Muscular weakness in adolescence is associated with disability 30 years later: a population-based cohort study of 1.2 million men

Genetic Liability to Higher Muscle Strength Associates With a Lower Risk of Cardiovascular Disease Mortality in Men Irrespective of Leisure-Time Physical Activity in Adulthood: A Longitudinal Cohort Study

BACKGROUND

Low muscle strength predicts premature mortality. We determined whether genetic liability to muscle strength is associated with mortality and whether this association is influenced by long-term leisure-time physical activity (LTPA).

METHODS AND RESULTS

We estimated the effects of a polygenic score for handgrip strength (PGS HGS) on all-cause and cardiovascular disease (CVD) mortality risk in the older Finnish Twin Cohort (N=8815, 53% women). LTPA was assessed longitudinally using validated questionnaires. During the 16.9-year median follow-up (143 723 person-years), 2896 deaths occurred, of which 1089 were attributable to CVD. We found a significant interaction between sex and PGS HGS (P=0.016) in relation to all-cause mortality. In men, 1-SD increase in the PGS HGS was associated with a decreased risk of all-cause (hazard ratio [HR], 0.93 [95% CI, 0.89-0.98]) and CVD mortality (HR, 0.88 [95% CI, 0.81-0.96]), but was not statistically significantly associated with mortality in women (HR, 1.01 [95% CI, 0.96-1.07]; and HR, 0.96 [95% CI, 0.87-1.05], respectively). In men, associations remained after adjusting for LTPA and persisted for CVD mortality (HR, 0.85 [95% CI, 0.76-0.96]), even after accounting for other lifestyle covariates. This remained statistically significant even when non-CVD death was accounted for as a competing risk event. No PGS HGS×LTPA interactions were found. The predictive area under the curve estimates for PGS HGS alone were limited (0.53-0.64) but comparable to that of several lifestyle factors.

CONCLUSIONS

Higher PGS HGS was associated with a decreased risk of CVD mortality in men. Long-term LTPA in adulthood did not potentiate this association.

Associations between absolute and relative handgrip strength with fitness and fatness

The main purpose of this study was to assess relationships between absolute and relative handgrip strength (HGS) versus other markers of health (body composition) and physical fitness (VO 2 max, vertical jump) in 220 (112 male) healthy young adults (25±10 years). HGS was measured using a hand dynamometer. Absolute HGS represented the highest grip strength measurement (kg) of the right and left hand combined, while relative HGS represented the absolute HGS divided by body weight (kg/kg). Body composition (lean and fat mass) was measured using dual energy x-ray absorptiometry. VO 2 max was measured using a treadmill peak speed protocol (ml/kg/min), while vertical jump was assessed using a countermovement jump (cm). Absolute HGS (mean=86±22 kg) was positively related with lean mass (r=0.82, p<0.001) and vertical jump (r=0.63, p<0.001), while relative HGS (mean=1.2±0.2 kg/kg) was negatively related with body fat (r=-0.69, p<0.001), but positively correlated with VO 2 max (r=0.47, p<0.001), and vertical jump (r=0.45, p<0.001). Linear models suggest that lean mass, body fat, and vertical jump predicted 69% of variance for absolute HGS (adjusted R 2 =0.71, p<0.001), while lean mass and body fat predicted 49% of variance for relative HGS (adjusted R 2 =0.49, p<0.001). Lower relative HGS scores (<1.0 kg/kg) were associated with higher body fat levels and may represent a quick, simple, marker of health.

RETRAGAM: Resistance training based on gamification during physical education. Rationale and study protocol

Children's physical inactivity and increasing sedentary behaviour have become major public health concerns, with a concurrent decline in muscular fitness (MF) contributing to poor physical outcomes during childhood and adolescence, highlighting the importance of developing resistance training (RT) programs. Furthermore, several educational strategies such as gamification seem to increase students' motivation which can produce an increase in performance outcomes. This study describes the rationale and protocol of a school-based randomized controlled trial called "RETRAGAM" (REsistance TRAining based on GAMification). For this investigation, a total of ≃180 children (grades 5 and 6; 10-12 years of age) from 6 randomly selected schools in Valencia (Spain) will be enrolled for 8 weeks in one of the experimental groups: EG (15 min of RT Functional HIIT circuit program), EG + G (the same EG program but with a gamification approach) or CG (Control Group). Outcomes will include physical activity profile, MF, anthropometry and body composition, as well as the enjoyment and motivation during Physical Education (PE). An interactive app for digital devices will be used for gamified storytelling, earning points for personalized children's avatars, and implementing a flipped classroom learning model. We conclude that the RETRAGAM will provide information about the effectiveness and implementation of a school-based RT intervention during PE with and without gamification in students' MF, body composition, motivation and enjoyment.

International norms for adult handgrip strength: A systematic review of data on 2.4 million adults aged 20 to 100+ years from 69 countries and regions

BACKGROUND

Muscular strength is a powerful marker of current health status and robust predictor of age-related disease and disability. Handgrip strength (HGS) using isometric dynamometry is a convenient, feasible, and widely used method of assessing muscular strength among people of all ages. While adult HGS norms have been published for many countries, no study has yet synthesized available data to produce international norms. The objective of this study was to generate international sex- and age-specific norms for absolute and body size-normalized HGS across the adult lifespan.

METHODS

Systematic searches were conducted in 6 databases/web search engines (MEDLINE, SPORTDiscus, Embase, Web of Science, CINAHL, and Google Scholar) up to December 1, 2023. We included full-text peer-reviewed observational studies that reported normative HGS data for adults aged ≥20 years by sex and age. Pseudo data were generated using Monte Carlo simulation following harmonization for methodological variation. Population-weighted Generalized Additive Models for Location, Scale, and Shape were used to develop sex- and age-specific norms for absolute HGS (kg) and HGS normalized by height (Ht, m) squared (i.e., HGS/Ht2 in kg/m2). Norms were tabulated as percentile values (5th to 95th) and visualized as smoothed percentile curves.

RESULTS

We included data from 100 unique observational studies representing 2,405,863 adults (51.9% female) aged 20 to 100+ years from 69 countries and regions tested from the year 2000 onward. On average, absolute and normalized HGS values negligibly improved throughout early adulthood, peaked from age 30-39 years (at 49.7 kg (males) and 29.7 kg (females) for absolute HGS or 16.3 kg/m2 (males) and 11.3 kg/m2 (females) for HGS/Ht2), and declined afterwards. The age-related decline in HGS accelerated from middle to late adulthood and was slightly larger for males than for females during middle adulthood.

CONCLUSION

This study provides the world's largest and most geographically comprehensive international norms for adult HGS by sex and age. These norms have utility for global peer-comparisons, health screening, and surveillance.

