The pacing differences in performance levels of marathon and half-marathon runners

Introduction

Many studies indicate a considerable impact of optimal pacing on long-distance running performance. Given that the amount of carbohydrates in metabolic processes increases supralinearly with the running intensity, we may observe differences between the pacing strategies of two long-distance races and different performance levels of runners. Accordingly, the present study aimed to examine the differences in pacing strategies between marathon and half-marathon races regarding the performance levels of runners.

Methods

The official results and split times from a total of 208,760 (marathon, N = 75,492; half-marathon, N = 133,268) finishers in the "Vienna City Marathon" between 2006 and 2018 were analyzed. The percentage of the average change of speed for each of the five segments (CS 1-5), as well as the absolute change of speed (ACS) were calculated. The CS 1-5 for the marathon are as follows: up to the 10th km, 10th - 20th km, 20th - 30th km, 30th - 40th km, and from the 40th km to the 42.195 km. For the half-marathon, the CS 1-5 are half of the marathon values. Four performance groups were created as quartiles of placement separately for sexes and races: high-level (HL), moderate to high-level (MHL), moderate to low-level (MLL), and low-level (LL).

Results

Positive pacing strategies (i.e., decrease of speed) were observed in all performance groups of both sex and race. Across CS 1-5, significant main effects (p < 0.001) were observed for the segment, performance level, and their interaction in both sex and race groups. All LL groups demonstrated higher ACS (men 7.9 and 6.05%, as well as women 5.83 and 5.49%, in marathon and half-marathon, respectively), while the HL performance group showed significantly lower ACS (men 4.14 and 2.97%, as well as women 3.16 and 2.77%, in marathon and half-marathon, respectively). Significant main effects (p < 0.001) for the race were observed but with a low effect size in women (ŋ2 = 0.001).

Discussion

Better runners showed more even pacing than slower runners. The half-marathoners showed more even pacing than the marathoners across all performance groups but with a trivial practical significance in women.

Physiological behavior during stress anticipation across different chronic stress exposure adaptive models

Anticipation of stress induces physiological, behavioral and cognitive adjustments that are required for an appropriate response to the upcoming situation. Additional research examining the response of cardiopulmonary parameters and stress hormones during anticipation of stress in different chronic stress adaptive models is needed. As an addition to our previous research, a total of 57 subjects (16 elite male wrestlers, 21 water polo player and 20 sedentary subjects matched for age) were analyzed. Cardiopulmonary exercise testing (CPET) on a treadmill was used as the laboratory stress model; peak oxygen consumption (VO₂) was obtained during CPET. Plasma levels of adrenocorticotropic hormone (ACTH), cortisol, alpha-melanocyte stimulating hormone (alpha-MSH) and N-terminal-pro-B type natriuretic peptide (NT-pro-BNP) were measured by radioimmunometric, radioimmunoassay and immunoassay sandwich technique, respectively, together with cardiopulmonary measurements, 10 minutes pre-CPET and at the initiation of CPET. The response of diastolic blood pressure and heart rate was different between groups during stress anticipation (p = 0.019, 0.049, respectively), while systolic blood pressure, peak VO₂ and carbon-dioxide production responses were similar. ACTH and cortisol increased during the experimental condition, NT-pro-BNP decreased and alpha-MSH remained unchanged. All groups had similar hormonal responses during stress anticipation with the exception of the ACTH/cortisol ratio. In all three groups, ΔNT-pro-BNP during stress anticipation was the best independent predictor of peak VO₂ (B = 36.01, r = 0.37, p = 0.001). In conclusion, the type of chronic stress exposure influences the hemodynamic response during anticipation of physical stress and the path of hormonal stress axis activation. Stress hormones released during stress anticipation may hold predictive value for overall cardiopulmonary performance during the stress condition.

Physical activity and exercise as an essential medical strategy for the COVID-19 pandemic and beyond

COVID-19 disease has been a problem in today's society, which has worldwide effects on different areas, especially on the economy; also, from a health perspective, the disease affects the daily life quality. Physical activity is one major positive factor with regard to enhancing life quality, as it can improve the whole psychological, social, and physical health conditions. Current measures such as social distancing are focused on preventing the viral spread. However, the consequences on other areas are yet to be investigated. Elderly, people with chronic diseases, obese, and others benefit largely from exercise from the perspective of improved health, and preventive measures can drastically improve daily living. In this article, we elaborate the effects of exercise on the immune system and the possible strategies that can be implemented toward greater preventive potential.

