Stanimir Stojiljkovic

The interface of hypothalamic–pituitary–adrenocortical axis and circulating brain natriuretic peptide in prediction of cardiopulmonary performance during physical stress

Brain natriuretic peptide (NT-pro-BNP) was implicated in the regulation of hypothalamic-pituitary-adrenocortical (HPA) responses to psychological stressors. However, HPA axis activation in different physical stress models and its interface with NT-pro-BNP in the prediction of cardiopulmonary performance is unclear. Cardiopulmonary test on a treadmill was used to assess cardiopulmonary parameters in 16 elite male wrestlers (W), 21 water polo player (WP) and 20 sedentary age-matched subjects (C). Plasma levels of NT-pro-BNP, cortisol and adrenocorticotropic hormone (ACTH) were measured using immunoassay sandwich technique, radioimmunoassay and radioimmunometric techniques, respectively, 10min before test (1), at beginning (2), at maximal effort (3), at 3rdmin of recovery (4). In all groups, NT-pro-BNP decreased between 1 and 2; increased from 2 to 3; and remained unchanged until 4. ACTH increased from 1 to 4, whereas cortisol increased from 1 to 3 and stayed elevated at 4. In all groups together, ΔNT-pro-BNP2/1 predicted peak oxygen consumption (B=37.40, r=0.38, p=0.007); cortisol at 3 predicted heart rate increase between 2 and 3 (r=-0.38,B=-0.06, p=0.005); cortisol at 2 predicted peak carbon-dioxide output (B=2.27, r=0.35, p<0.001); ΔACTH3/2 predicted peak ventilatory equivalent for carbon-dioxide (B=0.03, r=0.33, p=0.003). The relation of cortisol at 1 with NT-pro-BNP at 1 and 3 was demonstrated using logistic function in all the participants together (for 1/cortisol at 1 B=63.40, 58.52; r=0.41, 0.34; p=0.003, 0.013, respectively). ΔNT-pro-BNP2/1 linearly correlated with ΔACTH4/3 in WP and W (r=-0.45, -0.48; p=0.04, 0.04, respectively). These results demonstrate for the first time that HPA axis and NT-pro-BNP interface in physical stress probably contribute to integrative regulation of cardiopulmonary performance.

Relationships among the muscle strength properties as assessed through various tests and variables

We tested the hypotheses that the individual strength properties depend on the applied test and the variable extracted, rather than on the muscle group tested. Flexor and extensor muscles acting in the knee and elbow joint were tested in 58 participants. The standard strength test (SST; based on sustained maximum contraction) and alternating consecutive maximum contractions (ACMCs; alternating contractions of antagonistic muscles) performed under static conditions were separately applied to provide the maximum force (F) and the rate of force development (RFD) of each tested muscle. The principal component analysis applied on all 16 variables revealed three factors that explained 85.5% of the total variance. Contrary to our hypotheses, the individual factors were loaded with the variables recorded from individual muscles, rather than with either the particular variables or tests. The present findings suggest that recording both F and RFD in routine strength testing procedures could be redundant since they may assess the same strength property of the tested muscle. In addition, ACMC may be a feasible alternative to SST since it could assess the same strength properties from two antagonist muscles through a single trial, while being based on relatively low and transient forces.

Exercise capacity is not impaired after acute alcohol ingestion: a pilot study.

The usage of alcohol is widespread, but the effects of acute alcohol ingestion on exercise performance and the stress hormone axis are not fully elucidated. We studied 10 healthy white men, nonhabitual drinkers, by Doppler echocardiography at rest, spirometry, and maximal cardiopulmonary exercise test (CPET) in two visits (2–4 days in between), one after administration of 1.5 g/kg ethanol (whisky) diluted at 15% in water, and the other after administration of an equivalent volume of water. Plasma levels of NT-pro-BNP, cortisol, and adrenocorticotropic hormone (ACTH) were also measured 10 min before the test, at maximal effort and at the third minute of recovery. Ethanol concentration was measured from resting blood samples by gas chromatography and it increased from 0.00 ± 0.00 to 1.25 ± 0.54‰ (P < 0.001). Basal echocardiographic and spirometric parameters were normal and remained so after acute alcohol intake, whereas ACTH, cortisol, and NT-pro-BNP nonsignificantly increased in all phases of the test. CPET data suggested a trend toward a slight reduction of exercise performance (peak VO2 = 3008 ± 638 vs. 2900 ± 543 ml/min, ns; peak workload = 269 ± 53 vs. 249 ± 40 W, ns; test duration 13.7 ± 2.2 vs. 13.3 ± 1.7 min, ns; VE/VCO2 22.1 ± 1.4 vs. 23.3 ± 2.9, ns). Ventilatory equivalent for carbon dioxide at rest was higher after alcohol intake (28 ± 2.5 vs. 30.4 ± 3.2, P = 0.039) and maximal respiratory exchange ratio was lower after alcohol intake (1.17 ± 0.02 vs. 1.14 ± 0.04, P = 0.04). In conclusion, we showed that acute alcohol intake in healthy white men is associated with a nonsignificant exercise performance reduction and stress hormone stimulation, with an unchanged exercise metabolism.

