Near-infrared reactance spectroscopy-derived visceral adipose tissue for the assessment of metabolic syndrome in a multi-ethnic sample of young adults.

OBJECTIVES: Visceral adipose tissue (VAT) is highly associated with metabolic syndrome (MetS), which is rapidly increasing in young adults. However, accessible VAT measurement methods are limited, restricting the use of VAT in early detection. This cross-sectional study sought to determine if near-infrared reactance spectroscopy (NIRS)-derived VAT (VATNIRS) was associated with MetS in a multi-ethnic sample of young adults. METHODS: A total of 107 male and female (F:62, M:45) participants (age: 23.0 ± 4.3y; BMI: 27.1 ± 6.6 kg/m2) completed measurements of fasting blood pressure, blood glucose (FBG), blood lipids, and anthropometric assessments including waist circumference and VATNIRS. MetS severity (MetSindex) was calculated from the aforementioned risk factors using sex and race-specific equations. RESULTS: VATNIRS was higher in participants with, and at risk for, MetS compared to those with lower risks (all p < .001). VATNIRS was positively associated with MetSindex for all groups (all p < .001). VATNIRS showed positive associations with systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP), LDL-C and LDL-C-related biomarkers, and FBG; and negative associations with HDL-C and HDL-C-to-total cholesterol ratio (all p < .050). Associations between VATNIRS and blood pressure for females, and LDL-C and LDL-C-related biomarkers for males, were nonsignificant (all p > .050). VATNIRS was positively associated with DBP in African-American participants, and SBP in White participants, resulting in positive associations with MAP for both groups (all p < .050). CONCLUSIONS: VATNIRS is associated with MetS and individual MetS risks factors in a multi-ethnic sample of young adults; providing a noninvasive, cost-effective, portable, and accessible method that may assist in the early detection of MetS and other cardiometabolic abnormalities.

Hemodynamic responses to the cold pressor test in individuals with metabolic syndrome: a case-control study in a multiracial sample of adults.

Previous research shows that exercise pressor and metaboreflex responses are significantly exaggerated in individuals with metabolic syndrome, but it is unclear if these exaggerated responses extend to the cold pressor test (CPT). This study tested the hypothesis that, contrary to previously reported exaggerated responses during exercise, CPT responses would not be significantly exaggerated in individuals with MetS compared to matched controls. Eleven individuals with MetS and eleven control participants matched by age, race, sex, and ethnicity completed a cardiometabolic prescreening and a CPT. Each CPT required participants to immerse their hand in ice water for two minutes while beat-by-beat blood pressure, heart rate (HR), and leg blood flow (LBF) were continuously measured. Leg vascular conductance (LVC) was calculated as LBF divided by mean arterial pressure (MAP). The precent changes in MAP, systolic blood pressure (SBP), diastolic blood pressure (DBP), HR, LBF, and LVC were compared across time (BL vs. Minutes 1 and 2 of CPT) and between groups (MetS vs. Control) using repeated measures analyses of variance. As expected, MAP (f = 32.11, p < 0.001), SBP (f = 23.18, p < 0.001), DBP (f = 40.39, p < 0.001), and HR (f = 31.81, p < 0.001) increased during the CPT, and LBF (f = 4.75, p = 0.014) and LVC (f = 13.88, p < 0.001) decreased. However, no significant main effects of group or group by time interactions were observed (f ≤ 0.391, p ≥ 0.539). These findings indicate that the hemodynamic responses to the CPT are not significantly exaggerated in MetS, and therefore, previous reports of exaggerated exercise pressor and metaboreflex responses in MetS cannot be attributed to generalized sympathetic overexcitability.

Fat-free mass is associated with exercise pressor responses, but not cold pressor responses, in humans: influence of maximal voluntary contraction.

