Relationship between aerobic fitness and progression of coronary atherosclerosis

A review of the signaling pathways of aerobic and anaerobic exercise on atherosclerosis

Atherosclerosis (AS), a chronic inflammatory vascular disease with lipid metabolism abnormalities, is one of the major pathological bases of coronary heart disease. As people's lifestyles and diets change, the incidence of AS increases yearly. Physical activity and exercise training have recently been identified as effective strategies for lowering cardiovascular disease (CVD) risk. However, the best exercise mode to ameliorate the risk factors related to AS is not clear. The effect of exercise on AS is affected by the type of exercise, intensity, and duration. In particular, aerobic and anaerobic exercise are the two most widely discussed types of exercise. During exercise, the cardiovascular system undergoes physiological changes via various signaling pathways. The review aims to summarize signaling pathways related to AS in two different exercise types and provide new ideas for the prevention and treatment of AS in clinical practice.

The relationships among the skeletal muscle mass index, cardiorespiratory fitness and the prevalence of coronary artery disease in the elderly population

OBJECTIVE

Few studies have investigated the association between cardiorespiratory fitness (CRF) impairment and coronary artery disease (CAD) and the mediating mechanism. Therefore, we investigated the impact of skeletal muscle mass (SMM) on the relationship between CRF and coronary artery disease (CAD) in elderly people.

METHODS

In this cross-sectional study, 109 elderly patients with coronary artery stenosis ≥50% were included in the CAD group, and 148 patients with coronary artery stenosis <50% were included as controls. Mediation analyses were performed to determine the role of the skeletal muscle index (SMI) in the relationship between CRF and the prevalence of CAD. A receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive value of CRF markers and the SMI.

RESULTS

The oxygen pulse, VO₂ max, and MET max were significantly associated with the SMI. In the multiple logistic regression analyses, the oxygen pulse and SMI were both independently correlated with the prevalence of CAD. The mediation analyses showed that the SMI affects the relationship between CRF markers (oxygen pulse, VO₂ max, and MET max) and the prevalence of CAD. The receiver operating characteristic (ROC) curve analysis showed that when CRF and the SMI are considered together, the predictive power for CAD is stronger than that of the CRF alone.

CONCLUSION

Enhancing CRF can facilitate improvement in SMM and decrease the prevalence of CAD in the elderly population. The addition of the SMI to CRF markers may increase the predictive value of CAD.

Exercise and Coronary Atherosclerosis: Observations, Explanations, Relevance, and Clinical Management

Physical activity and exercise training are effective strategies for reducing the risk of cardiovascular events, but multiple studies have reported an increased prevalence of coronary atherosclerosis, usually measured as coronary artery calcification, among athletes who are middle-aged and older. Our review of the medical literature demonstrates that the prevalence of coronary artery calcification and atherosclerotic plaques, which are strong predictors for future cardiovascular morbidity and mortality, was higher in athletes compared with controls, and was higher in the most active athletes compared with less active athletes. However, analysis of plaque morphology revealed fewer mixed plaques and more often only calcified plaques among athletes, suggesting a more benign composition of atherosclerotic plaques. This review describes the effects of physical activity and exercise training on coronary atherosclerosis in athletes who are middle-aged and older and aims to contribute to the understanding of the potential adverse effects of the highest doses of exercise training on the coronary arteries. For this purpose, we will review the association between exercise and coronary atherosclerosis measured using computed tomography, discuss the potential underlying mechanisms for exercise-induced coronary atherosclerosis, determine the clinical relevance of coronary atherosclerosis in middle-aged athletes and describe strategies for the clinical management of athletes with coronary atherosclerosis to guide physicians in clinical decision making and treatment of athletes with elevated coronary artery calcification scores.

