Enrique G. Artero

Predictive Validity of Health-Related Fitness in Youth: A Systematic Review

The objective of the present systematic review was to investigate whether physical fitness in childhood and adolescence is a predictor of cardiovascular disease (CVD) risk factors, events and syndromes, quality of life and low back pain later in life. Physical fitness-related components were: cardiorespiratory fitness, musculoskeletal fitness, motor fitness and body composition. Adiposity was considered as both exposure and outcome. The results of 42 studies reporting the predictive validity of health-related physical fitness for CVD risk factors, events and syndromes as well as the results of five studies reporting the predictive validity of physical fitness for low back pain in children and adolescents were summarised. Strong evidence was found indicating that higher levels of cardiorespiratory fitness in childhood and adolescence are associated with a healthier cardiovascular profile later in life. Muscular strength improvements from childhood to adolescence are negatively associated with changes in overall adiposity. A healthier body composition in childhood and adolescence is associated with a healthier cardiovascular profile later in life and with a lower risk of death. The evidence was moderate for the association between changes in cardiorespiratory fitness and CVD risk factors, and between cardiorespiratory fitness and the risk of developing the metabolic syndrome and arterial stiffness. Moderate evidence on the lack of a relationship between body composition and low back pain was found. Due to a limited number of studies, inconclusive evidence emerged for a relationship between muscular strength or motor fitness and CVD risk factors, and between flexibility and low back pain.

Mortality trends in the general population: the importance of cardiorespiratory fitness

Cardiorespiratory fitness (CRF) is not only an objective measure of habitual physical activity, but also a useful diagnostic and prognostic health indicator for patients in clinical settings. Although compelling evidence has shown that CRF is a strong and independent predictor of all-cause and cardiovascular disease mortality, the importance of CRF is often overlooked from a clinical perspective compared with other risk factors such as hypertension, diabetes, smoking, or obesity. Several prospective studies indicate that CRF is at least as important as the traditional risk factors, and is often more strongly associated with mortality. In addition, previous studies report that CRF appears to attenuate the increased risk of death associated with obesity. Most individuals can improve their CRF through regular physical activity. Several biological mechanisms suggest that CRF improves insulin sensitivity, blood lipid profile, body composition, inflammation, and blood pressure. Based on the evidence, health professionals should encourage their patients to improve CRF through regular physical activity.

Criterion-related validity of field-based fitness tests in youth: a systematic review

The objective of this systematic review was to comprehensively study the criterion-related validity of the existing field-based fitness tests used in children and adolescents. The studies were scored according to the number of subjects, description of the study population and statistical analysis. Each study was classified as high, low and very low quality. Three levels of evidence were constructed: strong evidence, when consistent findings were observed in three or more high quality studies; moderate evidence, when consistent findings were observed in two high quality studies; and limited evidence when consistency of findings and/or the number of studies did not achieve the criteria for moderate. The results of 73 studies (50 of high quality) addressing the criterion-related validity of field-based fitness tests in children and adolescents indicate the following: that there is strong evidence indicating that the 20 m shuttle run test is a valid test to estimate cardiorespiratory fitness, that the hand-grip strength test is a valid measure of musculoskeletal fitness, that skin fold thickness and body mass index are good estimates of body composition, and that waist circumference is a valid measure to estimate central body fat. Moderate evidence was found that the 1-mile run/walk test is a valid test to estimate cardiorespiratory fitness. A large number of other field-based fitness tests presented limited evidence, mainly due to a limited number of studies (one for each test). The results of the present systematic review should be interpreted with caution due to the substantial lack of consistency in reporting and designing the existing validity studies.

Field-based fitness assessment in young people: the ALPHA health-related fitness test battery for children and adolescents

