Body mass index and the risk of COPD

BACKGROUND

Previous studies have documented the prognostic value of low body weight in patients with COPD and also in general populations. However, it is not clear whether low body weight is a risk factor for COPD or a consequence of established disease.

STUDY OBJECTIVE

To determine whether asymptomatic subjects with low initial body mass were at a greater risk of having COPD develop during subsequent follow-up.

DESIGN AND SUBJECTS

Observational retrospective study of 458 male and 192 female participants (age range, 40 to 73 years) in the Baltimore Longitudinal Study of Aging. At baseline, the participants did not have COPD. After mean follow-up periods of 10.2 years for the men and 6.4 years for the women, 40 men and 7 women received a diagnosis of COPD.

METHODS

Cox proportional-hazards regression models were used to assess the relationship between COPD diagnosis and baseline body mass index (BMI) in men.

RESULTS

The risk of COPD developing in men varied inversely with baseline BMI, even after adjusting for other risk factors, including cigarette smoking, age, FEV(1) percent predicted, abdominal obesity, and educational status. In men, the relative risk of COPD developing for the lowest BMI tertile relative to the highest tertile was 2.76 (95% confidence interval, 1.15 to 6.59). The small number of women who had COPD did not allow us to draw conclusions regarding BMI as a risk factor for COPD.

CONCLUSION

After controlling for confounding variables, men with low BMI are at increased risk for getting COPD.

Can exercise conditioning be effective in older heart failure patients?

Over the past two decades, considerable evidence has accrued that heart failure patients benefit from aerobic exercise training programs. Improvements in peak oxygen consumption and its components as well as increases in ventilatory threshold and submaximal endurance have been documented from such programs. Despite the fact that heart failure predominates among the elderly, very few training studies have included substantial numbers of older individuals, particularly older women. The limited data available suggests that older heart failure patients derive similar benefits from training as younger patients. A major challenge for the future is the inclusion of representative proportions of elderly individuals in heart failure training trials.

A comparison of longitudinal changes in aerobic fitness in older endurance athletes and sedentary men

OBJECTIVES

To compare the longitudinal changes in maximal aerobic capacity (VO2max) in healthy middle aged and older athletes and sedentary men.

DESIGN

A cohort study with mean follow-up of 8.7 years (range 4.0-12.8).

SETTING

Outpatient research at a tertiary hospital.

PARTICIPANTS

Forty-two healthy, middle aged, and older athletes (initial age 64 +/- 1 year) and 47 healthy sedentary men of comparable age recruited for research studies.

MEASUREMENTS

VO2max during a maximal treadmill test.

RESULTS

At baseline, the cross-sectional rates of decline in VO2max with age (slope) were virtually identical in the athletes and sedentary men (-0.42 versus -0.43 mL x kg(-1) x min(-1) x year(-1)). At follow-up, the VO2max had declined by 11.9 +/- 1.1 mL x kg(-1) x min(-1) (22%) in the athletes, a crude average rate of -1.4 +/- 0.14 mL x kg(-1)x min(-1) x year(-1). By comparison, the VO2max declined by 4.4 +/- 0.6 mL x kg(-1) x min(-1) (14%) in the sedentary men, a crude average rate of change of -0.48 +/- 0.07 mL x kg(-1) x min(-1) x year(-1). Therefore, the observed absolute rate of longitudinal decline in VO2max in the athletes was triple that of the sedentary men (P= .001) and significantly greater than the decline predicted by their baseline cross-sectional data (P= .001). Post hoc analyses of the longitudinal data in the athletes based on the training regimens over the follow-up period demonstrated that the seven individuals who continued to train vigorously ("high training") had no significant decline in VO2max (0.28% change in VO2max per year). By contrast, the VO2max declined by 2.6% per year in the "moderate training" group (N=21), 4.6% per year in the "low training" group (N=13), and 4.7% per year in the two individuals who developed cardiovascular disease.

CONCLUSION

The longitudinal decline in VO2max in older male endurance athletes is highly dependent upon the continued magnitude of the training stimulus. The majority of the athletes reduced their training levels over time, resulting in longitudinal reductions in VO2max two to three times as large as those predicted by cross-sectional analyses or those observed longitudinally in their sedentary peers.

Stress testing in the elderly

The ever-increasing number of older patients requiring diagnostic and prognostic assessment for coronary artery disease has necessitated accurate, noninvasive techniques applicable to this age group. Exercise testing, either alone or with radionuclide or echocardiographic imaging, remains a useful tool in elderly patients capable of performing vigorous treadmill or cycle exercise. Fortunately, for the large elderly subset incapable of such exercise, pharmacologic stress testing with dipyridamole, adenosine, or dobutamine offers an excellent alternative. Choosing the most appropriate stress testing modality for a given patient from among the many choices available remains the clinician's challenge.

Muscle size responses to strength training in young and older men and women

OBJECTIVES

To examine the possible influences of age and gender on muscle volume responses to strength training (ST).

DESIGN

Prospective intervention study.

SETTING

University of Maryland Exercise Science and Wellness Research Laboratories.

PARTICIPANTS

Eight young men (age 20-30 years), six young women (age 20-30 years), nine older men (age 65-75 years), and ten older women (age 65-75 years).

INTERVENTION

A 6-month whole-body ST program that exercised all major muscle groups of the upper and lower body 3 days/week.

MEASUREMENTS

Thigh and quadriceps muscle volumes and mid-thigh muscle cross-sectional area (CSA) were assessed by magnetic resonance imaging before and after the ST program.

RESULTS

Thigh and quadriceps muscle volume increased significantly in all age and gender groups as a result of ST (P < .001), with no significant differences between the groups. Modest correlations were observed between both the change in quadriceps versus the change in total thigh muscle volume (r = 0.65; P < .001) and the change in thigh muscle volume versus the change in mid-thigh CSA (r = 0.76, P < .001).

CONCLUSIONS

The results indicate that neither age nor gender affects muscle volume response to whole-body ST. Muscle volume, rather than muscle CSA, is recommended for studying muscle mass responses to ST.

The effect of anthropometric and socioeconomic factors on the racial difference in lung function

African-Americans have lower lung function than whites. However, the relative contributions of body habitus and socioeconomic factors are unknown. To address this question, we analyzed data from 1242 white (806 women, 436 men) and 1084 African-American (696 women, 388 men) asymptomatic, nonsmoking adult participants of the third National Health and Nutrition Examination Survey (NHANES III). African-Americans were poorer, had larger FEV(1)/FVC and body mass index (BMI), but lower sitting height, FEV(1) and FVC than whites. Cross-sectional regression analyses using spirometric, anthropometric, and socioeconomic data were performed separately by sex to investigate racial differences in lung function. Sitting height accounted for 35-39% of the race difference in both sexes. Poverty index accounted for about 7.5% and 2.5% of the racial difference in women and men, respectively, whereas the effect of education accounted for about 2% in women and 4.7% in men. With further adjustment for BMI, we could account for only about half of the racial difference in FEV(1) and FVC. We conclude that the racial difference in lung function is only partially explained by a shorter upper body segment in African-Americans. Although low socioeconomic indicators are related to lower lung function, they explain only a small proportion of this racial difference.