Sport participation, weight status, and physical fitness in French adolescents

The primary objective of this study was to investigate the associations between sport participation and weight status with physical fitness among French adolescents. The secondary aim was to establish sex- and age-specific physical fitness percentiles for French adolescents. The sample comprised 8084 adolescents (4126 boys, 3958 girls), aged 10-14 years. Participants were tested on cardiorespiratory fitness and muscular strength using the following tests: 20-m shuttle run test and handgrip strength test. A questionnaire on organized sport participation was completed. Physical fitness levels were better in boys (P < 0.005). Handgrip strength increased with age whereas 20-m shuttle run performance decreased with age. Overweight and obese adolescents had significantly lower cardiorespiratory fitness levels than their normal-weight peers (P < 0.005), whereas normal-weight adolescents had lower cardiorespiratory fitness than thin adolescents (P < 0.005). Sport participation was higher for boys (57.2% boys vs. 52.8% girls) (P < 0.001). Adolescents who participated in at least one organized sport (either through a club or at school) were fitter than those who did not participate in organized sports (P < 0.005). Adolescents who engaged in organized sports were more active and physically fit than those who did not participate. The fitness benefits of club sports are greater than those provided by school-based sports, highlighting the potential of sports clubs as a key setting for promoting health. What is Known: • Physical fitness is a strong marker of health in children and adolescents. • The last French Report Card highlighted the lack of fitness data and the need for nationwide programs, while showing a significant decline in cardiorespiratory fitness among youth in recent decades.. What is New: • This study reveals that adolescents participating in organized sports have better physical fitness compared to their peers who do not, emphasizing the potential advantages of club sports over school-based activities. • We highlight the need for targeted strategies, particularly for overweight or obese adolescents and girls, to increase participation in organized sports and enhance health outcomes. • The study emphasizes the need to develop policies that improve access to organized sports clubs and expand physical education in schools, aiming to improve CRF in adolescents.

Temporal trends in muscular fitness among French children and adolescents between 1999 and 2023

The aim was to estimate national temporal trends in muscular fitness for French youth between 1999 and 2023. Data were obtained from five cross-sectional studies on 53,314 children and adolescents (age range: 6-16 years). Lower- and upper-body strength were assessed by standing broad jump (SBJ) and handgrip strength (HGS). BMI z-scores (BMIz) were calculated using WHO growth curves. We found a statistically significant negligible decline in SBJ performance (standardised effect size (ES) trend per decade [95%CI]: -0.08 [-0.10, -0.07] or -2.1 cm [95%CI: -2.4, -1.8]) and a statistically significant negligible improvement in HGS (ES trend per decade [95%CI]: 0.11 [0.08, 0.13]) or 0.6 kg [(95%CI: 0.4, 0.8]). We found evidence of significant increases in distributional variability and asymmetry, with poorer trends in the low performers (<25th percentile) and better trends in the high performers (>75th percentile) compared to the average performers. Our data suggest negligible trends in mean SBJ and HGS, coupled with increased distributional variability and asymmetry. Trends were not uniform across the population distribution with data suggesting an increase over time in the gap between low and high performers. These results reinforce the importance of interventions and programmes aiming at improving muscular fitness specifically in children and adolescents with low muscular strength.

The Youth Fitness International Test (YFIT) battery for monitoring and surveillance among children and adolescents: A modified Delphi consensus project with 169 experts from 50 countries and territories

BACKGROUND

Physical fitness in childhood and adolescence is associated with a variety of health outcomes and is a powerful marker of current and future health. However, inconsistencies in tests and protocols limit international monitoring and surveillance. The objective of the study was to seek international consensus on a proposed, evidence-informed, Youth Fitness International Test (YFIT) battery and protocols for health monitoring and surveillance in children and adolescents aged 6-18 years.

METHODS

We conducted an international modified Delphi study to evaluate the level of agreement with a proposed, evidence-based, YFIT of core health-related fitness tests and protocols to be used worldwide in 6- to 18-year-olds. This proposal was based on previous European and North American projects that systematically reviewed the existing evidence to identify the most valid, reliable, health-related, safe, and feasible fitness tests to be used in children and adolescents aged 6-18 years. We designed a single-panel modified Delphi study and invited 216 experts from all around the world to answer this Delphi survey, of whom one-third are from low-to-middle income countries and one-third are women. Four experts were involved in the piloting of the survey and did not participate in the main Delphi study to avoid bias. We pre-defined an agreement of ≥80% among the expert participants to achieve consensus.

RESULTS

We obtained a high response rate (78%) with a total of 169 fitness experts from 50 countries and territories, including 63 women and 61 experts from low- or middle-income countries/territories. Consensus (>85% agreement) was achieved for all proposed tests and protocols, supporting the YFIT battery, which includes weight and height (to compute body mass index as a proxy of body size/composition), the 20-m shuttle run (cardiorespiratory fitness), handgrip strength, and standing long jump (muscular fitness).

CONCLUSION

This study contributes to standardizing fitness tests and protocols used for research, monitoring, and surveillance across the world, which will allow for future data pooling and the development of international and regional sex- and age-specific reference values, health-related cut-points, and a global picture of fitness among children and adolescents.

Temporal changes in the physical fitness of Chinese adolescents aged 13-18 years: an analysis of eight national successive surveys over three decades

Objective

The aim of this study was to assess temporal changes in physical fitness of Chinese adolescents aged 13-18 years from 1985 to 2019.

Methods

Body size /composition and physical fitness indicators, including body height, weight, body mass index (BMI), speed, power, flexibility, muscular endurance, and cardiorespiratory fitness (CRF), were selected from Chinese boys and girls aged 13-18 years from eight Chinese National Surveillance on Students' Constitution and Health from 1985 to 2019. Temporal changes in means were estimated by sample-weighted linear regression at the test × sex × age level, and national trends were estimated by a post-stratification population weighting procedure.

Results

Overall mean body height, weight and BMI increased significantly for Chinese adolescents over 34 years. There was a small improvement for boys in speed (Effect size [ES] = -0.21, 95% confidence interval [CI] = -0.44 ~ 0.02), a small improvement for boys in power (ES = 0.24, 95% CI = -0.20 ~ 0.69), a small improvement for girls in flexibility (ES = 0.45, 95% CI = 0.15 ~ 0.76), a moderate decline for boys (ES = -0.53 95% CI = -0.84 ~ -0.21) and a moderate improvement for girls (ES = 0.61, 95% CI = -0.03 ~ 1.26) in muscular endurance, and large declines in cardiorespiratory fitness (CRF) for boys (ES = 0.93, 95% CI = 0.64 ~ 1.21) and girls (ES = 0.93, 95% CI = 0.58 ~ 1.27) from 1985 to 2019. These trends in each component of fitness were more positive for adolescents aged 13-15 years than that of adolescents aged 16-18 years in both sexes, except for girls in flexibility.

Conclusion

The decline in CRF was most pronounced among Chinese children and adolescents from 1985 to 2019, suggesting a future decline in population health that needs attention.

