Maximal exercise hemodynamics and risk of mortality in apparently healthy men and women

The use of exercise electrocardiography (ECG) to detect latent coronary heart disease (CHD) is discouraged in apparently healthy populations because of low sensitivity. These recommendations however, are based on the efficacy of evaluation of ischemia (ST segment changes) with little regard for other measures of cardiac function that are available during exertion. The purpose of this investigation was to determine the association of maximal exercise hemodynamic responses with risk of mortality due to all-causes, cardiovascular disease (CVD), and coronary heart disease (CHD) in apparently healthy individuals. Study participants were 20,387 men (mean age = 42.2 years) and 6,234 women (mean age = 41.9 years) patients of a preventive medicine center in Dallas, TX examined between 1971 and 1989. During an average of 8.1 years of follow-up, there were 348 deaths in men and 66 deaths in women. In men, age-adjusted all-cause death rates (per 10,000 person years) across quartiles of maximal systolic blood pressure (SBP) (low to high) were: 18.2, 16.2, 23.8, and 24.6 (p for trend $<$0.001). Corresponding rates for maximal heart rate were: 28.9, 15.9, 18.4, and 15.1 (p trend $<$0.001). After adjustment for confounding variables including age, resting systolic pressure, serum cholesterol and glucose, body mass index, smoking status, physical fitness and family history of CVD, risks (and 95% confidence interval (CI)) of all-cause mortality for quartiles of maximal SBP, relative to the lowest quartile, were: 0.96 (0.70-1.33), 1.36 (1.01-1.85), and 1.37 (0.98-1.92) for quartiles 2-4 respectively. Similar risks for maximal heart rate were: 0.61 (0.44-0.85), 0.69 (0.51-0.93), and 0.60 (0.41-0.87). No associations were noted between maximal exercise rate-pressure product mortality. Similar results were seen for risk of CVD and CHD death. In women, similar trends in age-adjusted all-cause and CVD death rates across maximal SBP and heart rate categories were observed. Sensitivity of the exercise test in predicting mortality was enhanced when ECG results were evaluated together with maximal exercise SBP or heart rate with a concomitant decrease in specificity. Positive predictive values were not improved. The efficacy of the exercise test in predicting mortality in apparently healthy men and women was not enhanced by using maximal exercise hemodynamic responses. These results suggest that an exaggerated systolic blood pressure or an attenuated heart rate response to maximal exercise are risk factors for mortality in apparently healthy individuals. ^

On the physiological effects of severe and protracted muscular exercise; with special reference to its influence upon the excretion of nitrogen.

"Reprinted from the New York medical journal, June, 1871."

Body and will; being an essay concerning will in its metaphysical, physiological, and pathological aspects,

Mode of access: Internet.

Acetazolamide reduces exercise capacity and increases leg fatigue under hypoxic conditions

Acetazolamide (Acz) is used at altitude to prevent acute mountain sickness, but its effect on exercise capacity under hypoxic conditions is uncertain. Nine healthy men completed this double-blind, randomized, crossover study. All subjects underwent incremental exercise to exhaustion with an inspired O-2 fraction of 0.13, hypoxic ventilatory responses, and hypercapnic ventilatory responses after Acz (500 mg twice daily for 5 doses) and placebo. Maximum power of 203 +/- 38 (SD) Won Acz was less than the placebo value of 225 +/- 40 W (P < 0.01). At peak exercise, arterialized capillary pH was lower and PO2 higher on Acz (P < 0.01). Ventilation was 118.6 +/- 20.0 l/min at the maximal power on Acz and 102.4 +/- 20.7 l/min at the same power on placebo (P < 0.02), and Borg score for leg fatigue was increased on Acz (P < 0.02), with no difference in Borg score for dyspnea. Hypercapnic ventilatory response on Acz was greater (P < 0.02), whereas hypoxic ventilatory response was unchanged. During hypoxic exercise, Acz reduced exercise capacity associated with increased perception of leg fatigue. Despite increased ventilation, dyspnea was not increased.

