Heart Rate Variability as a Predictor of +Gz Tolerance During the High-G Selective Test.

INTRODUCTION: Preselection of pilot candidates in the military is critical and determines the quality of subsequent selection. The Aero Medical Institute in Belgrade uses the following centrifuge endpoints: peripheral vision loss, heart rate above 180 bpm, cardiac arrhythmias, and G-induced loss of consciousness to assess relaxed +Gz tolerance. The aim of this study was to evaluate heart rate variability (HRV) associated with cardiovascular adaptability to different types of stress as a predictor of +Gz tolerance.METHODS: Thirty-six candidates were exposed to centrifuge runs, consisting of the following +Gz-acceleration phases: a 2-G plateau followed by an increase to 5.5 G, a decrease to 2 G, and ending with a plateau. Time-domain HRV indices were calculated for candidates, for a 60-s 2-G plateau, and for the entire test. The correlation was made between the groups that did (Group 1) and did not meet the criteria (Group 2).RESULTS: The results show significantly lower values in all time domain HRV indices, namely standard deviation of the normal-to-normal interval (SDNN) and root mean square of successive differences, in Group 2. Mean SDNN values were 45.98 ± 24.80 ms (2-G plateau) and 109.99 ± 39.64 ms (entire test) in Group 1, while the SDNN were 22.99 ± 12.04 ms and 69.70 ± 33.45 ms in Group 2. Root mean square of successive differences was higher in Group 1 for the 2-G plateau and for the entire test.DISCUSSION: The results suggest that HRV is positively correlated with +Gz-tolerance and can be used as an additional selection tool for military aircrew.Bacevic N, Ninkovic M, Drvendzija M, Vidakovic J, Bacevic M, Stepanic P. Heart rate variability as a predictor of +Gz tolerance during the high-G selective test. Aerosp Med Hum Perform. 2024; 95(2):93-100.

Predictors of subclinical cardiovascular disease in women with polycystic ovary syndrome: interrelationship of dyslipidemia and arterial blood pressure.

Background. Women with polycystic ovary syndrome (PCOS) could develop subclinical atherosclerosis during life. Purpose. To analyze cardiovascular risk (CVR) factors and their relation to clinical markers of cardiovascular disease (CVD) in respect to their age. Material and Methods. One hundred women with PCOS (26.32 ± 5.26 years, BMI: 24.98 ± 6.38 kg/m(2)) were compared to 50 respective controls. In all subjects, total cholesterol (TC), HDL-C, LDL-C, triglycerides, TC/HDL-C and TG/HDL-C ratios, glucose, insulin and HOMA index, waist-to-hip ratio (WHR), systolic and diastolic blood pressure (SBP and DBP, resp.), and carotid intima-media thickness (CIMT) were analyzed in respect to their age and level of androgens. Results. PCOS over 30 years had higher WHR (P = 0.008), SBP (P < 0.001), DBP (P < 0.001), TC (P = 0.028), HDL-C (P = 0.028), LDL-C (P = 0.045), triglycerides (P < 0.001), TC/HDL-C (P < 0.001), and triglycerides/HDL-C (P < 0.001) and had more prevalent hypertension and pronounced CIMT on common carotid arteries even after adjustment for BMI (P = 0.005 and 0.036, resp.). TC/HDL-C and TG/HDL-C were higher in PCOS with the highest quintile of FAI in comparison to those with lower FAI (P = 0.045 and 0.034, resp.). Conclusions. PCOS women older than 30 years irrespective of BMI have the potential for early atherosclerosis mirrored through the elevated lipids/lipid ratios and through changes in blood pressure.