Cholesterol metabolism in non-obese women--Failure of physical conditioning to alter levels of high density lipoprotein cholesterol

Blood lipid and lipoprotein adaptations to exercise: a quantitative analysis

Dose-response relationships between exercise training volume and blood lipid changes suggest that exercise can favourably alter blood lipids at low training volumes, although the effects may not be observable until certain exercise thresholds are met. The thresholds established from cross-sectional literature occur at training volumes of 24 to 32 km (15 to 20 miles) per week of brisk walking or jogging and elicit between 1200 to 2200 kcal/wk. This range of weekly energy expenditure is associated with 2 to 3 mg/dl increases in high-density lipoprotein-cholesterol (HDL-C) and triglyceride (TG) reductions of 8 to 20 mg/dl. Evidence from cross-sectional studies indicates that greater changes in HDL-C levels can be expected with additional increases in exercise training volume. HDL-C and TG changes are often observed after training regimens requiring energy expenditures similar to those characterised from cross-sectional data. Training programmes that elicit 1200 to 2200 kcal/wk in exercise are often effective at elevating HDL-C levels from 2 to 8 mg/dl, and lowering TG levels by 5 to 38 mg/dl. Exercise training seldom alters total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C). However, this range of weekly exercise energy expenditure is also associated with TC and LDL-C reductions when they are reported. The frequency and extent to which most of these lipid changes are reported are similar in both genders, with the exception of TG. Thus, for most individuals, the positive effects of regular exercise are exerted on blood lipids at low training volumes and accrue so that noticeable differences frequently occur with weekly energy expenditures of 1200 to 2200 kcal/wk. It appears that weekly exercise caloric expenditures that meet or exceed the higher end of this range are more likely to produce the desired lipid changes. This amount of physical activity, performed at moderate intensities, is reasonable and attainable for most individuals and is within the American College of Sports Medicine's currently recommended range for healthy adults.

Physical activity and high density lipoprotein cholesterol levels: what is the relationship?

High density lipoprotein cholesterol (HDL-C) levels are strongly, inversely and independently associated with coronary heart disease (CHD). Increased physical activity is associated with reduced CHD mortality. This protection against CHD may partially be explained by the increase in HDL-C levels observed following aerobic exercise training. Many also agree that an exercise threshold needs to be met before such favourable changes in HDL-C metabolism can occur. Most likely, the exercise-induced changes in HDL-C are the result of the interaction amongst exercise intensity, frequency, duration of each exercise session and length of the exercise training period. Although a relative contribution of each exercise component (intensity, duration and frequency) is also likely, it has not been established. There is also substantial support for a dose-response relationship. Favourable changes in HDL-C appear to occur incrementally and reach statistical significance at approximately 7-10 miles per week or 1200 to 1600kcal. Exercise-induced changes in HDL-C may also be gender dependent. The volume of exercise required to increase HDL-C levels appears to be substantially more for women than men. This perhaps is due to higher HDL-C levels in women at baseline compared with men. However, the many other health benefits derived from increased physical activity should encourage women to participate in regular exercise regardless of the exercise effects on HDL-C levels. A practical approach in prescribing exercise for patients is to use moderate intensity exercises (70 to 80% of predicted maximal heart rate), 3 to 5 times per week, for a total of 7 to 14 miles per week. This is equivalent to approximately 1200 to 1600kcal per week. Moderate to low intensity exercise should be preferred because such exercise carries a lower risk for cardiac complications. In addition, patients are more likely to participate and sustain a lower than higher intensity exercise programme. It is also important to recognise that other modes of physical activity can also be encouraged for patients. Such activities should be associated with similar increases in HDL-C levels as long as they meet or exceed the caloric expenditure of 1200 to 1600kcal (7 to 14 miles per week of jogging).

Body composition and serum lipids in female runners: influence of exercise level and menstrual bleeding pattern

The impact of running and menstrual disturbances on regional and total body fat distribution and serum lipids was investigated in 205 women. Body composition was measured by dual-energy X-ray absorptiometry. The total fat mass in the elite runners was approximately half of the normally active's (7.3 [0.48] kg vs. 14.3 [0.49] kg, P < 0.001) (mean [SEM]). The difference was most pronounced in the abdomen (fat percentage 9.7 [0.85]% vs. 22.0 [0.88]%, P < 0.001). The elite runners tended to have a more favourable lipid profile than the normally active (NS). A significant relation was found between lipoproteins and body fatness. In comparison with the regularly menstruating runners (n = 93), the 13 runners with amenorrhea tended to have less body fat and slightly less favourable lipid profiles (NS). In conclusion, regular exercise was associated with a low abdominal fat percentage, which may affect cardiovascular risk beneficially. Running-associated menstrual dysfunctions were not significantly related to a specific body composition or serum lipid profile.

