Influence of intense training program on cardio stress index

Rekrute in die gewapende magte word met talle stressors gekonfronteer, onder meer ’n strawwe opleidingsprogram wat ’n impak op hul fisiologiese funksionering kan hê. Die kardiostresindeks (KSI) is ’n nie-indringende merker van die stres wat die hart ervaar. Die berekening van die KSI is gebaseer op die duur van vaskulêre eksitasie (duur van QRS), hartkloptempo, hartritme en die standaardafwyking van die tyd wat verloop tussen elke opeenvolgende kardiale siklus (RRinterval). Die doel van die huidige studie was om die fisiologiese impak van 20 weke van strawwe opleiding op rekrute te toets, met behulp van KSI as ’n nie-indringende biomerker van kardiostres. Proefnemings is by drie geleenthede tydens die basiese militêre opleiding van rekrute, tussen die ouderdomme van 18 en 24 jaar, in die gewapende magte onderneem (week 1, week 12 en week 20) (n = 202, manlik = 115, vroulik = 87). Veranderlikes wat gemeet is, het die volgende ingesluit: rustende KSI, hartkloptempo (HKT) en bloeddruk. Data-analise is uitgevoer deur middel van gepaarde t-toetse ten einde die volgende pare te vergelyk: week 1 (basislyn) met week 12; week 12 met week 20; en week 1 met week 20. Wat die manlike rekrute betref, was die gemiddelde KSI en harttempo by al drie toetse binne normale perke. Die basislynwaardes vir vroulike rekrute was in betekenisvolle mate hoër in die eerste week. Daar was ’n algehele afname van die KSI oor die hele tydperk van 20 weke. Uit hierdie studie wil dit voorkom asof die meting van die KSI ’n nieindringende metode is om die uitwerking van afrigting op die hart te bepaal.Armed service recruits are faced with many stressors, including a strenuous training regimen that may have an impact on their physiological functioning. The Cardio Stress Index (CSI) is a noninvasive marker of the stress that the heart is experiencing. The aim of the study was to test the physiological impact of 20 weeks of intense training of armed service recruits, using CSI as a noninvasive biomarker of cardiac stress. Armed service recruits are faced with many stressors, including a strenuous training regimen that may have an impact on their physiological functioning. The CSI is a noninvasive marker of the stress that the heart is experiencing. The calculation of the CSI is based on the duration of vascular excitation (QRS duration), heart rate, heart rhythm and standard deviation of the duration of time between each successive cardiac cycle (RR-interval). The aim of the present study was to test the physiological impact of 20 weeks of strenuous training of armed service recruits, using CSI as a noninvasive biomarker of cardiac stress. Experiments were conducted at three points in time (weeks 1, 12, 20) during the basic military training of armed service recruits (n = 202, males = 115, females = 87), aged between 18 and 24 years. Variables measured include: Resting CSI, heart rate and blood pressure. Data analysis was performed, using paired t-tests for pairwise comparisons of week 1 (baseline) with week 12; week 12 with week 20; and week 1 with week 20. The average CSI and heart rate remained within normal values for male participants on all three testing occasions. However, baseline readings for females were significantly higher during week 1. There was an overall decrease in the CSI in the 20 week time frame. From this study it seems as if the CSI measurement is a noninvasive method to establish the effects of training on the health of the heart.http://www.satnt.ac.zaam201

Change in renin, cardiovascular and inflammatory markers over three years in a black and white population: the SABPA study

Abstract Background To investigate if percentage change (%∆) in renin over a 3 year follow-up is associated with %∆ in cardiovascular and inflammatory markers in a low renin bi-ethnic group. Methods Blood pressure, active renin, C-reactive protein and interleukin-6 levels of 73 black and 81 white teachers were measured at baseline and after 3 years. Results In the black group, %∆ renin was inversely associated with %∆ systolic blood pressure (β = −0.27; p = 0.011). In the white group %∆ renin was inversely associated with %∆interleukin-6 (β = −0.24; p = 0.005). Conclusions These prospective results indicate that a decrease in renin over time is associated with an increase in blood pressure in a low renin black South African cohort

South African and international reference values for lung function and its relationship with blood pressure in Africans