Reference values for maximum work rate in apparently healthy Dutch/Flemish adults: data from the LowLands fitness registry

Background: The peak oxygen uptake (VO₂peak) test is the gold standard for cardiorespiratory fitness. However, the test is demanding, requiring sophisticated apparatus for measuring the oxygen uptake. Peak work rate (WRpeak) testing is a promising substitute for peak VO₂peak testing. However, there is a paucity of research conducted to determine reference values (RVs) for WRpeak. Methods: The database from the LowLands fitness registry was used, containing data from health checks from apparently healthy subjects among various professions. Exercise tests were performed using a cycle ergometer and a calibrated metabolic cart. Analysis was executed on 3463 subjects, 2868 male and 595 female. Reference values with corresponding centiles were developed using the LMS method. Results: VO₂peak and WRpeak where highly associated with Pearson's correlation of 0.9 (p = .001). Weight, height, maximum heart rate, and the respiratory exchange ratio had a positive significant effect (p < .001) on WRpeak, and age a negative significant effect, in both males and females. The following formulas were computed for RVs: WRpeak=-102+(1.5 * weight[kg])+(1.9 * height[cm])-(2.0 * age)-(sex * 60[M:0;V:1]) WRpeak/kg=2.45-(0.026 * weight[kg])+(0.024 * height[cm])-(0.024 * age)-(sex * 0.84 [M:0;V:1]) Conclusions: WRpeak can be used as a substitute for VO₂peak when a respiratory gas-analysis system is not available. This study provides RVs for WRpeak and WRpeak/kg in a healthy Dutch/Flemish adult population using cycle ergometry. Further research is needed to obtain RVs for elderly subjects, specific diseases, ethnicities and ergometers.

Physical Activity Protects Against the Risk of Erosive Esophagitis on the Basis of Body Mass Index

GOAL

To determine whether physical activity lowers the risk for erosive esophagitis on the basis of body mass index (BMI).

BACKGROUND

Although previous studies have shown that physical activity is closely associated with erosive esophagitis, these data may be confounded by obesity.

STUDY

In this retrospective study, we included 182,409 patients who underwent an upper endoscopy and were diagnosed with erosive esophagitis. The impact of the amount and intensity of physical activity on the risk for erosive esophagitis was analyzed based on BMI groups. Subjects were classified into three BMI groups with equal numbers in each group.

RESULTS

Overall, 10.3% (n=18,859) of patients were diagnosed with erosive esophagitis. After adjusting for confounding factors, a greater amount of exercise [lower tertile: odd ratio (OR), 0.86; 95% confidence interval (CI), 0.77-0.96; middle tertile: OR, 0.91; 95%, CI 0.84-1.00; upper tertile: OR, 0.79; 95% CI, 0.73-0.85) and increased exercise intensity (lower tertile, moderate: OR, 0.61; 95% CI, 0.52-0.71; vigorous: OR, 0.51; 95% CI, 0.44-0.58; middle tertile, moderate: OR, 0.62; 95% CI, 0.55-0.70; vigorous: OR, 0.58; 95% CI, 0.51-0.65; upper tertile, moderate: OR, 0.58; 95% CI, 0.53-0.65; vigorous: OR, 0.58; 95% CI, 0.53-0.64) was associated with a decreased risk for erosive esophagitis in all 3 BMI groups. In addition, we observed that increased physical activity intensity notably decreased the risk for erosive esophagitis in subjects performing lesser physical activity, but slightly decreased the risk for erosive esophagitis in subjects performing more physical activity.

CONCLUSION

Physical activity is inversely associated with erosive esophagitis.

Concomitant Associations of Healthy Food Intake and Cardiorespiratory Fitness With Coronary Artery Calcium

Conflicting findings remain regarding associations between lifestyle behaviors and coronary artery calcium (CAC). We investigated concomitant associations of healthy food intake and cardiorespiratory fitness (CRF) with CAC. Data from 706 men and women 50 to 64 years old from the Swedish SCAPIS pilot trial were analyzed. A CAC score was calculated using the Agatston method. A Healthy Food Index (HFI) was established using data from a web-based food frequency questionnaire. CRF was assessed from a bike exercise test. Regression analyses were performed with occurrence of CAC (dichotomous) and level of CAC score in patients with CAC (continuous) as outcomes. 58% had 0 CAC score. HFI was significantly associated with having no CAC (standardized coefficient β = 0.18, p <0.001) but not with level of CAC score (β = -0.09, p = 0.34). CRF showed no significant association with having no CAC (β = -0.08, p = 0.12) or with the level of CAC score (β = -0.04, p = 0.64). However, there was an interaction between HFI and CRF (β = -0.23, p = 0.02); for increasing levels of CRF there was stronger negative association between HFI and level of CAC score, reaching β = -0.48, p = 0.045 for the highest CRF level. In conclusion, these results emphasize the importance of a healthy food intake in combination with higher CRF to counteract CAC development.

