Obesity in youth has increased during the last 10 years in Western countries. Several studies have investigated physical activity and its effects on obesity and health, showing that regular physical activity combined with improved physical fitness reduces the risk of obesity and several metabolic problems (e.g. diabetes mellitus, metabolic syndrome, heart disease) and also improves overall health. However, there is only limited scientific information available concerning the changes in the physical fitness profiles of youth. It is obvious that only slight changes observed in endurance-type physical activity can also be observed in aerobic capacity. Today and in the future, a major public health concern for teenage and young adults is the combination of increasing body fatness together with decreasing physical fitness. In order to evaluate overall fitness level, it is particularly essential to examine both aerobic and neuromuscular fitness. Therefore, in clinical practice work and health behaviour education, a person's physical fitness should be measured more frequently with various measures. Furthermore, population-based surveys should be combined with regular measurement of physical fitness to study sedentary lifestyles, particularly in young people. This article presents a review of current physical fitness profiles of male children, adolescents and young adults, which hopefully initiates further studies in this relevant scientific field. In addition, the importance of physical fitness level is evaluated in relation to obesity and health. Collectively, studies examining physical fitness profiles of young men suggest a disturbing worldwide trend of decreased aerobic fitness and increased obesity. Continued efforts to foster improved physical fitness and healthy lifestyles should be encouraged to combat these trends. Such efforts should include frequent and objective assessment of physical fitness rather than solely relying on subjective assessment of physical activity.