Effect of kinesiologic recreation on plasma lipoproteins and apolipoproteins in fertile women

The effect of physical exercise on lipid and apoprotein levels was studied in 31 healthy fertile women (mean age, 39.7 +/- 2.3 years) working as civil servants and leading a mostly sedentary way of life (group 1). A control group consisted of 31 age-matched women (mean age, 39.2 +/- 2.4 years) with a comparable life-style (group 2). Group 1 performed physical exercise for at least 30 minutes three times per week. They also climbed a 500-m hill at least once per week. The study lasted 6 months, ie, from May to November 1990. Changes in maximum oxygen consumption (Vo2max), body weight, body mass index (BMI), waist to hip ratio (WHR), and levels of lipids and apolipoproteins (apos) A-1 and B were compared between the two groups of subjects. During the May-November period, the control group showed an increase in body weight (P < .02), total cholesterol, high-density lipoprotein (HDL) cholesterol, HDL3, and low-density lipoprotein (LDL) cholesterol (P < .01) and a decrease in HDL2 (P < .05). In contrast, group 1 did not show any increase in total cholesterol, and their body weight decreased (P < .01). Very-low-density lipoprotein (VLDL) cholesterol and triglyceride levels decreased (P < .02), as did LDL cholesterol and HDL2 levels (P < .05), whereas HDL cholesterol and HDL3 levels increased (P < .01). There were no statistically significant changes in WHR and apo A-1 level. The findings indicated possible seasonal variations in lipoprotein levels in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of long-term exercise of moderate intensity on anthropometric values and serum lipids and lipoproteins

The influence of endurance training on serum lipids and lipoproteins was investigated in 20 sedentary males and 14 sedentary females. The total group was trained 3 to 4 times a week for 9 months. After 24 weeks all subjects ran a 15 km-race and after 36 weeks a half-marathon (21 km) race. Anthropometric values were determined before and after the training programme. Blood samples were drawn before the start of the training programme and, in order to avoid the measurement of acute effects, 5 days before both races. In the male group, median body weight and body mass were significantly decreased (p < 0.01) after nine months of training, while in the female group body weight and body mass index remained essentially unchanged. Percentage body fat, measured by skinfold thickness was significantly decreased in both groups at the end of the training programme. During the training period, median serum total cholesterol, low density lipid cholesterol and triacylglycerol concentrations decreased significantly (p < 0.01) in the male group, while in the female population the median serum lipid- and lipoprotein concentrations did not differ from pre-training values. The changes in serum lipids or lipoproteins did not correlate significantly with changes in body weight, body mass index or percentage body fat. Stepwise multiple regression showed that these changes were mostly dependent on initial concentrations in serum. Finally, no significant increase in median high density lipid cholesterol was observed in either the male or female group.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma lipid, lipoprotein and apolipoprotein profiles in Nigerian university athletes and non-athletes

The fasting plasma lipid, lipoprotein and apolipoprotein profiles were determined in 14 healthy Nigerian male athletes and controls matched for sex and anthropometric parameters. The mean levels of total cholesterol (P < 0.05), low-density lipoprotein (LDL) cholesterol, apolipoprotein (apo) AII and E were significantly lower (P < 0.01) in the athletes than in the controls. However, there were no statistically significant differences (P > 0.05) between the mean values of the plasma triglycerides, high-density lipoprotein (HDL), very low-density lipoprotein (VLDL) cholesterol, apo AI, B, Lp(a), LpA1 and CIII:NonB respectively for the athletes and controls. A priori, the potential effect on cardiovascular disease (CVD) risk was also compared using three predictor ratios - total cholesterol: HDL cholesterol (TC:HDL), LDL cholesterol: HDL cholesterol and apo B:AI. The mean of the three ratios was lower in the athletes than in the controls; however, the differences were not statistically significant (P > 0.05). Based on our data, exercise appears to decrease the TC:HDL ratio in the athletes by lowering LDL-cholesterol, while the HDL-cholesterol is unaffected. We conclude that physical activity has salutary effects on the lipid, lipoprotein and apolipoprotein profiles of healthy Nigerian men.