Fitness attenuates the prevalence of increased coronary artery calcium in individuals with metabolic syndrome

Background

The association between cardiorespiratory fitness, physical activity and coronary artery calcium (CAC) is unclear, and whether higher levels of fitness attenuate CAC prevalence in subjects with metabolic syndrome is not fully elucidated. The present study aims to: a) investigate the independent association of fitness on the prevalence of CAC, after adjustment for moderate-to-vigorous physical activity and sedentary time, and b) study the possible attenuation of increased CAC by higher fitness, in participants with metabolic syndrome.

Design

Cross-sectional.

Methods

In total 678 participants (52% women), 50–65 years old, from the SCAPIS pilot study were included. Fitness (VO2max) was estimated by submaximal cycle ergometer test and moderate-to-vigorous physical activity and sedentary time were assessed using hip-worn accelerometers. CAC score (CACS) was quantified using the Agatston score.

Results

The odds of having a significant CACS (≥100) was half in participants with moderate/high fitness compared with their low fitness counterparts. Further consideration of moderate-to-vigorous physical activity, sedentary time and number of components of the metabolic syndrome did only slightly alter the effect size. Those with metabolic syndrome had 47% higher odds for significant CAC compared with those without metabolic syndrome. However, moderate/high fitness seems to partially attenuate this risk, as further joint analysis indicated an increased odds for having significant CAC only in the unfit metabolic syndrome participants.

Conclusions

Being fit is associated with a reduced risk of having significant CAC in individuals with metabolic syndrome. While still very much underutilized, fitness should be taken into consideration in everyday clinical risk prediction in addition to the traditional risk factors of the metabolic syndrome.

Impact of Exercise on the Relationship Between CAC Scores and All-Cause Mortality

OBJECTIVES

This study aims to assess the correlations among coronary artery calcium (CAC), self-reported exercise, and mortality in asymptomatic patients.

BACKGROUND

The interaction between reported exercise habits and CAC scores for predicting clinical risk is not yet well known.

METHODS

We followed 10,690 asymptomatic patients who underwent CAC scanning. Patients were divided into 4 groups based on a single-item self-reported exercise. Mean follow-up was 8.9 ± 3.5 years for the occurrence of all-cause mortality (ACM).

RESULTS

Annualized ACM progressively increased with increasing CAC score (p < 0.001) and decreasing exercise (p < 0.001). Among patients with CAC scores of 0, ACM was low regardless of the amount of exercise. Among patients with CAC scores from 1 to 399, there was a stepwise increase in ACM for each reported decrement in exercise, and this difference was markedly more pronounced among patients with CAC scores ≥400. Compared with highly active patients with a CAC score of 0, highly sedentary patients with CAC scores ≥400 had a 3.1-fold increase (95% confidence interval: 1.35 to 7.11) in adjusted ACM risk. Our single-item physical activity questionnaire was also predictive of risk factors and clinical and lipid profile measurements.

CONCLUSIONS

In asymptomatic patients, self-reported exercise is a significant predictor of long-term outcomes. Prognostic value of the reported exercise is additive to the increasing degree of underlying atherosclerosis. Among patients with high CAC scores, exercise may play a protective role, whereas reported minimal or no exercise substantially increases clinical risk. Our results suggest there is clinical utility for the use of a simple single-item exercise questionnaire for such assessments.

Change in Maximal Exercise Capacity Is Associated With Survival in Men and Women

OBJECTIVE

To describe the relationship between change in maximal exercise capacity (MEC) over time and risk of all-cause mortality separately in men and women.

