies. The study was registered in PROSPERO with the registration number CRD42020206963 and was funded mainly by the Ministry of Education of Humanities and Social Science project, China.

No Time to Lift? Designing Time-Efficient Training Programs for Strength and Hypertrophy: A Narrative Review

Abstract

Lack of time is among the more commonly reported barriers for abstention from exercise programs. The aim of this review was to determine how strength training can be most effectively carried out in a time-efficient manner by critically evaluating research on acute training variables, advanced training techniques, and the need for warm-up and stretching. When programming strength training for optimum time-efficiency we recommend prioritizing bilateral, multi-joint exercises that include full dynamic movements (i.e. both eccentric and concentric muscle actions), and to perform a minimum of one leg pressing exercise (e.g. squats), one upper-body pulling exercise (e.g. pull-up) and one upper-body pushing exercise (e.g. bench press). Exercises can be performed with machines and/or free weights based on training goals, availability, and personal preferences. Weekly training volume is more important than training frequency and we recommend performing a minimum of 4 weekly sets per muscle group using a 6–15 RM loading range (15–40 repetitions can be used if training is performed to volitional failure). Advanced training techniques, such as supersets, drop sets and rest-pause training roughly halves training time compared to traditional training, while maintaining training volume. However, these methods are probably better at inducing hypertrophy than muscular strength, and more research is needed on longitudinal training effects. Finally, we advise restricting the warm-up to exercise-specific warm-ups, and only prioritize stretching if the goal of training is to increase flexibility. This review shows how acute training variables can be manipulated, and how specific training techniques can be used to optimize the training response: time ratio in regard to improvements in strength and hypertrophy.

Graphic Abstract

The SIMAC study: A randomized controlled trial to compare the effects of resistance training and aerobic training on the fitness and body composition of Colombian adolescents

The aim of this study was to evaluate the impact on muscle strength, aerobic fitness and body composition, of replacing the physical education (PE) class of Colombian adolescents with resistance or aerobic training. 120 tanner stage 3 adolescents attending a state school were randomized to resistance training, aerobic training, or a control group who continued to attend a weekly 2- hour PE class for 16 weeks. The resistance training and aerobic training groups participated in twice weekly supervised after-school exercise sessions of < 1 hour instead of their PE class. Sum of skinfolds, lean body mass (bioelectrical impedance analysis), muscular strength (6 repetition maximum (RM)) bench press, lateral pulldown and leg press) and estimated cardiorespiratory fitness (multistage 20 meter shuttle run) were assessed at pre and post intervention. Complete data were available for n = 40 of the resistance training group, n = 40 of the aerobic training group and n = 30 PE (controls). Resistance training attenuated increases in sum of skinfolds compared with controls (d = 0.27, [0.09-0.36]). We found no significant effect on lean body mass. Resistance training produced a positive effect on muscle strength compared with both controls (d = 0.66 [.49-.86]) and aerobic training (d = 0.55[0.28-0.67]). There was a positive effect of resistance training on cardiorespiratory fitness compared with controls (d = 0.04 [-0.10-0.12]) but not compared with aerobic training (d = 0.24 [0.10-0.36]). Replacing a 2-hour PE class with two 1 hour resistance training sessions attenuated gains in subcutaneous adiposity, and enhanced muscle strength and aerobic fitness development in Colombian youth, based on a median attendance of approximately 1 session a week. Further research to assess whether adequate stimuli for the development of muscular fitness exists within current physical education provision is warranted.

Movement Competency Training Delivery: At School or Online? A Pilot Study of High-School Athletes

Movement competency (MC) development of high-school athletes can prepare them for the requirements of physical preparation training and the demands of sport. The aim of this study was to explore the physical effects of and athlete compliance to coach-led versus self-directed training approaches in this population. Thirty-nine high-school athletes (19 male, 14.5 ± 0.3 years old; 20 female, 14.6 ± 0.3 years) were allocated into two groups for a physical preparation program to improve MC. Groups were prescribed either (i) one face-to-face and one online (F2F, n = 18), or (ii) two online (OL, n = 21) sessions per week for 16-weeks. Before and after the intervention, the Athlete Introductory Movement Screen (AIMS) was used to assess MC alongside common physical capacity measures (triple-hop, star-excursion balance, medicine ball throw, 40m sprint and countermovement jump). Dropout left 22 participants with pre-post physical scores. Compliance with online training was low and F2F session attendance moderate. Semi-structured interviews were conducted to assess participant perceptions following the intervention. Assessing individual responses, the F2F group had a higher proportion of positive responders to AIMS scores, yet capacity measures were inconclusive across groups. Face-to-face coaching when acquiring MCs as part of physical preparation, may provide greater positive perceptions towards training compared to self-directed online prescriptions, and thereby greater compliance.

