Light Physical Activity Favors Central Hemodynamics In Metabolic Syndrome

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Altered aortic waveforms and insulin resistance are implicated in cardiovascular disease (CVD). While moderate-to-vigorous physical activity (MVPA) improves central hemodynamics (cHD), few data exist examining light physical activity (LPA) across the day in adults with metabolic syndrome (MetS). PURPOSE: Determine if LPA across the day relates to fasted and insulin-stimulated cHD in MetS. METHODS: Adults with MetS (ATP-III) were categorized as spending >50% of their time in morning (MOR, 0600-0900; n = 7 (6F), 53.6 ± 6.3y, 31.9 ± 2.3 kg/m2, APTIII = 3.9 ± 0.9), midday (MID, 1100-1400; n = 8 (6F), 53.6 ± 6.1y, 38.7 ± 5.8 kg/m2 APTIII = 3.5 ± 0.5), or afternoon LPA (AFT, 1500-1900; n = 8 (5F), 53.0 ± 5.1y, 39.9 ± 6.3 kg/m2, APTIII = 3.4 ± 0.7) based on tri-axial accelerometry over 7d. cHD were defined by: augmentation index (AIx75), brachial and central blood pressure, heart rate (HR), pulse pressure (bPP and cPP), mean arterial pressure (MAP), PP amplification (PPA), as well as forward pressure (Pf), backward pressure (Pb), and reflection magnitude (RM) using applanation tonometry at 0 and 120 min during a euglycemic clamp (40 mU/m2/min, 90 mg/dl). Plasma ICAM and VCAM were assessed at 0 min and 120 min. VO2max and MetS severity (z-score) were assessed for CVD risk. RESULTS: Age (P = 0.97) and fitness (P = 0.73) were not different amongst groups, although BMI was lower in MOR vs. AFT (31.9 ± 2.3 vs. 39.6.3 kg/m2, P = 0.02). MOR (24.8 ± 3.3%, P = 0.001) and MID (20.3 ± 7.3%, P = 0.03) performed more LPAmor than AFT (12.1 ± 5.7%). Similarly, MID (23.5 ± 5.6%, P = 0.03) spent more time in LPAmid than AFT (14.7 ± 5.9%). Fasting and 120 min indices of cHD were similar across groups. While time in LPAmor was related to fasting Pb (r = 0.41, P = 0.02), LPAmid associated with fasting RM (r = 0.37, P = 0.04) and PPA (r = -0.39, P = 0.04). Only LPAaft correlated with insulin-stimulated declines in RM (r = -0.38, P = 0.04). Further, MetS severity correlated with higher fasting bPP (r = 0.42, P = 0.02), cPP (r = 0.38, P = 0.04), Pf (r = 0.49, P < 0.01), and blunted insulin-mediated reductions in cDBP (r = 0.39, P = 0.04). Fasted ICAM was negatively related to LPAmid (r = -0.43, P = 0.02) and fasted AIx75 (r = -0.39, P = 0.04). CONCLUSION: Although time of day in which LPA is performed does not distinguish cHD in MetS, more time in LPA favorably relates to aortic waveforms.Funding: NIH RO1-HL130296.