Effects of physical activity on weight reduction in obese middle-aged women

Women Runners' Views of Running

A survey of 156 women runners varying greatly in age, experience, and ability was conducted to find out why these women were participating in what was once stereotyped as a masculine activity and what they perceived the psychological and behavioral effects of running to be. Statistical analyses indicated that almost all subjects had positive views of running, received support for running from others, and would encourage other women to run. They reported that running made them feel significantly stronger, happier, more relaxed, better about themselves, more attractive, more feminine, less masculine, and more energetic and also that stopping running made them feel guilty, fatter, depressed, tense, and less energetic. Other common changes with running were small weight losses, decreased quantity and improved quality of food eaten, reduced smoking and drinking, and lighter menstrual periods with less severe cramps. It appears that women runners view running as a positive experience which enhances their femininity rather than increasing masculinity or androgyny.

Attendance and Fitness in Aerobics Exercise

The effects of contracting and lottery procedures on exercise attendance and improvements in fitness were assessed using 37 female college students assigned to five groups. Three of the groups utilized contract procedures, one a lottery, and the fifth was a no-treatment control group. Subjects in two of the contracting groups ran over twice as much distance as subjects in the other three groups, providing an assessment of the effects of increased training on the measure of fitness (the 12-minute test). Results showed that all contracting groups and the lottery group attended the exercise sessions significantly more than did the control group.

The effects of isolated ankle strengthening and functional balance training on strength, running mechanics, postural control and injury prevention in novice runners: design of a randomized controlled trial

BACKGROUND

Risk factors have been proposed for running injuries including (a) reduced muscular strength, (b) excessive joint movements and (c) excessive joint moments in the frontal and transverse planes. To date, many running injury prevention programs have focused on a "top down" approach to strengthen the hip musculature in the attempt to reduce movements and moments at the hip, knee, and/or ankle joints. However, running mechanics did not change when hip muscle strength increased. It could be speculated that emphasis should be placed on increasing the strength of the ankle joint for a "ground up" approach. Strengthening of the large and small muscles crossing the ankle joint is assumed to change the force distribution for these muscles and to increase the use of smaller muscles. This would be associated with a reduction of joint and insertion forces, which could have a beneficial effect on injury prevention. However, training of the ankle joint as an injury prevention strategy has not been studied. Ankle strengthening techniques include isolated strengthening or movement-related strengthening such as functional balance training. There is little knowledge about the efficacy of such training programs on strength alteration, gait or injury reduction.

METHODS/DESIGN

Novice runners will be randomly assigned to one of three groups: an isolated ankle strengthening group (strength, n = 40), a functional balance training group (balance, n = 40) or an activity-matched control group (control, n = 40). Isokinetic strength will be measured using a Biodex System 3 dynamometer. Running kinematics and kinetics will be assessed using 3D motion analysis and a force platform. Postural control will be assessed by quantifying the magnitude and temporal structure of the center of pressure trace during single leg stance on a force platform. The change pre- and post-training in isokinetic strength, running mechanics, and postural control variables will be compared following the interventions. Injuries rates will be compared between groups over 6 months.

DISCUSSION

Avoiding injury will allow individuals to enjoy the benefits of participating in aerobic activities and reduce the healthcare costs associated with running injuries.

TRIAL REGISTRATION

Current Controlled Trial NCT01900262.

Effect of obesity on high-density lipoprotein metabolism

Reduced levels of high-density lipoproteins (HDL) in non-obese and obese states are associated with increased risk for the development of coronary artery disease. Therefore, it is imperative to determine the mechanisms responsible for reduced HDL in obese states and, conversely, to examine therapies aimed at increasing HDL levels in these individuals. This paper examines the multiple causes for reduced HDL in obese states and the effect of exercise and diet--two non-pharmacologic therapies--on HDL metabolism in humans. In general, the concentration of HDL-cholesterol is adversely altered in obesity, with HDL-cholesterol levels associated with both the degree and distribution of obesity. More specifically, intra-abdominal visceral fat deposition is an important negative correlate of HDL-cholesterol. The specific subfractions of HDL that are altered in obese states include the HDL2, apolipoprotein A-I, and pre-beta1 subfractions. Decreased HDL levels in obesity have been attributed to both an enhancement in the uptake of HDL2 by adipocytes and an increase in the catabolism of apolipoprotein A-I on HDL particles. In addition, there is a decrease in the conversion of the pre-beta1 subfraction, the initial acceptor of cholesterol from peripheral cells, to pre-beta2 particles. Conversely, as a means of reversing the decrease in HDL levels in obesity, sustained weight loss is an effective method. More specifically, weight loss achieved through exercise is more effective at raising HDL levels than dieting. Exercise mediates positive effects on HDL levels at least partly through changes in enzymes of HDL metabolism. Increased lipid transfer to HDL by lipoprotein lipase and reduced HDL clearance by hepatic triglyceride lipase as a result of endurance training are two important mechanisms for increases in HDL observed from exercise.