Objective: This study examined the contributions of fat mass (FM) and fat-free mass (FFM) to the magnitude of exercise pressor responses in humans. Methods: The cumulative blood pressure responses (blood pressure index; BPI) to handgrip exercise (BPIhg), post-exercise-circulatory-occlusion (BPIpeco), and cold-pressor activation (BPIcpt) were collected from 67 individuals grouped by BMI (27.8 ± 7.3 kg/m2), FFM index (FFMi, 29.1 ± 3.8 kg/m2), and FM index (FMi 12.5 ± 4.8 kg/m2) quartiles. BPI responses to HG were also normalized to the time-tension index of HG, providing a relative index of exercise pressor response magnitude (BPInorm). Results: BPIhg and BPIpeco were significantly elevated in the third FFMi quartile (p ≤ 0.034), while BPInorm significantly decreased in the second and fourth quartiles (p ≤ 0.029). In contrast, no differences in BPIcpt were observed across any FFMi, BMI, or FMi quartiles (p ≥ 0.268). FFM was independently associated with BPIhg, BPI-peco, and BPInorm (all p ≤ 0.049), however, FFM was eliminated as an independent predictor when maximal voluntary contraction (MVC) was included in these regression models (all p ≥ 0.495). Neither FFM nor MVC was associated with BPIcpt (p ≥ 0.229). Conclusions: These findings indicate that exercise pressor responses, but not cold-pressor responses, are significantly associated with FFM in humans, and that this association is driven by FFM related differences in MVC.

Exercise pressor responses are exaggerated relative to force production during, but not following, thirty-minutes of rhythmic handgrip exercise.

PURPOSE: This study tested the hypothesis that blood pressure responses would increase relative to force production in response to prolonged bouts of muscular work. METHODS: Fifteen individuals performed two minutes of static handgrip (SHG; 35% MVC), followed by three minutes of post-exercise-cuff-occlusion (PECO), before and after thirty minutes of rest (control), or rhythmic handgrip exercise (RHG) of the contralateral and ipsilateral forearms. Beat-by-beat recordings of mean arterial pressure (MAP), heart rate (HR), and handgrip force (kg) were averaged across one-minute periods at baseline, and minutes 5, 10, 15, 20, 25, and 30 of RHG. MAP was also normalized to handgrip force, providing a relative measure of exercise pressor responses (mmHg/kg). Hemodynamic responses to SHG and PECO were also compared before and after contralateral RHG, ipsilateral RHG, and control, respectively. Similar to the RHG trial, areas under the curve were calculated for MAP (blood pressure index; BPI) and normalized to the time tension index (BPInorm). RESULTS: HR and MAP significantly increased during RHG (15.3 ± 1.4% and 20.4 ± 3.2%, respectively, both p < 0.01), while force output decreased by up to 36.6 ± 8.0% (p < 0.01). This resulted in a 51.6 ± 9.4% increase in BPInorm during 30 min of RHG (p < 0.01). In contrast, blood pressure responses to SHG and PECO were unchanged following RHG (all p ≥ 0.07), and only the mean HR (4.2 ± 1.5%, p = 0.01) and ΔHR (67.2 ± 18.1%, p < 0.01) response to SHG were exaggerated following ipsilateral RHG. CONCLUSIONS: The magnitude of exercise pressor responses relative to force production progressively increases during, but not following, prolonged bouts of muscular work.

Associations between eating behaviors and metabolic syndrome severity in young adults.

Metabolic syndrome (MetS), a precursor to cardiovascular disease and type II diabetes, is rapidly increasing in young adults. Accordingly, earlier interventions aimed at combating the onset of MetS in young adults are required. However, current behavioral interventions have failed to consider the eating behaviors that precede disease development, likely contributing to the consistently high failure rates of these interventions. The purpose of this cross-sectional study was to evaluate the associations between eating behaviors and MetS severity (MetSindex) in a sample of young adults. A sample of 104 (non-Hispanic White: 45; non-Hispanic Black: 49; Hispanic White: 5; Asian: 5) young adult (age: 23.1 ± 4.4) males and females (F:61, M:43) completed anthropometric, blood pressure, blood glucose, and blood lipid assessments; each of which were used to calculate a continuous MetSindex score. Participants also completed the revised version of the 18-item Three-factor Eating Questionnaire to measure emotional eating (EmE), uncontrolled eating (UE), and cognitive restraint (CR). EmE was positively associated with MetSindex for young adult females (p = 0.033) and non-Hispanic Black participants (p = 0.050), but not male (p = 0.506) or non-Hispanic White participants (p = 0.558). Additionally, MetSindex was greater in the highest EmE tertile compared to the lowest EmE tertile for the total sample (p = 0.037) and young adult females (p = 0.015). UE and CR were not associated with MetSindex. These data suggest a potential link between EmE and MetS severity in young adults, and that behavioral interventions aimed at MetS prevention should focus on treating the underlying EmE behaviors common in young adults, particularly for young female and Black adults at the greatest risk.

