This study aims to analyze the relationship between subjects’ health, physical characteristics related to fitness, and VO2max measured by direct methods. The goal is to provide foundational data for developing safe, individualized, and systematic exercise prescription programs for health promotion and disease prevention. The study involved 30 men and 11 women in their 20s. All participants underwent measurements of body composition, anthropometry, muscle strength and endurance of the upper and lower extremities, and graded exercise tests (GXT) to determine VO2max, exercise load, heart rate, and blood pressure. Correlation analysis and multiple regression analysis were performed on all measured data to determine the relationship between VO2max and physical characteristics. Body Fat Percentage (%BF) showed the strongest negative correlation with VO2max, with a correlation coefficient of -0.817. The results of multiple regression analysis indicated that %BF had a significant relationship with VO2max, and the p-value was 0.000, which is statistically significant. Hip circumference exhibited a negative correlation with VO2max, with a correlation coefficient of -0.314. However, in the multiple regression analysis involving body measurements and VO2max, no statistically significant results were observed for any of the parameters. Upper body strength showed the strongest positive correlation with VO2max, with a correlation coefficient of 0.578. Nonetheless, the multiple regression analysis of physical function and VO2max did not yield statistically significant results. Maximum systolic blood pressure (SBPmax) during exercise demonstrated a strong positive correlation with VO2max, with a correlation coefficient of 0.787. The results of the multiple regression analysis indicated that SBPmax had a significant relationship with VO2max, with a p-value of0.000, which is statistically significant. This study emphasizes the importance of body fat percentage in relation to VO2max levels, which are known to be closely related to overall human health. Therefore, in terms of exercise prescription and programming, it is desirable to not only consider the relationship between cardiovascular fitness factors, such as VO2max, and body composition, which have traditionally been proven to be related, but also to take into account overall fitness factors, including improvements in strength and muscular endurance, which might otherwise be overlooked as important health-related fitness factors.