Cardiovascular Responses to Squatting Postural Stress among Non-Diabetic and Type-2 Diabetic Nigerian Black Africans.

Abstract

Background: A change in posture brings about a significant alteration in cardiovascular functions. The squat test has been used to study autonomic function in White Europeans but not Black Africans.  The aim of this study is to determine the cardiovascular effects of postural stress in Black African non-diabetics and Type-2 diabetics.

Method: Blood pressure (BP) and heart rate (HR) was measured in 40 non-diabetics and 40 Type-2 diabetics in sitting,  standing from sitting, squatting  and   standing from squatting positions Difference  in BP and HR between consecutive  positions was  tested using 2- way mixed ANOVA.  Proportions of those who showed orthostatic hypotension and hypertension were compared with Fishers exact test.  Significance was set at p < 0.05.

Result: BP and HR changes evoked by standing from sitting were not different, however  squatting evoked greater increase in BP in diabetics  (change (∆) SBP: 5.85 ± 9.95 vs 17.40 ± 13.75 mmHg: ∆ DBP: 0.15 ± 6.89 vs  5.10 ± 7.59 mmHg: ∆ MABP: 2.02 ± 6.98 vs  8.63 ± 9.34 mmHg, p < 0.05 )  and  standing from squatting  evoked  greater fall  BP in diabetics  (∆ SBP: -9.80 ± 13.89 vs  -24.35 ± 16.03 mmHg;  ∆ MABP: -2.02 ± 6.98 vs  -8.63 ± 9.34 mmHg: ∆ PP: -2.28 ±15.35  vs  -14.50 ±11.96 mmHg, p < 0.05) while ∆ HR did not differ.  A higher proportion of diabetics showed SBP and DBP orthostatic hypertension.

Conclusion. Relative to the non-diabetics, diabetics showed greater BP but not HR responses to postural stress.