[Electrophysiological characteristics of the athlete's heart]

INTRODUCTION

The athletic heart syndrome is characterized by morphological, functional and electrophysiological alterations as an adaptive response to vigorous physical activity. Athletes heart is predominantly associated with a programmed, intensive training. But as there are different kinds of physical activities, the degree of these changes is highly variable. ELECTROPHYSIOLOGICAL CHARACTERISTICS OF THE ATHLETE'S HEART: The response of the body to vigorous physical activity is a multiorgan system phenomenon. The integrated functioning of each of these organ systems is very important, but the cardiovascular system plays a critical role in mediating the activity. Because of that, most changes in the neurohumoral regulation predominantly affect the cardiovascular system. These changes include: depression of sympathetic activity and stimulation of parasympathetic activity, so electrophysiological characteristics of the athlete's heart must differ from the sedentary Although these facts, are well known, the athlete's heart is not a precisely defined concept. It is a gray zone between physiology, and pathology.

CONCLUSION

Considering the number of sudden cardiac deaths in athletes, it is needless to say how important it is to distinguish physiological changes of the heart due to physical activity, and pathological changes due to some cardiac diseases.

[Athlete's heart syndrome]

Performing vigorous physical activity means a multiorgan system engagement, but the cardiovascular system plays a critical role. In order to provide enough oxygen to activate muscles during repeated physical activity of high intensity, the heart undergoes profound morphologic, functional and electrophysiological alterations, which have been identified as the "athlete's heart syndrome". "The athlete's heart" is a complex, but not precisely defined concept, anatomically and functionally and in relation to health and disease. It means the whole heart enlargement and/or hypertrophy of the cardiac muscle, also increasing economy of cardiac performance at rest and during physical activity with higher maximal functional capacities, all that having an adaptive response to vigorous physical activity. For morphological changes called the "athlete's heart, full-time, programed and intensive physical activity at maximal levels is primarily responsible. But as there are different kinds of physical activities, the degree of those morphological changes is highly variable. Considering many sudden cardiac deaths in sports, it is needless to say how important it is to know where the borderline is between normal changes of the heart due to physical activity and pathological changes due to some cardiac diseases. As sport has a growing socio-economic significance, sudden cardiac death events have to be reduced.

[Causes of sudden cardiac death in athletes]

INTRODUCTION

Sudden cardiac death in athletes is a growing problem, despite the huge existing knowledge in medicine and sports.

EFFECTS OF VIGOROUS PHYSICAL ACTIVITY

In response to vigorous physical activity, the body undergoes profound morphologic and functional changes. These changes are usually healthy, but sometimes may gravitate to some cardiac diseases. But still, most saudden cardiac deaths are due to previous unknown diseases.

CAUSES OF SUDDEN CARDIAC DEATH

The most common cause of sudden cardiac death in athletes is hypertrophic cardiomyopathy. Other reasons are congenital coronary artery anomalies, nivocarditis, dilatative cardiomyopathy, arrhythmogenic cardiomyopathy of the right ventricle, sarcoidosis, mitral valve prolapse, aortic valve stenosis, atherosclerosis, long QT syndrome, and blunt impact to the chest.

CONCLUSION

Bearing in mind the above mentioned, more frequent physical examinations of athletes are recommended.

[Determination of ventilatory threshold based on subjective rating of perceived exertion]

The objective of the study was to test the possibility of using the fixed value (12-13) of the Rating of Perceived scale (RPE scale), as a valid method for determination of ventilatory threshold (VT). The sample of the subjects included 32 physically active males (age: 22.3; TV: 180.5; TM: 75.5 kg; VO2max: 57.1 mL/kg/min). During the continuous test of progressively increasing load on a treadmill, cardiorespiratory and other parameters were monitored using ECG and gas analyzer. Following the test, VT and VO2max were determined. During the test, at each level, at the scale from 6 to 20, the subjects pointed the number that suited best their currently feeling of strain. The RPE threshold was defined as constant value of 12-13. Average values of ventilatory and RPE threshold were expressed by parameters that were monitored and then compared by using t-test for dependent samples. No significant difference was found between mean values of VT and RPE threshold, when they were expressed by relevant parameters: speed, load, heart rate, absolute and relative oxygen consumption. Fixed value (12-13) of RPE scale may be used to detect the exercise intensity that corresponds to ventilatory threshold.