Training with elastic and conventional devices on body composition: systematic review and meta-analysis

Abstract Introduction: Given the practicality and low cost of elastic devices, a comparison with conventional devices may be able to quantify gains from both tools for further conclusions. Objective: Compare the effect of resistance training with elastic (tubes and resistance band) and conventional (weight machines and dumbbells) devices on body composition. Method: This is a systematic review and meta-analysis. The PubMed/MEDLINE, Embase, PEDro and CENTRAL databases were searched from the earliest records to July 25, 2018. Data were described in standardized mean difference (SMD) with a 95% confidence interval (95% CI). Results: Four studies were included. The results of the meta-analysis did not show superiority among the analyzed methods for the variables investigated (SMD = -2.04, 95% CI -7.56, 3.48, p < 0.00001, lean mass: SMD = 0.28, 95% CI -0.29, 0.85, p = 0.97, body fat: SMD = 2.77, 95% CI -0.05, 5.59, p = 0.92, body mass: SMD = 1.22, 95% CI -0.29, 2.74, p = 0.11). Conclusion: The results of the meta-analysis showed superiority of outcome from training in conventional devices only for the variable fat mass. For the other variables, no statistically significant differences were found. Elastic resistance can promote similar outcomes to resistance in different population profiles and from various protocols on variables related to body composition.

The Effect of Nurse-Led Diet and Physical Activity Program for Health on Diet and Physical Activity Behavior of Children

BACKGROUND

Many health problems encountered in childhood, adolescence, and adulthood periods arise from problematic eating behavior, an unhealthy dietary approach, and inactive lifestyles. The aim of this study was to determine the effect of the Diet and Physical Activity Program for Health, under the leadership of a nurse, on the dietary and physical activity behaviors of children.

METHODS

This study was planned in a quasi-experimental design with pretesting, posttesting, follow-up testing, and a control group. The study was conducted with 114 students in 2 schools. A total of 12 hours of training was given to the experimental group for 6 weeks. Institutional permission required for performing the study and an ethical consent from the commission for clinical trials of Marmara University institute of health sciences were received.

RESULTS

The results of the study reveal that Diet and Physical Activity Program for Health in posttest and follow-up periods was effective in improving dietary and physical activity behaviors of children within the program. However, the program's effect on dietary and physical activity self-efficacy was limited.

CONCLUSION

The results of the study indicate that this program was effective in development of children's behavior regarding diet and physical activity.

Effects of training with elastic resistance versus conventional resistance on muscular strength: A systematic review and meta-analysis

Given the practicality and low cost of using elastic resistance in training for different populations and its effectiveness in a range of outcomes, a comparison with conventional devices could clarify and quantify the benefits provided by both mode. To compare the effects of resistance training with elastic devices (tubes and Thera-Bands) and conventional devices (weight machines and dumbbells) on the outcome muscular strength. A search was performed in the databases PubMed/MEDLINE, EMBASE, PEDro (Physiotherapy Evidence Database), and CENTRAL (Cochrane Central Register of Controlled Trials) from the earliest records up to 20 December 2017. Data were pooled into a meta-analysis and described as standardized mean difference with a 95% confidence interval (registration number: CRD42016042152). Eight studies were included. The results of the meta-analysis demonstrated no superiority between the methods analyzed for upper limb (standardized mean difference = −0.011; 95% confidence interval = −0.40, 0.19; p = 0.48) or lower limb muscular strength (standardized mean difference = 0.09; 95% confidence interval = −0.18, 0.35; p = 0.52). Elastic resistance training is able to promote similar strength gains to conventional resistance training, in different population profiles and using diverse protocols.