The acute effects of low-intensity exercise on plasma lipids in endurance-trained and untrained young adults

The acute effects of low-intensity exercise on plasma lipids were assessed in 22 healthy, normolipidaemic volunteers [mean age (SEM) 21.1 (0.2) years] of whom 11 were untrained and 11 endurance trained. Each subject walked for 2 h on a treadmill at a speed selected to elicit 30% [29.8 (3.9)%] of his or her maximal oxygen uptake. All subjects consumed a similar diet, i.e. 48% of energy from carbohydrate, for 2 days prior to the test. Pre-exercise, high-density lipoprotein (HDL) cholesterol concentration was higher in the trained group than in the untrained group [0.88 (0.06) mmol.l-1 vs 0.73 (0.09) mmol.l-1, P less than 0.05]. The walk elicited an increase in blood lactate concentration (P less than 0.01) but glucose homeostasis was well maintained by both groups. After 2 h of walking total cholesterol had increased by 13 (0.6)% (P less than 0.05). HDL cholesterol concentration increased by 17 (1.6)%, so that the ratio of total to HDL cholesterol was lower after the walk than pre-exercise (P less than 0.05). In the endurance-trained group HDL cholesterol concentration increased progressively, being 7.9 (2.4)% higher after 1 h and 19.7 (1.6)% higher after 2 h. A different response was evident in the untrained group where a rise after the 1st h [25.1 (2.3)%] was followed by a decrease towards pre-exercise values. These results show that one prolonged bout of low-intensity exercise modifies lipoprotein metabolism and hold out the interesting possibility that this response may differ in trained and untrained individuals.

Effects of exercise training on cardiovascular function and plasma lipid, lipoprotein, and apolipoprotein concentrations in premenopausal and postmenopausal women

This study examined the effects of aerobic exercise on lipid levels in premenopausal and postmenopausal women. Fifty healthy middle-aged women (mean age, 50 years) were randomly assigned to 12 weeks of either aerobic exercise (walking and jogging) or nonaerobic strength exercise (circuit Nautilus training). Concentrations of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and very low density lipoprotein cholesterol were assessed, along with apolipoprotein (apo) A-I, apo A-II, apo B, and triglycerides. To document changes in aerobic capacity, maximum treadmill testing was performed with expired-gas analysis before and after the exercise program. Aerobic exercise was associated with an 18% improvement in peak VO2. Women in the aerobic group had an increased VO2, from 26.7 to 31.4 ml/kg/min (p less than 0.0001), while the VO2 of the women in the strength training group did not change (25.8 ml/kg/min before and after). There were no differential changes in lipid levels because all subjects experienced slight reductions in high density lipoprotein cholesterol and total cholesterol and increases in apo A-I and the apo A-I to apo B ratio. There was a tendency for the aerobic group to exhibit lower levels of apo A-II and a greater apo A-I to apo A-II ratio, however. We conclude that premenopausal and postmenopausal women experience similar changes in aerobic capacity and lipid levels with exercise and that the short-term effects of aerobic and nonaerobic exercise on lipid profiles are generally comparable.

Effect of physical training on lipids, lipoproteins, apolipoproteins, lipases, and endogenous sex hormones in men with premature myocardial infarction

In 17 men, aged 27 to 54 years, with myocardial infarction 2 to 10 months before the current exercise study, we aimed to determine whether 3 months of exercise training, at a level designed to elevate high-density lipoprotein cholesterol (HDLC), would be associated with changes in endogenous sex steroid hormones and postheparin lipoprotein and hepatic lipases, and whether the changes in sex hormones, lipids, lipoproteins, apolipoproteins, and physical activity were interrelated. Supervised bicycle ergometry, 30 minutes, 3 days per week, eliciting 75% of maximum heart rate, produced a significant training effect, with a 26% increase in the duration of the exercise test at a standardized, submaximal workload (P less than or equal to .001), and a reduction in heart rate measured at a standardized submaximal workload, P = .08. After 3 months' training, mean HDLC increased 23% (30 to 37 mg/dL), P less than or equal to .001, mean apo A2 increased 19% (43 to 51 mg/dL), P less than or equal to .001, and the ratio of total cholesterol (TC) to HDLC decreased 26% (P less than or equal to .01), while estradiol (E2) levels decreased 45% (50.1 to 27.8 pg/mL), P less than or equal to .0001. After 1 and 2 months' exercise, TC (12% [P less than or equal to .001], 11% [P less than or equal to .01]), and low-density lipoprotein cholesterol (LDLC) (13% [P less than or equal to .01], 12% [P less than or equal to .01]) were reduced. Hepatic lipase decreased 16% (P less than or equal to .01) and 16% (P less than or equal to .05) after 1 and 3 months' exercise. There were no significant changes in apo A1, lipoprotein lipase, testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), or weight. By stepwise regression analysis, after 3 months' training, 66% (P = .0025) of the variance for the increase in HDLC from baseline to day 90 was accounted for independently by a decrease in triglyceride (F = 13.2, P = .003), by reduced heart rate on a fixed submaximal load (F = 12.7, P = .0035), and by a decrease in hepatic lipase (F = 5.5, P = .036). A modest, achievable exercise program can have significant cardiovascular benefit for men after myocardial infarction by ameliorating their hyperestrogenemia, reducing TC and LDLC, improving the TC to HDLC ratio, and elevating HDLC and apo A2. The increment in HDLC was related independently to improved capacity to sustain submaximal exercise and to exercise-induced reductions in triglyceride and postheparin hepatic lipase.