Associations of aortic Windkessel function with age, gender and cardiovascular risk factors

Aortic Windkessel function is thought to represent a potential cardiovascular risk factor. As an indicator for the function, we have recently introduced the decay index (DI). DI is the coefficient of an exponential function applied to the postpeak portion of internal carotid artery Doppler waveform, and is inversely associated with the function. This study compares DI with age, gender and traditional cardiovascular risk factors in 220 apparently healthy volunteers (59 +/- 16 years). DI increased linearly with age (r = 0.51, p < 0.001), and was higher in women than in men at all ages (p < 0.001). Also, DI was positively associated with systolic blood pressure (beta = 0.17, p < 0.01) and diabetic medication (beta = 0.14, p < 0.05), independent of age (beta = 0.49, p < 0.0001), gender (beta = 0.27, p < 0.0001) and other traditional cardiovascular risk factors (model r(2) = 0.36). Based on the present results, the Windkessel function as assessed by DI declines with age and is lower in women. However, the associations with cardiovascular risk factors need to be established on a larger sample at higher cardiovascular risk.

Hormone replacement therapy and longitudinal changes in blood pressure in postmenopausal women

BACKGROUND

The incidence of hypertension in postmenopausal women exceeds that in age-matched men. Longitudinal studies relating hormone replacement therapy (HRT) to blood pressure changes are sparse.

OBJECTIVE

To investigate the association between HRT and longitudinal changes in blood pressure in postmenopausal women.

DESIGN

Longitudinal observational study.

SETTING

Community-dwelling volunteers.

PATIENTS

226 healthy, normotensive postmenopausal women from the Baltimore Longitudinal Study of Aging with a mean (+/-SD) age of 64 +/- 10 years were followed for 5.7 +/- 5.3 years. Seventy-seven women used both estrogen and progestin, and 149 used neither.

MEASUREMENTS

Lifestyle variables, blood pressure, and traditional cardiovascular risk factors were measured at baseline and approximately every 2 years thereafter.

RESULTS

Systolic blood pressure at baseline was similar in HRT users and nonusers (133.9 +/- 16.0 mm Hg vs. 132.4 +/- 14.8 mm Hg). Over time, average systolic blood pressure increased less in HRT users than nonusers, independent of other cardiovascular risk factors, physical activity, and alcohol use. For example, HRT users who were 55 years of age at their first Baltimore Longitudinal Study of Aging visit experienced a 7.6-mm Hg average increase in systolic blood pressure over 10 years; in contrast, the average increase in nonusers was 18.7 mm Hg. The lesser increase in systolic blood pressure in HRT users was more evident at older age. Diastolic blood pressure, which did not change statistically over time in either group, was not associated with HRT.

CONCLUSION

Postmenopausal women taking HRT have a smaller increase in systolic blood pressure over time than those not taking HRT. This difference is intensified at older ages.

The effect of gender on the relationship between body fat distribution and lung function

Although abdominal obesity, as measured by waist-to-hip ratio (WHR), has long been recognized as a risk factor for metabolic and cardiovascular diseases, little is known about the effect of WHR on pulmonary function, especially in women. In this study of 1094 men and 540 women (18-102 years) from the Baltimore Longitudinal Study of Aging (BLSA), we examined the effect of WHR on forced expiratory volume in 1 s (FEV(1)). Cross-sectional analyses, after accounting for body mass index (BMI) and other variables, showed a strong inverse association of WHR with FEV(1) in men (beta = -1.338, P=.0001) but not in women. Furthermore, larger values of WHR were associated with greater reductions of forced vital capacity (FVC) in men (beta = -1.383, P =.0005) compared to women (beta = -0.679, P =.02). Thus, body fat distribution has independent effects on lung function that are more prominent in men than women.

Effect of strength training on resting metabolic rate and physical activity: age and gender comparisons

PURPOSE

The purpose of this study was to compare age and gender effects of strength training (ST) on resting metabolic rate (RMR), energy expenditure of physical activity (EEPA), and body composition.

METHODS

RMR and EEPA were measured before and after 24 wk of ST in 10 young men (20-30 yr), 9 young women (20-30 yr), 11 older men (65-75 yr), and 10 older women (65-75 yr).

RESULTS

When all subjects were pooled together, absolute RMR significantly increased by 7% (5928 +/- 1225 vs 6328 +/- 1336 kJ.d-1, P < 0.001). Furthermore, ST increased absolute RMR by 7% in both young (6302 +/- 1458 vs 6719 +/- 1617 kJ x d(-1), P < 0.01) and older (5614 +/- 916 vs 5999 +/- 973 kJ x d(-1), P < 0.05) subjects, with no significant interaction between the two age groups. In contrast, there was a significant gender x time interaction (P < 0.05) for absolute RMR with men increasing RMR by 9% (6645 +/- 1073 vs 7237 +/- 1150 kJ x d(-1), P < 0.001), whereas women showed no significant increase (5170 +/- 884 vs 5366 +/- 692 kJ x d(-1), P = 0.108). When RMR was adjusted for fat-free mass (FFM) using ANCOVA, with all subjects pooled together, there was still a significant increase in RMR with ST. Additionally, there was still a gender effect (P < 0.05) and no significant age effect (P = NS), with only the men still showing a significant elevation in RMR. Moreover, EEPA and TEE estimated with a Tritrac accelerometer and TEE estimated by the Stanford Seven-Day Physical Activity Recall Questionnaire did not change in response to ST for any group.

CONCLUSIONS

In conclusion, changes in absolute and relative RMR in response to ST are influenced by gender but not age. In contrast to what has been suggested previously, changes in body composition in response to ST are not due to changes in physical activity outside of training.

Effect of estrogen and progestin replacement on arterial stiffness indices in postmenopausal women

Our objectives were to investigate whether long-term estrogen replacement therapy (ERT) is associated with a reduction in age-associated increases in arterial stiffness and blood pressure (BP), and whether the addition of progestin modifies the effects of estrogen. ERT has been found to have beneficial effects on cardiovascular risk. There are few data, however, delineating the effects of ERT on BP and arterial stiffness, and their age-associated changes. BP and aorto-femoral pulse wave velocity (PWV) were measured in 134 postmenopausal volunteers, aged 51 to 90 years, from the Baltimore Longitudinal Study of Aging, screened to exclude clinical and occult cardiovascular disease, and classified as ERT non-users (N=57) or ERT users (N=77). The latter group was further substratified according to the use of estrogen alone (N=32) or a combination of estrogen and progestins (N=45). ERT users showed similar body habitus, physical activity, and plasma lipids compared to non-ERT users. ERT was associated with an average 9.8 mmHg lower systolic BP (p<0.001), and a 6.3 mmHg lower pulse pressure (p<0.01) than in non-users. Multiple regression analysis showed that ERT was an independent predictor of lower SBP and PP (p<0.05). By analysis of covariance, ERT predicted a reduced age-associated increase in SBP, PP, and PWV (p<0.05). When systolic BP was >130 mmHg, the combination of ERT and progestins predicted a higher PWV than ERT alone. In conclusion, ERT in postmenopausal women can beneficially affect the vascular system, by reducing BP and the age-associated increase in arterial stiffness. The addition of progestins to ERT may reduce these beneficial effects.

Is the apoE4 allele an independent predictor of coronary events?

PURPOSE

Although the apolipoprotein E genotype epsilon4 (apoE4) has been associated with high cholesterol levels, whether it is an independent predictor of coronary events is not certain.