The National After-School Athletics Program Participation as a Tool to Reduce the Risk of Obesity in Adolescents after One Year of Intervention: A Nationwide Study

Regular exercise during school hours is encouraged; however many children and adolescents fail to meet the recommendations during this time. Extracurricular activities may be a more appealing way for youth to achieve guidelines, and it is recommended that they attend two sessions each week. The aim of the study was to assess the influence of participation in a national physical activity program accompanied by nutritional education for trainers on the risk of obesity and body composition in a nationwide sample of boys and girls, after one year of intervention. The #goathletics Study was conducted in a group of 1014 adolescents aged 12⁻13: 507 individuals for the Athletics for All program (210 boys, 297 girls) and 507 pair-matched individuals not participating in any physical activity program (matching including: gender, age, city of residence). The body mass (kg), Body Mass Index (BMI) (kg/m²), waist circumference (WC) (cm), waist-to-height ratio (WHtR) (-) and body composition (%) (measured using bioelectrical impedance method) were compared in a gender-related sub-groups using t-Student test (for parametric distributions) or Mann-Whitney U test (for nonparametric distributions) and chi² test (for the share of sub-groups). After one year of intervention, lower body mass percentile, BMI percentile, WC, WHtR and fat mass share, higher muscle mass share, as well as lower frequency of overweight/obesity and abdominal fat distribution were observed both for boys and girls participating in the physical activity intervention compared to the pair-matched controls. The after-school physical activity program accompanied by nutritional education for trainers may be a highly effective method for reducing the risk of obesity both for boys and girls, as regular participation is ensured.

The effect of resistance training interventions on weight status in youth: a meta-analysis

BACKGROUND

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.

METHODS

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).

RESULTS

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).

CONCLUSIONS

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.

Shoulder and arm muscle activity during elastic band exercises performed in a hospital bed

OBJECTIVE

Muscle atrophy is a common side-effect of bed rest during hospitalization. However, resistance training may minimize or even prevent these complications. Therefore, we evaluated the efficiency of four upper-body elastic resistance exercises that could be performed while lying or sitting in a hospital bed.

METHODS

Twenty-two healthy subjects performed three repetitions of each exercise in a supine and seated position with a perceived intensity of 3 (low) and 8 (high) on the Borg CR10 Scale. Surface electromyography was collected from 12 shoulder and arm muscles (e.g. trapezius, deltoideus, and biceps brachii), and normalized to a maximal voluntary isometric contraction (nEMG).

RESULTS

During all exercises performed at high intensity, moderate (>40%) to high (>60%) levels of nEMG were found for the majority of the analysed muscles, e.g. deltoideus (from 37% to 69%, median 57.5%), trapezius (from 43% to 66%, median 51%), and infraspinatus (from 54% to 66%, median 59%), with the exception of pectoralis major (from 29% to 47%, median 39.5%) and latissimus dorsi (from 15% to 22%, median 18.5%). No significant differences were found between the supine and seated positions for any of the exercises.

CONCLUSION

This study showed that high levels of shoulder and arm muscle activity can be achieved while lying or sitting in a hospital bed using appropriate exercises with elastic bands. The data presented here can be used by physiotherapists as a guideline for selecting suitable and effective strengthening exercises during in-hospital rehabilitation to counteract bed-rest related muscle atrophy in the upper body.

Reliability and validity of the adapted Resistance Training Skills Battery for Children

OBJECTIVES

Resistance training (RT) is emerging as a training modality to improve motor function and facilitate physical activity participation in children across the motor proficiency spectrum. Although RT competency assessments have been established and validated among adolescent cohorts, the extent to which these methods are suitable for assessing children's RT skills is unknown. This project aimed to assess the psychometric properties of the adapted Resistance Training Skills Battery for Children (RTSBc), in children with varying motor proficiency.

DESIGN

Repeated measures design with 40 participants (M age=8.2±1.7years) displaying varying levels of motor proficiency.

METHODS

Participants performed the adapted RTSBc on two occasions, receiving a score for their execution of each component, in addition to an overall RT skill quotient child (RTSQc). Cronbach's alpha, intra-class correlation (ICC), Bland-Altman analysis, and typical error were used to assess test-retest reliability. To examine construct validity, exploratory factor analysis was performed alongside computing correlations between participants' muscle strength, motor proficiency, age, lean muscle mass, and RTSQc.

RESULTS

The RTSBc displayed an acceptable level of internal consistency (alpha=0.86) and test-retest reliability (ICC range=0.86-0.99). Exploratory factor analysis supported internal test structure, with all six RT skills loading strongly on a single factor (range 0.56-0.89). Analyses of structural validity revealed positive correlations for RTSQc in relation to motor proficiency (r=0.52, p<0.001) and strength scores (r=0.61, p<0.001).

CONCLUSIONS

Analyses revealed support for the construct validity and test-retest reliability of the RTSBc, providing preliminary evidence that the RTSBc is appropriate for use in the assessment of children's RT competency.

