The impact of obesity on cardiac troponin levels after prolonged exercise in humans

Exercise-induced release of cardiac troponin is attenuated with repeated bouts of exercise: impact of cardiovascular disease and risk factors

Prolonged exercise can induce cardiac troponin release. As single bouts of exercise may protect against cardiac injury, we explored the hypothesis that the magnitude of exercise-induced release of troponin attenuates upon successive days of exercise. We also examined whether effects of successive exercise bouts differ between healthy participants and individuals with cardiovascular risk factors (CVRFs) and established cardiovascular disease (CVD). We examined cardiac troponin I (cTnI) concentrations from whole venous blood samples collected from the antecubital vein (10 mL) in 383 participants (61 ± 14 yr) at rest and immediately following four consecutive days of long-distance walking (30-50 km/day). Participants were classified as either healthy (n = 222), CVRF (n = 75), or CVD (n = 86). Baseline cTnI concentrations were significantly higher in participants with CVD and CVRF compared with healthy (P < 0.001). Exercise-induced elevations in cTnI were observed in all groups following all days of walking compared with baseline (P < 0.001). Tobit regression analysis on absolute cTnI concentrations revealed a significant day × group interaction (P = 0.04). Following day 1 of walking, post hoc analysis showed that exercise-induced elevations in cTnI attenuated on subsequent days in healthy and CVRF, but not in CVD. Odds ratios for incident cTnI concentrations above the upper reference limit were significantly higher compared with baseline on day 1 for healthy participants (4.90 [95% CI, 1.58-15.2]) and participants with CVD (14.9 [1.86-125]) and remained significantly higher than baseline on all subsequent days in CVD. The magnitude of postexercise cTnI concentrations following prolonged walking exercise significantly declines upon repeated days of exercise in healthy individuals and those with CVRF, whereas this decline is not present in patients with CVD.NEW & NOTEWORTHY We show the magnitude of postexercise cardiac troponin concentrations following prolonged walking exercise significantly declines upon repeated days of exercise in healthy individuals and those with cardiovascular risk factors, while this decline is not present in patients with established cardiovascular disease.

Influence of Obesity on Histological Tissue Structure of the Cardiovascular System in Horses

It has been well established that obesity in horses can have a negative impact on their health, including endocrine disturbances. In humans, it is well known that obesity leads to structural and functional changes of the cardiovascular system. The aim of the study was to assess the impact of obesity on the histological structure of the myocardial tissue, as well as great and peripheral arteries in horses. The heart, arteries (aorta, pulmonary artery and palmar arteries) specimens from 7 horses with normal BCS (4–5/9) and 12 extremely obese (BCS 9/9) draft slaughter horses were obtained for histopathological evaluation. The heart tissue and great arteries showed more intense disturbances in the architecture and vacuolization in the aorta in obese horses as compared to the healthy group. The intima in the pulmonary artery, coronary arteries and palmar arteries was thicker in the obese, rather than healthy horses. The palmar arteries in obese horses had a larger lumen diameter and the lumen-to-total diameter ratio as compared to the control group. The presented study showed a significant effect of obesity on the heart as well as the central and peripheral vessels in horses. This forms the basis for a deeper reflection on the impact of obesity on the equine body.

Changes in peripheral immune cell numbers and functions in octogenarian walkers - an acute exercise study

BACKGROUND

Age-related changes of the immune system, termed immunosenescence, may underlie the increased risk of infections and morbidity in the elderly. Little is known about the effects of acute exercise on peripheral immune parameters in octogenarians. Therefore, we investigated acute exercise-induced changes in phenotype and function of the immune system in octogenarians participating in the 2013 edition of the Nijmegen Four Days Marches. Blood sampling was performed at baseline and immediately after 4 days of the walking exercise (30 km/day). A comprehensive set of adaptive and innate immune traits were enumerated and analyzed by flow-cytometry. Peripheral blood mononuclear cells, isolated before and after walking were stimulated with LPS and supernatants were analysed for IL-1β, IL-6, IL-8 and TNF-α concentrations by ELISA. CMV serostatus was determined by ELISA.

RESULTS

The walking exercise induced a clear leucocytosis with numerical increases of granulocytes, monocytes and lymphocytes. These exercise-induced changes were most profound in CMV seropositive subjects. Within lymphocytes, numerical increases of particularly CD4+ T cells were noted. Further T cell differentiation analysis revealed profound increases of naïve CD4+ T cells, including naïve Treg. Significant increases were also noted for CD4+ memory T cell subsets. In contrast, only slight increases in naïve and memory CD8+ T cell subsets were detected. Exercise did not affect markers of immune exhaustion in memory T cell subsets. NK cells demonstrated a numerical decline and a change in cellular composition with a selective decrease of the mature CD56^dim NK cells. The latter was seen in CMV seronegative subjects only. Also, a higher IL-6 and IL-8 production capacity of LPS-stimulated PBMC was seen after walking.

