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.

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 (R = 0.829-0.864), and with upper body muscular strength tests (R = 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.

The aim of this study was to provide percentile values for 9 different muscular strength tests for Spanish children (1,513 boys and 1,265 girls) aged 6 to 17.9 years. The influence of body weight on the muscular strength level across age groups was also examined. Explosive strength was assessed by the throw ball test (upper body), standing broad jump, and vertical jump tests (lower body). Upper-body muscular endurance was assessed by push ups, bent arm hang, and pull ups tests, and abdominal muscular endurance was assessed by sit ups, curl ups in 30 seconds, and curl ups tests. Body mass index (BMI) was calculated. Participants were categorized according to the BMI international cut-off values as underweight, normalweight, overweight, and obese. Boys had significantly better scores than girls in all the studied tests, except in the 3 upper-body muscular endurance tests in the 6- to 7-year-old group and in the push ups test in the 8- to 9-year-old group. Underweight and normalweight individuals showed similar strength levels. Both underweight and normalweight children and adolescents had significantly higher performance than their overweight and obese counterparts in the lower-body explosive strength tests and in the push ups test in boys and bent arm hang test in both boys and girls. In conclusion, percentiles values of 9 muscular strength tests are provided. Percentiles values are of interest to identify the target population for primary prevention and to estimate the proportion of adolescents with high or low muscular strength levels. The overweight and obese groups had worse scores than their underweight and normalweight counterparts, whereas the underweight group had a similar performance to the normalweight group.

These findings suggest a link between cardiorespiratory fitness and fatness and positive health indicators, suggesting that improving both fitness and fatness could exert a favourable effect on positive health during childhood and adolescence.

We examined the association of muscular fitness with psychological positive health, health complaints, and health risk behaviors in 690 (n = 322 girls) Spanish children and adolescents (6-17.9 years old). Lower body muscular strength was assessed with the standing long jump test, and upper-body muscular strength was assessed with the throw basketball test. A muscular fitness index was computed by means of standardized measures of both tests. Psychosocial positive health, health complaints, and health risk behaviors were self-reported using the items of the Health Behavior in School-aged Children questionnaire. Psychological positive health indicators included the following: perceived health status, life satisfaction, quality of family relationships, quality of peer relationships, and academic performance. We computed a health complaints index from 8 registered symptoms: headache, stomach ache, backache, feeling low, irritability or bad temper, feeling nervous, difficulties getting to sleep, and feeling dizzy. The health risk behavior indicators studied included tobacco use, alcohol use, and getting drunk. Children and adolescents with low muscular fitness (below the mean) had a higher odds ratio (OR) of reporting fair (vs. excellent) perceived health status, low life satisfaction (vs. very happy), low quality of family relationships (vs. very good), and low academic performance (vs. very good). Likewise, children and adolescents having low muscular fitness had a significantly higher OR of reporting smoking tobacco sometimes (vs. never), drinking alcohol sometimes (vs. never), and getting drunk sometimes (vs. never). The results of this study suggest a link between muscular fitness and psychological positive health and health risk behavior indicators in children and adolescents.