SUBJECTS AND METHODS

We measured apoE genotypes in 730 participants in the Baltimore Longitudinal Study of Aging (421 men and 309 women, mean [+/- SD] age of 52+/-17 years) who were free of preexisting coronary heart disease. A proportional hazards regression model was used to study the association between risk factors and the occurrence of coronary events, defined as angina pectoris, documented myocardial infarction by history or major Q waves on the electrocardiogram (Minnesota Code 1:1 or 1:2), or coronary death, adjusted for other risk factors, including total plasma cholesterol level.

RESULTS

The apoE4 allele was observed in 200 subjects (27%), including 183 heterozygotes and 17 homozygotes. Coronary risk factor profiles were similar in those with and without apoE4. Coronary events developed in 104 (14%) of the 730 subjects, including 77 (18%) of the 421 men during a mean follow-up of 20 years and 27 (9%) of the 309 women during a mean follow-up of 13 years. Coronary events occurred significantly more frequently in subjects with apoE4 (n = 40, 20%) than in those without this allele (64, 12%, P <0.05). In a multivariate model, apoE4 was an independent predictor of coronary events in men (risk ratio [RR]= 2.9, 95% confidence interval [CI]: 1.8 to 4.5, P<0.0001) but not in women (RR = 0.9, 95% CI: 0.4 to 1.9, P = 0.62).

CONCLUSION

The apoE4 genotype is a strong independent risk factor for coronary events in men, but not women. The association does not appear to be mediated by differences in total cholesterol levels.

Effects of age, gender, and myostatin genotype on the hypertrophic response to heavy resistance strength training

BACKGROUND

Because of the scarcity of data available from direct comparisons of age and gender groups using the same relative training stimulus, it is unknown whether older individuals can increase their muscle mass as much as young individuals and whether women can increase as much as men in response to strength training (ST). In addition, little is known about whether the hypertrophic response to ST is affected by myostatin genotype, a candidate gene for muscle hypertrophy.

METHODS

Eleven young men (25 +/- 3 years, range 21-29 years), 11 young women (26 +/- 2 years, range 23-28 years), 12 older men (69 +/- 3 years, range 65-75 years), and 11 older women (68 +/- 2 years, range 65-73 years) had bilateral quadriceps muscle volume measurements performed using magnetic resonance imaging (MRI) before and after ST and detraining. Training consisted of knee extension exercises of the dominant leg three times per week for 9 weeks. The contralateral limb was left untrained throughout the ST program. Following the unilateral training period, the subjects underwent 31 weeks of detraining during which no regular exercise was performed. Myostatin genotype was determined in a subgroup of 32 subjects, of which five female subjects were carriers of a myostatin gene variant.

RESULTS

A significantly greater absolute increase in muscle volume was observed in men than in women (204 +/- 20 vs 101 +/- 13 cm3, p < .01), but there was no significant difference in muscle volume response to ST between young and older individuals. The gender effect remained after adjusting for baseline muscle volume. In addition, there was a significantly greater loss of absolute muscle volume after 31 weeks of detraining in men than in women (151 +/- 13 vs 88 +/- 7 cm3, p < .05), but no significant difference between young and older individuals. Myostatin genotype did not explain the hypertrophic response to ST when all 32 subjects were assessed. However, when only women were analyzed, those with the less common myostatin allele exhibited a 68% larger increase in muscle volume in response to ST (p = .056).

CONCLUSIONS

Aging does not affect the muscle mass response to either ST or detraining, whereas gender does, as men increased their muscle volume about twice as much in response to ST as did women and experienced larger losses in response to detraining than women. Young men were the only group that maintained muscle volume adaptation after 31 weeks of detraining. Although myostatin genotype may not explain the observed gender difference in the hypertrophic response to ST, a role for myostatin genotype may be indicated in this regard for women, but future studies are needed with larger subject numbers in each genotype group to confirm this observation.

Executive Summary: Pivotal Research in Cardiovascular Syndromes in the Elderly

The PRICE-1 conference was designed to identify near term priorities for funding cardiovascular research in the elderly. Twenty topics were identified with either break throughs in fundamental mechanisms of aging with cardiovascular systems or with critical importaance to cardiovascular carve of the elderly. (c) 2000 by CVRR, Inc.

The relationship between creatine kinase kinetics and exercise intensity in human forearm is unchanged by age

Using (31)P magnetic resonance spectroscopy, creatine kinase (CK) reaction kinetics was assessed in the forearm flexor digitorum profundus muscle of healthy young (n = 11, age 34.7 +/- 5 yr) and older (n = 20, age 73.5 +/- 8 yr) subjects at rest, intermittent exercise at 20% maximum voluntary contraction (MVC), and 40% MVC. Exercise resulted in a significant increase in the average ratio of inorganic phosphate (P(i)) to phosphocreatine (PCr) from resting values of 0.073 +/- 0.031 (young) and 0.082 +/- 0.037 (older) to 0. 268 +/- 0.140 (young, P < 0.01) and 0.452 +/- 0.387 (older, P < 0. 01) at 40% MVC. At 40% MVC, intracellular pH decreased significantly, from resting values of 7.08 +/- 0.08 (young) and 7.08 +/- 0.11 (older) to 6.84 +/- 0.19 (young, P < 0.05) and to 6.75 +/- 0.25 (older, P < 0.05). Average values of the pseudo-first-order reaction rate k((PCr-->ATP)) at rest were 0.07 +/- 0.04 s(-1) in the young and 0.07 +/- 0.03 s(-1) in the older group. At both exercise levels, the reaction rate constant increased compared with the resting value, but only the difference between the resting value and the 20% MVC value, which showed an 86% higher reaction rate constant in both groups, reached statistical significance (P < 0.05). No difference in the reaction rate constant between the young and older groups was observed at either exercise level. As with k((PCr-->ATP)), the average phosphorus flux through the CK reaction increased during exercise at 20% MVC (P < 0.05 in the older group) but decreased toward resting values at 40% MVC in both groups. The data in our study suggest that normal aging does not significantly affect the metabolic processes associated with the CK reaction.

Age and gender responses to strength training and detraining

PURPOSE

The purpose of this study was to examine the effects of age and gender on the strength response to strength training (ST) and detraining.

METHODS

Eighteen young (20-30 yr) and 23 older (65-75 yr) men and women had their one-repetition maximum (1 RM) and isokinetic strength measured before and after 9 wk of unilateral knee extension ST (3 d x wk(-1)) and 31 wk of detraining.

RESULTS

The young subjects demonstrated a significantly greater (P < 0.05) increase in 1 RM strength (34+/-3%; 73+/-5 vs 97+/-6 kg; P < 0.01) than the older subjects (28+/-3%; 60+/-4 vs 76+/-5 kg, P < 0.01). There were no significant differences in strength gains between men and women in either age group with 9 wk of ST or in strength losses with 31 wk of detraining. Young men and women experienced an 8+/-2% decline in 1 RM strength after 31 wk of detraining (97+/-6 vs 89+/-6 kg, P < 0.05). This decline was significantly less than the 14+/-2% decline in the older men and women (76+/-5 vs 65+/-4 kg, P < 0.05). This strength loss occurred primarily between 12 and 31 wk of detraining with a 6+/-2% and 13+/-2% decrease in the young and older subjects, respectively, during this period.

DISCUSSION

These results demonstrate that changes in 1 RM strength in response to both ST and detraining are affected by age. However, ST-induced increases in muscular strength appear to be maintained equally well in young and older men and women during 12 wk of detraining and are maintained above baseline levels even after 31 wk of detraining in young men, young women, and older men.