Diagnostic criteria, prevalence, and clinical outcomes of pediatric sarcopenia: A scoping review

BACKGROUND & AIMS

Sarcopenia, characterized by loss of muscle mass and decreased muscle strength, significantly affects adults but also influences pediatric health. However, definitions for low muscle mass, decreased strength, and sarcopenia in children are less established, impacting interventions for improving health outcomes. The objective of this scoping review is synthesize the existing literature on the diagnostic criteria, prevalence and clinical outcomes of sarcopenia.

METHODS

A scoping review, following the PRISMA extension for scoping reviews, examined pediatric sarcopenia literature until June 2023. The literature search was performed using MEDLINE and the Cochrane Central Register of Controlled Trials with the last search conducted on June 30, 2023. Criteria included studies on aged 0-20 years, covering healthy subjects, acutely ill patients, and chronic disease cases excluding specific conditions like neuromuscular diseases or prematurity.

RESULTS

Initial search found 503 studies, finally, we included 56 studies. Most studies diagnosed sarcopenia using skeletal muscle mass indicators like total psoas muscle area from Computed Tomography or Magnetic Resonance Imaging. Around half of the longitudinal studies highlighted sarcopenia as a risk factor for various clinical outcomes, predominantly in hospitalized patients. However, cutoff values for sarcopenia indicators lacked consistency, with studies employing diverse percentile-based measurements or z-scores.

CONCLUSION

Pediatric sarcopenia diagnosis primarily relies on skeletal muscle mass, with identified links to future clinical outcomes in specific conditions. The lack of standardized cutoffs for sarcopenia indicators underscores the necessity for age, gender, and race-specific cutoff values derived from studies establishing reference values for muscle mass and strength across diverse pediatric populations.

Resistance training effects on pubertal children with a risk of developing pediatric dynapenia

PURPOSE

Many modern-day children are at risk of pediatric dynapenia (muscle weakness). We examined the effects of a 12-week resistance training (RT) program on neuromuscular function and body composition parameters in pubertal children with a risk of dynapenia.

METHODS

Twelve children (13.4 ± 0.9 y) with dynapenia performed a progressive RT program consisting of knee extension and flexion, bench press, abdominal crunch, back extension, lateral pull-down, elbow flexion, and upright row (1-2 sets of 10-15 repetitions/exercise) twice/week for 12 weeks. Outcome measures included one-repetition maximum (1-RM) strength, maximal voluntary isometric contraction (MVIC) torque, rate of torque development (RTD), electromyographic (EMG) activity, muscle thickness (MT), muscle quality (MQ) assessed by echo intensity (MQEI) of the knee extensors and specific tension of MVIC torque to thigh fat-free mass (MQST), and total and regional body and bone composition assessed by dual-energy X-ray absorptiometry. Changes in the measures before and after the 12-week RT and associations among the measures were analyzed by linear mixed models.

RESULTS

Significant (p < 0.05) increases in 1-RM (63.9 ± 4.5%), MVIC torque (16.3 ± 17.8%), MT (18.8 ± 5.5%) and MQ (MQEI: -25.9 ± 15.2%; MQST: 15.1 ± 18.8%;) were evident from pre- to post-training. Total fat-free mass (FFM) increased by 2.3 ± 3.2% from baseline (p = 0.01), but no changes (p > 0.05) in the other measures were observed. Significant (p < 0.05) associations between the changes in 1-RM and/or MVIC torque and the changes in quadriceps MT, MQEI, MQST and total body FFM were evident.

CONCLUSIONS

The 12-week RT was effective for improving neuromuscular and body composition parameters, and thereby reversed the risk of pediatric dynapenia.

Association of Handgrip Strength with Hip Fracture and Falls in Community-dwelling Middle-aged and Older Adults: A 4-Year Longitudinal Study

OBJECTIVE

Hip fracture and falls are significant health concerns. Handgrip strength (HGS) is closely associated with overall muscle strength and physical health. However, the longitudinal relationship between HGS and the risk of hip fractures and falls remains unclear, particularly regarding gender differences. This longitudinal study aimed to investigate the association between HGS and the risk of hip fracture and falls in individuals aged 45 years and above, considering gender-specific differences over a 4-year period.

METHODS

This study included 10,092 participants (4471 men and 5621 women) aged 45 years and above from the China Health and Retirement Longitudinal Study (CHARLS). Incidents of hip fractures and falls were recorded during a 4-year follow-up, along with various demographic and clinical factors. Participants were categorized into five groups based on their HGS quintiles. Logistic regression models were employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) to assess the relationship between HGS and hip fracture/fall risk.

RESULTS

During the 4-year follow-up period, 223 cases of hip fracture (2.2%) and 1831 cases of falls (18.1%) were documented. Notably, higher HGS demonstrated a strong inverse association with the risk of hip fracture in both males and females (p < 0.05). In comparison to the lowest HGS quintile, the adjusted odds ratios (ORs) for hip fracture were 0.46 (0.27-0.78) for the total population, 0.4 (0.19-0.81) for males and 0.48 (0.23-0.98) for females in the highest HGS quintile. Furthermore, a profound and statistically significant negative correlation between HGS and falls was detected (p < 0.05). The adjusted ORs for falls in the highest HGS quintile, compared to the lowest quintile, were 0.62 (0.51-0.76) in the overall population, 0.59 (0.44-0.78) in males, and 0.78 (0.62-0.99) in females.

CONCLUSION

Our findings highlight the significant inverse association between HGS and the risk of hip fracture and falls in both males and females aged 45 years and above. Assessing handgrip strength may serve as a valuable tool for predicting fracture and fall risk.

Are Dryland Strength and Power Measurements Associated with Swimming Performance? Preliminary Results on Elite Paralympic Swimmers

This study aimed to identify the relationship between dryland tests and swimming performance in elite Paralympic swimmers. Fifteen competitive swimmers (age: 27.4 ± 5.4 years, height: 1.70 ± 6.8 m, body mass: 67.9 ± 9.2 kg; 9 males, 6 females) performed a lat pull-down and a bench press incremental load test to determine maximum power (Pmax), the strength corresponding to maximum power (F@Pmax), and the barbell velocity corresponding to maximum power (V@Pmax) from the force-velocity and power-velocity profiles. These outcomes were also normalized by the athlete's body mass. Swimming performance was carried out from the best result in a 100 m freestyle race registered during an international competition. Lat pull-down F@Pmax was significantly associated with 100 m freestyle chronometric time (ρ = -0.56, p < 0.05), and lat pull-down V@Pmax presented a relationship with mean swimming velocity (ρ = 0.71, p < 0.01). Similarly, bench press F@Pmax and the normalized F@Pmax were significantly related to the mean swimming velocity (ρ = -0.51, ρ = -0.62, p < 0.05). Stepwise multiple regression showed that lat pull-down V@Pmax, bench press normF@Pmax, and V@Pmax accounted for 40.6%, 42.3%, and 65.8% (p < 0.05) of the mean swimming velocity variance. These preliminary results highlighted that simple dryland tests, although with a moderate relationship, are significantly associated with 100 m freestyle swimming performance in elite Paralympic swimmers.

