Muscular Strength and Carotid Intima-Media Thickness in Physically Fit Young Adults: The CHIEF Atherosclerosis Study

The association between grip strength and carotid intima media thickness: A Mendelian randomization analysis of the Canadian Longitudinal Study on Aging

BACKGROUND

Several two-sample Mendelian randomization studies have reported discordant results concerning the association between grip strength and cardiovascular disease, possibly due to the number of instrumental variables used, pleiotropic bias, and/ or effect modification by age and sex.

METHODS

We conducted a sex- and age-stratified one-sample Mendelian randomization study in the Canadian Longitudinal Study on Aging. We investigated whether grip strength is associated with carotid intima media thickness (cIMT), a marker of vascular atherosclerosis event risk, using eighteen single nucleotide polymorphisms (SNP) identified as specifically associated with grip strength.

RESULTS

A total of 20,258 participants of self-reported European ancestry were included in the analytic sample. Our Mendelian randomization findings suggest a statistically significant association between grip strength and cIMT (MR coefficient of 0.02 (95% CI: 0.01, 0.04)). We found no statistically significant differences between sexes (p-value = 0.201), or age groups [(≤ 60 years old versus >60 years old); p-value = 0.421].

CONCLUSION

This study provides evidence that grip strength is inversely associated with cIMT. Our one-sample MR study design allowed us to demonstrate that there is no evidence of heterogeneity of effects according to age group or biological sex.

Mean power output for muscular endurance exercises and maximal oxygen uptake in military young adults

The American Heart Association recommends a cardiopulmonary exercise test (CPET) and some alternative exercise tests to evaluate maximal oxygen uptake (VO2 max) of youth. Power output has shown a high correlation with VO2 max on a CPET. However, the correlations between mean power output (MPO) for muscular endurance exercises and VO2 max measured from a CPET are not established in young adults. Forty-five volunteers, with an average age of 29.93 ± 7.05 years, from a sample of 1120 military personnel in Taiwan who attended a 2-minute pushup test and a 2-minute sit-up test were included in the current study. These volunteers subsequently underwent a CPET using the Bruce protocol to assess VO2 max. According to the physics rule, MPO (watts) for the muscular endurance test was defined as a product of moving distance and force: [1/5 × body height (m) × numbers performed × body mass (kg) × gravity (9.8 m/s2)]. Pearson correlation analyses were performed. For the 2-min pushups, the correlations (r) between pushup numbers and VO2 max with and without body mass adjustment were 0.541 (P < .01) and 0.188 (P = .21), respectively, while the correlation (r) between MPO and VO2 max with and without body mass adjustment were 0.410 and 0.557 (both P < .01), respectively. For the 2-minute sit-ups, the correlations (r) between sit-up numbers and VO2 max with and without body mass adjustment were 0.529 (P < .01) and 0.291 (P = .052), respectively, while the correlations (r) between MPO and VO2 max with and without body mass adjustment were 0.318 (P = .03) and 0.705 (P < .01), respectively. In military young adults, MPO for both the 2-minute sit-up and the 2-minute pushup tests could be used as alternative field-based methods to estimate VO2 max.

Localized periodontitis severity associated with carotid intima-media thickness in young adults: CHIEF atherosclerosis study

This study aimed to investigate the association of periodontitis with subclinical atherosclerosis in young adults. In total, 486 non-diabetic military personnel were included in Taiwan. Carotid intima-media thickness (cIMT) was assessed utilizing sonography for subclinical atherosclerosis. Periodontitis severity was defined based on the 2017 US/European consensus. Mean cIMT was compared by analysis of covariance (ANCOVA), and multiple logistic regression model was used to determine the association of periodontitis severity and the highest quintile of cIMT (≥ 0.8 mm) with adjustments for age, sex, metabolic risk factors and leukocyte counts. The mean cIMT increased in those with greater stages (periodontal health (N = 349): 0.65 mm, Stage I (N = 41): 0.72 mm, Stage II (N = 57): 0.74 mm and Stage III: 0.76 mm, respectively, p < 0.01). In multiple logistic regression, a dose-response association from Stage I to Stage III periodontitis for cIMT ≥ 0.8 mm was also found [ORs and 95% CIs 1.41 (0.60-3.29), 1.62 (0.79-3.31) and 3.20 (1.42-7.18)]. Leucocyte counts ≥ 7.6 × 103/µL (the highest quintile) was associated with cIMT ≥ 0.8 mm [OR 1.86 (1.11-3.12)], while no association existed for other metabolic risk factors. In conclusion, severe periodontitis and leukocyte counts are independent risk factors of increased cIMT, emphasizing the critical role of inflammation in subclinical atherosclerosis.

