The findings of this study suggest sport-specific cardiac adaptations.
- Prolonged QT dispersion derived from electrocardiograms has been used as an indicator of abnormal ventricular repolarization for several cardiac diseases.
- An increased QT dispersion has been documented in patients with arterial hypertension and left ventricular hypertrophy.
- In addition to clinical environments, left ventricular hypertrophy is observed in athletes completing regular training.
- This left ventricular hypertrophic cardiac response serves as a reactive mechanism to compensate for volume overload experienced during endurance training or pressure overload experienced during resistance training.
- Although athletes develop impressive left ventricular tissue growth, it is unknown whether this exercise-induced left ventricular hypertrophy is associated with increased QT dispersion as observed in patients with hypertensive myocardial hypertrophy.
- Despite evidence suggesting that cardiac remodeling varies in response to pressure overload (concentric hypertrophy) or volume overload (eccentric hypertrophy)...
...there is limited research on comparing QT dispersion and echocardiographic parameters across athletes competing in different sports varying in terms of the predominant type of overload imposed.
- In this way, sports may be classified according to the mechanical demands they elicit based on the peak static components (expressed as relative intensity of voluntary muscular contraction across three levels [A, B, C])...
...and the peak dynamic components (expressed as percentage of maximal oxygen uptake across three levels [I, II, III]) undertaken by athletes.
- This study aimed to compare QT dispersion and echocardiographic parameters between athletes competing in different sports and sedentary controls and assess the associations between QT dispersion and echocardiographic parameters among them.
- Advanced left ventricular hypertrophy, predominantly concentric in nature, induced by pressure overload, accompanied with an increased QT dispersion was observed in athletes predominantly completing static exercise (powerlifters and bodybuilders).
"These structural parameters we observed in powerlifters and bodybuilders represent remodeling adaptations in response to training that fall within a 'grey zone'...
"...where extreme expressions of athlete’s heart and mild morphological forms of hypertrophic cardiomyopathy may overlap...
"...Although these likely remodeling adaptations in powerlifters and bodybuilders mimic pathological hypertrophic cardiomyopathy, their LV end-diastolic diameters (~ 52–53 mm) were within clinically accepted partition values for the general population (45–55 mm)...
"...which is a useful and sensitive marker in distinguishing an athletic heart from hypertrophic cardiomyopathy diagnosis."
- On the other hand, mild left ventricular hypertrophy (toward the upper threshold of the normal reference range) induced by volume overload that was accompanied with a reduced QT dispersion was observed in long-distance runners, volleyball athletes, and football athletes.
"In addition to LV structural parameters, LV systolic indicators were also within clinically accepted reference ranges for the general population...
"...further supporting adaptive (rather than maladaptive) physiological cardiac remodeling in athlete groups predominantly undertaking dynamic (long-distance runners, football athletes, and volleyball athletes) or static exercise (powerlifters and bodybuilders)."
Sport-related differences in QT dispersion and echocardiographic parameters in male athletes (open access)
Here, a 4-week detraining period decreased the HIIT-induced increase in whole-body oxidative metabolism in insulin-resistant individuals, but this did not affect improvements in hepatic insulin sensitivity, hepatic lipid content, and glycemia.
- The aim of this study was to compare the sustainability of metabolic effects induced by a long-term HIIT intervention between people with different degrees of whοle-body insulin sensitivity and people with overt type 2 diabetes upon detraining.
- In this study, men with (20) and without type 2 diabetes (12 insulin-sensitive, 10 insulin-resistant) underwent hyperinsulinemic-euglycemic clamps, spiroergometry, ectopic lipid quantification and muscle biopsies at baseline, after 12-week HIIT and after 4-week detraining.
Here, short, moderate-to-high-intensity exercises multiple times throughout the day showed greater excess post-exercise oxygen consumption (EPOC) compared with continuous exercise and interval exercise, in which energy expenditure was homogenized, in healthy women.
- This crossover, randomized controlled trial aimed to compare the excess post-exercise oxygen consumption (EPOC) for different exercise modalities...
...including continuous exercise (moderate-intensity continuous exercise), interval exercise (high-intensity interval exercise), and accumulated exercise (short, moderate-to-high-intensity exercises multiple times throughout the day) that spent the homogenized energy expenditure during exercise in healthy women.
This one finds that long duration walking can induce small increases in IL-6 secretion at walking durations that were habitual on a nearly daily basis throughout the course of human evolution.
- This study aimed to examine whether IL-6 release occurs during evolutionarily normal physical activity contexts like long distance walking.
- A dose–response experiment to test the effect of walking duration on IL-6 secretion was performed.
This systematic review finds that the literature overall suggests that muscle volume is a major determinant of sprint cycling performance.
- This systematic review aimed to discern the relationships between muscle morphology, architecture, and quality with sprint cycling performance.
- In this systematic review, greater muscle volume and cross-sectional area were found to be concomitant with with peak power output, emphasising the importance of muscle size in sprint cycling.
This one found that, irrespective of intensity, longer duration of physical activity to be associated with a lower risk of all-cause, cancer, and cardiovascular disease mortality, without minimal or maximal threshold adults with type 2 diabetes.
- This study performed a prospective cohort study of 19,624 individuals with type 2 diabetes from the UK Biobank with a median follow-up of 6.9 years.
- Duration and intensity of physical activity were measured by wrist-worn accelerometers over a 7-day period.
The findings of this one suggest that an altered function of the autonomic nervous system and a compromised capacity for vasodilation in the microvasculature occur early in the development of insulin resistance.
- Skeletal muscle consists of type I and II fibers that differ from each other in terms of contractile speed, fatigue resistance, enzymatic capacity, and vascularization.
- Type I fibers exhibit high oxidative capacity and a high capillary density, whereas type II fibers exhibit high glycolytic capacity and lower capillary density.