The present study summarises the work developed by the ALPHA (Assessing Levels of Physical Activity) study and describes the procedures followed to select the tests included in the ALPHA health-related fitness test battery for children and adolescents. The authors reviewed physical fitness and health in youth findings from cross-sectional studies. The authors also performed three systematic reviews dealing with (1) the predictive validity of health-related fitness, (2) the criterion validity of field-based fitness tests and (3) the reliability of field-based fitness tests in youth. The authors also carried out 11-methodological studies to determine the criterion validity and the reliability of several field-based fitness tests for youth. Finally, the authors performed a study in the school setting to examine the reliability, feasibility and safety of the selected tests. The selected fitness tests were (1) the 20 m shuttle run test to assess cardiorespiratory fitness; (2) the handgrip strength and (3) standing broad jump to assess musculoskeletal fitness, and (4) body mass index, (5) skinfold thickness and (5) waist circumference to assess body composition. When there are time limits, the authors propose the high-priority ALPHA health-related fitness test battery, which comprises all the evidence-based fitness tests except the measurement of the skinfold thickness. The time required to administer this battery to a group of 20 youth by one physical education teacher is less than 2 h. In conclusion, the ALPHA fitness tests battery is valid, reliable, feasible and safe for the assessment of health-related physical fitness in children and adolescents to be used for health monitoring purposes at population level.

Effects of Muscular Strength on Cardiovascular Risk Factors and Prognosis

Physical fitness is one of the strongest predictors of individual future health status. Together with cardiorespiratory fitness (CRF), muscular strength has been increasingly recognized in the pathogenesis and prevention of chronic disease. We review the most recent literature on the effect of muscular strength in the development of cardiovascular disease, with special interest in elucidating its specific benefits beyond those from CRF and body composition. Muscular strength has shown an independent protective effect on all-cause and cancer mortality in healthy middle-aged men, as well as in men with hypertension and patients with heart failure. It has also been inversely associated with age-related weight and adiposity gains, risk of hypertension, and prevalence and incidence of the metabolic syndrome. In children and adolescents, higher levels of muscular fitness have been inversely associated with insulin resistance, clustered cardiometabolic risk, and inflammatory proteins. Generally, the influence of muscular fitness was weakened but remained protective after considering CRF. Also, interestingly, higher levels of muscular fitness seems to some extent counteract the adverse cardiovascular profile of overweight and obese individuals. As many of the investigations have been conducted with non-Hispanic white men, it is important to examine how race/ethnicity and gender may affect these relationships. To conclude, most important effects of resistance training are also summarized, to better understand how higher levels of muscular fitness may result in a better cardiovascular prognosis and survival.

Influence of socioeconomic factors on fitness and fatness in Spanish adolescents: The AVENA study

OBJECTIVE This study was to examine the influence of socioeconomic status on fitness and fatness in Spanish adolescents. SUBJECTS AND METHODS A total of 1 795 adolescents (833 boys) aged 12.5-18.5 years from the AVENA study participated in this study. The following physical fitness components were assessed: muscular strength (standing long jump), speed-agility (4 × 10 m shuttle run) and cardiorespiratory fitness (20 m shuttle run). Total and central body fat was assessed using skinfold thickness and waist circumference, respectively. Both parents reported their educational and professional level. RESULTS Girls with higher paternal educational level and boys with higher either maternal or paternal professional level had higher muscular strength levels (all P<0.05). Speed-agility and cardiorespiratory fitness were not associated with parental educational or professional levels in boys. In contrast, girls with higher paternal educational level or higher parental professional level had higher levels in both fitness components (all P<0.05). A higher maternal educational level was associated with lower total and central body fat in boys (all P<0.05), but not in girls. We observed a small effect size (Cohens d∼0.2) in most of these associations. CONCLUSIONS Our results suggest modest associations of high socioeconomic status with better fitness and fatness levels in Spanish adolescents. These associations greatly depend on the socioeconomic status and fitness parameters studied.

Assessing Muscular Strength in Youth: Usefulness of Standing Long Jump as a General Index of Muscular Fitness

Castro-Piñero, J, Ortega, FB, Artero, EG, Girela-Rejón, MJ, Mora, J, Sjöström, M, and Ruiz, JR. Assessing muscular strength in youth: usefulness of standing long jump as a general index of muscular fitness. J Strength Cond Res 24(7): 1810-1817, 2010-The purpose of the present study was to examine the association among different measures of lower body muscular strength in children, and the association between measures of lower- and upper-body muscular strength. The study population comprises 94 (45 girls) healthy Caucasian children aged 6-17 years. Children performed several lower body explosive muscular strength tests (i.e., standing long jump [SLJ], vertical jump, squat jump, and countermovement jump) and upper body muscular strength tests (i.e., throw basketball, push-ups, and isometric strength exercises). The association among the study tests was analyzed by multiple regression. The SLJ was strongly associated with other lower body muscular strength tests (R2 = 0.829-0.864), and with upper body muscular strength tests (R2 = 0.694-0.851). The SLJ test might be therefore considered a general index of muscular fitness in youth. The SLJ test is practical, time efficient, and low in cost and equipment requirements.

