Sex Differences in Autonomic Response to Hand Grip Exercise Among Individuals with Intellectual Disability

Abstract

Individuals with an intellectual disability (ID) are at increased risk for cardiovascular disease (CVD), which may be attributed to autonomic dysfunction. Sex differences in autonomic function are apparent in the general population but have not been investigated in persons with ID, and may help to further explain the high prevalence of CVD. Heart rate variability (HRV) is a non‐invasive measure for autonomic modulation and using a sympatho‐excitatory stimulus such as isometric handgrip (HG) exercise, may reveal altered autonomic function not observed at rest.PURPOSETo assess sex differences in cardiac autonomic function in individuals with and without ID using an isometric handgrip (HG) exercise test.METHODSHRV was assessed in 18 individuals with ID (Male: 9; 28±6yrs, 33±11.1kg/m2) and 23 without ID (Male: 13; 30±9.0yrs, 26±3.8kg/m2) in response to isometric HG exercise at 30% of maximal voluntary contraction. Heart rate was continuously recorded via ECG and the last 2 minutes of quiet rest and HG exercise were analyzed. HRV was analyzed in both the time (root mean square of successive differences (RMSSD) and percentage of RR intervals differing by <50ms (PNN50)) and frequency domains (low and high frequency (LF, HF), and LF/HF ratio). A change score was calculated from HG exercise ‐ baseline.RESULTSThere were no differences between controls and ID. However, males in both groups demonstrated a blunted response to HG exercise in RMSSD, pNN50, and LF (p<0.05) compared to females.CONCLUSIONMales in both groups appear to have a suppressed vagal withdrawal to HG when compared to the females. Future research should investigate autonomic regulation in sex‐specific groups with and without ID in a larger sample size. Control ID ANOVA Male Female Male Female Group Sex Group*Sex Time‐Domain RMSSD (ms2) −8±9 −21±24 −0±14 −12±12 0.05 0.00 0.35 pNN50 (%) −6±8 −13± 17 −4± 13 −9± 12 0.26 0.02 0.25 Frequency‐Domain LF (ms2) −337± 1098 −1401± 1638 125± 1038 −245±361 0.56 0.00 0.29 HF (ms2)¥ −211±254 −350±428 −118±510 −221±277 0.27 0.10 0.27 LF/HF Ratio§ 6± 1 6± 1 6±0 6± 1 0.64 0.65 0.39 Data presented as mean change ± standard deviation. Control= M (n=13), F (n=9); ID= M (n=9), F (n=9) Log‐transformed for the case of non‐normal data This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.