Hemodynamic responses to handgrip and metaboreflex activation are exaggerated in individuals with metabolic syndrome independent of resting blood pressure, waist circumference, and fasting blood glucose.

Introduction: Prior studies report conflicting evidence regarding exercise pressor and metaboreflex responses in individuals with metabolic syndrome (MetS). Purpose: To test the hypotheses that 1) exercise pressor and metaboreflex responses are exaggerated in MetS and 2) these differences may be explained by elevated resting blood pressure. Methods: Blood pressure and heart rate (HR) were evaluated in 26 participants (13 MetS) during 2 min of handgrip exercise followed by 3 min of post-exercise circulatory occlusion (PECO). Systolic (SBP), diastolic (DBP), and mean arterial pressure (MAP), along with HR and a cumulative blood pressure index (BPI), were compared between groups using independent samples t-tests, and analyses of covariance were used to adjust for differences in resting blood pressure, fasting blood glucose (FBG), and waist circumference (WC). Results: ΔSBP (∼78% and ∼54%), ΔMAP (∼67% and ∼55%), and BPI (∼16% and ∼20%) responses were significantly exaggerated in individuals with MetS during handgrip and PECO, respectively (all p ≤ 0.04). ΔDBP, ΔMAP, and BPI responses during handgrip remained significantly different between groups after independently covarying for resting blood pressure (p < 0.01), and after simultaneously covarying for resting blood pressure, FBG, and WC (p ≤ 0.03). Likewise, peak SBP, DBP, MAP, and BPI responses during PECO remained significantly different between groups after adjusting for resting blood pressure (p ≤ 0.03), with peak SBP, MAP, and BPI response remaining different between groups after adjusting for all three covariates simultaneously (p ≤ 0.04). Conclusion: These data suggest that exercise pressor and metaboreflex responses are significantly exaggerated in MetS independent of differences in resting blood pressure, FBG, or WC.

Additive influence of exercise pressor reflex activation on Valsalva responses in white and black adults.

AIM: This study aimed to determine if activation of the exercise pressor reflex exerts additive or redundant influences on the autonomic responses to the Valsalva maneuver (VL), and if these responses differ between White and Black or African American (B/AA) individuals. METHODS: Twenty participants (B/AA n = 10, White n = 10) performed three separate experimental trials. In the first trial, participants performed two VLs in a resting condition. In a second trial, participants performed 5 min of continuous handgrip (HG) exercise at 35% of the predetermined maximal voluntary contraction. In a third and final trial, participants repeated the 5-min bout of HG while also performing two VLs during the 4th and 5th minutes. Beat by beat blood pressure and heart rate (HR) were recorded continuously and the absolute systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP), and heart rate (HR) responses were reported for phases I-IV of each VL. RESULTS: No significant group by trial interactions or main effects of group were observed for any phase of the VL (all p ≥ 0.36). However, significant main effects of time were observed for blood pressure and heart rate during phases IIa-IV (all p ≤ 0.02). Specifically, the addition of HG exercise exaggerated the hypertensive responses during phases IIb and IV (all p ≤ 0.04) and blunted the hypotensive responses during phases IIa and III (all p ≤ 0.01). CONCLUSIONS: These results suggest that activation of the exercise pressor reflex exerts an additive influence on autonomic responses to the VL maneuver in both White and B/AA adults.