Management of the patient with a low HDL-cholesterol

While there is epidemiologic evidence linking a low high-density lipoprotein (HDL) cholesterol level with coronary disease events, and interventions that raise HDL while lowering low-density lipoprotein (LDL) cholesterol levels have been shown to reduce subsequent coronary events, there are no studies showing benefit from raising HDL when a low HDL level is the sole lipid abnormality. HDL is thought to play a key role in reverse cholesterol transport, removing lipids from peripheral cells, but the precise role of HDL in cholesterol metabolism is not understood. The measurement of HDL levels has not been well standardized. Reliance on ratios relating HDL to LDL or to total cholesterol may be misleading in the management of patients. It has not been shown that measuring HDL subfractions or apolipoprotein levels is superior to measuring total HDL levels in predicting coronary risk. HDL levels may be raised by hygienic measures such as smoking cessation and exercise, but a considerable amount of exercise over a long period of time is required. Alcohol consumption and weight loss through dieting inconsistently raise HDL. Estrogen therapy raises and progestational agents lower HDL. Certain beta-blocking drugs lower HDL levels. For the patient with an isolated low HDL level the hygienic measures may be advised, but drug therapy such as nicotinic acid or gem-fibrozil should be prescribed only when low HDL is accompanied by elevated LDL levels that are unresponsive to diet and hygienic measures.

Modest changes in high-density lipoprotein concentration and metabolism with prolonged exercise training

High-density lipoprotein (HDL) metabolism was studied in eight sedentary men before and after 14 and 32-48 weeks of exercise training. Subjects rode stationary bicycles 1 hour daily, 5 days each week for 14 weeks (n = 8), and 4 days each week thereafter for a total of 32-48 weeks (n = 7) of training. HDL metabolism was assessed with 125I-radiolabeled autologous HDL while subjects consumed defined diets. Maximal oxygen uptake increased 26 +/- 7% (p less than 0.001) after 14 weeks but did not increase further with more prolonged training. Body weight and estimated body fat did not change. HDL cholesterol increased 5 +/- 3 mg/dl, and triglycerides decreased 19 +/- 23 mg/dl after 14 weeks (p less than 0.025 for both), but there were no additional changes with continued training. Postheparin plasma lipoprotein lipase activity was 22% higher than baseline activity after both 14 (p less than 0.025) and 32 or more weeks of exercise. In contrast, hepatic triglyceride lipase activity was 16 +/- 8% and 15 +/- 8% lower than baseline at each measurement (p less than 0.005 for both). The disappearance rate of triglycerides after an intravenously administered fat solution was 24 +/- 24% higher at 14 weeks and 49 +/- 18% (p less than 0.005) higher after more prolonged training. Total and low-density lipoprotein cholesterol and apolipoprotein A-I and A-II concentrations at the end of study were not different from initial values. Plasma volume was 8% above initial values at both post-training measurements. The biological half-life of apolipoprotein A-I was unchanged at 14 weeks but was 10 +/- 13% longer (p = 0.07) and increased in all but one subject at the end of the study. Half-life for apolipoprotein A-II was 8 +/- 8% (p = 0.031) and 11 +/- 14% (p = 0.06) above baseline at 14 and 32 or more weeks, respectively. The synthetic rates for apolipoproteins A-I and A-II were not different from baseline values at 32-48 weeks. We conclude that 8-11 months of exercise training in previously sedentary men enhances fat tolerance and increases HDL cholesterol concentrations by prolonging HDL survival. The changes in HDL apolipoprotein survival, however, do not approximate the differences previously noted between elite endurance athletes and sedentary men. Changes in HDL cholesterol concentration were not large and suggest that the potential for exercise-related changes in HDL may be modest in many subjects.