Effectiveness of Traditional Strength vs. Power Training on Muscle Strength, Power and Speed with Youth: A Systematic Review and Meta-Analysis

Numerous national associations and multiple reviews have documented the safety and efficacy of strength training for children and adolescents. The literature highlights the significant training-induced increases in strength associated with youth strength training. However, the effectiveness of youth strength training programs to improve power measures is not as clear. This discrepancy may be related to training and testing specificity. Most prior youth strength training programs emphasized lower intensity resistance with relatively slow movements. Since power activities typically involve higher intensity, explosive-like contractions with higher angular velocities (e.g., plyometrics), there is a conflict between the training medium and testing measures. This meta-analysis compared strength (e.g., training with resistance or body mass) and power training programs (e.g., plyometric training) on proxies of muscle strength, power, and speed. A systematic literature search using a Boolean Search Strategy was conducted in the electronic databases PubMed, SPORT Discus, Web of Science, and Google Scholar and revealed 652 hits. After perusal of title, abstract, and full text, 107 studies were eligible for inclusion in this systematic review and meta-analysis. The meta-analysis showed small to moderate magnitude changes for training specificity with jump measures. In other words, power training was more effective than strength training for improving youth jump height. For sprint measures, strength training was more effective than power training with youth. Furthermore, strength training exhibited consistently large magnitude changes to lower body strength measures, which contrasted with the generally trivial, small and moderate magnitude training improvements of power training upon lower body strength, sprint and jump measures, respectively. Maturity related inadequacies in eccentric strength and balance might influence the lack of training specificity with the unilateral landings and propulsions associated with sprinting. Based on this meta-analysis, strength training should be incorporated prior to power training in order to establish an adequate foundation of strength for power training activities.

Resistance Training in Youth: Laying the Foundation for Injury Prevention and Physical Literacy

CONTEXT

The rising incidence of physical activity- and sports-related injuries has prompted the present-day investigation of resistance training as a potential means of injury prevention and physical literacy development among youth.

EVIDENCE ACQUISITION

Relevant studies on the topics of athlete development, physical literacy, resistance training, and injury prevention in children and adolescents were reviewed (PubMed and Sports Discus, 1982-2016). Recommendations from consensus guidelines and position statements applicable to resistance training and injury prevention in youth, in addition to young athlete development, were reviewed. Additionally, hand searches, expert requests, article reference lists, and gray literature were utilized and reviewed for pertinent content.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Youth throughout the physical activity spectrum are at risk for physical activity- and sports-related injury. Of highest priority are early specializers, physically inactive youth, and young girls, owing to increased injury rates. Resistance training among these at-risk populations has been shown to reduce injury risk by up to 68% and improve sports performance and health measures, in addition to accelerating the development of physical literacy. Recent recommendations, position statements, and national initiatives advocate for the incorporation of resistance training with qualified instruction among these groups.

CONCLUSION

Resistance training in addition to free play and other structured physical activity training can serve as a protective means against injury and a positive catalyst for the development of physical literacy to offset the impact of diminishing physical activity and early sport specialization in today's youth.

Tracking of muscular strength and power from youth to young adulthood: Longitudinal findings from the Childhood Determinants of Adult Health Study

OBJECTIVES

Low muscular fitness levels have previously been reported as an independent risk factor for chronic disease outcomes. Muscular fitness tracking, the ability to maintain levels measured at one point in time to another point in time, was assessed from youth to adulthood to provide insight into whether early identification of low muscular fitness in youth is possible.

DESIGN

Prospective longitudinal study.

METHODS

Study including 623 participants who had muscular fitness measures in 1985 (aged 9, 12 or 15 years) and again 20 years later in young adulthood. Measures of muscular fitness were strength (right and left grip, leg, shoulder extension and flexion measured by dynamometer, and a combined strength score) and power (standing long jump distance).

RESULTS

Strength and power were relatively stable between youth and adulthood; the strongest tracking correlations were observed for the combined strength score (r=0.47, p≤0.001), right grip strength (r=0.43, p≤0.001) and standing long jump (r=0.43, p≤0.001). Youth in the lowest third of muscular fitness had an increased risk of remaining in the lowest third of muscular fitness in adulthood (strength: relative risk (RR)=4.70, 95% confidence interval (CI) (3.19, 6.92); power: RR=4.06 (2.79, 5.90)).