Dieting is more effective in reducing weight but exercise is more effective in reducing fat during the early phase of a weight-reducing program in healthy humans

This study compared the relative effectiveness of two means of energy deficit, food restriction (FR) and increased physical activity (EX), on body weight, body composition and concentrations of serum leptin, insulin, glucose, and lipids in female subjects. Thirteen adult female volunteers participated in a two-phase crossover-treatment study. Each phase involved a 9-day energy deficit period and a 5-day follow up energy repletion period. A 25% energy deficit was achieved by either FR or EX. Baseline values were established prior to phase one. Results showed that FR had greater body weight loss, but less body fat loss compared to EX. FR and EX both reduced serum leptin, insulin, total triacylglycerol, LDL-C and VLDL-C concentrations. However, only EX elevated HDL-C. These effects were reversed during follow up energy repletion. Results suggest that under iso-caloric energy deficit conditions FR is more effective in reducing body weight but EX is more effective in reducing body fat and maintaining lean body mass. EX can lead to a more desirable blood lipid profile than can FR. Thus, it is desirable to include exercise in a weight reduction program.

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.

Effects of weight loss by diet alone or combined with aerobic exercise on body composition in older obese men

The effects of weight loss induced by hypocaloric diet (HD) alone or combined with aerobic exercise (AEX+HD) on body composition were compared in 61 sedentary obese men aged 60.6 +/- 1.0 years (mean +/- SEM). Twenty-three subjects in the AEX+HD intervention and 28 subjects in the HD intervention lost a similar amount of body weight (range, 3 to 22 kg). Fifteen men underwent no intervention and served as controls (CON). All groups were of similar body composition at baseline. The HD group decreased caloric intake for 10 months, whereas the AEX+HD group combined HD with AEX (3 times per week) for 10 months. The HD and AEX+HD groups had significant and comparable reductions in body weight (9.3 +/- 0.8 v 8.1 +/- 0.6 kg), fat mass (6.8 +/- 0.5 v 6.7 +/- 0.5 kg), and fat-free mass (2.1 +/- 0.3 v 1.3 +/- 0.3 kg; all P < .05). None of the variables changed significantly in the CON group. Regression lines depicting the relationship between the loss in fat-free mass and the decrease in body weight did not differ significantly in either slope or intercept between the treatment groups. These results suggest that in older obese men, hypocaloric dieting combined with AEX training does not attenuate the loss in fat-free mass that occurs during weight loss by hypocaloric dieting alone.

Comparison of energy expenditure in normal-weight and overweight women using the Caltrac Personal Activity Computer

Researchers have been unable to discern the relationship between energy expenditure and obesity because there has been no reliable, unobtrusive method to capture daily activity. The Caltrac Personal Activity Computer (Caltrac) is a small, portable accelerometer that translates motion into activity counts when worn by human subjects. It has shown high test-retest reliability during laboratory trials and has demonstrated a strong relationship to several measures of energy expenditure in some laboratory tests. In order to correlate activity with amount of body fat, 39 university women (mean age = 19.15 years, mean weight = 135 lb, SD = 27.17, range = 100-220 lb) wore Caltracs for either 3 (n = 39) or 6 (n = 26) consecutive days. Pearson product-movement correlation coefficients showed a moderate negative relationship between Caltrac counts and body mass index (BMI) (r = -.47, p < or = .01) for Days 4-6 in the subjects who wore the Caltrac for 6 days, but there was no correlation between Caltrac counts and any measures of body fat for the first 3-day period.

Insulin resistance in Mexican Americans--a precursor to obesity and diabetes?

Mexican Americans appear to have a strong genetic predisposition to insulin resistance, android obesity, and type II diabetes, apparently as a function of Native American genetic heritage. Theoretical considerations suggest that insulin resistance may be a primary factor that plays a causative role in the induction of both obesity and diabetes. Measures which promote optimal insulin sensitivity--chromium picolinate, brewer's yeast, soluble fiber supplements, metformin, very-low-fat diet, exercise training--may have value for preventing, treating, or retarding the onset of obesity and diabetes, and merit clinical evaluation in this regard. Correction of insulin resistance may also lessen cardiovascular risk, in part by reducing LDL cholesterol and improving risk factors associated with Syndrome X. These comments are likely to be valid for other Native American groups at high risk for diabetes.

Can physical activity mitigate the effects of aging in middle-aged women?