Impact of gender on risk stratification by exercise and dobutamine stress echocardiography: long-term mortality in 4234 women and 6898 men

Aims Prior research is limited with regard to the diagnostic and prognostic accuracy of commonplace cardiac imaging modalities in women. The aim of this study was to examine 5-year mortality in 4234 women and 6898 men undergoing exercise or dobutamine stress echocardiography at three hospitals. Methods and results Univariable and multivariable Cox proportional hazards models were used to estimate time to cardiac death in this multi-centre, observational registry. Of the 11 132 patients, women had a greater frequency of cardiac risk factors (P < 0.0001). However, men more often had a history of coronary disease including a greater frequency of echocardiographic wall motion abnormalities (P < 0.0001). During 5 years of follow-up, 103 women and 226 men died from ischaernic heart disease (P < 0.0001). Echocardiographic estimates of left ventricular function (P < 0.0001) and the extent of ischaernic watt motion abnormalities (P < 0.0001) were highly predictive of cardiac death. Risk-adjusted 5-year survival was 99.4, 97.6, and 95% for exercising women with no, single, and multi-vessel ischaemia (P < 0.0001). For women undergoing dobutamine stress, 5-year survival was 95, 89, and 86.6% for those with 0, 1, and 2-3 vessel ischaemia (P < 0.0001). Exercising men had a 2.0-fold higher risk at every level of worsening ischaemia (P < 0.0001). Significantly worsening cardiac survival was noted for the 1568 men undergoing dobutamine stress echocardiography (P < 0.0001); no ischaemia was associated with 92% 5-year survival as compared with death rates of &GE; 16% for men with ischaemia on dobutamine stress echocardiography (P < 0.0001). Conclusion Echocardiographic measures of inducible wall motion abnormalities and global and regional left ventricutar function are highly predictive of long-term outcome for women and men alike.

The effect of exercise on large artery haemodynamics in healthy young men

Background Brachial blood pressure predicts cardiovascular outcome at rest and during exercise. However, because of pulse pressure amplification, there is a marked difference between brachial pressure and central (aortic) pressure. Although central pressure is likely to have greater clinical importance, very little data exist regarding the central haemodynamic response to exercise. The aim of the present study was to determine the central and peripheral haemodynamic response to incremental aerobic exercise. Materials and methods Twelve healthy men aged 31 +/- 1 years (mean +/- SEM) exercised at 50%, 60%, 70% and 80% of their maximal heart rate (HRmax) on a bicycle ergometer. Central blood pressure and estimated aortic pulse wave velocity, assessed by timing of the reflected wave (T-R), were obtained noninvasively using pulse wave analysis. Pulse pressure amplification was defined as the ratio of peripheral to central pulse pressure and, to assess the influence of wave reflection on amplification, the ratio of peripheral pulse pressure to nonaugmented central pulse pressure (PPP : CDBP-P-1) was also calculated. Results During exercise, there was a significant, intensity-related, increase in mean arterial pressure and heart rate (P < 0.001). There was also a significant increase in pulse pressure amplification and in PPP : CDBP-P-1 (P < 0.001), but both were independent of exercise intensity. Estimated aortic pulse wave velocity increased during exercise (P < 0.001), indicating increased aortic stiffness. There was also a positive association between aortic pulse wave velocity and mean arterial pressure (r = 0.54; P < 0.001). Conclusions Exercise significantly increases pulse pressure amplification and estimated aortic stiffness.

Effects of a 12-week aerobic exercise intervention on eating behaviour, food cravings and 7-day energy intake and energy expenditure in inactive men

This study examined effects of 12 weeks of moderate-intensity aerobic exercise on eating behaviour, food cravings and weekly energy intake and expenditure in inactive men. Eleven healthy men (mean ± SD: age, 26 ± 5 years; body mass index, 24.6 ± 3.8 kg/m2; maximum oxygen uptake, 43.1 ± 7.4 mL/kg/min) completed the 12-week supervised exercise programme. Body composition, health markers (e.g. blood pressure), eating behaviour, food cravings and weekly energy intake and expenditure were assessed before and after the exercise intervention. There were no intervention effects on weekly free-living energy intake (p=0.326, d=-0.12) and expenditure (p=0.799, d=0.04), or uncontrolled eating and emotional eating scores (p>0.05). However, there was a trend with a medium effect size (p=0.058, d=0.68) for cognitive restraint to be greater after the exercise intervention. Total food cravings (p=0.009, d=-1.19) and specific cravings of high-fat foods (p=0.023, d=-0.90), fast-food fats (p=0.009, d=-0.71) and carbohydrates/starches (p=0.009, d=-0.56) decreased from baseline to 12 weeks. Moreover, there was a trend with a large effect size for cravings of sweets (p=0.052, d=-0.86) to be lower after the exercise intervention. In summary, 12 weeks of moderate-intensity aerobic exercise reduced food cravings and increased cognitive restraint, however, these were not accompanied by changes in other eating behaviours and weekly energy intake and expenditure. The results indicate the importance of exercising for health improvements even when reductions in body mass are modest.

