This systematic review examines the long-term (over 5 years) relationship between physical activity and the development of non-communicable diseases (NCDs), including weight gain, obesity, coronary heart disease (CHD), type 2 diabetes mellitus, Alzheimer's disease, and dementia. The review includes 15 longitudinal studies with a total of 288,724 participants, aged 18 to 85 years. The results indicate that physical activity has a positive long-term influence on all selected diseases. However, the review also highlights a lack of long-term studies on the relationship between physical activity and NCD incidence, particularly in diverse populations. The review suggests that more long-term studies are needed to fully understand the impact of physical activity on NCDs and to develop effective prevention programs.This systematic review examines the long-term (over 5 years) relationship between physical activity and the development of non-communicable diseases (NCDs), including weight gain, obesity, coronary heart disease (CHD), type 2 diabetes mellitus, Alzheimer's disease, and dementia. The review includes 15 longitudinal studies with a total of 288,724 participants, aged 18 to 85 years. The results indicate that physical activity has a positive long-term influence on all selected diseases. However, the review also highlights a lack of long-term studies on the relationship between physical activity and NCD incidence, particularly in diverse populations. The review suggests that more long-term studies are needed to fully understand the impact of physical activity on NCDs and to develop effective prevention programs.