BACKGROUND

Aging is associated with an increased risk of women dying from coronary heart disease as well as from all causes combined. Alterations in the major biological risk factors for early coronary heart disease and all-cause mortality are frequently seen in aging.

METHODS AND RESULTS

The present investigation tested the hypothesis that high levels of physical activity could protect against age-associated changes in biological risk factor levels. In the Healthy Women Study, 507 women were evaluated at study entry and 3 years later. Weekly physical activity level was measured at each examination via the Paffenbarger Physical Activity Questionnaire. During the 3-year period, women increased significantly in weight, blood pressure, levels of total and low-density lipoprotein cholesterol, triglycerides, and insulin and decreased significantly in levels of total high-density lipoprotein cholesterol (HDL-C) and HDL2-C.

CONCLUSIONS

Consistent with the study hypothesis, women who reported higher levels of activity at baseline had less weight gain over time. Furthermore, women who increased their activity during the 3-year interval had the smallest increases in weight and tended to have the smallest decreases in total HDL-C and HDL2-C. The changes in lipids due to activity were largely independent of changes in body weight.

Effects of physical exercise on sex hormone binding globulin, high density lipoprotein cholesterol, total cholesterol and triglycerides in postmenopausal women

This study was performed on 18 postmenopausal female volunteers in order to examine changes in sex hormone binding globulin (SHBG), high density lipoprotein cholesterol (HDLC), total cholesterol (TC) and serum triglyceride (TG) levels in a period of four months of moderate physical exercise. While SHBG decreased significantly (from 55.3 +/- 20.9 to 48.3 +/- 21.0 nM, P < 0.05), TG increased significantly (from 87 +/- 41.7 to 120.5 +/- 57.5 mg/dl, P < 0.001). These changes were accompanied by a significant decrease (P < 0.001) in body fat content. Other parameters such as HDL-cholesterol, TC and BMI did not change significantly. Plasma levels of SHBG were negatively correlated to serum TG both at the beginning (r = 0.492, P < 0.05) and at the end (r = 0.538, P < 0.05) of the period of moderate exercise. Also, changes in SHBG were negatively correlated with changes in BMI (r = 0.585, P < 0.05) and this could indicate that SHBG levels are more related to nutritional status than androgen/estrogen imbalance.

Plasma lipid and lipoprotein profile in elderly female runners

Plasma lipid and lipoprotein profiles were compared in elderly female runners (RU: n = 15, aged 66 +/- 5 years, body fat 20 +/- 4%, training distance 35 +/- 15 km week-1, VO2max 36 +/- 4 ml kg-1 min-1, mean +/- SD) and age-matched untrained women (UT: n = 28, 66 +/- 4 years, body fat 26 +/- 6%, VO2max 26 +/- 3 ml kg-1 min-1). There were insignificant differences in total cholesterol (RU: 5.04 +/- 0.60 vs. UT: 5.48 +/- 0.85 mmol l-1), HDL-cholesterol (RU: 1.97 +/- 0.41 vs. UT: 1.91 +/- 0.36 mmol l-1) and LDL-cholesterol (RU: 2.72 +/- 0.59 vs. UT: 3.03 +/- 0.80 mmol l-1) between the two groups. Plasma triglyceride concentration of the runners was significantly lower than that of the untrained women (RU: 0.80 +/- 0.27 vs UT: 1.14 +/- 0.36 mmol l-1, P less than 0.01). No difference was observed in the LDL-cholesterol/HDL-cholesterol ratio between the two groups (RU: 1.45 +/- 0.51 vs UT: 1.64 +/- 0.53 units). These results suggest that regularly performed running of 35 km week-1 in elderly women does not further elevate their HDL-cholesterol level which is already high compared to the levels found in elderly men. However, elderly female runners appear to be protected against age-related increases in the levels of triglyceride and LDL-cholesterol.

The relation between aerobic fitness and serum cholesterol levels in a large employed population

BACKGROUND

The purpose of this epidemiologic study was to determine the extent to which aerobic fitness was associated with total cholesterol/HDL-C ratios greater than 5.0 in 10,455 adults. The confounding effects of age, gender, income, body fat, smoking, and alcohol use were also examined.

METHODS

A step test was used to estimate aerobic fitness, and serum cholesterol was measured in a certified lab. Lifestyle information was gathered using written questionnaires, and body fat was assessed using skinfold measurements.

RESULTS

High fitness levels were associated with low prevalence of elevated total/HDL-C ratios. After controlling for the potential confounders, adults classified as having excellent, very good, good, or fair aerobic fitness levels were .46, .64, .61, and .85 times as likely to have elevated ratios compared to poorly fit adults, respectively. High-level fitness was also related to high HDL-C levels and low total cholesterol levels.