Background In South Africa respiratory diseases are highly prevalent, with cardiovascular disease being a manifestation. However, international reference values for lung function are commonly used, which may not be appropriate to correctly identify reduced lung function. An inverse relationship exists between lung function and blood pressure (BP) but is not investigated extensively in black South Africans. Methods We included 2010 Africans from the PURE (Prospective Urban Rural Epidemiology) study (aged > 35 years) in the North West Province. Spirometry was performed and predicted values for forced expiratory volume "in one second (FEV1) and forced vital capacity (FVC) were calculated from South African, European and" United States prediction equations. "Results With the exception of the European predicted values, all other predicted mean FEV1 and FVC were above" "80%. South African reference values displayed the highest percentages of the predicted values for FEV1 and FVC (87.9 and 99.7%, respectively.) BP increased from quintiles five to one for both FEV1 and FVC, (p for trend <0.05)." Conclusions South African reference values yielded higher percentages of predicted FEV1 and FVC values than European and US equations suggesting that South African prediction equations may be more useful when "investigating lung function in black South Africans. Elevated BP is related to reduced lung function, highlighting" the importance in managing both respiratory– and cardiovascular disease

Aldosterone and renin in relation to surrogate measures of sympathetic activity: the SABPA study

INTRODUCTION: Hypertension, particularly in black populations, is often accompanied by augmented sympathetic nervous system activity and suppressed renin activity, indicative of possible blood pressure (BP) dysregulation. The potential role of the interrelationship between the renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system in the context of low-renin conditions is unclear. We therefore explored whether surrogate measures of sympathetic activity [noradrenaline, 24-hour heart rate (HR) and percentage (%) dipping of night-time HR] relate to renin, aldosterone and aldosterone-to-renin ratio (ARR) in black and white South Africans. METHODS:We included black (n = 127) and white (n = 179) males and females aged 20-63 years. We measured 24-hour BP and HR, and calculated night-time dipping. We determined renin and aldosterone levels in plasma and calculated ARR. Noradrenaline and creatinine levels were determined in urine and the noradrenaline:creatinine ratio was calculated. RESULTS:More blacks had low renin levels (80.3%) compared to whites (58.7%) (p < 0.001). In univariate and after multivariate analyses the following significant associations were evident in only the black group: HR dipping was associated negatively with aldosterone level (β = -0.18, p = 0.024) and ARR (β = -0.20, p = 0.011), while 24-hour HR was associated positively with renin level (β = 0.20, p = 0.024). Additionally, there was a borderline significant positive association between noradrenaline:creatinine ratio and aldosterone level (β = 0.19, p = 0.051). CONCLUSIONS:The observed associations between surrogate measures of sympathetic nervous system activity and components of the RAAS in the black group suggest that the adverse effects of aldosterone and its ratio to renin on the cardiovascular system may be coupled to the effects of the sympathetic nervous system

Exploring the link between cardiovascular reactivity and end–organ damage in African and Caucasian men: the SABPA study

BACKGROUND Heart failure in the African population is reaching alarming levels. Increased afterload as a result of increased vasoconstriction during stress may lead to impaired ventricular function and stroke volume (SV) as well as vascular hypertrophy. In this study, we challenged the cardiovascular system in order to evaluate the possible contribution of indicators of α-adrenergic vasoconstriction (i.e., vascular resistance and SV reactivity) on left ventricular mass and carotid intima-media thickness (CIMT) in African and Caucasian men. METHODS We evaluated 101 African and 101 Caucasian male schoolteachers. Ambulatory blood pressure measurements were taken. Total peripheral resistance, Windkessel compliance and SV, and resting and reactivity values were obtained using a Finometer device while the Stroop color word conflict test was being applied. The electrocardiogram was recorded to obtain the Cornell product as indication of left ventricular mass. The CIMT was measured and the cross-sectional wall area (CSWA) calculated. RESULTS African men showed higher total vascular resistance resting values as well as higher positive reactivity values compared with Caucasian men. The SV decreased significantly during stress in African men while resting blood pressure and the Cornell product value increased. SV showed a consistent association with left ventricular mass (β = –0.21; P = 0.04) and CSWA (β = –0.24; P = 0.01) in single and multiple regression analyses. No such associations were evident in the Caucasian men. CONCLUSIONS African men showed a suppressed SV, possibly as a result of an increased ventricular afterload leading to end-organ damage