Effects of smoking cessation on weight gain, metabolic rate, caloric consumption, and blood lipids.

Thirteen sedentary adult females successfully quit smoking cigarettes for 48 days. Mean daily caloric consumption increased 227 kcal and mean weight gain was 2.2 kg. There were no measurable acute effects of smoke inhalation and no chronic net effects of smoking cessation on resting metabolic rate, as determined by oxygen consumption and respiratory exchange ratio. After 1 yr, subjects who continued to abstain gained an average of 8.2 kg. HDL-cholesterol increased 7 mg/dl in 48 days; however, this effect was lost in those who returned to smoking. Increased caloric consumption accounted for 69% of weight gained immediately following smoking cessation. Factors other than changes in caloric consumption and metabolic rate may be responsible for a significant proportion (31%) of the weight gained in individuals who quit smoking.

Cigarette smoking, exercise and high density lipoprotein cholesterol.

Cigarette smoking is associated with depressed levels of HDL-C, whereas exercise is associated with elevated levels of HDL-C. The purpose was to determine effects of smoking and exercise on blood lipids and lipoproteins in middle-aged males. It was hypothesized that smoking may attenuate the effects of exercise to elevate HDL-C. A total of 269 males (70 smokers) met all criteria for inclusion in the study population. Age, height, weight, body fatness via hydrostatic weighing, daily caloric consumption and alcohol intake, and smoking habits and history were determined. Interviews concerning physical activity patterns were conducted and cardiovascular responses to treadmill exercise were determined. Subjects were grouped as sedentary (low activity), participants in vigorous recreational activities (moderate activity) and joggers/runners (high activity). Analysis of covariance with adjustments for factors which may affect blood lipids and lipoproteins was employed. Smokers demonstrated lower HDL-C and higher total cholesterol levels than nonsmokers. High activity subjects demonstrated significantly higher HDL-C levels than the low and moderate groups which did not differ. High activity smokers did not differ from low activity nonsmokers with respect to HDL-C. This supports the proposed hypothesis. Nonsmokers were higher in weight and body fatness than smokers even though smokers consumed 288 more calories per day on the average. This suggests that smoking may account for a significant number of calories through altered metabolism or some other means.

Smoking multiple high- versus low-nicotine cigarettes: impact on resting energy expenditure.

The thermic effect of smoking multiple cigarettes varying substantially in nicotine yield was investigated. Three treatments were imposed: nonsmoking at baseline, smoking six low-nicotine (0.8 mg nicotine) cigarettes (LOW), and smoking six high-nicotine (1.74 mg nicotine) cigarettes (HIGH). An initial increase of 6.8% in resting energy expenditure (REE) above baseline REE occurred after consumption of two consecutive cigarettes for both the HIGH and LOW treatments. With consumption of more cigarettes, the peak increase for the HIGH treatment was 9.3%, significantly greater than the peak of 5.9% for the LOW. Averaged over 2 hours, the HIGH treatment significantly increased REE by 6.9% and the LOW treatment significantly increased REE by 5.2%. Expired carbon monoxide (CO) measurements indicated that LOW cigarettes were smoked more aggressively than HIGH cigarettes. It was concluded that, initially, the nicotine yield of cigarettes is not an important influence on the thermic effect of smoking. But over a longer period and after multiple cigarettes, the nicotine yield may become an important influential factor.

Influence of worksite environmental tobacco smoke on serum lipoprotein profiles of female nonsmokers.

The purpose of this study was to examine the influence of environmental tobacco smoke (ETS) in the workplace on high-density lipoprotein cholesterol (HDL-C), HDL-C subfractions, and apolipoprotein (apo) A-I and apo B in female workers. Premenopausal women free from factors known to influence HDL-C (cigarette smoking, vigorous physical exercise, etc) who were not taking oral contraceptives, were moderate consumers of alcohol, caffeine, and dietary fat, and were between the ages of 21 and 50 years participated in one of two groups: (1) nonsmokers who had never smoked cigarettes and were generally free from ETS exposure (nonsmokers), and (2) nonsmokers who had never smoked but were subjected to concentrated doses of ETS at least 6 hours per day, 4 days per week, for at least 6 consecutive months (ETS-exposed). A third group consisting of current cigarette smokers who smoked a minimum of 20 cigarettes per day for at least the past 5 consecutive years served as smoking control (smokers). Subjects were matched by group as closely as possible with regard to criteria that can influence blood lipoprotein levels. Participants were solicited from taverns and restaurants where they were employed. It was hypothesized that individuals chronically exposed to ETS would demonstrate unfavorable lipoprotein profiles. Results showed that HDL-C, HDL2, and apo A-I were significantly (P < .05) depressed for ETS-exposed and smokers as compared with nonsmokers. Values for ETS-exposed were not different from those for smokers. Total cholesterol, triglycerides, HDL3, and apo B did not differ among the three groups. It was concluded that excessive exposure to ETS in female workers can have deleterious effects on HDL-C, HDL2, and apo A-I in nonsmokers that are similar to effects observed in cigarette smokers. It is possible that these effects increase coronary artery disease (CAD) risk.

