Abstract
PurposeTo investigate the effects of an oral glucose tolerance test (OGTT) on baroreflex sensitivity (BRS) in a sample of healthy adolescents, and how acute exercise bouts of different intensities alter the effects of the OGTT on BRS.MethodsThirteen male adolescents (14.0 ± 0.5 years) completed three conditions on separate days in a counterbalanced order: (1) high-intensity interval exercise (HIIE); (2) moderate-intensity interval exercise (MIIE); and (3) resting control (CON). At ~ 90 min following the conditions, participants performed an OGTT. Supine heart rate and blood pressure were monitored continuously at baseline, 60 min following the conditions, and 60 min following the OGTT. A cross-spectral method (LFgain) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain divided by AC (LFgain/AC) was used as the autonomic component.ResultsAlthough non-significant, LFgain moderately decreased post-OGTT when no exercise was performed (pre-OGTT = 24.4 ± 8.2 ms mmHg− 1; post-OGTT = 19.9 ± 5.6 ms mmHg− 1; ES = 0.64, P > 0.05). This was attributed to the decrease in LFgain/AC (pre-OGTT = 1.19 ± 0.5 ms µm− 1; post-OGTT = 0.92 ± 0.24 ms µm− 1; ES = 0.69, P > 0.05). Compared to CON (Δ = − 4.4 ± 8.7 ms mmHg− 1), there were no differences for the pre–post-OGTT delta changes in LF/gain for HIIE (Δ = − 3.5 ± 8.2 ms mmHg− 1) and MIIE (Δ = 1.3 ± 9.9 ms mmHg− 1) had no effects on BRS following the OGTT (all ES < 0.5). Similarly, compared to CON (Δ = − 0.23 ± 0.40 ms µm− 1) there were no differences for the pre–post-OGTT delta changes in LF/gain for HIIE (Δ = − 0.22 ± 0.49 ms µm− 1) and MIIE (Δ = 0.13 ± 0.36 ms µm− 1).ConclusionA moderate non-significant decrease in BRS was observed in adolescents following a glucose challenge with no apparent effects of exercise.
Highlights
Atherosclerosis has its origins during childhood with elevated blood pressure contributing to plaque formation independently of other cardiovascular disease risk factors in youth (Franks et al 2010; McGill et al 2001)
The aims of the present study were to investigate in healthy adolescents: (1) the effect of an oral glucose tolerance test (OGTT) on baroreflex sensitivity (BRS) and its vascular and autonomic components; and (2) whether an acute bout of moderate- and high-intensity exercise alters the effects of an OGTT on BRS and its associated mechanisms
One participant was excluded from the BRS assessment due to errors in the electrocardiographic signal, and two from the common carotid artery (CCA) analysis due to technical issues with the ultrasound
Summary
Atherosclerosis has its origins during childhood with elevated blood pressure contributing to plaque formation independently of other cardiovascular disease risk factors in youth (Franks et al 2010; McGill et al 2001). European Journal of Applied Physiology (2019) 119:867–878 in normotensive children of hypertensive parents (Boutcher et al 2011), and impaired BRS is associated with high blood pressure in normotensive adolescents (Fitzgibbon et al 2012; Honzikova and Zavodna 2016). These studies indicate BRS dysfunction may be associated with cardiovascular disease burden in youth and is worthy of further research so as to inform preventative health strategies. Baroreflex sensitivity is composed of autonomic and vascular components which contribute towards the beat-to-beat detection and adjustment of blood pressure fluctuations (Hunt et al 2001). Using ultrasound (Taylor et al 2014; Tzeng 2012), the contribution of the autonomic and vascular determinants of BRS can be non-invasively estimated in a reliable manner (Oliveira et al 2018b), and are ideally suited for studying BRS in paediatric groups
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