Leisure-time physical activities and their relationship to cardiorespiratory fitness in healthy men and women 18-95 years old

PURPOSE

We examined leisure-time physical activities (LTPA) and their contribution to peak oxygen consumption (VO2) in healthy men (N = 619) and women (N = 497) aged 18-95 yr (mean 51 +/- 17) who were participants of the Baltimore Longitudinal study of Aging.

METHODS

Calculations of LTPA were based on the average self-reported time spent performing 97 activities and converted into MET-min x 24 h(-1). The activities were divided into three levels of LTPA based on absolute intensity. Peak VO2 was determined from a maximal treadmill exercise test.

RESULTS

Total LTPA was inversely related to age in both sexes (r = -0.26, P < 0.0001 in men and r = -0.23, P < 0.0001 in women), mediated primarily by less high-intensity activities in older subjects, with only minor differences in moderate- and low-intensity activities across age. Peak VO2 correlated positively with LTPA; the correlations were strongest for high-intensity LTPA (r = 0.33 in men and 0.27 in women, each P < 0.0001), intermediate for moderate-intensity activity (r = 0.12, P < 0.004 in men and r = 0.17, P < 0.0001 in women) and minimal for low-intensity activity (r = 0.08, P = 0.05 in men and r = 0.06, P = 0.20 in women). On univariate analysis, total LTPA accounted for 12.9% of peak VO2 variance for men and 10.6% for women. By multivariate analysis, LTPA independently accounted for 1.6% of the peak VO2 variance in men and 1.8% in women after controlling for age and body mass index.

CONCLUSIONS

In healthy adults across a broad age range, LTPA is a relatively minor independent contributor to aerobic capacity.

The relationship between aerobic exercise capacity and circulating IGF-1 levels in healthy men and women

OBJECTIVES

To determine whether aerobic capacity is associated independently with insulin-like growth factor-I (IGF-1) levels in healthy community-dwelling men and women.

SETTING

The Baltimore Longitudinal Study on Aging (BLSA).

DESIGN

A cross-sectional analysis of data from the population-based cohort of the Baltimore Longitudinal Study of Aging (BLSA).

PARTICIPANTS

We studied 181 men and 92 women aged 20 to 93 years, volunteers in the Baltimore Longitudinal Study on Aging (BLSA). Subjects were free of endocrine, renal, hepatic, gastrointestinal, or cardiac diseases, and they were taking no medications known to interfere with the growth hormone-IGF-1 axis.

MEASUREMENTS

All subjects underwent a single measurement of serum IGF-1 in the fasting state, as well as peak VO2 determinations during maximal treadmill exercise testing performed within one visit of the IGF-1 determination. Dual energy X-ray absorptiometry (DEXA) scans were performed in a subset of 171 subjects (64 women and 107 men) for determination of fat free mass (FFM).

RESULTS

In the pooled group of women and men, univariate regression analysis revealed that age was correlated strongly with decreasing IGF-1 levels (r = -0.53, P < .001) and with peak VO2r = -0.56, P < .001). IGF-1 levels were also significantly correlated with peak VO2 (r = 0.29, P < .001). There were no significant gender-related differences in these relationships. On multivariate analysis, age (beta = -0.54, P < .001), but not peak VO2 (P = -0.01, P = .840), remained strongly associated with IGF-1 levels. After adjustment of peak VO2 for FFM in subjects with DEXA scans, results were similar.

CONCLUSIONS

These findings indicate that although both peak aerobic capacity and circulating IGF-1 levels decline with age, aerobic capacity is not independently related to circulating IGF-1 in healthy men and women across the adult life span.

Early repolarization: an electrocardiographic predictor of enhanced aerobic fitness

The presence or absence of early repolarization on the electrocardiogram at rest was correlated with aerobic exercise capacity in healthy volunteers from the Baltimore Longitudinal Study of Aging. Patients with early repolarization had both longer treadmill exercise duration and higher peak oxygen consumption than age-and gender-matched control subjects.

Enhanced endothelial vasoreactivity in endurance-trained older men

Using external vascular ultrasound, we measured brachial artery diameter (Diam) at rest, after release of 4 min of limb ischemia, i. e., endothelium-dependent dilation (EDD), and after sublingual nitroglycerin, i.e., non-endothelium-dependent dilation (NonEDD), in 35 healthy men aged 61-83 yr: 12 endurance athletes (A) and 23 controls (C). As anticipated, treadmill exercise maximal oxygen consumption (VO(2 max)) was significantly higher in A than in C (40. 2 +/- 6.6 vs. 27.9 +/- 3.8 ml. kg(-1). min(-1); respectively, P < 0. 0001). With regard to arterial physiology, A had greater EDD (8.9 +/- 4.2 vs. 5.7 +/- 3.5%; P = 0.02) and a tendency for higher NonEDD (13.9 +/- 6.7 vs. 9.7 +/- 4.2%; P = 0.07) compared with C. By multiple linear regression analysis in the combined sample of older men, only baseline Diam (beta = -2.0, where beta is the regression coefficient; P = 0.005) and VO(2 max) (beta = 0.23; P = 0.003) were independent predictors of EDD; similarly, only Diam (beta = -4.0; P = 0.003) and VO(2 max) (beta = 0.27; P = 0.01) predicted NonEDD. Thus endurance-trained older men demonstrate both augmented EDD and NonEDD, consistent with a generalized enhanced vasodilator responsiveness, compared with their sedentary age peers.

Hemodynamic effects of unloading the old heart

A reduction in upright exercise capacity with aging in healthy individuals is accompanied by acute left ventricular (LV) dilatation and impaired LV ejection. To determine whether acute vasodilator administration would improve LV ejection during exercise, sodium nitroprusside (NP) was administered to 16 healthy subjects, ages 64-84 yr, who had been screened for the absence of coronary heart disease by prior exercise thallium scintigraphy. Infusion of NP (0. 3-1.0 microgram. kg(-1). min(-1)), titrated to reduce the resting mean arterial pressure 10% (and eliminate the late augmentation of carotid arterial pressure), increased LV ejection fraction (EF) compared with placebo during upright, maximal graded cycle exercise at all work rates and permitted an equivalent stroke volume and stroke work from a smaller end-diastolic volume. The maximum increase in exercise EF in older subjects during NP infusion was equal to that in healthy, younger (22-39 yr) control subjects. The maximum cycle work rate and cardiac index were unchanged compared with placebo. Thus combined preload and afterload reduction with NP in older individuals improves overall LV ejection phase function: exercise LV stroke work is reduced, EF is increased, and stroke volume is maintained in the setting of a reduced ventricular size. These findings suggest that at least some of the age-associated decline in cardiac function during maximal aerobic exercise may be secondary to adverse loading conditions.

Decay Index: a new carotid Doppler waveform measure associated with the Windkessel function of elastic arteries

The Windkessel function of elastic arteries determines the postpeak contour of the internal carotid artery (ICA) Doppler waveform. To introduce an indicator for the function, the postpeak contour was reproduced by an exponential function, and the exponential coefficient was termed "Decay Index" (DI). DI obtained from 108 stenosis-free ICAs (55.2 +/- 15.8 y) was compared with surrogate measures for the Windkessel function (aortic pulse wave velocity, pulse pressure) and ICA peripheral resistance (resistive index, pulsatility index, systolic-to-diastolic ratio). DI was moderately correlated with the Windkessel and the resistance measures (r ranged 0.44-0.57). To clarify these intercorrelations, principal component analysis revealed two components. The first was loaded by the resistance measures (component load > or = 0.93) although the second was loaded by the Windkessel measures and DI (> or = 0.70), supporting an association between DI and the Windkessel function. Thus, DI is likely to represent an indicator for the Windkessel function.