Cigarette smoking, physical activity, and alcohol consumption: relationship to blood lipids and lipoproteins in premenopausal females.

A total of 164 premenopausal female subjects were randomly selected for evaluation from a much larger pool of volunteers. The relationships between blood lipid and lipoprotein levels as dependent variables and cigarette smoking, physical activity, and alcohol consumption were determined from partial regression coefficients. A lower HDL-C level (10.1 mg/dL) was seen in smokers v nonsmokers. For each ounce of alcohol consumed, HDL-C level was higher by 2.8 mg/dL, and greater physical activity was associated with a higher HDL-C level of 8.6 mg/dL. An analysis of covariance with covariance adjustments for age and body fat revealed that smokers who regularly exercise or consume alcohol had significantly lower HDL-C levels than nonsmokers with similar habits. Subjects who both exercise and consume alcohol demonstrated higher HDL-C levels than those who indulge in one or the other separately. Results suggest that cigarette smoking may attenuate the effects of chronic exercise or alcohol consumption, or of both, to raise HDL-C levels. Also, chronic exercise and alcohol consumption may exert an additive effect, raising HDL-C level.

Intensity and energy cost of weighted walking vs. running for men and women.

The energy cost and intensity of exercise performed at 0% grade were determined for walking at 2, 3, and 4 mph, running at 5, 6, and 7 mph, and walking at 2, 3, and 4 mph with ankle and/or hand weights. Subjects were young moderately trained males (4) and females (3). The energy cost per kilogram of body weight was similar between sexes, and data were combined for among-treatment comparisons. Intensity of effort and energy cost per minute and per mile were increased when weight was added during walking and were increased more with hand weights compared with ankle weights regardless of speed. The average increase in O2 uptake (ml X kg-1 X min-1 X 100 g-1 of added wt) was 0.8% for ankle, 1.3% for hand, and 0.9% for ankle and hand weights. Gross energy cost per mile during weighted walking (120-158 kcal/mile) was comparable to and in some cases exceeded that of running which was independent of speed (120-130 kcal/mile). During nonweighted walking, the energy cost (kcal/mile) was significantly greater at 4 mph compared with 2 and 3 mph which did not differ. The intensity of walking at 4 mph with ankle and hand weights was comparable to running at 5 mph.

Gas exchange and lactate anaerobic thresholds: inter- and intraevaluator agreement.

Twenty-four coded graph sets of gas exchange variables and blood lactate concentration (LA) plotted against time at 15-s intervals were analyzed by nine evaluators who determined the gas exchange (ATGE) and LA (ATLA) anaerobic thresholds. In addition, ATGE and ATLA were determined by a linear regression computer program. Agreement between ATGE and ATLA was poor; the median intraclass correlation coefficient (ri) was 0.53. Among evaluators, ATLA agreement (median ri = 0.81) was better than ATGE agreement (median ri = 0.70). In general, the ability of any evaluator to choose similar values from duplicate plots for either ATGE (median ri = 0.97) or ATLA (median ri = 0.995) was good. There was better agreement between the mean ATLA of the evaluators and the computer ATLA (ComLA) (ri = 0.88) than between the mean ATGE of the evaluators and the computer ATGE (ComVE), (ri = 0.58). Agreement between ComVE and ComLA was poor (ri = 0.29). These results suggest that ATGE does not accurately predict ATLA and that different evaluators choose different thresholds from the same data. Further assessment of the validity and precision of ATGE based on breath-by-breath and minute-by-minute data is needed.

Body fat content and serum lipid levels.