DISCUSSION

Cause-and-effect conclusions are not warranted; however, poorly fit adults appear to be at increased risk of elevated levels of serum cholesterol.

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.

Leisure time exercise and lipid and lipoprotein levels in an older population

Plasma lipid and lipoprotein levels were measured in 1,019 men and 1,273 women, aged 50 to 89, who were classified according to whether they reported participation in regular strenuous exercise. In men and women, strenuous exercisers had significantly (P less than .01) higher age-adjusted high-density lipoprotein (HDL) cholesterol levels than nonstrenuous exercisers, and male strenuous exercisers also had lower plasma triglyceride levels. Adjusting for differences in cigarette smoking, alcohol consumption, or obesity did not alter these results. A subgroup of 498 consecutive men and 615 consecutive women that completed a more detailed exercise questionnaire were classified into categories of light, moderate, heavy, or no exercise. In men, age-adjusted HDL cholesterol levels were higher and triglyceride levels lower with higher exercise-intensity categories (P for trend less than .001). In the heavy exercise category, HDL cholesterol levels were 15% higher and plasma triglyceride levels were 41% lower than in the sedentary group. In women, HDL cholesterol levels were significantly higher and triglyceride levels lower at the more moderate levels of exercise. In both genders results among exercise-intensity groups did not change after adjusting for age, cigarette smoking, and alcohol consumption. In men, adjusting for obesity did not significantly alter the intergroup differences, whereas in women adjusting for body mass index or waist-to-hip ratio reduced differences in HDL cholesterol levels between exercising and sedentary participants to nonsignificance. We conclude that exercise levels attainable by older adults may significantly improve HDL cholesterol levels and could theoretically reduce the risk of ischemic heart disease.

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.

Plasma lipid and lipoprotein profiles in pre- and post-menopausal middle-aged runners

Plasma lipid and lipoprotein profiles were compared in middle-aged trained and untrained women before and after menopause. Subjects were assigned to one of four groups: (1) pre-menopausal trained (Pre-T: n = 17, aged 42 +/- 5 years, body fat 19 +/- 5%, training distance 53 +/- 20 km week-1, VO2max 49 +/- 4 ml kg-1 min-1, mean +/- SD); (2) pre-menopausal untrained (Pre-UT: n = 26, 42 +/- 5 years, 24 +/- 7%, 34 +/- 6 ml kg-1 min-1); (3) post-menopausal trained (Post-T: n = 16, 54 +/- 3 years, 20 +/- 4%, 43 +/- 19 km week-1, 41 +/- 5 ml kg-1 min-1); and (4) post-menopausal untrained (Post-UT: n = 15, 55 +/- 3 years, 25 +/- 6%, 31 +/- 3 ml kg-1 min-1). There were no significant differences in total cholesterol (range 173-194 mg dl-1), triglyceride (56-72 mg dl-1), and HDL-cholesterol (HDLC: 76-85 mg dl-1) among the four groups. LDL-cholesterol (LDLC) in the post-menopausal women (Post-T: 96 +/- 32 mg dl-1; Post-UT: 104 +/- 23 mg dl-1) tended to be higher than in the premenopausal women (Pre-T: 86 +/- 25 mg dl-1, Pre-UT: 81 +/- 23 mg dl-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting maximal oxygen uptake from treadmill testing in trained and untrained women

This study was conducted to develop an equation to predict maximal oxygen uptake from exercise time during a standardized treadmill test in women aged 29 to 75 years before and after aerobic training. Treadmill tests were administered to 181 women with measurement of maximal oxygen uptake, and an equation predicting maximal oxygen uptake was derived: maximal oxygen uptake (ml.kg-1.min-1) = 10.34 + 1.29 (exercise time), r = 0.88, standard error of the estimate = 2.1, p less than 0.0001. Thirty-three women were retested after 6 and 12 months of aerobic exercise training. Maximal oxygen uptake was predicted from the equation developed and compared with the measured values at 6 and 12 months. The predicted and measured maximal oxygen uptake values after training were not significantly different. These results indicate that it is possible to predict maximal oxygen uptake for clinical purposes with a single equation from exercise time in untrained and trained women across a wide range of ages.

Hypocholesterolemic effect of vegetable protein in a hypocaloric diet

Eleven obese volunteers took part in a 12-week study during 8 weeks of which 2 meals of their control 1000 kcal diets were replaced by a soya based liquid formula (1 month) or a milk based liquid formula (1 month). The mean weight loss per month was 2.5 kg (P less than 0.05). On the soya formula total and LDL cholesterol levels were reduced significantly over the month by 10.0 +/- 2.7% (P less than 0.01) and 17.5 +/- 5.6% (P less than 0.02), respectively. Neither the milk based formula or the control low calorie diet lowered serum cholesterol significantly over the diet period. No change was seen in serum triglycerides on any of the 3 diets. No difference was seen between treatments in 24-h urinary C-peptide excretion. The results indicated that use of a vegetable protein supplement in a weight loss program which induced moderate weight loss was associated with a reduction in blood lipids, whereas moderate weight loss on a control low calorie diet or milk based formula was not.