Increased carotid artery intimal-medial thickness: risk factor for exercise-induced myocardial ischemia in asymptomatic older individuals

Asymptomatic coronary artery disease (CAD) is prevalent in the general population and has been associated with an increased risk for symptomatic CAD. Although the diagnosis of asymptomatic CAD is currently dependent on exercise testing and coronary angiography, other vascular diagnostic techniques could potentially be of aid in the assessment. Increased intimal-medial thickness (IMT) of the common carotid artery as assessed by B-mode ultrasonography is a purported index of atherosclerosis, and is associated with symptomatic CAD. Based on a recent report, this article will focus on the relationship between IMT and asymptomatic CAD as evidenced by exercise ECG, and in combination with exercise thallium scintigraphy. It was found that exercise-induced ST segment depression was associated with increased IMT independent of age, coronary risk factors and manifest CAD. After adjustment for age, IMT progressively increased from healthy subjects to asymptomatic subjects with positive exercise ECG alone, to those with concordant positive ECG and thallium scintigraphic findings who had IMT virtually identical to that in subjects with manifest CAD. Each 0.1 mm increase in IMT was associated with a 1.91-fold (95% CI 1.46-2.50) increased risk for concordant positive exercise tests or manifest CAD, independent of other coronary risk factors. These findings and the review of the literature suggest the potential utility of carotid ultrasonography in identifying asymptomatic individuals at higher risk for CAD.

Strength training normalizes resting blood pressure in 65- to 73-year-old men and women with high normal blood pressure

OBJECTIVE

To determine the effects of heavy resistance strength training (ST) on resting blood pressure (BP) in older men and women.

DESIGN

Prospective intervention study.

SETTING

University of Maryland Exercise Science Laboratory.

PARTICIPANTS

Twenty-one sedentary, healthy older men (69 +/- 1 year, n = 11) and women (68 +/- 1 year, n = 10) served as subjects for the study.

INTERVENTION

Six months of progressive whole body ST performed 3 days per week using Keiser K-300 air-powered resistance machines.

MEASUREMENTS

One-repetition maximum (1 RM) strength was measured for seven different exercises before and after the ST program. Resting BP was measured on six separate occasions before and after ST for each subject.

RESULTS

Substantial increases in 1 RM strength were observed for upper body (UB) and lower body (LB) muscle groups for men (UB: 215 vs 265 kg; LB: 694 vs 838 kg; P < .001) and women (UB: 128 vs 154 kg; LB: 441 vs 563 kg; P < .001). The ST program led to reductions in both systolic (131 +/- 2 vs 126 +/- 2 mm Hg, P < .010) and diastolic (79 +/- 2 vs 75 +/- 1 mm Hg, P < .010) BP. Systolic BP was reduced significantly in men (134 +/- 3 vs 127 +/- 2 mm Hg, P < .01) but not in women (128 +/- 3 vs 125 +/- 3 mm Hg, P < .01), whereas diastolic BP was reduced following training in both men (81 +/- 3 vs 77 +/- 1, mm Hg, P = .054) and women (78 +/- 2 vs 74 +/- 2 mm Hg, P = .055).

CONCLUSIONS

Six months of heavy resistance ST may reduce resting BP in older persons. According to the latest guidelines from the Joint National Committee for the Detection, Evaluation, and Treatment of Hypertension, the changes in resting BP noted in the present study represent a shift from the high normal to the normal category.

Carotid arterial stiffness as a surrogate for aortic stiffness: relationship between carotid artery pressure-strain elastic modulus and aortic pulse wave velocity

Common carotid arterial (CCA) stiffness can be assessed during carotid ultrasonography, but its association with aortic stiffness, a well-defined cardiovascular risk factor, has not been clarified. This study examines the relationship between CCA and aortic stiffness. CCA pressure-strain elastic modulus (Ep) and aortic pulse wave velocity (APWV) were evaluated in 110 healthy volunteers (age 56.2 +/- 14.6 y) by B-mode and Doppler ultrasonography. CCA Ep increased linearly with age and was higher in men than in women (model r2 = 0.50, p < 0.001). APWV increased quadratically with age (model r2 = 0.54, p < 0.001), similarly for women and men. Both CCA Ep and APWV were linearly associated with systolic blood pressure (BP) (r = 0.53 and 0.46, respectively) but not with diastolic BP. A linear relationship was found between CCA Ep and APWV (APWV = 194.7 + 5.67 x Ep [model r2 = 0.42, p < 0.001]). CCA Ep was associated with APWV (p < 0.001) independent of age, gender, and BP (model r2 = 0.62, p < 0.001), and the most parsimonious model to explain APWV included CCA Ep and age (APWV = 601.73 - 15.64 x age + 0.223 x age2 + 2.69 x Ep [model r2 = 0.60, p < 0.001]). Thus, CCA Ep is moderately associated with APWV. CCA stiffness as assessed by B-mode may be useful as a surrogate for aortic stiffness.

Muscle quality. I. Age-associated differences between arm and leg muscle groups

To determine the differences between arm and leg muscle quality (MQ) across the adult life span in men and women, concentric (Con) and eccentric (Ecc) peak torque (PT) were measured in 703 subjects (364 men and 339 women, age range 19-93 yr) and appendicular skeletal muscle mass (MM) was determined in the arm and leg in a subgroup of 502 of these subjects (224 men and 278 women). Regression analysis showed that MQ, defined as PT per unit of MM, was significantly higher in the arm ( approximately 30%) than in the leg across age in both genders (P < 0.01). Arm and leg MQ declined at a similar rate with age in men, whereas leg MQ declined approximately 20% more than arm MQ with increasing age in women (P </= 0.01 and P < 0.05 for Con and Ecc PT, respectively). Moreover, the age-associated decrease in arm MQ was steeper in men than in women whether Con or Ecc PT was used (both P < 0.05). Arm MQ as determined by Con PT showed a linear age-related decline in men and women (28 and 20%, respectively, P < 0.001), whereas arm MQ as determined by Ecc PT showed a linear age-related decline in men (25%, P < 0.001) but not in women (not significant). In contrast, both genders exhibited an age-related quadratic decline in leg MQ as determined by Con PT ( approximately 40%) and Ecc PT ( approximately 25%; both P < 0.001), and the rate of decline was similar for men and women. Thus MQ is affected by age and gender, but the magnitude of this effect depends on the muscle group studied and the type of muscle action (Con vs. Ecc) used to assess strength.