The relationship between the percentage of body fat and serum lipids was studied in middle-aged persons (112 men and ninety-two women) whose body fat levels were determined by hydrostatic weighing. Individuals classified as "overfat" exhibited significantly higher total serum cholesterol and total serum triglycerides than those classified as "normal fat " A trend for lower high-density-lipoprotein cholesterol levels in overfat women and higher low-density-lipoprotein cholesterol in both overfat men and women was observed. Overfat men and women had significantly higher very-low-density-lipoprotein cholesterol levels. These findings suggest that an accumulation of excess body fat may result in unfavorable serum lipid levels.

Risk versus effort in the assessment of motor fatigue.

The choice of probability leffort (COPE) devices require fatigued subjects to choose between risk and effort. In a first experiment, where fatigue was induced by an intense or by a prolonged motor task and where the required effort was perceptual, the fatigue did not generalize to the test mode. A second experiment used motor fatigue of the arm or leg, and tested with arm muscle effort, showing that subjects fatigued with either limb chose riskier alternatives in order to avoid the effort. The data correlated with self-rated fatigue, and closely paralleled earlier work using perceptual fatigue and perceptual effort.

Exercise and the elderly.

Data from cross-sectional studies suggest that VO2max declines in adulthood at a rate of 0.40-0.45 ml.kg-1.min-1 per year in males and 0.30 ml.kg-1.min-1 per year in females. Longitudinal studies suggest that the loss is much greater for males, approximating 1.0 ml.kg-1.min-1 per year or more. The rate of loss may be greater in sedentary compared to active individuals. The decline in VO2max with age appears to be inevitable, and a major contributing factor may be the decline in maximal cardiac output. A reduced maximal heart rate is a consistent finding, and this may be due to decreased end-organ sensitivity to catecholamines. Maximal stroke volume may or may not decrease, and physical training status may be a determining factor. The most recent evidence suggests increased dependence upon the Frank-Starling mechanism, resulting in an increased stroke volume to offset the decline in maximal heart rate. Cardiac output is thought to be maintained in this manner. Use of this mechanism may depend upon the absence of underlying disease. Therefore, investigators who vigorously screen potential subjects for occult coronary disease may report findings different from those who do not. Maximal a-vO2 difference may or may not decline in the elderly. The research is divided, and there is support for both beliefs. Several factors typical of the elderly, including a decline in muscle mass, increased blood distribution to the skin during exercise, and a potentially lower capillary/fiber ratio, would contribute to a lower a-vO2 difference. On the other hand, in those subjects with reduced cardiac output, there may be greater dependence upon a-vO2 difference during maximal exercise. Pulmonary function does not appear to limit VO2max, although the elderly may be less efficient while breathing during exercise. However, the higher ventilation and higher ventilatory equivalent for oxygen observed during submaximal exercise could be due to higher relative stress in the elderly. Elderly males and females are capable of demonstrating a training effect in response to endurance training regardless of previous physical activity patterns and current training status. The degree of change with training, expressed in relative terms, appears to be comparable to that demonstrated by younger subjects. Physiological factors contributing to an increased VO2max as a result of training appear to be similar in elderly and younger subjects, with the possible exception of no change in maximal a-vO2 difference in the elderly. This point is somewhat controversial.(ABSTRACT TRUNCATED AT 400 WORDS)

Validity and Reliability of Subjective Ratings of Perceived Exertion During Work.

The purpose of the present investigation was to determine the reliability of the Borg (RPE) Scale under a variety of experimental conditions. Fourteen sedentary female subjects performed six repeated work tasks (12 in all) distributed over four experimental testing sessions and presented in a randomized order. Work tasks involved treadmill walking and jogging, cycling, and stool stepping. Work loads were presented in progressive (step-wise), oscillating, or single load submaximal intensities. During work, heart rate (HR) was recorded at regular intervals and ratings of perceived exertion (RPE) were elicited either at regular intervals (interval) or only during the final minute of work (terminal). RPE responses were found to be highly reproducible whether interval or terminal. High correlations were also found between interval and terminal RPE responses. RPE demonstrated a strong relationship with HR and work intensity. It was concluded that category ratings of perceived exertion according to the Borg (RPE) Scale offer a sensitive and reliable measure of stress encountered during work.

Step increment versus constant load tests for determination of maximal oxygen uptake.