The effect of exercise on lipid metabolism in men and women

Lipoprotein abnormalities constitute a major risk for development of cardiovascular disease. These substances, which are comprised of various lipids and proteins (apoproteins), are influenced by specific enzymes which effect their concentrations. It has been demonstrated that elevated total cholesterol and LDL cholesterol are directly associated with the development of coronary artery disease, whereas HDL cholesterol has an inverse relationship with coronary heart disease (CHD). Although more controversial, triglycerides may also be directly associated with coronary atherosclerosis. Favourable changes in lipid levels have been shown to reduce coronary mortality. Exercise may constitute a non-pharmacological approach to lipoprotein therapy. Many exogenous factors also influence lipoprotein concentrations. Changes in diet, body composition, age, as well as medication and alcohol usage may directly alter lipid levels. In addition, they can be artificially affected by the analytical method. The immediate effects of one to several bouts of physical activity appear to influence lipoprotein level. A reduction in triglycerides has been shown after physical exertion, especially among trained individuals and those with hypertriglyceridaemia. These acute changes may reflect the utilisation of both muscle and plasma triglycerides as fuels during exertion. After more prolonged training, changes in lipoproteins may also occur. However, since exercise is accompanied by many co-variables which also favourably alter these levels (e.g. lower percentage of body fat, dietary alterations), it is difficult to determine the direct effect of regular physical activity. Initial studies of exercise training's effects on total cholesterol did not differentiate changes in HDL and LDL cholesterol. Subsequent research has observed these specific cholesterol fractions. Consistent reduction in LDL cholesterol levels have not been convincingly demonstrated. Although HDL cholesterol has been shown to increase in certain studies, the response has been variable in other investigations. These latter responses may have been due to the fact that HDL cholesterol changes may be dependent on levels prior to conditioning. Assessment of HDL cholesterol subfractions (HDL2 and HDL3), which could additionally impact on cardiovascular risk reduction, have shown favourable increases in HDL2, but as yet these HDL moieties have not been adequately investigated. Reductions in triglyceride levels after training among those with elevated values and beneficial apoprotein changes post-training have been reported, although few studies exist.(ABSTRACT TRUNCATED AT 400 WORDS)

A two year randomized exercise trial in older women: effects on HDL-cholesterol

Most of the research on the level of high density lipoprotein cholesterol (HDL-C) and physical activity (PA) has been cross-sectional and thus self-selection of the exercisers may occur. In the current research, 229 white postmenopausal women, mean age 57.7 years, were randomized into either a walking or a control group. Of these 229 women, 204 women had blood samples available for lipid determinations. PA was measured subjectively by the Paffenbarger Survey and objectively with activity monitors. At baseline, there were no differences in PA, total HDL-C (HDL-TC), HDL-2C or HDL-3C between the two randomized groups. After two years, the PA of the walking group was significantly higher than the PA of the control group. This increase in PA was not accompanied by changes in any of the lipids or lipoproteins. Examination of the lipid changes in the walking group by compliance status and actual activity changes revealed little difference between groups. These results suggest that it is possible to increase physical activity in older women. However, the long-term effects of the increased activity on HDL-C were not apparent despite an observed strong cross-sectional relationship between PA and HDL-C.

The acute effect of marathon running on plasma lipoproteins in female subjects

The acute effect of running a 42.2 km marathon race on plasma lipoproteins was investigated in 12 female subjects (aged 21 to 41 years). During the race there was a significant increase (P less than 0.01) in the concentration of total plasma cholesterol. The mean post-race concentration of high density lipoprotein cholesterol (HDL-C) was 64.0 +/- 16.2 (SD) mg 100 ml-1, compared with 52.1 +/- 14.0 mg 100 ml-1 before the race, representing a significant increase (P less than 0.002). There was no significant difference in the concentration of very low density lipoprotein (VLDL) or low density lipoprotein (LDL) before and after the exercise. The mean concentration of the cholesteryl ester moiety of the HDL increased from 43.7 +/- 12.3 to 54.3 +/- 15.7 mg 100 ml-1 (P less than 0.002), while there was no significant changes in the concentration of the unesterified cholesterol, phospholipid, triacylglycerol or protein moieties of the HDL. The relative proportions of apolipoproteins A-I, A-II, C and E remained unchanged during the exercise. The changes in the concentration of each of the lipoprotein fractions observed during the marathon varied considerably between subjects. The individual increases in the concentration of HDL-C ranged from 4.1 to 28.4 mg 100 ml-1, while both increases and decreases in individual concentrations of VLDL and LDL as well as of total plasma cholesterol were observed. These observations suggest that women undergo greater changes in HDL-C concentration that men during acute exercise, while considerable variation between individuals occurs.