Muscle quality. II. Effects Of strength training in 65- to 75-yr-old men and women

To determine the effects of strength training (ST) on muscle quality (MQ, strength/muscle volume of the trained muscle group), 12 healthy older men (69 +/- 3 yr, range 65-75 yr) and 11 healthy older women (68 +/- 3 yr, range 65-73 yr) were studied before and after a unilateral leg ST program. After a warm-up set, four sets of heavy-resistance knee extensor ST exercise were performed 3 days/wk for 9 wk on the Keiser K-300 leg extension machine. The men exhibited greater absolute increases in the knee extension one-repetition maximum (1-RM) strength test (75 +/- 2 and 94 +/- 3 kg before and after training, respectively) and in quadriceps muscle volume measured by magnetic resonance imaging (1,753 +/- 44 and 1, 955 +/- 43 cm3) than the women (42 +/- 2 and 55 +/- 3 kg for the 1-RM test and 1,125 +/- 53 vs. 1,261 +/- 65 cm3 for quadriceps muscle volume before and after training, respectively, in women; both P < 0.05). However, percent increases were similar for men and women in the 1-RM test (27 and 29% for men and women, respectively), muscle volume (12% for both), and MQ (14 and 16% for men and women, respectively). Significant increases in MQ were observed in both groups in the trained leg (both P < 0.05) and in the 1-RM test for the untrained leg (both P < 0.05), but no significant differences were observed between groups, suggesting neuromuscular adaptations in both gender groups. Thus, although older men appear to have a greater capacity for absolute strength and muscle mass gains than older women in response to ST, the relative contribution of neuromuscular and hypertrophic factors to the increase in strength appears to be similar between genders.

The relationship of obesity and the development of coronary heart disease to longitudinal changes in systolic blood pressure

In an investigation of the relationship of obesity and the development of coronary heart disease (CHD) to longitudinal changes in systolic blood pressure (SBP), a sample of 1029 male participants from the Baltimore Longitudinal Study of Baltimore (BLSA), who were free of CHD at the beginning of the study, were examined with a total of 4111 examinations (mean of four examinations per person) conducted during the study period. The mean follow-up time was 8.1 years with a maximum of 16 examinations and 30.9 years of follow-up. During the follow-up period, 192 participants developed CHD, and these participants' data collected after the CHD event were excluded from the analysis. A proportional hazards regression model was used to calculate the relative risk of developing CHD for several CHD risk factors. Both simple and multiple proportional hazards regression models indicate a strong association between body mass index (BMI), cholesterol, cigarette smoking, and systolic blood pressure (SBP) with the risk of developing CHD. In addition, a linear mixed-effects model was used to examine changes in SBP measurements over time and to identify factors, including the age at first examination and time in study, that are related to that change. The results from the linear mixed-effects model analysis indicate that those in the obese group (BMI > or = 30 kg/m2) have SBP measurements that are on average 9.0 mm Hg higher than those in the normal group (20 < or = BMI < 25). Also, SPB measurements were on average 6.6 mm Hg higher in those who developed CHD during the study period than those who remained free of disease. In addition, SPB showed a quadratic relationship with time, and its patterns of change with time were different among the different age groups. Also, the relationship between changes in SBP with respect to cholesterol was dependent on time in the study as well.

Increased carotid artery intimal-medial thickness in asymptomatic older subjects with exercise-induced myocardial ischemia

BACKGROUND

Previous studies have shown an association between symptomatic coronary artery disease (CAD) and increased intimal-medial thickness of the common carotid artery (CCA IMT), a purported index of atherosclerosis. This study determines whether CCA IMT is increased in asymptomatic older subjects with an ischemic ST-segment response to treadmill exercise.

METHODS AND RESULTS

CCA IMT was measured by B-mode ultrasound in community-dwelling volunteers from the Baltimore Longitudinal Study of Aging, including 397 healthy subjects (age, 58.5+/-15.8 years) with normal ECG responses to maximum treadmill exercise, 72 asymptomatic subjects (age, 66.1+/-13.4 years) with exercise-induced horizontal or downsloping ST-segment depression >/=1 mm, and 38 subjects (age, 77. 4+/-7.8 years) with clinically manifest CAD as diagnosed by medical history and resting ECG. Forty-three subjects with abnormal exercise ECGs also underwent exercise thallium scintigraphy. Exercise-induced ST-segment depression was associated with increased IMT (P<0.0001) independent of age and manifest CAD. After adjustment for age, IMT values progressively increased from healthy subjects to asymptomatic subjects with positive exercise ECG alone to those with concordant positive ECG and thallium scintigraphic findings who had virtually identical IMT to subjects with manifest CAD. Each 0.1-mm increase in IMT was associated with a 1.91-fold (95% CI, 1.46 to 2.50; P<0.0001) increased risk for concordant positive exercise tests or manifest CAD, independent of other significant predictors of CAD.

CONCLUSIONS

CCA IMT is increased in older subjects with asymptomatic myocardial ischemia as evidenced by exercise ECG alone or in combination with thallium scan. Carotid ultrasound may help to identify asymptomatic individuals with CAD.

Expanded blood volumes contribute to the increased cardiovascular performance of endurance-trained older men

To determine whether expanded intravascular volumes contribute to the older athlete's higher exercise stroke volume and maximal oxygen consumption (VO2 max), we measured peak upright cycle ergometry cardiac volumes (99mTc ventriculography) and plasma (125I-labeled albumin) and red cell (NaCr51) volumes in 7 endurance-trained and 12 age-matched lean sedentary men. The athletes had approximately 40% higher VO2 max values than did the sedentary men and larger relative plasma (46 vs. 38 ml/kg), red cell (30 vs. 26 ml/kg), and total blood volumes (76 vs. 64 ml/kg) (all P < 0.05). Athletes had larger peak cycle ergometer exercise stroke volume indexes (75 vs. 57 ml/m2, P < 0.05) and 17% larger end-diastolic volume indexes. In the total group, VO2 max correlated with plasma, red cell, and total blood volumes (r = 0.61-0.70, P < 0.01). Peak exercise stroke volume was correlated directly with the blood volume variables (r = 0.59-0.67, P < 0.01). Multiple regression analyses showed that fat-free mass and plasma or total blood volume, but not red cell volume, were independent determinants of VO2 max and peak exercise stroke volume. Plasma and total blood volumes correlated with the stroke volume and end-diastolic volume changes from rest to peak exercise. This suggests that expanded intravascular volumes, particularly plasma and total blood volumes, contribute to the higher peak exercise left ventricular end-diastolic volume, stroke volume, and cardiac output and hence the higher VO2 max in master athletes by eliciting both chronic volume overload and increased utilization of the Frank-Starling effect during exercise.

Independent prognostic significance of ischemic ST-segment response limited to recovery from treadmill exercise in asymptomatic subjects

BACKGROUND

Although exercise-induced ST depression is an independent predictor of future coronary events in asymptomatic populations, the predictive value of ST depression beginning after exercise cessation is unknown.

METHODS AND RESULTS

We analyzed the treadmill exercise tests of 825 healthy volunteers who were 22 to 89 years of age from the Baltimore Longitudinal Study of Aging. All subjects were free from coronary heart disease by history, physical examination, and resting ECG. From 825 participants, 611 (group 0) had no ischemic ST-segment changes during or after treadmill exercise, while 214 subjects developed > or = 1-mm flat or downsloping ST depression: 151 (group 1) had ST changes starting during exercise, and 63 (group 2) had changes limited to recovery. Groups 1 and 2 were similar in age, sex, smoking status, hypertension prevalence, fasting plasma glucose, and serum cholesterol (CHOL). However, both groups were older and had higher CHOL and prevalence of hypertension than group 0. Treadmill exercise duration, peak oxygen consumption, and maximal heart rate were similar between groups 1 and 2 but were lower than in group 0 (each P < 0.05). During a mean follow-up time of 9 years, 55 subjects developed coronary events (angina pectoris, myocardial infarction, or coronary death): 21 of 611 (3.4%) in group 0, 22 of 151 (14.6%) in group 1, and 12 of 63 (19%) in group 2 (P = 0.001). By survival analysis, the risk of coronary events was similar in groups 1 and 2 but significantly higher than in group 0 (P < 0.0001). Multiple logistic regression showed that age (odds ratio [OR] = 1.07 per year, P = 0.00001), CHOL (OR = 1.02 per 1 mg, P = 0.0001), and presence of ST-segment depression (OR = 2.59, P = 0.007 and OR = 2.38, P = 0.04 for groups 1 and 2, respectively) were independent predictors of events.