Electrocardiographic and echocardiographic predictors of greater carotid intima-media thickness in tactical athletes: The CHIEF atherosclerosis study

OBJECTIVE

Both electrocardiographic and echocardiographic left ventricular hypertrophy (LVH) have been reported with an association with greater carotid intima-media thickness (cIMT), a marker of subclinical atherosclerosis in patients with hypertension, while the associations are unclear in physically fit young adults.

METHODS

A total of 1822 Taiwanese military personnel, aged 18-40 years, received an annual health examination including electrocardiography (ECG) and echocardiography in 2018-2020. Left carotid bulb cIMT was measured by high-resolution ultrasonography. Multiple logistic regression analysis with adjustments for age, sex, smoking, alcohol consumption, body mass index, mean blood pressure, and physical fitness was used to determine the associations between echocardiographic and ECG parameters and the highest quintile of cIMT (≥0.8 mm).

RESULTS

Cornell-based LVH, Myers et al.-based RVH and heart rate ≥75/min were associated with cIMT ≥0.8 mm [odds ratios (ORs) and 95% confidence intervals: 1.54 (1.01, 2.35), 1.66 (1.18, 2.33), and 1.39 (1.06, 1.83), respectively], while echocardiographic LVH defined as ≥46.0 g/m^2.7 for men and ≥38.0 g/m^2.7 for women was inversely associated with cIMT ≥0.8 mm [OR: 0.45 (0.24, 0.86)].

CONCLUSION

In tactical athletes of military, the associations of ECG and echocardiographic LVH with cIMT were in opposite directions. Higher physical fitness may cause cardiac muscle hypertrophy and reduce the atherosclerosis severity, possibly leading to the paradoxical echocardiographic finding. This study suggests that ECG-based LVH remains a good marker of subclinical atherosclerosis in our military population.

Association between tobacco smoking and heart disease in older adults: a cross-sectional study based on the Chinese Longitudinal Healthy Longevity Survey

Background

The association between the risk of heart disease and tobacco smoking has been studied in previous work, but there are arguments among various population. We aimed to investigate the association between heart disease incidence and smoking status among older adults.

Methods

A cross-sectional analysis was conducted with 10,891 older adults in the 2 most recent waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), 2011-2014 and 2014-2018. The data included individual weighting variables to ensure they were nationally representative. The parameters consisted of age, sex, body mass index (BMI), smoking status, and disease history was collected. Smoking measures included current/former/never status, pack-years and the time to first cigarette. Heart disease included coronary artery disease, arrhythmias, heart failure, valve diseases and other heart conditions. Respondents with missed values were excluded. Multivariable logistic regression analyses were performed.

Results

Among the 10,006 respondents included in the analyses, 4,501 (44.9%) were men. The median age was 88 years old [interquartile range (IQR), 78-96]. A total of 6,713 respondents (67.1%) were nonsmokers, 1,695 respondents (16.9%) were former smokers, and 1,598 respondents (16.0%) were current smokers. The incidence of heart disease was significantly higher in smokers compared with nonsmokers (14.5% vs. 12.8%, P=0.018). Female smokers and those over 80 years old had higher morbidity than male smokers. After adjusting for sex, age, BMI, hypertension, diabetes, area of residency, alcohol status, and exercise status, smokers still had an increased risk of heart disease [odds ratio (OR) 1.29, 95% confidential interval (CI): 1.10-1.50, P=0.001]. The incidence of heart disease also increased with higher intensity of smoking for each additional pack-year (OR 1.01, 95% CI: 1.00-1.02, P=0.011).

Conclusions

For elderly adults, current or former smoking was largely associated with heart disease incidence, especially in females and those over 80 years old. These variables could be considered for inclusion in future heart disease risk prediction models.