Brain natriuretic peptide predicts forced vital capacity of the lungs, oxygen pulse and peak oxygen consumption in physiological condition

Brain natriuretic peptide (NT-pro-BNP) is used as marker of cardiac and pulmonary diseases. However, the predictive value of circulating NT-pro-BNP for cardiac and pulmonary performance is unclear in physiological conditions. Standard echocardiography, tissue Doppler and forced spirometry at rest were used to assess cardiac parameters and forced vital capacity (FVC) in two groups of athletes (16 elite male wrestlers (W), 21 water polo player (WP)), as different stress adaptation models, and 20 sedentary subjects (C) matched for age. Cardiopulmonary test on treadmill (CPET), as acute stress model, was used to measure peak oxygen consumption (peak VO2), maximal heart rate (HRmax) and peak oxygen pulse (peak VO2/HR). NT-pro-BNP was measured by immunoassey sandwich technique 10min before the test - at rest, at the beginning of the test, at maximal effort, at third minute of recovery. FVC was higher in athletes and the highest in W (WP 5.60±0.29 l; W 6.57±1.00 l; C 5.41±0.29 l; p<0.01). Peak VO2 and peak VO2/HR were higher in athletes and the highest in WP. HRmax was not different among groups. In all groups, NT-pro-BNP decreased from rest to the beginning phase, increased in maximal effort and stayed unchanged in recovery. NT-pro-BNP was higher in C than W in all phases; WP had similar values as W and C. On multiple regression analysis, in all three groups together, ΔNT-pro-BNP from rest to the beginning phase independently predicted both peak VO2 and peak VO2/HR (r=0.38, 0.35; B=37.40, 0.19; p=0.007, 0.000, respectively). NT-pro-BNP at rest predicted HRmax (r=-0.32, B=-0.22, p=0.02). Maximal NT-pro-BNP predicted FVC (r=-0.22, B=-0.07, p=0.02). These results show noticeable predictive value of NT-pro-BNP for both cardiac and pulmonary performance in physiological conditions suggesting that NT-pro-BNP could be a common regulatory factor coordinating adaptation of heart and lungs to stress condition.

Efekti programa High-low aerobika na morfološke karakteristike i funkcionalne sposobnosti učenica osmih razreda osnovne škole

Istraživanje je sprovedeno sa ciljem da se utvrde efekti programirane nastave high-low aerobika na morfoloske karakteristike i funkcionalne sposobnosti ucenica osmih razreda osnovne skole. Istraživanje je primenjeno na uzorku 31 ucenice, osmih razreda Osnovne skole „Vožd Karađorđe” iz Leskovca, koje su bile podeljene u dve grupe: eksperimentalnu (N=16) i kontrolnu (N=15). Eksperimentalni faktor predstavljala je posebno programirana nastava high-low aerobika, koja je trajala osam nedelja i realizovala se u okviru redovne nastave fizickog vaspitanja. Kontrolna grupa pohađala je program propisan po Nastavnom planu i programu, Ministarstva prosvete Republike Srbije. Efekti programa high-low aerobika praceni su u prostoru morfoloskih karakteristika (osam varijabli) i u prostoru funkcionalnih sposobnosti (jedna varijabla). Rezultati istraživanja su pokazali da je program high-low aerobika, uticao na poboljsanje morfoloskih karakteristika i funkcionalnih sposobnosti ucenica, u odnosu na ucenice iz kontrolne grupe. Dobijeni rezultati istraživanjem ukazuju na pozitivne aspekte high-low aerobika na ocuvanje pravilnog rasta i razvoja dece.

[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.