[Running velocity at the ventilatory threshold and at VO2max before and after the eight-week cardiovascular endurance training]

INTRODUCTION

The purpose of this research was to compare changes in running velocity at ventilatory threshold with the veliocity at VO2max, before and after the eight-week exercise program.

MATERIAL AND METHODS

32 male subjects (age: 22.3 +/- 2.5 years, height: 179.8 +/- 7.6 cm, body mass: 76.8 +/- 9.0 kg) performed a progressive test for ventilatory threshold (VT) measurement and VO2max on treadmill. After 8 weeks of endurance training (3 times per week, 30 to 70 min, in different zones in respect to the ventilatory threshold) the performed the same test.

RESULTS

Running velocity at ventilatory threshold increased significantly (p = 0.0001), between initial and final measurements (10.88 +/- 2.09, 12.94 +/- 1.90 km/h, respectively); as well as at VO2max (14.63 +/- 1.86, 16.44 +/- 1.59 km/h, respectively). At the initial test, velocity at ventilatory threshold was 74.11 % of VO2max. At the final test, velocity at ventilatory threshold was 78.43% of VO2max. Running velocity at ventilatory threshold has significantly increased at final test (p = 0.001).

DISCUSSION

Running velocity at ventilatory threshold has significantly increased after eight weeks of endurance training (p = 0.001), when expressed in absolute values and percentage of velocity at VO2max.

CONCLUSION

Comparison between the initial and final test demonstrated a significant increase of observed variables, under experimental conditions: at final test running velocity has increased at ventilatory threshold, in respect to absolute values and expressed as percentage at VO2max.

Urinary PC-1 and N-acetyl-beta-D-glucosaminidase activity in patients with type 2 diabetes treated with metformin, gliclazide or glibenclamide

BACKGROUND

Insulin resistance is a key feature of type 2 diabetes mellitus. Plasma cell differentiation antigen (PC-1) is an inhibitor of insulin receptor tyrosine kinase, and has been implicated in the pathogenesis of insulin resistance.

METHODS

Urinary excretion of PC-1 was determined in 45 newly detected, obese diabetic patients treated with metformin (16 patients), gliclazide (14 patients) or glibenclamide (15 patients). Urinary N-acetyl-beta-D-glucosaminidase (NAGA), a lysosomal enzyme, was determined as a marker of tubular damage in diabetes.

RESULTS

Basal urinary PC-1 excretion in all three groups of diabetic patients was at the level of healthy controls. Treatment with oral hypoglycaemic drugs did not change significantly the group level or the number of patients in each group with increased PC-1 activity. Urinary excretion of NAGA in patients with type 2 diabetes was not statistically different from the control level. Metformin and gliclazide treatment did not change significantly the group levels of NAGA excretion. However, glibenclamide treatment produced an increased urinary NAGA excretion in the whole group, and in about twice as many patients as in the pre-treatment period.

Urinary PC-1 activity in patients with type 1 diabetes mellitus

BACKGROUND

Insulin resistance characterizes type 1 diabetes mellitus with nephropathy. The molecular mechanisms of insulin resistance are not completely understood. Recently some advances have been made in identification of transmembrane glycoprotein PC-1 as a potential factor of insulin resistance.

METHODS

We measured urinary excretion of PC-1 (alkaline phosphodiesterase I), a potential factor of insulin resistance, and N-acetyl-beta-D-glucosaminidase (NAGA) in 62 type 1 diabetic patients with different damage to the kidney.

RESULTS

In newly detected type 1 diabetes patients, before insulin therapy, urine PC-1 excretion was significantly increased (P<0.05) over the control level. However, in patients after 12.4 years of therapy, urinary PC-1 was significantly decreased (P<0.05). Decreased urine PC-1 activity (P<0.05) was found also in type 1 diabetes patients with microalbuminuria and manifest nephropathy, including those with renal failure. Urinary NAGA excretion was found to be significantly increased (P=0.001) in all but the group of type 1 diabetes patients without nephropathy.

CONCLUSION

This study of urinary PC-1 in patients with type 1 diabetes shows increased excretion in newly detected patients with poor glycaemic control, but decreased excretion in patients with micro-/macroalbuminuria as well as in those without apparent kidney damage. In patients with primary glomerulonephritis, urinary excretion of PC-1 was significantly decreased and that of NAGA significantly increased compared with the excretion in healthy controls.