Adolescent Cardiorespiratory Fitness and Future Work Ability

Importance

Although research indicates that low fitness in youth is associated with a higher risk of chronic disability in men, the association of fitness in adolescence with work ability in working men and women remains unknown.

Objective

To examine the associations of adolescent health-related physical fitness with future work ability.

Design, Setting, and Participants

This 45-year observational cohort study, conducted in Finland, examined the direct and indirect longitudinal associations of objectively measured health-related fitness in adolescence (in 1976) with self-reported work ability and sickness absence in early middle age (in 2001) and the Work Ability Index in late middle age (in 2021). A countrywide stratified random baseline sample included fitness measurements for cardiorespiratory fitness (CRF) (running 1.5 km for girls and 2 km for boys), musculoskeletal fitness (MF; standing broad jump and sit-ups for both sexes, pull-ups for boys, and flexed-arm hang for girls), and height and weight, from which body mass index (BMI) was calculated. Structural equation modeling-based path analysis, adjusted for age and sex at baseline and for educational level, work-related physical strain, and leisure-time physical activity in late middle age, was conducted. Data analysis was performed from January to July 2023.

Main Outcomes and Measures

Self-reported work ability was measured with structured questions in early middle age and with the validated Work Ability Index in late middle age.

Results

The final sample from longitudinal analyses (1207 individuals; 579 [48%] male individuals) consisted of participants with fitness measurement from age 12 to 19 years, and work ability assessment from age 37 to 44 years and/or age 57 to 64 years. Higher adolescent CRF was associated with higher work ability (839 participants; β = 0.12; 95% CI, 0.01 to 0.22; P = .03) and lower sickness absence (834 participants; β = -0.07; 95% CI, -0.12 to -0.02; P = .004) in early middle age and, indirectly, mediated by work ability in early middle age, with a higher work ability at the end of working age (603 participants; β = 0.04; 95% CI, 0.001 to 0.08; P = .04). The results remained consistent in both sexes and after adjustment for the confounders. Neither MF nor BMI was associated with work ability (MF, 1192 participants; β = -0.07; 95% CI, -0.17 to 0.03; BMI, 1207 participants, β = 0.09; 95% CI, -0.004 to 0.19) or sickness absence (MF, 1185 participants, β = 0.02; 95% CI, -0.03 to 0.06; BMI, 1202 participants, β = -0.03; 95% CI, -0.09 to 0.03) in early middle age or with late middle age work ability, mediated by work ability in early middle age (MF, 603 participants, β = -0.02; 95% CI, -0.06 to 0.01; BMI, 603 participants, β = 0.03; 95% CI, -0.004 to 0.07).

Conclusions and Relevance

These findings suggest that low CRF in youth is associated with poor work ability at the middle and end of working life, which highlights the informative and prognostic value of CRF assessment early in youth. Enhancing CRF in the first decades of life might contribute to better work capacity and productivity in the labor force, which would have implications for health, quality of life, society, and the economy.

Physical fitness in male adolescents and atherosclerosis in middle age: a population-based cohort study

OBJECTIVES

To examine the associations between physical fitness in male adolescents and coronary and carotid atherosclerosis in middle age.

METHODS

This population-based cohort study linked physical fitness data from the Swedish Military Conscription Register during adolescence to atherosclerosis data from the Swedish CArdioPulmonary bioImage Study in middle age. Cardiorespiratory fitness was assessed using a maximal cycle-ergometer test, and knee extension muscular strength was evaluated through an isometric dynamometer. Coronary atherosclerosis was evaluated via Coronary Computed Tomography Angiography (CCTA) stenosis and Coronary Artery Calcium (CAC) scores, while carotid plaques were evaluated by ultrasound. The associations were analysed using multinomial logistic regression, adjusted (marginal) prevalences and restricted cubic splines.

RESULTS

The analysis included 8986 male adolescents (mean age 18.3 years) with a mean follow-up of 38.2 years. Physical fitness showed a reversed J-shaped association with CCTA stenosis and CAC, but no consistent association was observed for carotid plaques. After adjustments, compared with adolescents in the lowest tertile of cardiorespiratory fitness and muscular strength, those in the highest tertile had 22% (OR 0.78; 95% CI 0.61 to 0.99) and 26% (OR 0.74; 95% CI 0.58 to 0.93) lower ORs for severe (≥50%) coronary stenosis, respectively. The highest physical fitness group (high cardiorespiratory fitness and muscular strength) had 33% (OR 0.67; 95% CI 0.52 to 0.87) lower OR for severe coronary stenosis compared with those with the lowest physical fitness.

CONCLUSION

This study supports that a combination of high cardiorespiratory fitness and high muscular strength in adolescence is associated with lower coronary atherosclerosis, particularly severe coronary stenosis, almost 40 years later.

May the Force Be with Youth: Foundational Strength for Lifelong Development

ABSTRACT

Today's youth are weaker than previous generations, and measurable reductions in physical fitness are beginning to emerge. Without targeted initiatives that recognize the foundational importance of resistance training, weaker children and adolescents may be more likely to experience the inevitable consequences of neuromuscular dysfunction and less likely to experience the pleiotropic benefits of exercise and sport. Early exposure to strength-building activities is needed to prepare today's youth for ongoing participation in varied physical activities throughout this developmental phase of life. The novel iceberg of physical development is a metaphoric image that illustrates the sequential and cumulative influence of muscular strength on motor skills and physical abilities. Efforts to enhance the physical capacity of youth should include resistive skills that improve basic movement patterns and enhance motoric competence. A shift in our conceptual thinking about youth resistance training is needed to alter the current trajectory toward physical inactivity and related comorbidities.

Short-Term Impact of Exercise Fitness Testing in a Pediatric Metabolic and Obesity Clinic: Initiative to Improve Health Care Quality

This 2-phase pilot initiative determined whether (1) fitness testing could feasibly be implemented in pediatric practice, and (2) short-term changes in fitness and body mass index occur with Specific, Measurable, Attainable, Relevant, and Time-based (SMART) goals. Phase 1 (N = 580), clinic feasibility: evidence-based prognostic tests were successfully performed to measure cardiorespiratory fitness (CRF; 3-minute bench step), strength (handgrip dynamometry), and flexibility (sit-and-reach distance). Mean CRF percentile was 58.1 (worst >95 percentile, best <5 percentile), strength percentile was 73.5, and flexibility was 42.3 (worst <5 percentile, best >95 percentile). Phase 2, goal setting and follow-up: SMART fitness goals were developed. In phase 2, patients demonstrated 11.9% and 12.4% improvements in CRF and strength percentiles (P < .05) respectively. All patients who were assigned a strength goal improved handgrip strength. Body mass index percentile changes were not different by SMART goal target. Fitness testing was feasible and successfully improved CRF and strength in children at high risk of metabolic complications and future disability.