CONCLUSIONS

Thus, ischemic ST-segment changes developing during recovery from treadmill exercise in apparently healthy individuals have adverse prognostic significance similar to those appearing during exercise.

The relationship between cardiothoracic ratio and left ventricular ejection fraction in congestive heart failure. Digitalis Investigation Group

BACKGROUND

Left ventricular ejection fraction (EF) is a valuable prognostic index in patients with congestive heart failure (CHF). Although EF can be readily measured, many clinicians use roentgenographic heart size as a clue to differentiate systolic from diastolic dysfunction, even in the absence of solid supportive data.

OBJECTIVE

To test the hypothesis that the cardiothoracic ratio (CTR) measured from the chest roentgenogram can be used to estimate left ventricular EF in individuals with CHF.

METHODS

To answer this question, the database of the Digitalis Investigation Group trial was used. The CTR, determined using the Danzer method, and quantitative EF, measured locally using angiographic, radionuclide, or 2-dimensional echocardiographic techniques, were compared in 7476 patients with clinical CHF (New York Heart Association functional classes I-IV) due to acquired left-sided cardiac disease of ischemic, hypertensive, idiopathic, and alcohol-related causes.

RESULTS

Mean (+/-SD) CTR for the cohort was 0.53+/-.07. Mean (+/-SD) EF was 31.7%+/-12.2%. A weak, negative correlation between CTR and EF was observed (r=-0.176). Similar findings were obtained when the results were stratified by cause of CHF, presence of clinically defined right ventricular dysfunction, and method of EF measurement. Categorical analysis failed to yield a CTR cutoff point that facilitated useful segregation of individuals with an EF greater than 35% or 35% and below; greater than 40% or 40% and below; and greater than 45% or 45% and below in any patient group.

CONCLUSIONS

Although a weak, negative correlation exists between CTR and EF, this relationship does not allow for accurate determination of systolic function in individual patients with CHF. Considering the morbidity and mortality associated with CHF, and the clinical implications of systolic function in this syndrome, direct measurement of EF is recommended.

Physician management of patients with heart failure and normal versus decreased left ventricular systolic function. Council on Geriatric Cardiology

A questionnaire was administered to a random sample of family practitioners, internists, cardiologists, and geriatricians to examine the current management of heart failure patients with preserved versus reduced left ventricular systolic function. In patients with preserved systolic function, electrocardiogram at rest, chest x-ray, echocardiography, digitalis, angiotensin-converting enzyme inhibitors, and restriction of dietary sodium and physical activity are used less often, whereas calcium channel blockers and beta blockers are given more often than to patients with reduced systolic function.

Exercise-induced silent myocardial ischemia in master athletes

High-physical activity levels are associated with reduced risk of symptomatic coronary artery disease (CAD). However, there are a number of reports of exercise-related sudden death and myocardial infarction in aerobically trained athletes. This study compared the prevalence of exercise-induced silent myocardial ischemia on maximum graded exercise tests with tomographic thallium scintigraphy in 70 master male athletes (63 +/- 6 years, mean +/- SD) (maximum aerobic capacity, VO2max >40 ml/kg/min) and in 85 healthy untrained men (61 +/- 7 years) with no history of CAD. The prevalence of silent ischemia (exercise-induced ST-segment depression on electrocardiogram and perfusion abnormalities on thallium scintigraphy) was similar in athletes and untrained men; 16% of the athletes (11 of 70) had silent ischemia compared with 21% of the untrained men (chi-square = 0.81, p = 0.36). No athletes had hyperlipidemia, systemic hypertension, or diabetes mellitus. However, the apolipoprotein E4 allele was present in 9 of the 11 athletes with silent ischemia compared with 2 of 32 athletes with normal exercise tests (chi-square = 24, p = 0.0001). These results suggest that older male athletes with the apolipoprotein E4 allele are at increased risk for the development of exercise-induced silent ischemia.

Myocardial Ischemia in the Asymptomatic Older Patient

Although clinically manifest CAD is present in about one-fourth of individuals older than 65 years, a like proportion of additional persons have asymptomatic coronary artery stenoses, manifest only by inducible myocardial ischemia. A major challenge to contemporary cardiology is to detect the subset of such asymptomatic subjects at highest risk for future coronary events, especially myocardial infarction and sudden death. In the BLSA, we have employed various strategies toward this goal. In apparently healthy BLSA men and women, conversion from a normal to an ischemic ST segment response to treadmill exercise testing on serial biennial visits did not improve the prediction of subsequent coronary events. However, the combination of ischemic ST segment depression and a segmental thallium-201 perfusion defect induced by treadmill exercise identified a small subset of asymptomatic older subjects, 48% of whom developed a coronary event over a 4.6 year mean follow up period. The pathophysiology, risk factors, and treatment of silent myocardial ischemia are also briefly reviewed.

Intravascular magnetic resonance imaging of aortic atherosclerotic plaque composition

Magnetic resonance imaging (MRI) may be an excellent tool to define atherosclerotic plaque composition, but surface MRI (SMRI) suffers from a low signal-to-noise ratio and low resolution of arterial images. Intravascular MRI (IVMRI) represents a potential solution for acquiring high-quality in vivo images of atherosclerotic plaques. Isolated segments of 11 thoracic human aortas obtained at autopsy were imaged by IVMRI using an intravascular receiver catheter coil designed and built at our institution. Images obtained by IVMRI were compared with corresponding images obtained by SMRI and with histopathological aortic cross sections. The intensity of intimal thickness and plaque components was graded by IVMRI and histopathology using a score of 1 for mild, 2 for moderate, and 3 for severe intensity. IVMRI had an agreement of 75% with histopathology in fibrous cap grading (37.5% expected, kappa = 0.60, P < 0.001) and of 74% in necrotic core grading (39% expected, kappa = 0.57, P < 0.001). Intraplaque calcification was correctly graded by IVMRI in six of the eight plaques in which histopathology recognized calcium. The analysis of intimal thickness showed 80% agreement between IVMRI and histopathology (52% expected, kappa = 0.59, P < 0.001). IVMRI image features were similar to those of SMRI. In addition, IVMRI accurately determined atherosclerotic plaque size in comparison with histopathology and SMRI (slope = 1.25 cm2, r = 0.99, P < 0.001 for luminal area by IVMRI vs histopathology; slope = 0.97 cm2, r = 0.996, P < 0.001 for luminal area by IVMRI vs SMRI). IVMRI has the potential to provide important prognostic information in patients with atherosclerosis because of its ability to accurately assess both plaque composition and size.

