Cardioautonomic responses to acute ingestion of ice water and its correlation to body mass index.

Background A significant relationship has been documented in the literature between the autonomic nervous system imbalance and cardiovascular mortality. In patients with autonomic failure, water ingestion has been shown to increase blood pressure (BP), induce bradycardia, and cause low heart rate variability (HRV). A few studies showed the altered HRV as an acute effect of ice water intake in healthy subjects. None of the studies have shown light on the relationship of BP and HRV to ice water intake in obese and overweight subjects. The present study is aimed to correlate BP and HRV with body mass index (BMI) after ice water ingestion. Methods This cross-sectional study included a total of 60 subjects of both sexes aged between 18 and 24 years old. Subjects were assigned into three groups based on their BMI: normal, overweight, and obese. Before and after ice water ingestion, BP and HRV parameters were recorded and compared between the groups. Statistically data were analyzed by Student's paired t-test and one-way analysis of variance. Results Basal HF was significant (p<0.05) in all three groups after ice water ingestion [F(2, 27), 44.1; p-value, 0.02]. After ice water ingestion, all HRV values were significant (p<0.001) in the three groups. The post-hoc Tukey HSD test demonstrated the less mean score for mean RR interval, standard deviation of all NN interval, standard deviation of differences between adjacent, HF and high for HR, LF, and LHR in overweight and obese subjects. Conclusions Because of the effective buffering system, healthy subjects showed increased HR and unchanged BP. Overweight and obese subjects showed decreased HR and increased BP.