Thomas W. Rowland

Youth Resistance Training: Updated Position Statement Paper From the National Strength and Conditioning Association

Faigenbaum, AD, Kraemer, WJ, Blimkie, CJR, Jeffreys, I, Micheli, LJ, Nitka, M, and Rowland, TW. Youth resistance training: Updated position statement paper from the National Strength and Conditioning Association. J Strength Cond Res 23(5): S60-S79, 2009-Current recommendations suggest that school-aged youth should participate daily in 60 minutes or more of moderate to vigorous physical activity that is developmentally appropriate and enjoyable and involves a variety of activities (219). Not only is regular physical activity essential for normal growth and development, but also a physically active lifestyle during the pediatric years may help to reduce the risk of developing some chronic diseases later in life (196). In addition to aerobic activities such as swimming and bicycling, research increasingly indicates that resistance training can offer unique benefits for children and adolescents when appropriately prescribed and supervised (28,66,111,139,147,234). The qualified acceptance of youth resistance training by medical, fitness, and sport organizations is becoming universal (5,6,8,12,18,33,104,167,192,215). Nowadays, comprehensive school-based programs are specifically designed to enhance health-related components of physical fitness, which include muscular strength (169). In addition, the health club and sport conditioning industry is getting more involved in the youth fitness market. In the U.S.A., the number of health club members between the ages of 6 and 17 years continues to increase (127,252) and a growing number of private sport conditioning centers now cater to young athletes. Thus, as more children and adolescents resistance train in schools, health clubs, and sport training centers, it is imperative to determine safe, effective, and enjoyable practices by which resistance training can improve the health, fitness, and sports performance of younger populations. The National Strength and Conditioning Association (NSCA) recognizes and supports the premise that many of the benefits associated with adult resistance training programs are attainable by children and adolescents who follow age-specific resistance training guidelines. The NSCA published the first position statement paper on youth resistance training in 1985 (170) and revised this statement in 1996 (72). The purpose of the present report is to update and clarify the 1996 recommendations on 4 major areas of importance. These topics include (a) the potential risks and concerns associated with youth resistance training, (b) the potential health and fitness benefits of youth resistance training, (c) the types and amount of resistance training needed by healthy children and adolescents, and (d) program design considerations for optimizing long-term training adaptations. The NSCA based this position statement paper on a comprehensive analysis of the pertinent scientific evidence regarding the anatomical, physiological, and psychosocial effects of youth resistance training. An expert panel of exercise scientists, physicians, and health/physical education teachers with clinical, practical, and research expertise regarding issues related to pediatric exercise science, sports medicine, and resistance training contributed to this statement. The NSCA Research Committee reviewed this report before the formal endorsement by the NSCA. For the purpose of this article, the term children refers to boys and girls who have not yet developed secondary sex characteristics (approximately up to the age of 11 years in girls and 13 years in boys; Tanner stages 1 and 2 of sexual maturation). This period of development is referred to as preadolescence. The term adolescence refers to a period between childhood and adulthood and includes girls aged 12-18 years and boys aged 14-18 years (Tanner stages 3 and 4 of sexual maturation). The terms youth and young athletes are broadly defined in this report to include both children and adolescents. By definition, the term resistance training refers to a specialized method of conditioning, which involves the progressive use of a wide range of resistive loads and a variety of training modalities designed to enhance health, fitness, and sports performance. Although the term resistance training, strength training, and weight training are sometimes used synonymously, the term resistance training encompasses a broader range of training modalities and a wider variety of training goals. The term weightlifting refers to a competitive sport that involves the performance of the snatch and clean and jerk lifts. This article builds on previous recommendations from the NSCA and should serve as the prevailing statement regarding youth resistance training. It is the current position of the NSCA that:A properly designed and supervised resistance training program is relatively safe for youth.A properly designed and supervised resistance training program can enhance the muscular strength and power of youth.A properly designed and supervised resistance training program can improve the cardiovascular risk profile of youth.A properly designed and supervised resistance training program can improve motor skill performance and may contribute to enhanced sports performance of youth.A properly designed and supervised resistance training program can increase a young athletes resistance to sports-related injuries.A properly designed and supervised resistance training program can help improve the psychosocial well-being of youth.A properly designed and supervised resistance training program can help promote and develop exercise habits during childhood and adolescence.

The biological basis of physical activity.

Successful efforts to improve levels of physical activity in the population are contingent upon an accurate understanding of the determinants of habitual activity. While most research has focused on psychosocial and environmental influences, the potential effect of intrinsic biological control on regular activity has received little attention. This review examines evidence for the existence of such central control, offers a rationale for its function, and suggests implications for preventive health strategies resulting from a biological contribution to habitual activity levels.

Intensive training and sports specialization in young athletes.

Children involved in sports should be encouraged to participate in a variety of different activities and develop a wide range of skills. Young athletes who specialize in just one sport may be denied the benefits of varied activity while facing additional physical, physiologic, and psychologic demands from intense training and competition. This statement reviews the potential risks of high-intensity training and sports specialization in young athletes. Pediatricians who recognize these risks can have a key role in monitoring the health of these young athletes and helping reduce risks associated with high-level sports participation.