Physiological differences between genders. Implications for sports conditioning

It is commonly accepted that there are physiological and morphological gender differences. These differences become evident in the specific responses or magnitude of response to various training regimens. Very little difference is seen in the response to different modes of progressive resistance strength training. Men and women experience similar relative strength gains when training under the same programme. The evidence on body composition changes that occur with strength training is equivocal at this point. Researchers, however, suggest that there appears to be less muscle hypertrophy with strength improvement in women when compared to men. The data suggest that there are no differences between genders in central or peripheral cardiovascular adaptations to aerobic training. However, women in general have a reduced O2 carrying capacity. Another factor that may be responsible for the sex differences seen in the metabolic responses to exercise may be the greater, essential sex specific fat of women. Sparling and Cureton (1983) have shown that differences in similarly trained male and female distance runners are due largely to percentage body fat, less to cardiorespiratory fitness and least to running economy. Pate et al. (1985) determined that men and women who are capable of similar performances, in this case a 15 mile race, do not differ in body composition, cardiorespiratory response or metabolic response. There appear to be no differences in relative increases in VO2max for men and women when they are trained under the same intensity, frequency and duration. Mode of training also appears to elicit no sex difference. Hormonal factors lead to greater initial levels of high density lipoproteins in women. This appears to cause a smaller change in the total cholesterol-high density lipoprotein ratio than occurs with aerobic training in men. Generally, the menstrual cycle phase makes no difference to performance in women. The special cases of exercise in hot and cold environments present conflicting evidence. When men and women are matched for surface area:mass, VO2max and percentage body fat, the major disadvantages women have in the heat disappear. The question of gender differences in the cold has yet to be fully explored. When the general population is compared, men appear to have an advantage over women.

Effect of alcohol intake and exercise on plasma high-density lipoprotein cholesterol subfractions and apolipoprotein A-I in women

Abstinence from alcohol consumption for 3 weeks was followed by 3 weeks of wine intake in 18 inactive and 18 physically active premenopausal women (runners). The runners weighed less and had higher plasma high-density lipoprotein (HDL) cholesterol and lower low-density lipoprotein cholesterol levels than the inactive women. There were no differences between groups in plasma total cholesterol, triglyceride and apolipoprotein A-I concentrations. Runners had higher plasma HDL2 cholesterol concentrations than inactive women (34 +/- 17 vs 19 +/- 12 mg/dl), but HDL3 cholesterol concentration did not differ between the groups (41 +/- 10 vs 39 +/- 9 mg/dl). Addition of 35 g/day of ethanol for 3 weeks did not result in a significant change in either group for any of the variables measured. The amount of exercise appears to be a more important determinant of plasma lipoproteins and apolipoprotein A-I than alcohol intake in premenopausal women.

Serum lipids: interactions between age and moderate intensity exercise

The purpose of this study was to examine relationships between age and selected serum lipids and lipoproteins in women before and after a physical fitness programme. Twenty females 27-59 years of age who had participated in the Purdue University Physical Fitness Programme were selected and placed into one of two groups: "junior" (mean age 34, all under 40 yrs) or "senior" (mean age 50, all over 43). A two way factorial design was used to study differences in serum triglycerides (TG), total cholesterol (TC), low density lipoprotein cholesterol (LDLC), high density lipoprotein cholesterol (HDLC), and the risk ratios TC/HDLC and LDLC/HDLC associated with physical fitness and the eight month physical fitness programme. The ability of the biochemical variables to discriminate between the age groups was investigated using discriminant function analyses. The analyses of variance indicated that although the two age groups were matched on the basis of a multivariate physical fitness score (Ismail et al, 1965) the older group was heavier (p less than 0.05), and had higher systolic and pulse pressures (p less than 0.05). Both groups increased their physical fitness score from pre to post programme (p less than 0.01). No significant age related biochemical differences were noted in the univariate analyses; however, in the discriminant function analyses the biochemical variables significantly discriminated between the two groups before, but not after the programme. A decrease in serum triglycerides was observed in the more highly fit women in each age group. These findings suggest that moderate levels of physical activity may help to counteract some of the undesirable changes in the lipid profile associated with age.