Current situation and factors influencing physical fitness among adolescents aged 12 ∼ 15 in Shandong Province, China: A cross-sectional study

Adolescent physical fitness serves not merely as a current barometer of well-being but as a significant prognosticator of future health trajectories. Amidst the tumult of socioeconomic metamorphoses and pronounced lifestyle transitions enveloping China-mirroring global trends-the imperative to elucidate the present landscape of adolescent physical fitness intensifies. Moreover, discerning the myriad determinants underpinning it becomes paramount. In this context, our research endeavored to meticulously delineate the physical fitness milieu of adolescents residing in Shandong Province, systematically unpacking the multifarious influencers thereof. The insights garnered herein furnish an empirical foundation, primed to guide the sculpting of calibrated interventions, targeting the enhancement of health in this pivotal population cohort. In an extensive evaluative survey conducted in 2023 concerning the physical fitness of Shandong's student populace, a cohort of 33,211 adolescents aged 12 to 15 years was delineated utilizing a stratified random cluster sampling technique. This exercise meticulously quantified the physical fitness indices across diverse gender, age, and household registration classifications, subsequently computing the concomitant qualified rates. Employing multivariable logistic regression analysis, this investigation delved into the determinants modulating the adolescents' physical fitness qualified rate. For 2023, the aggregate fitness qualified rate stood at 91.94 % for the adolescents aged 12 ∼ 15 in Shandong Province. Gender-wise, female adolescents registered a qualified rate of 92.25 %, marginally eclipsing their male peers at 91.63 % (P < 0.05). An age-related trend in qualified rates was discernible, with marked variations across different age bands (P < 0.05): 91.37 % for 12-year-olds, 91.79 % for 13-year-olds, 91.81 % for 14-year-olds, and a zenith of 92.87 % for 15-year-olds. A geographical dichotomy emerged wherein rural adolescents distinctly outperformed their urban counterparts, notching up a 92.28 % qualified rate versus 91.64 % in urban settings (P < 0.05). The multivariable logistic regression analysis showed that after adjusting for gender, age, and household registration characteristics, adolescents had a lower odds of failing the physical fitness tests whose parents both liked physical exercises, whose parents supported children's participation in physical exercise, who participated in physical exercise sessions 3 ∼ 5 times per week or more than 5 times per week, who exercised for 0.5 ∼ 1 h each time or more than 1 h each time, who engaged in moderate intensity physical exercise, who slept 6 ∼ 8 h per day or more than 8 h per day, who consumed breakfast 3 ∼ 6 times per week or daily. On the other hand, adolescents had a higher odds of failing the physical fitness tests who always exposed to passive smoking, who spent 1 ∼ 3 h on screen per day or more than 3 h on screen per day, who spent more than 3 h doing homework per day, who consumed fast food 2 ∼ 3 times per week or more than 3 times per week. The physical fitness trajectory of adolescents residing within Shandong Province is tethered to a mosaic of determinants. This underscores the imperative for a synergistic strategy, harmonizing parental, scholastic, and societal vectors, to cultivate the salubrious maturation of this pivotal cohort.

Temporal Trends in the Physical Fitness of Hong Kong Adolescents Between 1998 and 2015

Low physical fitness in adolescence is linked with increased cardiometabolic risk and early all-cause mortality. This study aimed to estimate temporal trends in the physical fitness of Hong Kong adolescents aged 12-17 years between 1998 and 2015. Physical fitness (9-min run/walk, sit-ups, push-ups, and sit-and-reach) and body size data in a total of 28,059 adolescents tested across five population-representative surveys of Hong Kong secondary school pupils, were reported. Temporal trends in means were estimated at the gender-age level by best-fitting sample-weighted linear regression, with national trends estimated by a post-stratified population-weighting procedure. Overall, there were small declines in 9-min run/walk (effect size (ES)=-0.29 (95%CI: -0.32, -0.26)) and sit-ups performance (ES=-0.24 (95%CI: -0.27, -0.21)), with negligible changes in push-ups and sit-and-reach performance. There were small concurrent increases in both mean height and body mass, with a negligible increase in sum of skinfolds. Trends in mean physical fitness and body size/were not always uniform across the population distribution. The small declines in mean 9-min run/walk and sit-ups performance for Hong Kong adolescents are suggestive of corresponding declines in cardiorespiratory fitness and abdominal/core endurance, respectively. Increased national health promotion strategies are required to improve existing trends.

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.

Physical Fitness Among Adolescents Who are Hispanic With Overweight or Obesity

PURPOSE

To describe cardiorespiratory, strength, muscular endurance, and flexibility fitness outcomes in a sample of adolescents who are Hispanic aged 11 to 15 years with overweight or obesity, stratified by age and sex.

METHODS

The sample included 280 adolescents (mean age: 13.0 ± 0.83 years, mean body mass index percentile: 94.6). Anthropometric measures included height, weight, body mass index percentile, and waist and hip circumference. Fitness measures included handgrip strength, sit-ups in 60 seconds, sit-and-reach test, and 6-minute walk test. We report mean scores for each fitness outcome measure and correlation coefficients with anthropometric measures.

RESULTS

Mean handgrip was 23.7 ± 6.48 kg, sit-and-reach test was 25.3 ± 8.13 cm, average sit-ups in 60 seconds were 19.4 ± 9.28, and 6-minute walk distance was 1960 ± 271 ft. Males outperformed females in all tests except sit-and-reach test.

DISCUSSION

Compared with published fitness values of healthy weight adolescents, our sample of adolescents who are Hispanic with overweight/obesity living in southern Florida is unconditioned in terms of cardiorespiratory fitness, strength, muscular endurance, and flexibility.

European fitness landscape for children and adolescents: updated reference values, fitness maps and country rankings based on nearly 8 million test results from 34 countries gathered by the FitBack network

OBJECTIVES

(1) To develop reference values for health-related fitness in European children and adolescents aged 6-18 years that are the foundation for the web-based, open-access and multilanguage fitness platform (FitBack); (2) to provide comparisons across European countries.

METHODS

This study builds on a previous large fitness reference study in European youth by (1) widening the age demographic, (2) identifying the most recent and representative country-level data and (3) including national data from existing fitness surveillance and monitoring systems. We used the Assessing Levels of PHysical Activity and fitness at population level (ALPHA) test battery as it comprises tests with the highest test-retest reliability, criterion/construct validity and health-related predictive validity: the 20 m shuttle run (cardiorespiratory fitness); handgrip strength and standing long jump (muscular strength); and body height, body mass, body mass index and waist circumference (anthropometry). Percentile values were obtained using the generalised additive models for location, scale and shape method.

RESULTS

A total of 7 966 693 test results from 34 countries (106 datasets) were used to develop sex-specific and age-specific percentile values. In addition, country-level rankings based on mean percentiles are provided for each fitness test, as well as an overall fitness ranking. Finally, an interactive fitness platform, including individual and group reporting and European fitness maps, is provided and freely available online (www.fitbackeurope.eu).