Aerobic response to endurance training in prepubescent children : a critical analysis

Children and adolescents possess higher weight-related maximum oxygen consumption (VO2max) levels than older individuals. The capacity of prepubescent children to improve aerobic fitness with endurance training is controversial, and reported data have provided conflicting evidence. In the adult, physical activity of certain form (endurance), duration (15-60 min), frequency (3-5 times per wk), and intensity (heart rate 60-90 percent of maximum) are necessary to improve VO2max with training. When training programs in children are examined, those regimens failing to demonstrate a beneficial effect on aerobic fitness are observed not to comply with adult standards. Conversely, despite important experimental weaknesses, exercise training programs in children which employ adult criteria often show improved VO2max similar to that observed in older subjects. At the present stage of knowledge exercise training programs directed toward improving aerobic power in children should incorporate exercise intensity and duration in accord with adult-related criteria.

Congenital heart disease in infants of diabetic mothers

A review of 470 infants of diabetic mothers followed at the Joslin Clinic, Boston, revealed a 4 per cent incidence of proved congenital heart disease, five times the number expected to appear in the general population. Transposition of the great arteries, ventricular septal defect, and coarctation of the aorta together composed over one half of the 19 cases reported. No relationship between gestational factors and incidence of heart defects was observed. Although no single specific clue exists to identify congenital heart disease in infants of diabetic mothers, the abnormal electrocardiogram, presence of cyanosis without radiographic evidence of pulmonary disease, or significant murmur should bring attention to the likelihood of heart disease.

Does peak VO2 reflect VO2max in children ? : evidence from supramaximal testing

A plateau in oxygen uptake during the terminal phases of a progressive exercise test has been considered a requisite indicator of achievement of a true VO2max. Whether this concept is valid in pediatric subjects is unclear, however, since children do not often demonstrate such a VO2 plateau during exercise testing. In this study, nine children underwent three treadmill tests with successively higher supramaximal workloads after an initial standard progressive test to exhaustion. Three subjects (33%) satisfied the criterion for a VO2 plateau on the initial test. Mean peak oxygen uptake values during the supramaximal tests did not increase significantly above that achieved on the progressive test. These results suggest that peak VO2 on the initial test was indicative of true VO2max despite the absence of a VO2 plateau. The findings further imply that a VO2 plateau should not be used as a requirement for defining a maximal exercise test in children.

Double-chamber right ventricle: experience with 17 cases☆

Abstract Double-chamber right ventricle (DCRV) is a distinct anatomic entity created by a high take-off of the moderator band resulting in obstruction to flow within the sinus portion of the right ventricle. Frequently associated with a VSD, DCRV exhibits no typical clinical findings, and thus cardiac catheterization and angiography are requisite for its identification. Proper presurgical diagnosis and full knowledge of associated cardiac lesions should provide a minimal operative risk and excellent prognosis for patients with DCRV.

Left ventricular size and function in body builders using anabolic steroids.

Although controversial, there is evidence to support a direct effect of improved skeletal muscle strength and mass by anabolic steroids in weight-training athletes. The influence of these drugs on the myocardial hypertrophy demonstrated by these individuals is unknown. Echocardiographic measurements of left ventricular dimensions and function were evaluated in 15 steroid-using body builders and compared to body builders not taking these drugs as well as an inactive control group. Significant increase in left ventricular posterior wall (LVPW) and ventricular septal (VS) thickness as well as an elevated VS/LVPW ratio were noted in both weight-lifting groups compared to controls. There were no differences, however, between the weight lifters with and without anabolic steroid use in any of the measurements. These data indicate no potentiating effects of these drugs on the myocardial hypertrophy observed with weight training.

Maternal Diabetic Control and Hypertrophic Cardiomyopathy in Infants of Diabetic Mothers

Hypertrophic cardiomyopathy has been well documented in infants of diabetic mothers (IDMs). If this asymmetric septal enlargement is an anabolic result of fetal hyperinsulinemia triggered by maternal hyperglycemia during the third trimester, maternal glycosylated hemoglobin (HbA1) levels, an indicator of glycemic control, should then correlate positively at delivery with newborn ventricular septal thickness. In this study of 20 infants of well-controlled diabetic mothers, no relationship was observed between echocardiographic evidence of hypertrophic cardiomyopathy and maternal HbA1 levels. Seven babies (35%) exhibited exaggerated septal thickening, but none had cardiac-specific symptoms. Although 60 percent of the IDMs were large for gestational age and 45 percent demonstrated neonatal hypoglycemia, neither of these complications correlated with maternal HbA 1. In this group of babies of well-controlled diabetic women, echocardiographic indicators of cardiomyopathy were common, but clinical evidence of cardiac embarrassment was not observed. Moreover, these data do not support third trimester maternal hyperglycemia as instrumental in the etiology of cardiomyopathy and other complications of IDMs.

Doppler Echocardiography for the Estimation of Cardiac Output with Exercise

Insights into both normal and pathological cardiac responses to exercise have been hampered by lack of a safe, accurate, feasible means of estimating cardiac output (.Q) during high-intensity and maximal exercise. Doppler ultrasound noninvasively measures blood velocity as it exits the heart and can be performed during exhaustive exercise without interference of the subject or need for steady state. From the product of aortic blood velocity and cross-sectional area of the aorta, stroke volume (SV) can be calculated. Despite these advantages of the Doppler technique, a number of potential sources of error have raised concern regarding the accuracy of this method. These include transducer angulation, change in aortic cross-sectional area during exercise, turbulence and alteration of a flat velocity profile in the aorta with increased.Q, and uncertainties regarding the proper location for measurement of aortic outflow area.The magnitude of the influence of these potentially confounding variables on the accuracy of SV measurements determined by the Doppler technique is unknown. Estimates of both construct and concurrent validity suggest that the overall error may be small. Test-retest studies have indicated a high level of reliability with this technique.