The effects of exercise and weight loss on plasma lipids in young obese men

We studied the independent and combined effects of exercise training and weight loss on blood lipids under fixed diet and exercise conditions. Twenty-one obese sedentary men were randomly allocated to one of four treatment groups: (1) inactive and constant weight (control), (2) exercise training and constant weight, (3) inactive and weight loss, and (4) exercise training and weight loss. There were three study periods: a 3 week baseline period inactive and on an isocaloric diet, a 12 week treatment period, and a 3 week weight stabilization period. Exercise consisted of treadmill walking at an energy cost of 3500 kcal/wk for groups 2 and 4 with replacement caloric intake only in group 2. Group 3 reduced caloric intake by 3500 kcal/wk during the treatment period. Weight loss for groups 3 and 4 were 13.4 pounds and 13.7 pounds, respectively. Maximal oxygen uptake (mL/min) increased 6% in both exercise groups (2 and 4), and percent body fat decreased only in these groups. Regression analysis by group assignment on HDL cholesterol (HDL-C) showed that the inactivity-weight loss modality (group 3) and the exercise-constant weight modality (group 2) each significantly increased HDL-C, with an additive effect of exercise and weight loss (group 4). The rate of HDL-C change differed significantly between groups (P = 0.01). HDL-C increased 0.63, 0.61, and 1.89 mg/dL per 3 weeks or 2%, 2.4%, and 5.5% above baseline levels in groups 2, 3, and 4, respectively, while the control group decreased 0.11 mg/dL. Plasma triglycerides and very low-density lipoprotein (VLDL) cholesterol increased with exercise at constant weight (group 2) and decreased with exercise associated with weight loss (group 4). In conclusion, exercise and weight loss separately and independently increase HDL-C, and their effects are additive.

Effect of exercise training on plasma high-density lipoprotein cholesterol level at constant weight

Previous investigations have demonstrated an increase of plasma high-density lipoprotein cholesterol (HDL-Chol) and a decrease in the ratio of low density lipoprotein (LDL)-Chol/HDL-Chol (Atherogenic Index; AI) as a result of exercise training. The question of whether elevation of HDL-Chol was a consequence of weight reduction or physical training itself was unsolved. The present study was designed to prevent the weight reduction that is associated with exercise training. Five healthy and mildly active male volunteers, aged 28-31 years, participated in a 4-week training programme. They ran on a treadmill at 140-160 m/min at 0% grade for 50 min, 5 times a week, equivalent to an energy expenditure of 9 kcal/kg body weight/day. Subjects maintained their body weights by increasing calorie intake to match increased energy expenditure. No changes were observed in mean body weight, skinfold thickness, basal metabolism, and maximal oxygen uptake after the training programme. The HDL-Chol level increased from 54 to 73 mg/dl (P less than 0.05), and the reduction of AI was 30.8% (P less than 0.05) in response to the exercise training. However, the exercise training did not induce changes in plasma total cholesterol and triglyceride (TG) levels. The results of this experiment suggested that moderate physical training itself can be a potent factor for the regulation of HDL-Chol level and improvement of the AI in the absence of alterations in body weight.

Physical fitness. Its contribution to serum high density lipoprotein

The effects of exercise conditioning on serum high density lipoprotein cholesterol (HDL-C) were studied using 20 members of a regular joggers club and other healthy non-member subjects of varying degrees of habitual physical activity (253 males and 391 females). Both the HDL-C and HDL-C/serum total cholesterol (TC) levels were significantly higher with the 20 regular joggers than with the sedentary controls matched for age, TC, serum triglycerides (TG) and weight index (WI). A significant correlation was found between HDL-C/TC and the exercise conditioning value obtained by using the results of the 12-min performance test as an index among the non-member subjects. In order to ascertain the relative significance of exercise conditioning in influencing HDL-C/TC, a multiple regression analysis was conducted using HDL-C/TC as the variable criterion. The results showed that TG affected HDL-C/TC the most among both males and females, while exercise conditioning affected it second among males and fourth among females.