Nonselective beta-receptor blocker effect on high density lipoprotein cholesterol after chronic exercise

High density lipoprotein (HDL) cholesterol changes were followed in 45 men with coronary heart disease who underwent 12 weeks of monitored aerobic exercise. Twenty-five patients who were taking a nonselective beta-receptor blocking drug (Group 1) did not demonstrate a significant change in HDL cholesterol after exercise (mean difference 2.8 +/- 11.5 mg/dl), whereas patients who had not received a beta-blocking drug for greater than or equal to 3 months (Group 2) showed a significant increase (mean difference 8.4 +/- 5.5 mg/dl; p less than 0.05). However, for those patients in each group who had an initial HDL cholesterol level less than 35 mg/dl before exercise, there was a significant increase in HDL cholesterol levels (mean difference 8 +/- 6.9 mg/dl [p less than 0.02] and 11 +/- 3 mg/dl [p less than 0.001] for Group 1 and Group 2, respectively) and a significant decrease in the low density lipoprotein (LDL/HDL cholesterol ratio (mean difference -1.2 +/- 1.6 [p less than 0.05] and -0.9 +/- 0.57 [p less than 0.001], respectively). Patients in both groups who started exercise with an HDL cholesterol level greater than 35 mg/dl did not show a significant change after exercise. Patients in Groups 1 and 2 achieved similar levels of exercise training after 12 weeks and were closely matched in age, medications, alcohol intake and smoking. The results indicate that among high risk patients (with an abnormally low HDL cholesterol level) exercise training can induce an augmentation of HDL cholesterol in those receiving a beta-blocking drug similar to that of patients not receiving such a drug.

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)

Family-focused behavioral approach to weight control in children

To treat the obese child or the child who is becoming obese appropriately, the clinician must determine if the adiposity is temporary or the beginning of a permanent trend that requires intervention. The concept of the "adiposity rebound" helps with this decision. The child's family is important and contributes to his or her body adiposity through both nature--an inherited metabolic tendency towards obesity--and nurture--the eating and activity environment and the family functioning. The activity level and energy intake, which although out of balance for the obese child, may not be low or excessive when compared to recommended amounts for children of that age or to that of peers. A child-family pattern can be defined in overweight children based on presence of a metabolic tendency, energy intake, activity level, and family functioning. In looking at the pattern rather than just the child's weight, the clinician can be much more effective with a weight control program, and with proper referral for changing family functioning prior to such a program if necessary.

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.

Effectiveness of self-monitored, home-based, moderate-intensity exercise training in middle-aged men and women

The effects of 6 months of self-monitored, home-based exercise training on maximal oxygen uptake (VO2 max), body composition and plasma lipid levels of healthy, sedentary, middle-aged persons were evaluated in 60 men, aged 49 +/- 6 years, and 60 women, aged 47 +/- 5 years. Moderate-intensity training was performed 5 times per week in sessions of 47 +/- 7 minutes and 54 +/- 8 minutes for men and women, respectively. The individually prescribed range of heart rate corresponded to 65 to 77% of the peak value during symptom-limited treadmill testing (mean of 72% for men and 69% for women). Caloric expenditure per training session was approximately 345 kcal for men and 235 kcal for women. VO2 max increased 15% in men and 9% in women (both p less than 0.01). The greater increase in VO2 max in men than in women primarily reflected greater adherence to training in men (greater than or equal to 90% vs greater than or equal to 75%). The increase in VO2 max in women who showed very high adherence was comparable to that of men. Body weight decreased, by 1.5 +/- 10 kg, in men (p less than 0.05) but not in women undergoing training. No significant training-induced changes in plasma lipid levels were noted in either men or women. Baseline orientation and follow-up telephone calls required less than 1 hour of staff time per participant. Self-monitored, moderate-intensity, home-based exercise training significantly increases functional capacity in healthy, middle-aged men and women. Such training provides an alternative to group-based exercise training.

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.