CONCLUSION

This study discusses the major implications of fitness assessment in youth from health, educational and sport perspectives, and how the FitBack reference values and interactive web-based platform contribute to it. Fitness testing can be conducted in school and/or sport settings, and the interpreted results be integrated in the healthcare systems across Europe.

Relationship between age and handgrip strength: Proposal of reference values from infancy to senescence

Introduction

Measurement of hand grip strength (HGS) has been proposed as a key component of frailty and has also been suggested as a central biomarker of healthy aging and a powerful predictor of future morbidity and mortality.

Objectives

(a) To determine whether a nonlinear relationship model could improve the prediction of handgrip strength (HGS) compared to the linear model and (b) to propose percentiles to evaluate HGS according to age and sex for a regional population of Chile from infancy to senescence.

Methods

A cross-sectional descriptive study was developed in a representative sample of the Maule region (Chile). The volunteers amounted to 5,376 participants (2,840 men and 2,536 women), with an age range from 6 to 80 years old. Weight, height, HGS (right and left hand) according to age and sex were evaluated. Percentiles were calculated using the LMS method [(L (Lambda; asymmetry), M (Mu; median), and S (Sigma; coefficient of variation)].

Results and discussion

There were no differences in HGS from 6 to 11 years of age in both sexes; however, from 12 years of age onwards, males presented higher HGS values in both hands (p < 0.05). The linear regression between age with HGS showed values of R ² = 0.07 in males and R ² = 0.02 in females. While in the non-linear model (cubic), the values were: R ² = 0.50 to 0.51 in men and R ² = 0.26 in women. The percentiles constructed by age and sex were: P5, P15, P50, P85, and P95 by age range and sex. This study demonstrated that there is a nonlinear relationship between chronological age with HGS from infancy to senescence. Furthermore, the proposed percentiles can serve as a guide to assess and monitor upper extremity muscle strength levels at all stages of life.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study

BACKGROUND

The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts.

OBJECTIVE

This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents.

METHODS

Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel.

RESULTS

There was strong between-panel agreement (panel 1: r_s = 0.76, p < 0.01; panel 2: r_s = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures".

CONCLUSIONS

The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Esports players, got muscle? Competitive video game players' physical activity, body fat, bone mineral content, and muscle mass in comparison to matched controls

BACKGROUND

Esports players, like traditional athletes, practice for long hours and, thus, are vulnerable to the negative health effects of prolonged sitting. There is a lack of research on the physical activity and the health ramifications of prolonged sitting by competitive players. The purpose of this study was to investigate activity levels, body mass index (BMI), and body composition in collegiate esports players as compared to age-matched controls.

METHODS

Twenty-four male collegiate esports players and non-esports players between 18 and 25 years of age signed a written consent to participate. Physical activity was examined using daily activity (step count) with a wrist-worn activity tracker. A questionnaire assessing physical activity was also administered. Secondary outcomes included body-fat percentage, lean-body mass, BMI, and bone mineral content measured using dual X-ray absorptiometry.

RESULTS

The step count in the esports players was significantly lower than the age-matched controls (6040.2 ± 3028.6 vs. 12843.8 ± 5661.1; p = 0.004). Esports players exhibited greater body-fat percentage (p = 0.05), less lean body mass (p = 0.003), and less bone mineral content (p = 0.03), despite no difference in BMI between the esports and non-esports players.

CONCLUSION

As compared to non-esports players, collegiate esports players were significantly less active and had a higher body-fat percentage, with lower lean body mass and bone mineral content. The BMIs showed no difference between the 2 groups. Esports athletes displayed significantly less activity and poor body composition, which are all correlated with potential health issues and risk of injury. BMI did not capture this difference and should not be considered as an accurate measure of health in competitive esports players.

Secular trends in physical fitness of Slovenian boys and girls aged 7 to 15 years from 1989 to 2019: a population-based study

Using the population-based data we aim to estimate the general population trends of multiple components of physical fitness of children, identify critical structural changes in these trends, and evaluate the potential changes in differences in the test scores between the children. During the entire study period, 1989-2019, median body mass index and triceps skinfold increased in both genders and all age groups. Muscular fitness, in general, showed negative trends, with some exceptions: during the post-2010 period, children were mostly experiencing the improvement of isometric strength of the upper body. The neuromuscular components of physical fitness showed positive trends, especially in girls. Cardiorespiratory fitness has been declining in all age groups until the last decade, with the largest decreases occurring before 2000. In the last decade, the trends reversed. The flexibility indicator revealed the largest differences between boys and girls, with boys mainly experiencing negative and girls mostly positive trends. The variability of the test scores mostly increased during the study period. This increasing variance suggests that-despite generally favourable trends in the last decade-children in Slovenia have been facing increasing inequalities in their development, which can potentially lead to future inequalities in health.

Handgrip strength and all-cause dementia incidence and mortality: findings from the UK Biobank prospective cohort study

BACKGROUND

This study aimed to investigate the associations of grip strength with incidence and mortality from dementia and whether these associations differ by sociodemographic and lifestyle factors.

METHODS

A total of 466 788 participants of the UK Biobank (median age 56.5 years, 54.5% women). The outcome was all-cause dementia incidence and mortality and the exposure was grip strength. Grip strength was assessed using a Jamar J00105 hydraulic hand dynamometer.

RESULTS

Excluding the first 2 years of follow-up (landmark analysis), mean follow-up was 9.1 years (inter-quartile range: 8.3; 9.7) for incidence and 9.3 (inter-quartile range: 8.7; 10.0) for mortality. During this time, 4087 participants developed dementia, and 1309 died from it. Lower grip strength was associated with a higher risk of dementia incidence and mortality independent of major confounding factors (P < 0.001). Individuals in the lowest quintile of grip strength had 72% [95% confidence interval (CI): 1.55; 1.92] higher incident dementia risk and 87% [95% CI: 1.55; 2.26] higher risk of dementia mortality compared with those in the highest quintile. Our PAF analyses indicate that 30.1% of dementia cases and 32.3% of dementia deaths are attributable to having low grip strength. The association between grip strength and dementia outcomes did not differ by lifestyle or sociodemographic factors.

CONCLUSIONS

Lower grip strength was associated with a higher risk of all-cause dementia incidence and mortality, independently of important confounding factors.

Association between handgrip strength and mental health in Korean adolescents

BACKGROUND AND OBJECTIVES

Muscle strength is associated with adverse mental health outcomes in adults; however, few studies have examined this association among adolescents. This study investigated the association between handgrip strength and mental health in a nationally representative sample of Korean adolescents.

METHODS

We performed a cross-sectional study of 3530 adolescent (12-18 years old) from the 2014-2017 Korean National Health and Nutrition Survey. Handgrip strength was defined as the maximum measurement in kilograms from the dominant hand. Adverse mental health included the presence of perceived stress, depressive mood and suicidal ideation. Logistic regression models were used with adjustment for potential confounders.

