Sex differences in central adiposity, hemodynamic, and respiratory parameters among healthy young Nigerian adults: a cross-sectional study

Background Body mass index does not capture regional fat distribution, which is now recognised as a stronger determinant of cardiometabolic and pulmonary function than total adiposity. Whether these associations are already detectable in apparently healthy young adults, and whether they extend to respiratory endurance, remains poorly characterised in sub-Saharan African populations. Methods In a cross-sectional study of 81 apparently healthy undergraduates (45 male, 36 females; aged 18–30 years) at the Federal University of Technology, Owerri, Nigeria, we measured waist circumference, waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and conicity index (ConI) alongside systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), resting heart rate (HR), and breath-holding time (BHT). Between-sex comparisons used independent-samples t-tests, corroborated by Mann-Whitney U tests after Shapiro-Wilk and Levene’s testing indicated departures from normality for several variables. Associations were examined using Spearman’s rank correlation, with sex-stratified analysis, exact coefficients and 95% confidence intervals (bootstrap, 10,000 resamples), and a significance threshold of p < 0.05. Multiplicity was controlled with the Benjamini-Hochberg false discovery rate (FDR, q < 0.05) applied consistently across both the nine between-sex comparisons and the correlation family; key associations were additionally tested by partial correlation adjusting for age and body mass index (BMI). Results Waist circumference did not differ by sex (80.54 ± 8.04 cm vs 79.00 ± 8.41 cm, p = 0.403), but WHR was significantly higher in males (0.85 ± 0.04 vs 0.80 ± 0.05, p < 0.001, surviving correction), indicating a more android fat distribution despite equivalent waist girth. Males had nominally higher SBP (122.04 ± 7.82 vs 118.25 ± 7.13 mmHg, p = 0.027) and longer BHT (43.02 ± 13.15 vs 36.94 ± 13.91 s, p = 0.047), neither surviving FDR correction (q = 0.076 and q = 0.092, respectively), whereas males had significantly lower resting HR than females at both thresholds (70.96 ± 10.68 vs 78.56 ± 11.40 bpm, p = 0.003, q = 0.014). Mann-Whitney U tests confirmed all between-sex conclusions except for WHtR, which reached nominal significance non-parametrically (U test p = 0.038) but not by t-test (p = 0.057); neither survived FDR correction. HR correlated positively with SBP in males (ρ = 0.325, nominal p = 0.030) but not females, and did not survive correction (q = 0.201). WHR correlated modestly and positively with BHT in males (ρ = 0.294, nominal p = 0.050), which likewise did not survive correction (q = 0.201) and weakened further after adjustment for age and BMI (partial ρ = 0.279, p = 0.063); no adiposity index correlated with BHT in females. Conclusion Even where absolute waist circumference is equivalent between sexes, WHR was robustly higher in males, consistent with a more android pattern of fat distribution. Sex differences in SBP and BHT, and a correlation between WHR and BHT in males, were observed at nominal significance but did not survive correction for multiple comparisons or adjustment for age and BMI; these findings are hypothesis-generating and require confirmation in an adequately powered study with objective pulmonary function testing before any claim of a sex-specific adiposity–respiratory relationship can be made. WHR may add information beyond BMI and waist circumference alone for early cardiometabolic screening, but this cross-sectional, single-centre dataset cannot establish the direction or mechanism of any association.