Age and gender comparisons of muscle strength in 654 women and men aged 20-93 yr

To assess age and gender differences in muscle strength, isometric, concentric (Con), and eccentric (Ecc) peak torque was measured in the knee extensors at a slow (0.52 rad/s) and fast (3.14 rad/s) velocity in 654 subjects (346 men and 308 women, aged 20-93 yr) from the Baltimore Longitudinal Study of Aging. Regression analysis revealed significant (P < 0.001) age-related reductions in Con and Ecc peak torque for men and women at both velocities, but no differences were observed between the gender groups or velocities. Age explained losses in Con better than Ecc peak torque, accounting for 30% (Con) vs. 19% (Ecc) of the variance in men and 28% (Con) vs. 11% (Ecc) in women. To assess age and gender differences in the ability to store and utilize elastic energy, the stretch-shortening cycle was determined in a subset of subjects (n = 47). The older women (mean age = 70 yr) showed a significantly greater enhancement in the stretch-shortening cycle, compared with men of similar age (P < 0.01) and compared with younger men and women (each P < 0.05). Both men and women showed significant declines in muscle quality for Con peak torque (P < 0.01), but no gender differences were observed. Only the men showed a significant decline in muscle quality (P < 0.001) for Ecc peak torque. Thus both men and women experience age-related losses in isometric, Con, and Ecc knee extensor peak torque; however, age accounted for less of the variance in Ecc peak torque in women, and women tend to better preserve muscle quality with age for Ecc peak torque. In addition, older women have an enhanced capacity to store and utilize elastic energy compared with similarly aged men as well as with younger women and men.

Abnormal exercise electrocardiograms in master athletes after three months of deconditioning

OBJECTIVE

To determine the effects of 3 months of voluntary deconditioning on cardiac function in master athletes.

DESIGN

A prospective study.

SETTING

Research participants at the University of Maryland School of Medicine and Johns Hopkins Bayview Medical Center.

PARTICIPANTS

Ten older (59 +/- 8 years, mean +/- SD), highly conditioned (maximal aerobic capacity VO2 max 50 +/- 5 mL/kg/min), aerobically trained athletes.

MEASUREMENTS AND RESULTS

Three months after the cessation of training, three of the 10 athletes had unexpected, new, markedly asymptomatic, ischemic-appearing, exercise-induced ST-segment depression on their maximal exercise tests. After retraining, the ST-segment changes disappeared in two of the subjects, but it persisted, although at a higher work load, in one of the athletes.

CONCLUSION

In three master athletes, voluntary cardiopulmonary deconditioning was associated with the development of new, asymptomatic, exercise-induced ST-segment depression on exercise ECG. The mechanisms underlying these new ischemic-appearing ST-segment changes accompanying detraining and their clinical significance are not known and warrant further investigation.

Age-associated changes in blood pressure in a longitudinal study of healthy men and women

BACKGROUND

Current knowledge of age-associated increases in blood pressure is based primarily on unscreened population studies that may not be representative of healthy men and women. We examined longitudinal patterns of change in blood pressure in healthy male and female volunteers from the Baltimore Longitudinal Study of Aging (BLSA).

METHODS

Longitudinal mixed-effects regression models are used to estimate the age-associated changes in blood pressure in 1307 men (age 17-97) and 333 women (age 18-93) who have been followed for up to 32 years (mean: 8.4 years for men and 3.4 years for women) and who have been screened for health problems or medications that affect blood pressure.

RESULTS

On average, systolic pressure is relatively stable in men and women until approximately age 45, increases at 5-8 mm Hg per decade in middle age, then accelerates in men and stabilizes in women. Diastolic pressure increases at 1 mm Hg per decade at all ages in men, whereas in women the rate of change in diastolic pressure increases in middle age and then plateaus and may decline after age 70. Additional findings include: (a) BLSA cross-sectional and longitudinal findings are more similar than has been observed in studies of unscreened samples; (b) there is no evidence of a gender cross-over in this group of healthy men and women; and (c) compared to previous studies of unscreened samples, healthy BLSA men and women show a weaker association between baseline blood pressure and subsequent rate of blood pressure change.

CONCLUSIONS

These findings suggest that several previously described age-associated patterns of blood pressure change partially reflect the effects of hypertension and its treatment, rather than intrinsic age changes in the blood pressure of healthy individuals.

Do echocardiographic changes explain the age-associated increase in exercise-induced supraventricular arrhythmias?

Although exercise-induced supraventricular arrhythmias (EISVA) increase with advancing age, it is unclear whether age-associated changes in cardiac structure or function play a major role in this increase. To address this question, we examined the relationship between M-mode echocardiographic variables and EISVA occurring during maximal treadmill exercise in 366 healthy volunteers aged 20 to 90 years from the Baltimore Longitudinal Study of Aging. Simple (i.e., isolated) EISVA were detected in 69 subjects (19%), and complex EISVA (i.e., comprising > 10% of beats in any minute or occurring in runs) in another 29 subjects (8%). Univariate predictors of any EISVA, whether simple or complex, were older age (p < 0.0001), male gender (p < 0.05), greater left atrial size (p < 0.01), left ventricular mass index (p < 0.0001), interventricular septal thickness (p < 0.001), isovolumic relaxation time (p < 0.01), atrial filling fraction (p < 0.01), reduced mitral E-F closure slope (p < 0.001), peak E velocity (p < 0.02), and peak E/A ratio (p < 0.0001). Lesser exercise duration (p < 0.01), lower maximal heart rate (p < 0.0001), and higher peak systolic and diastolic blood pressures (p < 0.001) were also associated with EISVA. However, by multiple logistic regression analysis, age (p < 0.0001) was the only independent predictor of any EISVA. Univariate predictors of complex EISVA were greater age (p < 0.0001), and atrial filling fraction (p < 0.001), diastolic blood pressure (p < 0.05), lesser mitral E-F slope (p < 0.004), exercise duration (p < 0.005) and maximal heart rate (p < 0.01). However, only age (p < 0.0001) independently predicted complex EISVA. Thus, in healthy volunteers undergoing maximal treadmill exercise. EISVA are associated with greater left ventricular wall thickness, reduced early diastolic performance, diminished exercise capacity and elevated exercise blood pressure. However, none of these variables are independent predictors of EISVA over and above the powerful effect of age.

Age-associated changes in left ventricular outflow tract geometry in normal subjects

This study examined age-associated changes in the geometry of the left ventricular outflow tract in normal subjects using Doppler echocardiography. With advancing age, the angle between the interventricular septum and the aortic root became more acute and a discrete bulging of the proximal septum was more common, but neither finding appeared to affect resting outflow tract velocity or left ventricular mass significantly.

Role of aerobic capacity and body mass index in the age-associated decline in heart rate variability

The extent to which age-associated changes in aerobic capacity and body composition modulate the age-associated decline in heart rate variability (HRV) is unknown. We therefore measured HRV, peak O2 consumption (VO2peak) during treadmill testing, and relative weight (body mass index; BMI) in 164 healthy normotensive adults (75 men, age 20-87 yr) from the Baltimore Longitudinal Study on Aging. Two components of HRV, respiratory sinus arrhythmia (RSA; 0.12-0.40 Hz) and 0.10-Hz variability (0.06-0.10 Hz), were extracted from 8-min electrocardiogram recordings in the supine, seated, and standing postures. RSA, 0.10-Hz variability, and VO2peak varied inversely with age; BMI was unrelated to age. Age contributed 15.5-21.1% independent variance to RSA and 13.2-17.3% independent variance to 0.10-Hz HRV. VO2peak did not contribute significantly to RSA or 0.10-Hz HRV beyond the effect of age in any posture. There were no consistent independent contributions of BMI to HRV. Thus, in this population-based sample, age-associated changes in aerobic capacity and relative body weight do not provide the primary explanation for the decline in HRV observed with advancing age.