CONCLUSIONS

Youth with low muscular fitness are at increased risk of maintaining a low muscular fitness level into adulthood. These findings warrant investigation into the long term effects of early interventions that focus on improving low muscular fitness levels in youth which could potentially improve adult muscular fitness and reduce future chronic disease outcomes.

Assessing the sustained impact of a school-based obesity prevention program for adolescent boys: the ATLAS cluster randomized controlled trial

BACKGROUND

Obesity prevention interventions targeting 'at-risk' adolescents are urgently needed. The aim of this study is to evaluate the sustained impact of the 'Active Teen Leaders Avoiding Screen-time' (ATLAS) obesity prevention program.

METHODS

Cluster RCT in 14 secondary schools in low-income communities of New South Wales, Australia. Participants were 361 adolescent boys (aged 12-14 years) 'at risk' of obesity. The intervention was based on Self-Determination Theory and Social Cognitive Theory and involved: professional development, fitness equipment for schools, teacher-delivered physical activity sessions, lunch-time activity sessions, researcher-led seminars, a smartphone application, and parental strategies. Assessments for the primary (body mass index [BMI], waist circumference) and secondary outcomes were conducted at baseline, 8- (post-intervention) and 18-months (follow-up). Analyses followed the intention-to-treat principle using linear mixed models.

RESULTS

After 18-months, there were no intervention effects for BMI or waist circumference. Sustained effects were found for screen-time, resistance training skill competency, and motivational regulations for school sport.

CONCLUSIONS

There were no clinically meaningful intervention effects for the adiposity outcomes. However, the intervention resulted in sustained effects for secondary outcomes. Interventions that more intensively target the home environment, as well as other socio-ecological determinants of obesity may be needed to prevent unhealthy weight gain in adolescents from low-income communities.

TRIAL REGISTRATION

Australian Clinical Trial Registry ACTRN12612000978864.

Improving health-related fitness in adolescents: the CrossFit Teens™ randomised controlled trial

The aim of this study was to evaluate the preliminary efficacy and feasibility of the CrossFit Teens™ resistance training programme for improving health-related fitness and resistance training skill competency in adolescents. This assessor-blinded randomised controlled trial was conducted in one secondary school in the Hunter Region, Australia, from July to September 2013. Ninety-six (96) students (age = 15.4 (.5) years, 51.5% female) were randomised into intervention (n = 51) or control (n = 45) conditions for 8-weeks (60 min twice per week). Waist circumference, body mass index (BMI), BMI-Z score (primary outcomes), cardiorespiratory fitness (shuttle run test), muscular fitness (standing jump, push-up, handgrip, curl-up test), flexibility (sit and reach) and resistance training skill competency were measured at baseline and immediate post-intervention. Feasibility measures of recruitment, retention, adherence and satisfaction were assessed. Significant group-by-time intervention effects were found for waist circumference [-3.1 cm, P < 0.001], BMI [-1.38 kg · m(‒)(2), P < 0.001], BMI-Z [-0.5 z-scores, P < 0.001], sit and reach [+3.0 cm, P < 0.001], standing jump [+0.1 m, P = 0.021] and shuttle run [+10.3 laps, P = 0.019]. Retention rate was 82.3%. All programme sessions were delivered and participants' mean satisfaction scores ranged from 4.2 to 4.6 out of 5. The findings demonstrate that CrossFit Teens™ is a feasible and efficacious programme for improving health-related fitness in adolescents.

Development, test-retest reliability, and construct validity of the resistance training skills battery

The aim of this study was to describe the development and assess test-retest reliability and construct validity of the Resistance Training Skills Battery (RTSB) for adolescents. The RTSB provides an assessment of resistance training skill competency and includes 6 exercises (i.e., body weight squat, push-up, lunge, suspended row, standing overhead press, and front support with chest touches). Scoring for each skill is based on the number of performance criteria successfully demonstrated. An overall resistance training skill quotient (RTSQ) is created by adding participants' scores for the 6 skills. Participants (44 boys and 19 girls, mean age = 14.5 ± 1.2 years) completed the RTSB on 2 occasions separated by 7 days. Participants also completed the following fitness tests, which were used to create a muscular fitness score (MFS): handgrip strength, timed push-up, and standing long jump tests. Intraclass correlation (ICC), paired samples t-tests, and typical error were used to assess test-retest reliability. To assess construct validity, gender and RTSQ were entered into a regression model predicting MFS. The rank order repeatability of the RTSQ was high (ICC = 0.88). The model explained 39% of the variance in MFS (p ≤ 0.001) and RTSQ (r = 0.40, p ≤ 0.001) was a significant predictor. This study has demonstrated the construct validity and test-retest reliability of the RTSB in a sample of adolescents. The RTSB can reliably rank participants in regards to their resistance training competency and has the necessary sensitivity to detect small changes in resistance training skill proficiency.