Aging, long-distance running, and the development of musculoskeletal disability. A controlled study

Four hundred ninety-eight long-distance runners aged 50 to 72 years were compared with 365 community control subjects to examine associations of repetitive, long-term physical impact (running) with musculoskeletal disability and medical service utilization in a cross-section study. Runners had less physical disability than age-matched control subjects (p less than 0.01) and maintained more functional capacity (p less than 0.001) as measured by a modified Health Assessment Questionnaire Disability Index. Runners sought medical services less often, but one third of the visits that they did make were for running-related injuries. No differences were found between groups in conditions thought to predispose to osteoarthritis and musculoskeletal disability. Ligamentous laxity and family history of arthritis were similar in both groups. Runners demonstrated better cardiovascular fitness and weighed less. Differences persisted after adjustment for age, occupation, and sex, and after inclusion or exclusion of subjects with major medical problems. Musculoskeletal disability appeared to develop with age at a lower rate in runners (0.003 units per year versus 0.028) than in community control subjects, and the decreased rate was observed with both lower extremity and upper extremity functions. These data suggest positive effects of systematic aerobic running activity upon functional aspects of musculoskeletal aging.

Combined effects of exercise and restriction of energy intake on moderately obese women

The current study was designed to assess the contribution of dietary-induced weight reduction on improvements in functional capacity in moderate obesity. Twelve females (means age = 29 yr, means fat percentage = 37%) served as subjects for the study. Subjects trained on a cycle ergometer 30 min.day-1, six day.wk-1 for three or six weeks at 75 to 85 per cent of maximum heart rate (HR max). Improvements in maximal oxygen uptake (delta VO2 max I.min-1) and functional capacity (delta VO2 max ml.kg-1 min-1) were compared in an attempt to separate out training and dietary effects respectively. Measurements were also taken on both the cycle ergometer and treadmill to test for any specificity of training effects. Changes in body composition were assessed by densitometry. Following three weeks of training, there was an average increase in VO2 max ml.kg-1 min-1 on the cycle ergometer and the treadmill of 14 and 19 per cent respectively. By six weeks, this had increased to 18 and 26 per cent respectively. The contribution of weight reduction to the improvements in functional capacity was calculated to range from 20 to 33 per cent. Thus, both energy restriction and exercise training appear to be effective means of improving functional capacity in moderately obese women.

High-Frequency, Moderate-Intensity Training in Sedentary Middle-aged Women

In brief: The effects of a five-day-a-week, moderate-intensity aerobic training program were studied in previously sedentary middle-aged women. The subjects trained for ten weeks, and the periods of continuous exercise within each training session were lengthened gradually to allow them to adapt physiologically. Afterward the subjects showed a 20% improvement in V o2 max but no change in body weight or compsition. None of the women suffered an orthopedic injury. The study suggests that this type of program is a safe and effective exercise prescription for sedentary middle-aged women.

Relationship of exercise, oral contraceptive use, and body fat to concentrations of plasma lipids and lipoprotein cholesterol in young women

To investigate the relationship of exercise and oral contraceptive use to plasma lipids and lipoproteins, a cross-sectional study was designed to compare lipid levels in 96 exercising and non-exercising women who used or did not use oral contraceptives. Exercisers had significantly lower plasma triglyceride concentrations and low-density/high-density lipoprotein ratios than non-exercisers after adjustment for differences in pill type distribution between groups. Women using progestin-dominant pills had significantly lower plasma triglyceride and high-density lipoprotein concentrations and significantly higher low-density/high-density lipoprotein ratios compared with women using estrogen/progestin-balanced pills. As body fat was significantly associated with both pill type and physical activity, it is unclear how much of these lipoprotein differences were due to body fat, exercise, or pill use. Regular physical activity together with reduced body fat partially compensated for plasma lipoprotein differences associated with oral contraceptive use.

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.

Nutrition and exercise

The nutritional aspects of exercise are topics of popular interest, misconception, and active research. In this article, the authors review basic concepts of muscle metabolism; information concerning the role of exercise in weight loss; dietary supplements for athletes, including nutrition for competition; and eating disorders among those performing vigorous exercise.

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.

Effects on blood lipids and body weight in high risk men of a practical exercise program

The effects of moderate exercise on serum total cholesterol (TC), high density (HDL-C), low density (LDL-C), and very low density (VLDL-C) lipoprotein cholesterol fractions, triglycerides (TG), body weight (BW) and skinfolds (SF) were studied during a 12-week period among 23 sedentary middle-aged men. The results show that regular exercise in men eating a fat-modified diet alters in a favorable direction body fat, weight and lipoprotein fractions. Weight loss with exercise significantly increased HDL-C (P = 0.01), although this increase in HDL-C occurred after a latency period of at least 6 weeks and an average weight loss of at least 4 lbs. The amount of exercise effective in risk factor reduction is within the capacity of most middle-aged men.