CONCLUSION

In this exceptional cohort of octogenarian walkers, acute exercise induced changes in immune cell numbers and functions. A clear response of CD4+ T cells, rather than CD8+ T cells or NK cells was noted. Remarkably, the response to exercise within the CD4+ T cell compartment was dominated by naïve CD4+ subsets.

Troponin and exercise

Cardiac troponins are the preferred biomarkers in diagnostic of myocardial infarction, but these markers also can rise in response to exercise. Multiple studies have assessed troponins post-exercise, but the results have varied and there have been disagreements about the mechanism of troponin release. The aim of this paper was to review the literature, and to consider factors and mechanisms regarding exercise-induced increase of troponin. 145 studies were found after a search in pubmed and inclusion of additional articles found in the reference list of the first articles. Results showed that troponin rises in 0-100% of subjects after prolonged heavy exercise like marathon, but also after short-term and intermittent exercise like 30min of running and basketball. The variation can be due to factors like intensity, age, training experience, variation in sample size, blood sample timing and troponin assay. The pattern of troponin level post-exercise corresponds to release from the cytosolic compartment of cardiomyocytes. Increased membrane permeability might be caused by production of reactive oxygen species or alterations in calcium, pH, glucose/fat metabolism or in communication between integrins. Other suggested mechanisms are increased cardiovascular stress, inflammation, vasculitis, release of troponin degradation products in "blebs", dehydration, impaired renal clearance and expression of cardiac troponin in skeletal muscle. It can be concluded that both heavy and light exercise may cause elevated troponin, which have to be considered when patient are suspected to have a myocardial infarction. Several factors probably influence post-exercise levels of troponin, but the mechanism of release is most likely physiologic.

Serum cardiac troponin I analysis to determine the excessiveness of exercise intensity: A novel equation

Physical exertion is often promoted because of its beneficial health effects. This only holds true, however, as long as the optimal exercise intensity is not exceeded. If physical exertion becomes too strenuous or prolonged, cardiac injury or dysfunction may occur. Consequently, a significant elevation of the serum concentration of the sensitive and specific cardiac biomarker troponin I can be observed. In this article, we present the derivation of a novel equation that can be used to evaluate to what extent the intensity of conducted endurance exercise was excessive, based on a post-exercise assessment of serum cardiac troponin I. This is convenient, as exercise intensity is difficult for an athlete to quantify accurately and the currently used heart rate indices can be affected by various physiological and environmental factors. Serum cardiac troponin I, on the other hand, is a post-hoc parameter that directly reflects the actual effects on the myocardium and may therefore be a promising alternative. To our knowledge, this is the first method to determine relative exercise intensity in retrospect. We therefore believe that this equation can serve as a potentially valuable tool to objectively evaluate the benefits or harmful effects of physical exertion.

Are There Deleterious Cardiac Effects of Acute and Chronic Endurance Exercise?

Multiple epidemiological studies document that habitual physical activity reduces the risk of atherosclerotic cardiovascular disease (ASCVD), and most demonstrate progressively lower rates of ASCVD with progressively more physical activity. Few studies have included individuals performing high-intensity, lifelong endurance exercise, however, and recent reports suggest that prodigious amounts of exercise may increase markers for, and even the incidence of, cardiovascular disease. This review examines the evidence that extremes of endurance exercise may increase cardiovascular disease risk by reviewing the causes and incidence of exercise-related cardiac events, and the acute effects of exercise on cardiovascular function, the effect of exercise on cardiac biomarkers, including "myocardial" creatine kinase, cardiac troponins, and cardiac natriuretic peptides. This review also examines the effect of exercise on coronary atherosclerosis and calcification, the frequency of atrial fibrillation in aging athletes, and the possibility that exercise may be deleterious in individuals genetically predisposed to such cardiac abnormalities as long QT syndrome, right ventricular cardiomyopathy, and hypertrophic cardiomyopathy. This review is to our knowledge unique because it addresses all known potentially adverse cardiovascular effects of endurance exercise. The best evidence remains that physical activity and exercise training benefit the population, but it is possible that prolonged exercise and exercise training can adversely affect cardiac function in some individuals. This hypothesis warrants further examination.

Cardiac biomarkers at high altitude

BACKGROUND

Classically, biomarkers such as the natriuretic peptides (NPs) BNP/NT-proBNP are associated with the diagnosis of heart failure and hs-cTnT with acute coronary syndromes. NPs are also elevated in pulmonary hypertension. High pulmonary artery systolic pressure (PASP) is a key feature of high altitude pulmonary edema (HAPE), which may be difficult to diagnose in the field. We have previously demonstrated that NPs are associated with high PASP and the presence of acute mountain sickness (AMS) in a small cohort at HA. We aimed to investigate the utility of several common cardiac biomarkers in diagnosing high PASP and AMS.