School-based physical activity and nutritional education interventions on body mass index: a meta-analysis of randomised community trials - project PANE

OBJECTIVE

To evaluate the effect of school-based physical activity (PA) and nutritional education (NE) interventions on children's and adolescents' body mass index.

METHODS

We conducted a systematic search in fourteen databases until September 2012 for randomised controlled trials on PA and NE, conducted in the school setting, and delivered to children and adolescents. Additionally, we performed a cross-reference check in related papers. The title and abstract review and the quality assessment were performed by two independent researchers. The software EPPI-Reviewer3 was used to store, manage and analyse all data. The meta-analysis was conducted using the random-effects model, and the outcomes were reported as standardised mean difference (SMD). As a secondary analysis, we pooled together the interventions that considered PA or NE alone.

RESULTS

Thirty-eight studies met the eligibility criteria. The main analysis showed a SMD between intervention and control groups of -0.03 (95% CI: -0.09, 0.04; n=28,870; I(2)=83%). When we considered all 57 trials, there was no difference between the results of the primary analysis.

CONCLUSION

The synthesis of school-based PA and NE interventions showed no statistically significant mean reduction on children's and adolescents' body mass index. The high heterogeneity among studies requires caution in the generalisation of the results.

Rater agreement of a test battery designed to assess adolescents' resistance training skill competency

OBJECTIVES

The study aim was to assess rater agreement of the Resistance Training Skills Battery (RTSB) for adolescents. The RTSB provides an assessment of resistance training skill competency and includes six exercises. The RTSB can be used to assess performance and progress in adolescent resistance training programmes and to provide associated feedback to participants. Individual skill scores are based on the number of performance criteria successfully demonstrated and an overall resistance training skill quotient (RTSQ) is created by summing the six skill scores.

DESIGN/METHODS

The eight raters had varying experience in movement skill assessment and resistance training and completed a 2-3h training session in how to assess resistance training performance using the RTSB. The raters then completed an assessment on six skills for 12 adolescents (mean age=15.1 years, SD=1.0, six male and six female) in a randomised order.

RESULTS

Agreement between seven of the eight raters was high (20 of the 21 pairwise correlations were greater than 0.7 and 13 of the 21 were greater than 0.8). Correlations between the eighth rater and each of the other seven raters were generally lower (0.45-0.78). Most variation in the assigned RTSB scores (67%) was between cases, a relatively small amount of the variation (10%) was between raters and the remainder (23%) was between periods within raters. The between-raters coefficient of variation was approximately 5%.

CONCLUSIONS

The RTSB can be used reliably by those with experience in movement skill assessment and resistance training to assess the resistance skill of adolescents.

School-based obesity prevention programs: a meta-analysis of randomized controlled trials

OBJECTIVE

Attempts have been made to reduce childhood obesity through school-based programs. Systematic reviews of studies until 2006 reported a lack of consistency about effectiveness of such programs. Presented is an updated systematic review and meta-analysis.

DESIGN AND METHODS

Replication of methodology used in previous comprehensive systematic review and meta-analysis of randomized controlled trials of school-based obesity prevention programs covering studies until 2006 to review studies thru January 2012.

RESULTS

Based on 32 studies (n = 52,109), programs were mildly effective in reducing BMI relative to controls not receiving intervention. Studies of children had significant intervention effects, those of teenagers did not, though the difference between the two groups was not statistically significant. Meta-regression showed a significant linear hierarchy of studies with the largest effects for comprehensive programs more than 1 year long that aimed to provide information on nutrition and physical activity, change attitudes, monitor behavior, modify environment, involve parents, increase physical activity and improve diet, particularly among children.

CONCLUSIONS

Unlike earlier studies, more recent studies showed convincing evidence that school-based prevention interventions are at least mildly effective in reducing BMI in children, possibly because these newer studies tended to be longer, more comprehensive and included parental support.