Influence of exercise and life-style variables upon high density lipoprotein cholesterol after myocardial infarction

Two groups of postcoronary patients (n = 35 and n = 27) were followed for 1 year. Group 1, recruited 2 to 3 months after infarction, showed a 9% gain of maximum oxygen intake in response to an average of 878 km of walking at speeds increasing to 6.9 km.hr-1. High density lipoprotein (HDL) cholesterol showed a statistically significant, but small, increase over the period of training. If expressed as a ratio to either low density lipoprotein or total cholesterol, the change was correlated with decreases of cigarette consumption, alcohol intake, and body mass, but was unrelated to speed or training distance. Group 2 patients trained an average of 50 to 80 km a week. In this group, HDL cholesterol correlated well with the weekly running distance, declining in those subjects who detrained, and increasing in those who intensified their training. We conclude that the dose of exercise necessary for inducing any substantial increase of HDL cholesterol is about 20 km.wk-1.

Association between coronary heart disease risk factors and physical fitness in healthy adult women

We examined associations between physical fitness and risk factors for coronary heart disease in healthy women ages 18-65 years. Physical fitness was objectively determined by the duration of a maximal treadmill exercise test. Six physical fitness categories (very poor to superior), specific within 10-year age increments, were established. Mean risk factor levels varied across categories, but so did potential confounders such as age and weight. Multiple linear regression modeling was used to control for the effects of age, weight and year of exam on coronary risk factors. After adjustment, physical fitness was independently associated with triglycerides (p less than 0.001), high-density lipoprotein cholesterol (HDL-C) (p less than or equal to 0.001), total cholesterol/HDL-C ratio (p less than or equal to 0.001), blood pressure (p less than or equal to 0.001) and cigarette smoking (p less than or equal to 0.001).

Exercise, diet, or physical characteristics as determinants of HDL-levels in endurance athletes

Serum lipids, lipoproteins, apolipoproteins, physical characteristics, and 10-day dietary records of 20 male distance runners (aged 20-42 years) were compared with those of 14 sedentary controls (aged 23-34 years). Runners had significantly greater levels (mean +/- SD) of high density lipoproteins (HDL) whether estimated as HDL-cholesterol (66 +/- 12 vs 46 +/- 10 mg/dl) or as the major HDL apolipoproteins, apoA-I (170 +/- 36 vs 124 +/- 27 mg/dl) or apoA-II (39 +/- 5 vs 34 +/- 4 mg/dl). Runners were leaner with considerably less body fat (8.3 +/- 1.7 vs 16.2 +/- 3.9%) than the sedentary men despite consuming 20% more calories. Moreover, the additional calories consumed were largely carbohydrate. This comparison illustrates that high absolute quantities of dietary carbohydrate do not depress HDL levels in lean individuals engaged in exercise training. Furthermore, the results suggest that dietary factors may be as important as exercise itself in producing the lipoprotein pattern characteristic of endurance athletes.

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.

Changes in plasma lipid and lipoprotein levels in men and women after a program of moderate exercise

Levels of high-density lipoprotein (HDL) cholesterol and other lipids and lipoproteins of 24 men and 37 women were measured before and after a 10-week exercise program. The program involved three sessions of aerobic exercise each week, with 15-20 minutes of activity at 70% of maximal heart rate. Men and women had significantly different lipid patterns in response to exercise, despite equivalent increases in maximal oxygen uptake. Men showed a 5.1% increase in HDL cholesterol, a 6% decrease in low-density lipoprotein (LDL) cholesterol, and a 12.4% increase in the HDL/LDL ratio. In contrast, women showed a 1% decrease in HDL cholesterol, a 4.3% decrease in LDL cholesterol, and no significant change in HDL/LDL ratio. The number of sessions attended correlated positively with HDL/LDL changes in men and correlated negatively with HDL/LDL changes in women. These findings suggest that moderate exercise may have different effects on men and women.

High density lipoprotein cholesterol and body composition of female runners

Twenty-two women participating in an endurance running program had determinations of body composition, of plasma total cholesterol (TC) and HDL cholesterol (HDLC) concentrations before and after increasing their running by 30 miles/wk. Mean total body weight, fat weight and relative body fat showed significant decreases, while mean lean weight significantly increased. Mean HDLC increased 5 mg/dl (p less than 0.01). Although increases of HDLC correlated with increases in lean weight, exercise per se appears to increase HDLC of women.

The Effect of Track-and-Field Training on Cardiovascular Fitness

In brief: Distance runners, sprinters, jumpers, and weightmen in track and field offer advantages for studying the effects of physical exertion on selected cardiovascular parameters because they undertake a variety of training programs. Fifty-six athletes and 40 controls were tested for percent body fat, maximal oxygen consumption, and plasma lipids before and after a seven-month training season. Sprinters had lower percent body fat and distance runners had higher vo2 max values than the other groups, but all groups had low plasma lipids. However, a season of training did not beneficially change these variables-probably because the athletes were already fit.

