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Since the 1968 Mexico City Olympics, Kenyan and Ethiopian runners have dominated the middle- and longdistance events in athletics and have exhibited comparable dominance in international cross-country and roadracing competition. Several factors have been proposed to explain the extraordinary success of the Kenyan and Ethiopian distance runners, including (1) genetic predisposition, (2) development of a high maximal oxygen uptake as a result of extensive walking and running at an early age, (3) relatively high hemoglobin and hematocrit, (4) development of good metabolic “economy/efficiency” based on somatotype and lower limb characteristics, (5) favorable skeletal-muscle-fiber composition and oxidative enzyme profile, (6) traditional Kenyan/Ethiopian diet, (7) living and training at altitude, and (8) motivation to achieve economic success. Some of these factors have been examined objectively in the laboratory and field, whereas others have been evaluated from an observational perspective. The purpose of this article is to present the current data relative to factors that potentially contribute to the unprecedented success of Kenyan and Ethiopian distance runners, including recent studies that examined potential links between Kenyan and Ethiopian genotype characteristics and elite running performance. In general, it appears that Kenyan and Ethiopian distance-running success is not based on a unique genetic or physiological characteristic. Rather, it appears to be the result of favorable somatotypical characteristics lending to exceptional biomechanical and metabolic economy/efficiency; chronic exposure to altitude in combination with moderate-volume, high-intensity training (live high + train high), and a strong psychological motivation to succeed athletically for the purpose of economic and social advancement.

This study examined the beliefs and sources of information regarding muscle development among 742 high school athletes in one rural county. About 40% of the athletes stated that muscle development was very important and 50% said it was somewhat important. Most of them recognized the dangers of steroids but still thought these were important in muscle development. A majority also thought nutritional and genetic factors were important. Physicians were seen as providing the most accurate information about muscle development, followed by coaches and trainers. Understanding the athletes’ beliefs and information sources about muscle development may be useful in dispelling misconceptions and providing education on the topic.

The maximal amount of bone mass gained during growth (peak bone mass) is an important determinant of bone mass in later life and thereby an important determinant of fraeiure risk. Although genetic factors appear lo be primary determinants of peak bone mass, environmental factors such as physical activity and nutrition also contribute. In this article, bone growth and maintenance are reviewed, and mechanisms are described whereby physical activity can affect bone mass. Studies addressing the effects of physical activity on bone status in youth are reviewed: Although conclusive data are not yet available, considerable evidence supports the importance of activity, especially activity initiated before puberty. The critical role of energy in bone growth is outlined, and studies assessing the impact of calcium intake during childhood and adolescence are reviewed. Although results of intervention trials are equivocal, other evidence supports a role for calcium intake during growth. Recommendations for physical activity and nutrition, directed lochildren and adolescents, are presented.

Aging is characterized by numerous physical, physiological, biochemical, and molecular changes. The rates at which aging processes occur are highly variable among individuals and are thought to be governed by both environmental and genetic factors. Lifestyle factors such as exercise, dietary, and smoking habits have been demonstrated to alter many of the changes usually associated with human aging. However, at present caloric restriction is the only experimental paradigm that has consistently been demonstrated in animal models to extend not only physiological vigor but also life span. The positive effects of exercise on physiological fitness and the reduction in the risks of certain diseases have been well documented. However, its effects on life span are not as clear. This article explores some of the basic mechanisms thought to be involved causally in the processes of aging, and outlines current and potential interventive strategies to retard or ameliorate the rates of decline in physiological function with advancing age.

Recent research has analyzed the genetic factors that influence world-class athletic status. Much of what we know comes from association studies, with the ACE I/D and ACTN3 R577X polymorphisms having been extensively studied. The association between the ACTN3 R577X variation and elite athlete status in power sports is strongly documented, yet whether the current body of knowledge on other variants can be extrapolated to athletic champion status remains to be determined. Athletic champion status is a complex polygenic trait in which numerous candidate genes, complex gene–gene interactions, and environment–gene interactions are involved. Besides the need for more studies and new approaches taking into account the complexity of the problem, we believe that factors beyond genetic endowment are likely to have a stronger influence in the attainment of athletic champion status.

In patients with cystic fibrosis (CF), physical capacity (PC) has been correlated with mortality risk. In turn, PC is dependent on genetic factors. This study examines several polymorphisms associated with PC and healthrelated phenotype traits (VO_2peak, FEV₁, FVC, PI_max and muscular strength) in a group of children with CF (n = 66, primary purpose). The same analyses were also performed in a control group of healthy children (n = 113, secondary purpose). The polymorphisms determined were classified as muscle function polymorphisms (ACE rs1799752; AGT rs699; ACTN3 rs1815739; PTK2 rs7843014 and rs7460; MSTN rs1805086; TRHR rs7832552; NOS3 rs2070744) or energy metabolism polymorphisms (PPARGC1A rs8192678; NRF1 rs6949152; NRF2 rs12594956; TFAM rs1937; PPARD rs2267668; ACSL1 rs6552828). No significant polymorphism/phenotype correlations were detected in children with CF, with marginal associations being observed between NOS3 rs2070744 and VO_2peak and FEV₁, as well as between PPARGC1A rs8192678 and FEV₁. Overall, similar findings were observed in the control group, i.e., no major associations. The PC-related polymorphisms examined seem to have no effects on the PC or health of children with CF.

This review summarizes the research relating anaerobic function to growth among children and adolescents. Pediatric practitioners and scientists are always struck by the impressive accumulation of results relating to the cardiopulmonary system. However, anaerobic fitness has received much less research attention. This is surprising, considering that high-intensity exercises lasting only a few seconds is a more “natural” pattern during growth than prolonged low-intensity exercises. In anaerobic tasks or sport events such as sprint running, sprint swimming, sprint cycling, jumping, or throwing, the child’s performance is distinctly lower than that of the adult. This partly reflects the child’s lesser ability to generate mechanical energy from chemical energy sources during short-term intensive work or exercise. Because both intramuscular high energy phosphate kinetics and muscle cross-section vary during growth and maturation, this review examines some developmental aspects of energetic- and mechanical factors involved in anaerobic performance. Anaerobic muscle function and performance are quantitative traits influenced by several determinants such as genetic factors, age and gender, muscle fiber characteristics, hormonal and training factors. Because of ethical and methodological constraints when investigating healthy children, this review also includes fundamental work done on some animal models.