The role of body fat in the relationship of cardiorespiratory fitness with cardiovascular risk factors in Brazilian children

The Longitudinal Association of Cardiorespiratory Fitness and Adiposity With Clustered Cardiometabolic Risk: A Mediation Analysis

PURPOSE

Previous literature has demonstrated the mediating role of adiposity in the association between cardiorespiratory fitness (CRF) and cardiometabolic risk as well as the potential role of CRF in attenuating the adverse consequences associated with excess weight. This study aimed to evaluate the mediating role of CRF and adiposity in the possible association with cardiometabolic risk.

METHOD

Observational 3-year longitudinal study that included 420 children and adolescents (10.50 [2.05] y of age at baseline; 56.2% girls). Body mass index (BMI) was calculated, and CRF was evaluated using field assessments. A clustered cardiometabolic risk score (cMetS) was calculated from glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, and triglycerides z scores. Analyses evaluated the mediating role of BMI in the association between CRF and cMetS as well as whether CRF mediated the association between BMI and cMetS.

RESULTS

BMI at baseline was directly associated with the cMetS at follow-up (0.102; 95% confidence interval, 0.020 to 0.181), independently of CRF, whereas CRF was only indirectly associated with cMetS at follow-up through BMI (-0.036; 95% confidence interval, -0.070 to -0.009), meaning that the association between CRF and cMetS was explained via the mediation role of BMI.

CONCLUSIONS

BMI presented direct association with cMetS, whereas CRF exhibited indirect association with cMetS mediated via BMI.

The impact of reduced muscular fitness on cardiometabolic risk factors in children aged 9-11 years

AIM

To analyse the relationships between muscular fitness (MF), fat mass (FM), fat-free mass (FFM) and its combined ratio with cardiometabolic risk (CMR) and whether the relationship between MF and CMR is mediated by body composition in schoolchildren.

METHODS

A cross-sectional study was conducted on schoolchildren from Cuenca, Spain, between September and November 2017. FM and FFM were estimated using bioimpedance analysis. The CMR index was calculated from triglycerides-HDL-c ratio, arterial pressure and fasting insulin. The MF index was assessed using handgrip and standing long jump tests. Analysis of covariance models assessed CMR index differences across the MF index and the FM/FFM ratio categories. Mediation analysis examined whether the MF index and the CMR index association were mediated by FM, FFM or FM/FFM ratio.

RESULTS

The analyses involved 485 schoolchildren aged 9-11 years (55.4% girls). Children with a higher MF index had a lower CMR index (p < 0.05). This association did not persist after controlling for FM/FFM. FM, FFM and FM/FFM ratio mediated the relationship between the MF index and the CMR index.

CONCLUSION

Better levels of MF are associated with better cardiometabolic profile, but a healthy body composition is determinant to improve future health.

Glucose Levels as a Mediator of the Detrimental Effect of Abdominal Obesity on Relative Handgrip Strength in Older Adults

Excess central adiposity accelerates the decline of muscle strength in older people. Additionally, hyperglycemia, independent of associated comorbidities, is related to the loss of muscle mass and strength, and contributes to functional impairment in older adults. We studied the mediation effect of glucose levels, in the relationship between abdominal obesity and relative handgrip strength (HGS). A total of 1571 participants (60.0% women, mean age 69.1 ± 7.0 years) from 86 municipalities were selected following a multistage area probability sampling design. Measurements included demographic and anthropometric/adiposity markers (weight, height, body mass index, and waist circumference). HGS was measured using a digital dynamometer for three sets and the mean value was recorded. The values were normalized to body weight (relative HGS). Fasting glucose was analyzed by enzymatic colorimetric methods. Mediation analyses were performed to identify associations between the independent variable (abdominal obesity) and outcomes (relative HGS), as well as to determine whether fasting glucose levels mediated the relationship between excess adiposity and relative HGS. A total of 1239 (78.8%) had abdominal obesity. Abdominal obesity had a negative effect on fasting glucose (β = 9.04, 95%CI = 5.87 to 12.21); while fasting glucose to relative HGS was inversely related (β = −0.003, 95%CI = −0.005 to −0.001), p < 0.001. The direct effect of abdominal obesity on relative HGS was statistically significant (β = −0.069, 95%CI = −0.082 to −0.057), p < 0.001. Lastly, fasting glucose levels mediates the detrimental effect of abdominal obesity on relative HGS (indirect effect β = −0.002, 95%CI = −0.004 to −0.001), p < 0.001. Our results suggest that the glucose level could worsen the association between abdominal obesity status and lower HGS. Thus, it is plausible to consider fasting glucose levels when assessing older adults with excess adiposity and/or suspected loss of muscle mass.

Physical fitness as a moderator in the relationship between adiposity and cardiometabolic risk factors in children and adolescents

BACKGROUND

The aim of this study was to verify the moderator role of physical fitness in the relationship between adiposity and cardiometabolic risk factors in normal weight and overweight/obese children and adolescents.

METHODS

Cross-sectional study comprising 2482 children and adolescents, aged 7-17 years. Physical fitness was evaluated according the procedures of Projeto Esporte Brazil, and waist circumference (WC) with an inelastic tape. Cardiometabolic risk score was defined by the z-score sum of glucose, total cholesterol, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol. Moderation analysis was done through linear regression models.

RESULTS

Significant interaction term for cardiorespiratory fitness (CRF)×WC with cardiometabolic risk factors (P<0.001), as well as for lower limbs strength (LLS)×WC (P<0.001) and agility × WC (P=0.01) in normal weight girls. For normal weight boys it was found a significant interaction term for CRF×WC with cardiometabolic risk factor (P=0.007), and also for agility × WC (P=0.003), while overweight/obese boys showed a significant interaction term only for agility × WC with cardiometabolic risk factor (P=0.001).

CONCLUSIONS

CRF, LLS and agility are moderators in the relationship between WC and cardiometabolic risk factors in normal weight girls, while CRF and agility were moderators for normal weight boys and only agility for overweight/obese boys.