Health-related fitness in adolescents: underweight, and not only overweight, as an influencing factor. The AVENA study

This study investigated differences in health‐related fitness (20‐m shuttle run, handgrip, bent arm hang, standing long jump, shuttle run 4 × 10 m and sit and reach tests) in 2474 Spanish adolescents (1196 boys and 1278 girls; age 13–18.5 years) classed as underweight, normal weight, overweight or obese according to body mass index. Body fat and fat‐free mass were derived from skinfold thickness. The prevalence of underweight was higher than obesity in girls (4.8% vs 3.0%, respectively; P<0.05) and the opposite in boys (3.9% vs 5.8%, respectively; P<0.05). Underweight was associated with a higher performance in the bent arm hang test in girls (P<0.05) and a lower performance in handgrip in both genders (P<0.01) compared with normal weight. Overweight and obese adolescents presented a lower performance in 20‐m shuttle run, bent arm hang, standing long jump and shuttle run 4 × 10 m tests (P<0.001), but a higher performance in handgrip strength (P<0.001) compared with normal weight. In weight‐bearing tests, the association became non‐significant after adjusting for fat mass. In conclusion, not only overweight and obesity but also underweight seem to be determinants of health‐related fitness in adolescents. The associations could be related to differences in body composition.

Elbow position affects handgrip strength in adolescents: validity and reliability of Jamar, DynEx, and TKK dynamometers.

España-Romero, V, Ortega, FB, Vicente-Rodríguez, G, Artero, EG, Rey, JP, and Ruiz, JR. Elbow position affects handgrip strength in adolescents: validity and reliability of Jamar, DynEx, and TKK dynamometers. J Strength Cond Res 24(1): 272-277, 2010-We examined whether elbow position affects the handgrip strength in adolescents. The criterion-related validity and reliability of the Jamar, DynEx, and TKK dynamometers were also analyzed. A total of 66 adolescents aged 12 to16 years performed the handgrip strength test with the elbow extended and flexed at 90°. The validity and reliability of the Jamar, DynEx, and TKK dynamometers was analysed by using known weights. The highest score was obtained when the test was performed with the elbow in full extension and when using the TKK dynamometer. The criterion-related validity analyses showed a systematic bias of −1.92, −1.43, and 0.49 kg for the Jamar, DynEx, and TKK dynamometers, respectively (all p < 0.05). The reliability analyses revealed a systematic bias of 0.23, 0.26, and 0.02 kg in the Jamar, DynEx, and TKK dynamometers, respectively (all p > 0.05). Performing the handgrip strength test with the elbow extended appears the most appropriate protocol to evaluate maximal handgrip strength in adolescents when using the TKK. In addition, the TKK dynamometer appears to provide the highest criterion-related validity and reliability. The present study provides useful and relevant information indicating which elbow position, and which type of dynamometer, yield maximal handgrip strength in adolescents.

Hand span influences optimal grip span in boys and girls aged 6 to 12 years.

PURPOSE The first aim was to determine whether there is an optimal grip span for determining the maximum hand grip strength in boys and girls aged 6 to 12 years and whether the optimal grip span was related to hand span. If so, the second aim was to derive a mathematical equation relating hand span and optimal grip span. METHODS A total of 123 boys (9 y +/- 2) and 70 girls (8 y +/- 2) were evaluated. Each hand was randomly tested on 10 occasions using 5 different grip spans, allowing a 1-minute rest between attempts. The hand span was measured from the tip of the thumb to the tip of the little finger with the hand opened widely. RESULTS An optimal grip span to determine maximum hand grip strength was identified for both genders. Hand span and optimal grip span showed a significant linear association in the studied children. The equation relating grip span as a function of hand span in boys is formulated as y = x/4 + 0.44 and in girls as y = 0.3x - 0.52, where x is the hand span (maximal width between first and fifth fingers) and y is the optimal grip span. CONCLUSIONS The results suggest that there is an optimal grip span to which the dynamometer should be adjusted when measuring hand grip strength in children. The optimal grip span was influenced by hand span in both genders.