RESULTS

The mean age ± SD of the study participants was 14.9 ± 2.0 years. Girls (47.5% of participants) had poorer mental health than boys. For boys, each 1-kg increase in handgrip strength was associated with a 3% decrease in the odds of having perceived stress and depressive moods. For girls, there was a positive association between handgrip strength and perceived stress. The relationship between handgrip strength and perceived stress was dose dependent for both sexes.

CONCLUSIONS

Low handgrip strength was associated with poor mental health among boys. Future research is required to validate our findings and to establish whether interventions to increase muscular strength can reduce the prevalence of perceived stress and depressive mood in boys.

Neck-related function and its connection with disability in chronic whiplash-associated disorders: secondary analysis of a randomized controlled study

BACKGROUND

More than 40% of individuals with whiplash injury experience persistent neck pain and disability years later, called whiplash-associated disorders (WAD). A randomized controlled trial evaluated three exercise interventions in WAD and found that neck-specific exercise (NSE) and NSE with a behavioral approach (NSEB) significantly improve disability compared to prescribed physical activity (PPA). However, the relationship between neck-related function and disability is inconclusive and needs to be further investigated.

AIM

The present study compares the effect of NSE, NSEB, and PPA on neck muscle endurance (NME), active cervical range of motion (AROM), grip strength, and pain intensity immediately before and after the physical tests, and neck disability in individuals who are below or above the cut-off for normative reference values regarding NME, AROM, and grip strength.

DESIGN

Follow-up to a multicenter randomized clinical trial.

SETTING

Primary healthcare centers and hospital outpatient services.

POPULATION

The selected population of this study included 216 patients with persistent WAD grades II and III.

METHODS

This is a secondary analysis including 12 months' follow-up. NME, AROM, grip strength, pain, and self-reported disability were recorded at baseline, 3, 6, and 12 months. Linear mixed models were used, and sub-group analyses evaluated by non-parametric tests.

RESULTS

NSE and NSEB resulted in greater improvements compared to PPA (P<0.01) in ventral (only males) and dorsal NME, AROM, and pain intensity during testing. We found no significant between-group differences in grip strength and no significant differences between the NSE and NSEB groups. Improvement in disability was seen at the 12-month follow-up of NSE and/or NSEB for individuals both below and above the cut-off reference values for NME and AROM. Individuals in the PPA group below the reference values for NME and AROM reported increasing disability at 12 months compared to baseline.

CONCLUSIONS

The results suggest that neck-specific exercises (i.e., NSE, NSEB) improve clinical function and decrease disability in chronic WAD compared to PPA, but PPA can increase disability for patients with low neck-related function.

CLINICAL REHABILITATION IMPACT

Higher neck-related function seems to be important for reduced disability in persistent WAD grades II and III. Neck-specific exercises could lead to higher neck-related function.

Temporal Trends in the Standing Broad Jump Performance of 10,940,801 Children and Adolescents Between 1960 and 2017

BACKGROUND

The standing broad jump (SBJ) is an excellent functional measure of explosive lower-body strength that is significantly related to health among children and adolescents.

OBJECTIVES

The aim of this study was to estimate national (country-level) and international (pooled global data) temporal trends in SBJ performance for children and adolescents, and to examine the relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

METHODS

Data were obtained from a systematic search of studies reporting temporal trends in SBJ performance for 9- to 17-year-olds, and by examining national fitness datasets. Sample-weighted regression models estimated trends at the study/dataset-country-sex-age level, with national and international trends estimated by a post-stratified population-weighting procedure. Pearson's correlations quantified relationships between national trends in SBJ performance and national trends in health-related and socioeconomic/demographic indicators.

RESULTS

Data from 34 studies/datasets were extracted to estimate trends for 10,940,801 children and adolescents from 24 high-, 4 upper-middle-, and 1 low-income countries between 1960 and 2017. Collectively, there was a negligible (per decade) improvement in SBJ performance of 1.73 cm (95% CI 1.71-1.75), 0.99% (95% CI 0.97-1.01) or a standardized effect size of 0.07 (0.07-0.07) over the entire period, with the rate of improvement steady from the 1960s to the 1980s, slowing in the 1990s, before declining. Sex- and age-related temporal differences were negligible. Trends differed between countries, with most countries experiencing declines. National trends in SBJ performance were not significantly related to national trends in health-related and socioeconomic/demographic indicators.

CONCLUSIONS

SBJ performance of children and adolescents has declined since 2000 (at least among most of the countries in this analysis) and is suggestive of a modern decline in functional explosive lower-body strength. Growing recognition of the importance of muscular fitness as a marker of population health highlights the need for continued tracking of temporal trends in SBJ, especially among low- and lower-middle-income countries for which temporal data are lacking.

PROSPERO REGISTRATION NUMBER

CRD42013003657.

Cardiorespiratory fitness, muscular strength, and obesity in adolescence and later chronic disability due to cardiovascular disease: a cohort study of 1 million men

Aims

Cardiorespiratory fitness, muscular strength, and obesity in adulthood are risk factors for cardiovascular disease (CVD). However, little is known regarding the associations of these risk factors, already in adolescence, with later disability due to chronic CVD. Hence, we investigated associations of cardiorespiratory fitness, muscular strength, and body mass index (BMI) in adolescence with later chronic disability due to specific causes of CVD disability (i.e. cerebrovascular disease, ischaemic heart disease and heart failure).

Methods and results

This population-based cohort study included 1 078 685 male adolescents (16–19 years) from the Swedish military conscription register from 1972 to 1994. Cardiorespiratory fitness (bicycle ergometer test), muscular strength (knee extension strength), and BMI were measured during the conscription examination. Information about disability pension due to CVD was retrieved from the Social Insurance Agency during a mean follow-up of 28.4 years. Cardiorespiratory fitness was strongly and inversely associated with later risk of chronic CVD disability for all investigated causes. The association was particularly strong for ischaemic heart diseases (hazard ratio 0.11, 95% confidence interval 0.05–0.29 for highest vs. lowest fitness-quintiles). Furthermore, overweight/obesity were associated with CVD disability for all investigated causes. Conversely, associations of muscular strength with CVD disability were generally weak.

Conclusions

This study provides evidence for associations between low levels of cardiorespiratory fitness and obesity with later risk of chronic disability due to CVD. Preventive actions may begin at young ages and include promotion of cardiorespiratory fitness and healthy body weight.

Impact of COVID-19 Confinement on Physical Activity and Sedentary Behaviour in Spanish University Students: Role of Gender

During the COVID-19 pandemic, entire populations were instructed to live in home-confinement to prevent the expansion of the disease. Spain was one of the countries with the strictest conditions, as outdoor physical activity was banned for nearly two months. This study aimed to analyse the changes in physical activity and sedentary behaviours in Spanish university students before and during the confinement by COVID-19 with special focus on gender. We also analysed enjoyment, the tools used and motivation and impediments for doing physical activity. An online questionnaire, which included the International Physical Activity Questionnaire Short Form and certain "ad hoc" questions, was designed. Students were recruited by distributing an invitation through the administrative channels of 16 universities and a total of 13,754 valid surveys were collected. Overall, university students reduced moderate (-29.5%) and vigorous (-18.3%) physical activity during the confinement and increased sedentary time (+52.7%). However, they spent more time on high intensity interval training (HIIT) (+18.2%) and mind-body activities (e.g., yoga) (+80.0%). Adaptation to the confinement, in terms of physical activity, was handled better by women than by men. These results will help design strategies for each gender to promote physical activity and reduce sedentary behaviour during confinement periods.

