Associations of maximum oxygen uptake and body composition with arterial stiffness and blood lipids : a cross-sectional study among physically active females in two different training periods

In general, physical activity and especially endurance sports are known to reduce the risk of cardiovascular diseases and all-cause mortality. It is also established that increased arterial stiffness and un-optimal levels of blood lipids increase the risk of cardiovascular diseases. Previous studies have shown that endurance training decreases arterial stiffness, particularly in people who have greater arterial stiffness at baseline. In addition, endurance training can lead to increased HDL-cholesterol and decreased LDL-cholesterol and triglyceride levels. The main purpose of this thesis was to determine if the arterial stiffness, blood lipid levels, maximum oxygen uptake or body composition of adult elite Finnish female endurance athletes vary between the training periods of preparation period and competition period. The aim was also to determine if better physical performance and body composition have any associations to arterial stiffness or blood lipid levels. Developmental females and female rugby players were used as controls. Data of this study was based on an on-going three-year follow-up study NoREDS conducted at the University of Jyväskylä. The results of this study showed that there were no significant differences between two timepoints but there were significant differences between endurance athletes and other groups in maximum oxygen uptake, body composition and blood lipids. Group differences in arterial stiffness and associations with maximum oxygen uptake or body composition with arterial stiffness were not found. Maximum oxygen uptake and body composition had associations with blood lipids. Maximum oxygen uptake had a positive relation to TC (r = 0.33, p = 0.035) and to HDL (r = 0.326, p = 0.037) in the preparation period. There was a negative relation in total body weight to non-HDL in preparation period (r = -0.35, p = 0.025) and in competition period (r = -0.34, p = 0.028); BMI to TC (r = -0.32, p = 0.040) and HDL (r = -0.33, p = 0.034) in preparation period and to TC (r = -0.33, p = 0.038) in competition period; TLM to non-HDL in preparation period (r = -0.38, p= 0.014) and in competition period (r = -0.52, p = <0.001), to LDL in preparation period (r = -0.40, p = 0.009) and to TC (r = -0.46 , p = 0.003), TG (r = -0.39, p = 0.013) and LDL (r = -0.52, p = <0.001) in competition period. The findings in this study suggests that body composition might have a bigger role than physical performance in maintaining favourable blood lipid profile in preventing cardiovascular health but the periodization of training in endurance sports does not seem to effect these levels significantly. Association of body composition might be stronger with blood lipids than physical performance’s, but the impact of nutritional and dietical changes towards competition period must be noted. For general population it could be more important to have enough muscle mass despite the absolute amount of fat mass. Because of the higher risk of amenorrhea and RED-S among endurance athletes leading to hormonal and endothelial changes, future studies should be more comprehensive and include the assessment of athletes’ nutritional and hormonal status, psychological stress and the amount of training to be able to evaluate their potential risks for athletes’ cardiovascular health.