Effect of a controlled exercise program on serum lipoprotein levels in women on oral contraceptives

The effects of a 10-wk individualized bicycle ergometer interval training program were investigated in a group of 13 sedentary women on a specific oral contraceptive (50 micrograms mestranol, 1 mg norethisterone) to determine if, like men on physical training, their high-density lipoprotein cholesterol levels would increase. Six additional women on the oral contraceptive served as a nonexercising control group. All subjects were between 18 and 30 yr and were nonsmokers. Diet and alcohol intake were stable throughout the study period, and were monitored throughout. The interval training program was three times per week, 30-min exercise per session, at 70% maximum heart rate reserve (resting heart rate + 0.7 x [maximum heart rate-resting heart rate]). Training produced increases (p < 0.05) in maximum oxygen uptake. Body weight was unchanged. However, unlike similar training programs with males, there were no significant changes in plasma high-density lipoprotein cholesterol or triglycerides. In women receiving estrogen progestin oral contraceptives, consistent exercise programs may fail to elevate high density lipoprotein cholesterol levels, consistent with an interaction of sex hormone-exercise effects and/or with the less marked effect of exercise on high-density lipoprotein cholesterol in women.

Metabolic effects of physical training

Effects of physical training on factors associated with diabetes mellitus and its increased risk for cardiovascular disease are reviewed. Plasma insulin levels are decreased by training particularly in obesity and glucose tolerance seems to be improved. Training leads also in general to diminished body fat, but this is not obligatory for the plasma insulin decrease. There are no changes in concentrations of amino acids growth hormone or catecholamines, which can explain the insulin decrease. Cortisol is decreased the days after an acute exercise as well as after training in parallel with the plasma insulin decrease. The cortisol decrease may lead to changes in insulin receptor density in tissues leading to increased insulin sensitivity. The insulin decrease seems to be due to both a decreased production (to about 2/3) and an increased clearance (to about 1/3). Physical training leads to a decrease in plasma triglycerides and to a decrease in blood pressure. All these effects of physical training seem to be beneficial in the treatment of diabetes mellitus.

Effect of exercise conditioning on plasma high density lipoproteins and other lipoproteins

Epidemiologic studies have demonstrated an inverse correlation between HDL-cholesterol and the incidence of coronary artery disease. Although physically active individuals tend to have higher HDL levels than their sedentary peers, they also have lower body weights. It has yet to be shown that physical activity by itself can raise HDL when other variables such as body weight are maintained constant. We examined the effect of a 6-week exercise conditioning program on 10 young normal subjects who were maintained on a constant composition, iso-weight diet. A training effect was documented by an increase in maximum oxygen consumption from 44 to 49 ml/min/kg and by a fall in heart rate at submaximal exercise from 120 to 109 beats/min. Total plasma cholesterol levels decreased significantly from 156 to 140 mg/dl. However, there was no significant change in plasma triglyceride, VLDL, LDL or HDL-cholesterol levels, although all these values decreased. Thus, under the conditions of this study in which diet and weight were controlled, exercise conditioning did not elevate HDL-cholesterol levels. HDL levels have been shown to be inversely related to body weight. These data are consistent with the concept that exercise conditioning may affect HDL via alterations in body weight.

Normalization of triglycerides in type IV hyperlipoproteinemia fails to correct low levels of high-density-lipoprotein cholesterol

High-density-lipoprotein (HDL) cholesterol protects against coronary heart disease, and ways to raise low HDL values are being sought. Cross-sectional population surveys have shown that HDL cholesterol is inversely related to plasma triglycerides, yet to our knowledge no longitudinal studies have shown that a decrease in elevated triglycerides will raise depressed HDL levels. We therefore used dietary therapy to lower the triglyceride levels of 29 men with Type IV hyperlipoproteinemia and evaluated the effects on HDL-cholesterol levels. Despite a reduction in triglyceride levels from 697 +/- 90 to 333 +/- 37 mg per deciliter (P < 0.01), initially low HDL-cholesterol values did not change (29 +/- 1 to 30 +/- 1 mg per deciliter). Even in a subgroup of 12 men whose triglyceride levels fell to normal (from 670 +/- 99 to 170 +/- 7, P < 0.01) and whose weight and triglycerides remained stable for two years, HDL cholesterol remained unchanged (29 +/- 1 vs. 32 +/- 1). The persistently low HDL-cholesterol level in the presence of normalization of triglycerides suggests that depressed HDL cholesterol may be an independent metabolic abnormality in Type IV hyperlipoproteinemia.

Walking for Rehabilitation: The First Step

Walking can be a positive approach for patients in rehabilitation programs. They can condition themselves, lose weight, and relieve stress without risking musculoskeletal problems.