Physical fitness and white matter microstructure in children with overweight or obesity: the ActiveBrains project

Recent studies investigated the association of cardiorespiratory fitness with white matter microstructure in children, yet little work has explored to what extent other components of physical fitness (i.e., muscular or motor fitness) are associated with white matter microstructure. Indeed, this association has not been previously explored in children with overweight/obesity who present a different white matter development. Therefore, we aimed to examine associations between physical fitness components and white matter microstructure in children with overweight/obesity. In total, 104 (10.04 ± 1.15 years old; 43 girls) children were included in this cross-sectional study. Physical fitness was assessed using the ALPHA-fitness test battery. Fractional anisotropy (FA) and mean diffusivity were derived from diffusion tensor imaging (DTI). No association was found between physical fitness and global DTI metrics (all P > 0.082). Within individual tracts, all associations became non-significant when analyses were adjusted for multiple comparisons. Using the voxel-wise approach, we identified a small cluster in the left lateral frontal lobe where children with greater upper-body muscular fitness showed higher FA (P_{FWE-corrected} = 0.042). Although our results cannot conclude physical fitness is related to white matter microstructure in children with overweight/obesity; those findings indicate that the association of muscular fitness with white matter microstructure might be more focal on frontal areas of the brain, as opposed to global differences.

Relationships between cardiorespiratory fitness/muscular strength and 18F-fluorodeoxyglucose uptake in brown adipose tissue after exposure to cold in young, sedentary adults

Humans have metabolically active brown adipose tissue (BAT). However, what is the relation between exercise or physical activity with this tissue remains controversial. Therefore, the main aim of the present study is to examine whether cardiorespiratory fitness and muscular strength are associated with brown adipose tissue (BAT) volume and activity after exposure to cold in young, sedentary adults. Cardiorespiratory fitness was determined in 119 young, healthy, sedentary adults (68% women, age 21.9 ± 2.1 years, body mass index 25 ± 4.8 kg/m2) via the maximum treadmill exercise test, and their muscular strength assessed by the handgrip strength test and the 1-repetition maximum bench and leg press tests. Some days later, all subjects were exposed to 2 h of personalized exposure to cold and their cold-induced BAT volume and activity determined by a combination of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography and computed tomography scan. Cardiorespiratory fitness was associated with neither the BAT volume nor BAT activity (P ≥ 0.05). However, handgrip strength with respect to lean body mass was positively (though weakly) associated with BAT activity as represented by the 18F-FDG mean standardised uptake value (SUV) (β = 3.595, R2 = 0.039, P = 0.031) and SUVpeak value (β = 15.314, R2 = 0.037, P = 0.035). The above relationships remained after adjusting for several confounders. No other associations were found. Handgrip strength with respect to lean body mass is positively associated with BAT activity (SUVmean and SUVpeak) in young adults after exposure to cold - but only weakly. Further studies are needed to reveal the relationship between muscular fitness and human BAT characteristics.

Functional and/or structural brain changes in response to resistance exercises and resistance training lead to cognitive improvements - a systematic review

BACKGROUND

During the aging process, physical capabilities (e.g., muscular strength) and cognitive functions (e.g., memory) gradually decrease. Regarding cognitive functions, substantial functional (e.g., compensatory brain activity) and structural changes (e.g., shrinking of the hippocampus) in the brain cause this decline. Notably, growing evidence points towards a relationship between cognition and measures of muscular strength and muscle mass. Based on this emerging evidence, resistance exercises and/or resistance training, which contributes to the preservation and augmentation of muscular strength and muscle mass, may trigger beneficial neurobiological processes and could be crucial for healthy aging that includes preservation of the brain and cognition. Compared with the multitude of studies that have investigated the influence of endurance exercises and/or endurance training on cognitive performance and brain structure, considerably less work has focused on the effects of resistance exercises and/or resistance training. While the available evidence regarding resistance exercise-induced changes in cognitive functions is pooled, the underlying neurobiological processes, such as functional and structural brain changes, have yet to be summarized. Hence, the purpose of this systematic review is to provide an overview of resistance exercise-induced functional and/or structural brain changes that are related to cognitive functions.

METHODS AND RESULTS

A systematic literature search was conducted by two independent researchers across six electronic databases; 5957 records were returned, of which 18 were considered relevant and were analyzed.

SHORT CONCLUSION

Based on our analyses, resistance exercises and resistance training evoked substantial functional brain changes, especially in the frontal lobe, which were accompanied by improvements in executive functions. Furthermore, resistance training led to lower white matter atrophy and smaller white matter lesion volumes. However, based on the relatively small number of studies available, the findings should be interpreted cautiously. Hence, future studies are required to investigate the underlying neurobiological mechanisms and to verify whether the positive findings can be confirmed and transferred to other needy cohorts, such as older adults with dementia, sarcopenia and/or dynapenia.

Role of Physical Activity and Fitness in the Characterization and Prognosis of the Metabolically Healthy Obesity Phenotype: A Systematic Review and Meta-analysis

The aims of the present article are to systematically review and meta-analyze the existing evidence on: 1) differences in physical activity (PA), sedentary behavior (SB), cardiorespiratory fitness (CRF) and muscular strength (MST) between metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO); and 2) the prognosis of all-cause mortality and cardiovascular disease (CVD) mortality/morbidity in MHO individuals, compared with the best scenario possible, i.e., metabolically healthy normal-weight (MHNW), after adjusting for PA, SB, CRF or MST. Our systematic review identified 67 cross-sectional studies to address aim 1, and 11 longitudinal studies to address aim 2. The major findings and conclusions from the current meta-analysis are: 1) MHO individuals are more active, spend less time in SB, and have a higher level of CRF (yet no differences in MST) than MUO individuals, suggesting that their healthier metabolic profile could be at least partially due to these healthier lifestyle factors and attributes. 2) The meta-analysis of cohort studies which accounted for PA (N = 10 unique cohorts, 100% scored as high-quality) support the notion that MHO individuals have a 24-33% higher risk of all-cause mortality and CVD mortality/morbidity compared to MHNW individuals. This risk was borderline significant/non-significant, independent of the length of the follow-up and lower than that reported in previous meta-analyses in this topic including all type of studies, which could be indicating a modest reduction in the risk estimates as a consequence of accounting for PA. 3) Only one study has examined the role of CRF in the prognosis of MHO individuals. This study suggests that the differences in the risk of all-cause mortality and CVD mortality/morbidity between MHO and MHNW are largely explained by differences in CRF between these two phenotypes.