Inequidad y posición socioeconómica en la reproducción de la actividad física en entornos educativos. Análisis conceptual.

Objetivo: analizar cómo influye la inequidad y la posición socio económica como factores determinantes de la conceptualización de la actividad física, desde la concepción de los determinantes sociales, de forma tal que su revisión conceptual, ayude a constituir la re configuración del concepto de actividad física. Métodos: Exploración de la literatura científica desde la revisión conceptual de artículos seleccionados, utilizando las categorías inequidad y posición socioeconómica para establecer la influencia del concepto de la actividad física en entornos educativos. Y a partir de ella interpretar la re configuración del concepto de la actividad física, desde diferentes concepciones asociadas a los determinantes sociales. Resultados: Se hallaron concepciones de los diferentes autores respecto al concepto de la actividad física. (Peso, raza, índice de masa corporal, edad). Se interpretaron distintos niveles de influencia desde la inequidad y la posición socio económica asociados a la ocupación, el género, sitio de vivienda, nivel de estudio, y la estructura física del entorno. Posteriormente se reportaron resultados desde un análisis explicativo en el cual se interpretan las concepciones de los autores en cuanto al concepto de la actividad física, y como desde ella se establecen relaciones entre la inequidad, la posición socioeconómica y los entornos educativos que incluyen diferentes aspectos sociales para finalmente poder establecer un concepto claro de la re configuración social del concepto de la actividad física, concluyendo que este nuevo concepto social de la actividad física no posee una definición exacta, el análisis de los aspectos sociales de ésta, involucra innumerables concepciones que la influencian y la determinan, en consecuencia el concepto de la actividad física debe ser un concepto en constante evolución y reconfiguración debido a la naturaleza cambiante del ser humano, de las dinámicas sociales y las asociaciones de la salud con los aspectos sociales que se presentan en el diario vivir. Así mismo se evidencia que el concepto de la actividad física se fundamenta en estudios que dejan de lado los aspectos sociales que influencia el concepto y en consecuencia la práctica de la actividad física, esta investigación establece un punto de partida frente a la re configuración social del concepto de la actividad física. Conclusiones: Diferentes organizaciones en el mundo reconocen a la actividad física como una herramienta que favorece la socialización de las personas. Es así como la actividad física, desde el deporte en el campo competitivo y la educación física desde el campo educativo exploran la interacción social de los individuos, esto permite la construcción de valores y fortalece la sana convivencia dentro de las comunidades. Esta trasformación desde el concepto de la actividad física biomédica hasta la actividad física social se evidencia en los documentos revisados, en los cuales la actividad física es estudiada desde las categorías de inequidad y posición socio económica, De ahí que en su conceptualización se involucren diferentes conceptos asociados a los determinantes sociales de la salud, que en definitiva establecen un nuevo concepto de la re configuración social de la actividad física trascendiendo desde la actividad física biomédica o fisiológica hasta un concepto complejo que incluye intereses y particularidades de las personas como lo son la ocupación, la educación, el entorno, el medio ambiente y la estructura física.

Physiological and symptomatic responses to cycling and walking in intermittent claudication

To shed light on the potential efficacy of cycling as a testing modality in the treatment of intermittent claudication (IC), this study compared physiological and symptomatic responses to graded walking and cycling tests in claudicants. Sixteen subjects with peripheral arterial disease (resting ankle: brachial index (ABI) < 0.9) and IC completed a maximal graded treadmill walking (T) and cycle (C) test after three familiarization tests on each mode. During each test, symptoms, oxygen uptake (VO2), minute ventilation (VE), respiratory exchange ratio (RER) and heart rate (HR) were measured, and for 10 min after each test the brachial and ankle systolic pressures were recorded. All but one subject experienced calf pain as the primary limiting symptom during T; whereas the symptoms were more varied during C and included thigh pain, calf pain and dyspnoea. Although maximal exercise time was significantly longer on C than T (690 +/- 67 vs. 495 +/- 57 s), peak VO2, peak VE and peak heart rate during C and T were not different; whereas peak RER was higher during C. These responses during C and T were also positively correlated (P < 0.05) with each other, with the exception of RER. The postexercise systolic pressures were also not different between C and T. However, the peak decline in ankle pressures from resting values after C and T were not correlated with each other. These data demonstrate that cycling and walking induce a similar level of metabolic and cardiovascular strain, but that the primary limiting symptoms and haemodynamic response in an individual's extremity, measured after exercise, can differ substantially between these two modes.