It is true that sometimes people who do not do a lot of physical activity score better on fitness tests than others who are more active. That is more likely to be true when you are young than when you get older. The reasons some less active people can do well on fitness tests include heredity, maturation (age), and sex. Some people inherit physical characteristics from their parents that help them to do well on fitness tests. For example, there are various types of muscle fibers, and you may score well if you inherit the types of fibers that help you perform certain tests. The types of bones, joints, and body organs (such as the heart and lungs) that you inherit can affect your performance on fitness tests.
Also, some teens mature earlier than others. This means that they grow faster and their bodies produce hormones earlier than other teens do. People who mature early tend to do better on fitness tests than those who mature later. Teens in the same class who are older than others typically do better on fitness tests. As described in the book, males often do better than females in fitness activities that require muscle size.
As teens grow older, maturation and age become less of a factor because at some point all teens mature and get the fitness benefits of maturation. Also, heredity becomes less of a factor as you age. Among adults, healthy lifestyles are the main reason for good (or not so good) performance on fitness tests. For the reasons described here, we encourage you to focus on avoiding comparisons to others. Trying to reach the healthy fitness zone on all fitness tests is most important. We believe that self-comparisons over time are much more important than comparisons to other people.