PATIENTS AND METHODS

Consecutive patients (n=10,854; mean ± SD age, 54±11 years; 43% women; 30% nonwhite) who completed 2 physician-referred exercise tests between January 2, 1991, and May 28, 2009, were identified from the Henry Ford Exercise Testing (FIT) Project. The MEC was quantified in metabolic equivalents of task (METs) calculated from peak workload on a treadmill and adjusted to the equivalent for a 50-year-old man. Multivariable Cox proportional hazards regression was performed to assess risk of all-cause mortality associated with change in MEC based on (1) change from age-/sex-adjusted low fitness (<8 METs) to intermediate or high fitness and (2) an absolute change in METs.

RESULTS

Relative to patients with low fitness at both tests, increasing from low to intermediate or high fitness was associated with lower risk of all-cause mortality (adjusted hazard ratio [aHR] = 0.63 [95% CI, 0.45-0.87] in men and 0.56 [95% CI, 0.34-0.91] in women). Each 1-MET increase in age-/sex-adjusted MEC between baseline and follow-up was associated with an aHR of 0.87 (95% CI, 0.84-0.91) in men and 0.84 (95% CI, 0.79-0.89) in women, with no significant interaction by sex (P=.995). Similar aHRs were observed in a subgroup with intermediate fitness at baseline.

CONCLUSION

In men and women referred for an exercise stress test, change in MEC over time is inversely related to risk of all-cause mortality.

Combined effects of physical exercise and education on age-related cortical thinning in cognitively normal individuals

We investigated the association between self-reported physical exercise and cortical thickness in a large sample of cognitively normal individuals. We also determined whether a combination of physical exercise and education had more protective effects on age-related cortical thinning than either parameter alone. A total of 1,842 participants were included in this analysis. Physical exercise was assessed using a questionnaire regarding intensity, frequency, and duration. Cortical thickness was measured using a surface-based method. Longer duration of exercise (≥1 hr/day), but not intensity or frequency, was associated with increased mean cortical thickness globally (P-value = 0.013) and in the frontal regions (P-value = 0.007). In particular, the association of exercise with cortical thinning had regional specificity in the bilateral dorsolateral prefrontal, precuneus, left postcentral, and inferior parietal regions. The combination of higher exercise level and higher education level showed greater global and frontal mean thickness than either parameter alone. Testing for a trend with the combination of high exercise level and high education level confirmed this finding (P-value = 0.001–0.003). Our findings suggest that combined exercise and education have important implications for brain health, especially considering the paucity of known protective factors for age-related cortical thinning.

Repetitive restriction of muscle blood flow enhances mTOR signaling pathways in a rat model

Skeletal muscle is a plastic organ that adapts its mass to various stresses by affecting pathways that regulate protein synthesis and degradation. This study investigated the effects of repetitive restriction of muscle blood flow (RRMBF) on microvascular oxygen pressure (PmvO2), mammalian target of rapamycin (mTOR) signaling pathways, and transcripts associated with proteolysis in rat skeletal muscle. Eleven-week-old male Wistar rats under anesthesia underwent six RRMBF consisting of an external compressive force of 100 mmHg for 5 min applied to the proximal portion of the right thigh, each followed by 3 min rest. During RRMBF, PmvO2 was measured by phosphorescence quenching techniques. The total RNA and protein of the tibialis anterior muscle were obtained from control rats, and rats treated with RRMBF 0-6 h after the stimuli. The protein expression and phosphorylation of various signaling proteins were determined by western blotting. The mRNA expression level was measured by real-time RT-PCR analysis. The total muscle weight increased in rats 0 h after RRMBF, but not in rats 1-6 h. During RRMBF, PmvO2 significantly decreased (36.1 ± 5.7 to 5.9 ± 1.7 torr), and recovered at rest period. RRMBF significantly increased phosphorylation of p70 S6-kinase (p70S6k), a downstream target of mTOR, and ribosomal protein S6 1 h after the stimuli. The protein level of REDD1 and phosphorylation of AMPK and MAPKs did not change. The mRNA expression levels of FOXO3a, MuRF-1, and myostatin were not significantly altered. These results suggested that RRMBF significantly decreased PmvO2, and enhanced mTOR signaling pathways in skeletal muscle using a rat model, which may play a role in diminishing muscle atrophy under various conditions in human studies.