The effect of school-based physical activity interventions on body mass index: a meta-analysis of randomized trials

This study reviewed the effectiveness of school-based physical activity interventions aimed at reducing overweight, obesity and hypertension in children. We searched 14 databases and analyzed studies published between April 2009 and September 2012. Only randomized controlled trials performed at the school level that included elements of physical activity but did not include nutritional co-interventions were analyzed. Studies were assessed by two recommended tools (EPHPP and GRADE), and the standardized mean differences with 95% confidence intervals were collected for a random-effect meta-analysis. A total of 12 papers were included in the meta-analysis, and these were divided according to three outcomes: body mass index (11 trials, n = 4,273, -0.02, 95% CI: -0.13 to 0.17, p = 0.8); body weight (5 trials, n = 1,330, -0.07, 95% CI: -0.18 to 0.04, p = 0.2); and blood pressure (6 trials, n = 1,549), including systolic (0.11, 95% CI: -0.10 to 0.31, p = 0.3) and diastolic pressure (-0.00, 95% CI: -0.10 to 0.10, p = 0.9). This meta-analysis of data from 11 randomized, school-based physical activity interventions suggests that, regardless of the potential benefits of physical activity in the school environment, the interventions did not have a statistically significant effect. However, it is difficult to generalize from these results because the duration, intensity and type of physical activity used in the interventions varied greatly.

Strength Training Improves Body Image and Physical Activity Behaviors Among Midlife and Older Rural Women

The effect of strength training on body image is understudied. The Strong Women Program, a 10-week, twice weekly strength-training program, was provided by Extension agents to 341 older rural women (62±12 years); changes in body image and other psychosocial variables were evaluated. Paired-sample t-test analyses were conducted to assess mean differences pre- to post-program. Strength training was associated with significant improvements in several dimensions of body image, health-related quality of life, and physical activity behaviors, satisfaction, and comfort among rural aging women-an often underserved population that stands to benefit considerably from similar programs.

School-based physical activity programs for promoting physical activity and fitness in children and adolescents aged 6 to 18

BACKGROUND

The World Health Organization (WHO) estimates that 1.9 million deaths worldwide are attributable to physical inactivity and at least 2.6 million deaths are a result of being overweight or obese. In addition, WHO estimates that physical inactivity causes 10% to 16% of cases each of breast cancer, colon, and rectal cancers as well as type 2 diabetes, and 22% of coronary heart disease and the burden of these and other chronic diseases has rapidly increased in recent decades.

OBJECTIVES

The purpose of this systematic review was to summarize the evidence of the effectiveness of school-based interventions in promoting physical activity and fitness in children and adolescents.

SEARCH METHODS

The search strategy included searching several databases to October 2011. In addition, reference lists of included articles and background papers were reviewed for potentially relevant studies, as well as references from relevant Cochrane reviews. Primary authors of included studies were contacted as needed for additional information.

SELECTION CRITERIA

To be included, the intervention had to be relevant to public health practice (focused on health promotion activities), not conducted by physicians, implemented, facilitated, or promoted by staff in local public health units, implemented in a school setting and aimed at increasing physical activity, included all school-attending children, and be implemented for a minimum of 12 weeks. In addition, the review was limited to randomized controlled trials and those that reported on outcomes for children and adolescents (aged 6 to 18 years). Primary outcomes included: rates of moderate to vigorous physical activity during the school day, time engaged in moderate to vigorous physical activity during the school day, and time spent watching television. Secondary outcomes related to physical health status measures including: systolic and diastolic blood pressure, blood cholesterol, body mass index (BMI), maximal oxygen uptake (VO2max), and pulse rate.

DATA COLLECTION AND ANALYSIS

Standardized tools were used by two independent reviewers to assess each study for relevance and for data extraction. In addition, each study was assessed for risk of bias as specified in the Cochrane Handbook for Systematic Reviews of Interventions. Where discrepancies existed, discussion occurred until consensus was reached. The results were summarized narratively due to wide variations in the populations, interventions evaluated, and outcomes measured.

