Browsing by keyword "Exertion"
Now showing items 1-6 of 6
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A comparison of exercise-induced hematocrit (Hct) changes between non-invasive infrared sensors (NIRS) and venous blood drawsBackground:Near Infrared spectroscopy (NIRS) uses the principle of light absorbance by hemoglobin, coupled with complex mathematical algorithms, to obtain a relative value of the blood’s hematocrit (Hct), a reflection of its oxygen carrying capacity. Because of the rapid, non-invasive nature of NIRS, it could be very useful in a variety of clinical settings for determining patients’ homological status and immediate response to treatment (e.g. during shock and trauma). Objectives:To compare the Hct values calculated using the NIRS sensor with those obtained from venous blood samples, the ultimate goal being to develop an NIRS system that accurately and continuously determines a patient’s hematocrit. Methods:Healthy volunteer subjects (n=5) were challenged with a one-handed grip exercise test, with the NIRS sensor secured to the subjects’ forearm. Subjects underwent four separate exercise sessions, each of five minutes duration and separated by thirty minute intervals. NIRS readings were taken immediately before each session (baseline values). They were then taken every minute during the exercise period, and subsequently averaged (exercise values). Venous blood samples were also taken from the same arm at each of these time points. Each blood sample was drawn into three microcapillary tubes, centrifuged, and measured on a capillary tube reader scaled for hematocrit. Results: For the NIRS data, the Hct values consistently decreased with exercise amongst all five patients. On average, the NIRS values decreased by 0.004 points of the readout (P Conclusion:Based on this set of values, there was a lack of consistency between Hct values obtained by NIRS and those taken from venous blood samples, as they trended in opposite directions. Though this was a small sample size, these differences were statistically significant and were seen consistently amongst all subjects. Further subject trials must be conducted, as well as continued work on the mathematical algorithms, to determine if a direct correlation in Hct values determined by these two techniques can be consistently recorded.
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Correlates of angina pectoris among men awaiting coronary by-pass surgeryBiomedical, behavioral, and psychological correlates of angina pectoris were identified in 204 men awaiting coronary artery by-pass graft surgery. Angina was rated by use of a precoded series of interview questions. Four circumstances of anginal symptoms were investigated: exertional, emotional, post-prandial, and while resting or sleeping. These were uncorrelated with one another, except for exertional and post-prandial. Two-thirds of these patients experienced angina less often than daily in the most recent unrestricted month. Severity of coronary artery obstruction was not positively associated with frequency or severity of any type of angina, and were primarily behavioral and psychological. Disturbances of sleep, physical inactivity, history of cigarette smoking, distressed response to life crises, life dissatisfactions, hostility, use of propranolol, duration of cardiac illness, and age were among the predictors in the multiple regression equations. These results from selected by-pass candidates may apply more directly to such persons than to unselected community residents reporting angina symptoms. The findings suggest the need for greater focus on sources of variability in myocardial oxygen supply and demand in understanding the dynamics of angina episodes.
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Functional benefits following coronary artery bypass graft surgeryWhile some studies of patients who undergo cardiac surgery have included such outcome measures as amounts of symptom reduction and rates of resumption of employment, little attention has been focused on the extent to which these patients have experienced the simple, yet very important, broad range of functional benefits that might be anticipated by clinicians to result from operation. The present report seeks to document the extent of improvement that does exist in terms of physical, sexual, and social-role functioning. In a cohort of 340 patients (age, 32 to 69 years) studied before and six months after coronary artery bypass operation, improvements were noted in each of three dimensions of functional benefit: physical functioning (fewer total activity restrictions or incapacitated days per month), sexual functioning (through increased energy and desire and decreased pain and worry), and role functions (ability to work, social participation, and pursuit of hobbies). Further improvements might be anticipated with additional months of recovery.
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Moderate to vigorous physical activity and risk of upper-respiratory tract infectionPURPOSE: A "J"-shaped model has been proposed to describe the relationship between physical activity and risk of upper-respiratory tract infection (URTI). However, little epidemiologic evidence is available to support the contention that moderately active individuals are at lowest risk of URTI. This investigation examined differences in URTI risk between physically inactive and moderately active adults. METHODS: Observational study of 547 healthy adults (49% women) aged 20-70 yr reported URTI events at 90-d intervals over 12-month of follow-up (5 evaluations). Three 24-h physical activity recalls per evaluation were obtained and averaged to quantify total moderate-vigorous activity (> or =3.0 metabolic equivalents [MET]). Associations between URTI and physical activity levels were estimated using incidence rate ratios (IRR) derived using Poisson regression while adjusting for a number of potential confounders including age, education, anxiety, cynicism, and selected dietary factors. RESULTS: Men and women reported 1.2 (1.4) and 1.2 (1.2) URTI events per year, respectively (mean [(SD]). Adjusting for gender and potential confounders, the IRR for less than 3.93, 3.94-7.15, 7.16-11.95, and > or = 11.96 MET-h.d(-1) among men, and less than 2.38, 2.39-4.09, 4.10-6.24, and > or = 6.25 MET-h.d(-1) among women, were 1.00 (referent), 0.87 (95% confidence interval [CI], 0.70-1.07), 0.88 (95% CI, 0.71-1.09), and 0.77 (95% CI, 0.62-0.95), respectively (P(trend) = 0.03). This effect was stronger in men (P(trend) = 0.03) than women (P(trend) = 0.17), although at similar expenditure levels (6-7 MET-h.d-1), risk was reduced by about 20% in men and women. Risk reduction was most pronounced in the fall of the year (P(trend) = 0.02). CONCLUSIONS: These data support the hypothesis that moderate levels of physical activity are associated with a reduced risk for URTI.
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Seasonal variation of blood cholesterol levels: study methodologyThis manuscript provides a description of the methodology used in the Seasonal Variation of Blood Cholesterol Levels (SEASON) study, with the intent of informing the scientific community of the available data sets and to invite a dialogue with scientists in complementary fields. The primary aim of the SEASON study is to describe and delineate the causes of seasonal variation of blood lipid levels in the general population. This research project is designed specifically to systematically collect and analyze a number of important variables necessary to study the role of seasonality in blood lipids and relevant covariates.
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Smoking cessation and change in diastolic blood pressure, body weight, and plasma lipids. MRFIT Research GroupCigarette smoking cessation was examined for its impact on diastolic blood pressure, weight, and plasma lipids in 3,470 special intervention males in the Multiple Risk Factor Intervention Trial. Change in smoking status (quitters vs nonquitters) was not independently associated with change in diastolic blood pressure or the subsequent use of antihypertensive medication for smokers who were normotensive at entry. More quitters (35%) became hypertensive than nonquitters (27%, P less than 0.01), although the groups had similar baseline diastolic blood pressure levels. Weight gain subsequent to cessation probably contributed to this excess incidence of hypertension in quitters. Stepped-care antihypertensive therapy lowered diastolic blood pressure similarly for hypertensive quitters and nonquitters. Weight increases of 6 lb or more by the 72-month visit occurred in 47% of quitters vs 25% of nonquitters (P less than 0.01); quitters did not differ from nonquitters in their change in total kilocalories from baseline to the 72-month visit. Quitters who gained 6 lb or more tended to be less obese at baseline, be less physically active, and smoke more cigarettes per day than those who did not gain this amount. Finally, quitters relative to nonquitters experienced an adjusted increase of 2.4 mg/dl high-density lipoprotein cholesterol, but no difference in total or low-density lipoprotein cholesterol. The implications for intervention are discussed as they relate to the common, but not inevitable, increase in weight subsequent to cessation.