Exercise does not change high-density lipoprotein cholesterol in women after ten weeks of training

Effects of a 10 wk, three times per wk individualized bicycle ergometer training program were investigated in 16 healthy sedentary women 19-29 yr-old who were not taking oral contraceptives or other medications. Twelve women were in an interval type program, 6 in a continuous program, all performing 30 min exercise per session at 70% maximum heart rate reserve. Conditioning responses did not differ between the training regimens. Training produced increases in maximum oxygen uptake and physical work capacity. Percent body fat determined by underwater weighing was significantly reduced as was resting heart rate, after the training program. Maximum heart rate was unchanged. Despite changes in "fitness" variables, post-training values of high density lipoprotein cholesterol and triglycerides did not differ from pretraining. High-density lipoprotein cholesterol was significantly reduced at 2 and 5 wk of training and returned to control levels at 10 wk. Exercise conditioning leading to improved physical fitness in healthy women may not be associated with increments in high density lipoprotein cholesterol levels.

Regulation of high density lipoprotein levels

Current concepts of the structure and metabolism of high density lipoproteins are presented and factors that influence their levels in human beings are surveyed.

High-density lipoprotein cholesterol: methods and clinical significance

The known limitations and advantages of methods for determining serum high-density lipoprotein (HDL) cholesterol concentration are reviewed with special emphasis on the applicability of each method to clinical medicine. The evidence for and against the relevance of serum HDL cholesterol to the prediction of the likelihood of an individual man or woman developing clinically evident ischemic heart disease is discussed. The possibility that HDL subfractions may be more relevant to this issue is also discussed. Information about serum HDL cholesterol concentration in diseases other than ischemic heart disease is reviewed. The effect of diet, body-weight, exercise, cigarette-smoking, alcohol intake, and hyperlipoproteinemia and the effect of modification of these factors on serum HDL cholesterol levels is discussed. Finally, a practical approach to the patient with a low concentration of serum HDL cholesterol is suggested.

Plasma high density lipoproteins in coronary, cerebral and peripheral vascular disease. The influence of various risk factors

High density lipoprotein (HDL) cholesterol and the HDL/total cholesterol ratio have been measured in 440 patients with coronary, cerebral or peripheral vascular disease and in 440 matched controls. The patients were subdivided into sex- and age-groups and according to physical activity, smoking, hypertension and non-insulin-dependent and insulin-dependent diabetes mellitus. The average HDL cholesterol level was significantly decreased in all the three groups of localization of ischaemic vascular disease (IVD). Plasma HDL concentration in men was lower than in women in every age-group. Lowest values were measured in patients with cerebral vascular diseases. From among the risk factors supposed to be related to IVD, lack of physical exercise resulted in a decrease of HDL cholesterol and HDL/total cholesterol values. In all the three localizations of IVD cigarette smokers had lower HDL levels than non-smokers. The influence of hypertension on serum HDL concentration was not unidirectional. The coexistence of non-insulin-dependent diabetes and IVD resulted in decreased lipid parameters. The sera of insulin-dependent diabetics had higher HDL contents and higher HDL/total cholesterol ratios than those of non-diabetics in all the three localizations of the vascular disease in men and in women suffering from peripheral vascular disease.

Physical activity and plasma lipoprotein lipid concentrations in men

Twenty-three apparently normal untrained men aged 20--55 participated in a 4-month self-regulated training programme ending in a marathon run. Fasting plasma and lipoprotein lipid concentrations, adipose tissue lipoprotein lipase activity, anthropometric data, alcohol consumption, smoking habits, weekly mileage run and performance on a bicycle ergometer were recorded before and after the training period. Training induced an increase in high density lipoprotein cholesterol (HDL-C) concentration which was not directly related to concomitant decreases in mean very low density lipoprotein cholesterol (VLDL-C) concentration or mean total skinfold thickness. The degree of the changes in VLDL lipids and HDL-C levels were related to pretraining values, and changes in HDL-C and VLDL triglycerides (VLDL-TG) were also associated. Initial total skinfold thickness correlated inversely with the change in VLDL-TG levels during training. The pretaining concentration of VLDL-C was related to the corresponding value for HDL-C after training. The magnitude of exercise-induced changes in VLDL-C and HDL-C levels are more related to pre-training levels than to changes in measured exercise parameters, indices of obesity or adipose tissue lipoprotein lipase activity. However, the level of adiposity of subjects at the beginning of the study influenced the response of VLDL-TG levels to increased physical activity. The data suggest that VLDL contributes to the increase in HDL-C levels with exercise but is not the major source of the increment.