MAIN RESULTS

In the original review, 13,841 records were identified and screened, 302 studies were assessed for eligibility, and 26 studies were included in the review. There was some evidence that school-based physical activity interventions had a positive impact on four of the nine outcome measures. Specifically positive effects were observed for duration of physical activity, television viewing, VO2 max, and blood cholesterol. Generally, school-based interventions had little effect on physical activity rates, systolic and diastolic blood pressure, BMI, and pulse rate. At a minimum, a combination of printed educational materials and changes to the school curriculum that promote physical activity resulted in positive effects.In this update, given the addition of three new inclusion criteria (randomized design, all school-attending children invited to participate, minimum 12-week intervention) 12 of the original 26 studies were excluded. In addition, studies published between July 2007 and October 2011 evaluating the effectiveness of school-based physical interventions were identified and if relevant included. In total an additional 2378 titles were screened of which 285 unique studies were deemed potentially relevant. Of those 30 met all relevance criteria and have been included in this update. This update includes 44 studies and represents complete data for 36,593 study participants. Duration of interventions ranged from 12 weeks to six years.Generally, the majority of studies included in this update, despite being randomized controlled trials, are, at a minimum, at moderate risk of bias. The results therefore must be interpreted with caution. Few changes in outcomes were observed in this update with the exception of blood cholesterol and physical activity rates. For example blood cholesterol was no longer positively impacted upon by school-based physical activity interventions. However, there was some evidence to suggest that school-based physical activity interventions led to an improvement in the proportion of children who engaged in moderate to vigorous physical activity during school hours (odds ratio (OR) 2.74, 95% confidence interval (CI), 2.01 to 3.75). Improvements in physical activity rates were not observed in the original review. Children and adolescents exposed to the intervention also spent more time engaged in moderate to vigorous physical activity (with results across studies ranging from five to 45 min more), spent less time watching television (results range from five to 60 min less per day), and had improved VO2max (results across studies ranged from 1.6 to 3.7 mL/kg per min). However, the overall conclusions of this update do not differ significantly from those reported in the original review.

AUTHORS' CONCLUSIONS

The evidence suggests the ongoing implementation of school-based physical activity interventions at this time, given the positive effects on behavior and one physical health status measure. However, given these studies are at a minimum of moderate risk of bias, and the magnitude of effect is generally small, these results should be interpreted cautiously. Additional research on the long-term impact of these interventions is needed.

Sex-Related Effects in Strength Training during Adolescence: A Pilot Study

The objective was to investigate the effects of high-velocity strength training on isometric strength of the leg extensors and jump height in female and male adolescents. Twenty-eight students (13 boys, 15 girls) ages 16 to 17 years participated in this study and were assigned to either a strength training group or a control group. Strength training was conducted over 8 weeks (2 times per week). Pre- and post-training tests included the measurements of maximal isometric force and rate of force development of the leg extensors as well as countermovement jump height. Both girls (effect size = 1.37) and boys (effect size = 0.61) showed significant improvements in jump height. However, significant increases in maximal isometric force (effect size = 1.85) and rate of force development (effect size = 2.23) were found only in girls. In female and male adolescents, high-velocity strength training is an effective training regimen that produced improvements in countermovement jump height in both sexes but higher gains in maximal isometric force and rate of force development in girls.

The effects of concurrent resistance and endurance training follow a specific detraining cycle in young school girls

The purpose of this study was to compare the effects of an 8-week training period of strength training alone (GR), or combined strength and endurance training (GCOM), followed by 12-weeks of de-training (DT) on body composition, power strength and VO2max adaptations in a schooled group of adolescent girls.

METHODS

Sixty-seven healthy girls recruited from a Portuguese public high school (age: 13.5+1.03 years, from 7(th) and 9th grade) were divided into three experimental groups to train twice a week for 8 wks: GR (n=21), GCOM (n=25) and a control group (GC: n=21; no training program). Anthropometric parameters variables as well as performance variables (strength and aerobic fitness) were assessed.

RESULTS

No significant training-induced differences were observed in 1kg and 3kg medicine ball throw gains (2.7 to 10.8%) between GR and GCOM groups, whereas no significant changes were observed after a DT period in any of the experimental groups. Significant training-induced gains in CMVJ (8 to 12%) and CMSLJ (0.8 to 5.4%) were observed in the experimental groups. Time of 20m significantly decreased (GR: -11.5% and GCOM: -10%) after both treatment periods, whereas only the GR group kept the running speed after a DT period of 12 weeks. After training VO2max increased only slightly for GCOM (4.0%). No significant changes were observed after the DT period in all groups, except to GCOM in CMVJ and CMSLJ.

CONCLUSION

Performing simultaneous strength and endurance training in the same workout does not appear to negatively influence power strength and aerobic fitness development in adolescent girls. Indeed, concurrent strength and endurance training seems to be an effective, well-rounded exercise program that can be prescribed as a means to improve initial or general strength in healthy school girls. De-training period was not sufficient to reduce the overall training effects.