Ten male subjects performed five maximal treadmill running tests at 7 mph. Tests included two (test-retest) progressive, step increment (2 1/2% grade elevation), discontinuous tests (DCT); a progressive, step increment, continuous test (ct) and two constant load tests (CL and CL +2 1/2%). A DCT test was performed first for establishment of peak elevation levels as constant load tests were performed at the peak elevation level attained (CL) and at a level 2 1/2% higher (CL + 2 1/2%). The second DCT test and the remaining three tests were administered randomly. Peak preformance capability (operationally defined as duration at highest grade elevation) was markedly reduced during progressive tests as compared with constant load tests. There was a similar reduction in peak performance capability during the CT test as compared with DCT test. Maximal oxygen uptake (VO2max) was quite similar among the various tests. It was concluded that VO2max attained during progressive, step increment, tests is unaffected by cumulative submaximal work. Discontinuous and continuous progressive tests provide similar VO2max results.

Maximal oxygen uptake during treadmill walking and running at various speeds.

Three groups of male subjects, average fitness (AF, N = 12), high fitness (HF, N = 7) and highly fit competitive race walkers (CRW, N = 3) performed maximal treadmill tests walking at 3.5 and 4.5 mph and running at 4.5, 5.5, 7.0, and 8.5 mph. In addition, the HF group performed a running test at 10.0 mph and the CRW group performed a walking test at 5.5 mph. All maximal oxygen uptake (VO2 max) tests with the exception of the 3.5 mph walking test (modified Balke test) were discontinuous in nature. VO2 max obtained from walking tests was similar regardless of speed within each group. Walking VO2 max was significantly lower than running VO2 max which was found to be similar over a speed range of 4.5 to 8.5 mph in the AF group. Running at 4.5 mph (HF group) and 4.5 and 5.5 mph (CRW group) resulted in lower VO2 max levels than running at speeds greater than or equal to 7.0 mph. Associated physiological variables (heart rate, ventilation, and respiratory exchange ratio) did not demonstrate a discernable pattern with reference to mode of locomotion (walking versus running) or speed. It was concluded that VO2 max elicited during walking is independent of speed and less than VO2 max obtained during running. Running VO2 max was interrelated with speed of running and state of training.

Effects of pedalling rate changes on maximal oxygen uptake and perceived effort during bicycle ergometer work.

The present investigation determined the efficacy of progressively increased pedalling rate (P) or resistance (R) during assessment of maximal oxygen uptake (VO2max) on the bicycle ergometer. Twenty male and nine female university students performed randomly assigned discontinuous P and R maximal stress tests. Male subjects immedicately repeated each test within the same experimental session. Regardless of test protocol, VO2max was quite similar. Magnitude estimates of perceived effort were significantly lower for male subjects during P testing (P less than .05) and 80% of male subjects preferred P testing. Conversely, magnitude estimates were significantly lower for female subjects for R testing (P LESS THAN .05). P testing could be reliably repeated within the same experimental session whereas with R testing VO2max was significantly reduced (P LESS THAN .05). It was concluded that progressively increased pedalling rate offers a physiologically acceptable means to VO2max assessment on the bicycle ergometer for males and females. In addition, progressively increased pedalling rate offers a perceptually preferable means to VO2max assessment for males but not for females.

Effects of prolonged warm-up exercise above and below anaerobic threshold on maximal performance.

The purpose of the present study was to determine the effects of prolonged warm-up exercise above and below anaerobic threshold (AT) on maximal performance. Warm-up exercise consisted of pedalling the Monark cycle ergometer at either 40% (Below AT) or 68% (Above AT) of VO2max for 60 min. Each maximal performance consisted of two 40 s bouts of "all out" pedalling on the Monark cycle ergometer against 5.5 kg resistance separated by a 5 min rest period. These tests were administered on two occasions without warm-up exercise and were found to be reproducible for work output and peak blood lactate concentration. Below AT warm-up exercise significantly increased core temperature with no increase in steady state blood lactate concentration and was thus representative of a desired warmed-up status. This condition did not contribute to an improved maximal performance. Above AT warm-up exercise resulted in significant increases in core temperature and steady state blood lactate concentration. Work output and peak blood lactate concentration for maximal exercise were significantly decreased. It was concluded that task specific prolonged warm-up exercise below AT does not contribute to an improved maximal performance of the type employed in the present study. Following warm-up exercise above AT, maximal performance was impaired. This was attributed to probable glycogen depletion in fast twitch muscle fibers which in turn may have contributed to a decreased lactate production.