Key result
Acute elevations in plasma glucose and insulin impaired spontaneous cardiac BRS (P<0.05), and this reduction was unaffected by reduced insulin sensitivity via short-term physical inactivity.
Why the study?
Does short-term reduction in physical activity reduce cardiac baroreflex sensitivity at rest and following an oral glucose tolerance test in young, healthy men?
Does short-term reduction in physical activity reduce cardiac baroreflex sensitivity at rest and following an oral glucose tolerance test in young, healthy men?
Acute elevations in plasma glucose and insulin impair spontaneous cardiac baroreflex sensitivity in young healthy men, but this reduction is unaffected by short-term reductions in physical activity.
Acute glucose/insulin elevations may impair cardiac BRS independent of short-term inactivity; hypothesis-generating and requires confirmation before clinical consideration.
Reduced insulin sensitivity and impaired glycemic control are among the consequences of physical inactivity and have been associated with reduced cardiac baroreflex sensitivity (BRS). However, the effect of reduced insulin sensitivity and acute hyperglycemia following glucose consumption on cardiac BRS in young, healthy subjects has not been well characterized. We hypothesized that a reduction in insulin sensitivity via reductions in physical activity would reduce cardiac BRS at rest and following an oral glucose tolerance test (OGTT). Nine recreationally active men (23 ± 1 yr; >10,000 steps/day) underwent 5 days of reduced daily physical activity (RA5) by refraining from planned exercise and reducing daily steps (<5,000 steps/day). Spontaneous cardiac BRS (sequence technique) was compared at rest and for 120 min following an OGTT at baseline and after RA5. A substudy (n = 8) was also performed to independently investigate the influence of elevated insulin alone on cardiac BRS using a 120-min hyperinsulinemic-euglycemic clamp. Insulin sensitivity (Matsuda index) was significantly reduced following RA5 (BL 9.2 ± 1.3 vs. RA5 6.4 ± 1.1, P < 0.001). Resting cardiac BRS was unaffected by RA5 and significantly reduced during the OGTT similarly at baseline and RA5 (baseline 0 min, 28 ± 4 vs. 120 min, 18 ± 4; RA5 0 min, 28 ± 4 vs. 120 min, 21 ± 3 ms/mmHg). Spontaneous cardiac BRS was also reduced during the hyperinsulinemic-euglycemic clamp (P < 0.05). Collectively, these data demonstrate that acute elevations in plasma glucose and insulin can impair spontaneous cardiac BRS in young, healthy subjects, and that reductions in cardiac BRS following acute hyperglycemia are unaffected by reduced insulin sensitivity via short-term reductions in physical activity.
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Holwerda et al. (2015) studied Healthy (n=9). Reduced daily physical activity vs. Baseline (>10,000 steps/day) was evaluated on Spontaneous cardiac baroreflex sensitivity at rest and following an oral glucose tolerance test. Acute elevations in plasma glucose and insulin impaired spontaneous cardiac BRS (P<0.05), and this reduction was unaffected by reduced insulin sensitivity via short-term physical inactivity.
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