METHODS

48 participants were assessed post-trekking and at rest at three altitudes: 3833 m, 4450 m, and 5129 m. NPs, hs-cTnT and hsCRP, were quantified using immunoassays, PASP was measured by echocardiography, and AMS scores were recorded.

RESULTS

Significant changes occurred with ascent in NPs, hs-cTnT, hsCRP (all p<0.001) and PASP (p=0.006). A high PASP (≥40 mm Hg) was associated with higher NPs, NT-proBNP: 137±195 vs. 71.8±68 (p=0.001); BNP 15.3±18.1 vs. 8.7±6.6 (p=0.001). NPs were significantly higher in those with AMS or severe AMS vs. those without (severe AMS: NT-proBNP: 161.2±264 vs. 76.4±82.5 (p=0.008)). The NPs correlated with hsCRP. cTnT increased with exercise at HA and was also higher in those with a high PASP (13.8±21 vs. 7.8±6.5, p=0.018).

CONCLUSION

The NPs and hs-cTnT are associated with high PASP at HA and the NPs with AMS.

Running economy, not aerobic fitness, independently alters thermoregulatory responses during treadmill running

We sought to determine the independent influence of running economy (RE) and aerobic fitness [maximum oxygen consumption (V̇O 2max)] on thermoregulatory responses during treadmill running by conducting two studies. In study 1, seven high (HI-FIT: 61 ± 5 ml O2 · kg(-1) · min(-1)) and seven low (LO-FIT: 45 ± 4 ml O2 · kg(-1) · min(-1)) V̇O 2max males matched for physical characteristics and RE (HI-FIT: 200 ± 21; LO-FIT: 200 ± 18 ml O2 · kg(-1) · km(-1)) ran for 60 min at 1) 60%V̇O 2max and 2) a fixed metabolic heat production (Hprod) of 640 W. In study 2, seven high (HI-ECO: 189 ± 15.3 ml O2 · kg(-1) · km(-1)) and seven low (LO-ECO: 222 ± 10 ml O2 · kg(-1) · km(-1)) RE males matched for physical characteristics and V̇O 2max (HI-ECO: 60 ± 3; LO-ECO: 61 ± 7 ml O2 · kg(-1) · min(-1)) ran for 60 min at a fixed 1) speed of 10.5 km/h and 2) Hprod of 640 W. Environmental conditions were 25.4 ± 0.8°C, 37 ± 12% RH. In study 1, at Hprod of 640 W, similar changes in esophageal temperature (ΔTes; HI-FIT: 0.63 ± 0.20; LO-FIT: 0.63 ± 0.22°C; P = 0.986) and whole body sweat losses (WBSL; HI-FIT: 498 ± 66; LO-FIT: 497 ± 149 g; P = 0.984) occurred despite different relative intensities (HI-FIT: 55 ± 6; LO-FIT: 39 ± 2% V̇O 2max; P < 0.001). At 60% V̇O 2max, ΔTes (P = 0.029) and WBSL (P = 0.003) were greater in HI-FIT (1.14 ± 0.32°C; 858 ± 130 g) compared with LO-FIT (0.73 ± 0.34°C; 609 ± 123 g), as was Hprod (HI-FIT: 12.6 ± 0.9; LO-FIT: 9.4 ± 1.0 W/kg; P < 0.001) and the evaporative heat balance requirement (Ereq; HI-FIT: 691 ± 74; LO-FIT: 523 ± 65 W; P < 0.001). Similar sweating onset ΔTes and thermosensitivities occurred between V̇O 2max groups. In study 2, at 10.5 km/h, ΔTes (1.16 ± 0.31 vs. 0.78 ± 0.28°C; P = 0.017) and WBSL (835 ± 73 vs. 667 ± 139 g; P = 0.015) were greater in LO-ECO, as was Hprod (13.5 ± 0.6 vs. 11.3 ± 0.8 W/kg; P < 0.001) and Ereq (741 ± 89 vs. 532 ± 130 W; P = 0.007). At Hprod of 640 W, ΔTes (P = 0.910) and WBSL (P = 0.710) were similar between HI-ECO (0.55 ± 0.31°C; 501 ± 88 g) and LO-ECO (0.57 ± 0.16°C; 483 ± 88 g), but running speed was different (HI-ECO: 8.2 ± 0.6; LO-ECO: 7.2 ± 0.4 km/h; P = 0.025). In conclusion, thermoregulatory responses during treadmill running are not altered by V̇O 2max, but by RE because of differences in Hprod and Ereq.