D. R. Seals

Resistive training can reduce coronary risk factors without altering VO2max or percent body fat.

Eleven healthy, untrained males (age = 44 +/- 1 yr; range = 40 to 55 yr) were studied to determine the effects of 16 wk of high-intensity resistive training on risk factors for coronary artery disease. Lipoprotein-lipid profiles, plasma glucose and insulin responses during an oral glucose tolerance test, and blood pressure at rest were determined before and after training. The training program resulted in a 13% increase in high-density lipoprotein-cholesterol (39 +/- 2 vs 44 +/- 3 mg.dl-1, P less than 0.05), a 43% increase in high-density lipoprotein-cholesterol (7 +/- 2 vs 10 +/- 2 mg.dl-1, P less than 0.05), a 5% reduction in low-density lipoprotein cholesterol (129 +/- 5 vs 122 +/- 5 mg.dl-1, P less than 0.05), and an 8% decrease in the total cholesterol/high-density lipoprotein-cholesterol ratio (5.1 +/- 0.3 vs 4.7 +/- 0.3, P less than 0.01), despite no changes in VO2max, body weight, or percent body fat. Glucose-stimulated plasma insulin concentrations during oral glucose tolerance testing were significantly lower, and supine diastolic blood pressure was reduced (P less than 0.05) as a result of the training program. No changes in any of these variables occurred in a sedentary control group. These findings indicate that resistive training can lower risk factors for coronary artery disease independent of changes in VO2max, body weight, or body composition.

Effects of high-intensity strength training on cardiovascular function

Thirteen healthy, untrained males (age 44 +/- 1 yr, range 40-55 yr) were studied to determine the effects of 16 wk of high-intensity, variable-resistance, Nautilus strength training on cardiovascular function. A control group consisting of 10 untrained males (age 52 +/- 2 yr, range 40-64 yr) underwent the same evaluation procedures as the training group. Maximal oxygen uptake (VO2max), cardiac output during submaximal exercise, and body composition were determined before and after training. In addition, the physiological responses to an acute training session were evaluated. Muscular strength increased markedly, as evidenced by a 44% average increase in the one-repetition maximum in the various exercises. Body weight and percent body fat did not change with training, though fat-free weight did increase (66.9 +/- 2.6 vs 68.8 +/- 2.7 kg, P less than 0.05) significantly. Maximal oxygen uptake did not change significantly in either the training or the control group, and there were no changes in the hemodynamic responses to submaximal exercise after training. These findings indicate, therefore, that high-intensity, variable-resistance strength training produces no adaptative improvement in cardiovascular function. The physiological responses measured during a training session provide evidence that this lack of cardiovascular adaptation may be due to the low percentage of VO2max elicited by this form of exercise.

Enhanced left ventricular performance in endurance trained older men.

BACKGROUNDnThe age-associated decline in aerobic exercise capacity is partially reversible by endurance exercise training. Moderate-intensity endurance exercise training increases aerobic exercise capacity mediated, in part, by improvement of stroke volume and left ventricular performance in older men. The present study was designed to characterize the nature of cardiovascular adaptations to strenuous endurance exercise of long duration and to delineate the mechanisms underlying increased stroke volume and cardiac output in highly trained older endurance athletes.nnnMETHODS AND RESULTSnNine male master athletes (MA: 64 +/- 2 years old, mean +/- SEM) and 9 older sedentary healthy men (controls: 63 +/- 1 year) were studied. Left ventricular systolic function was evaluated with the use of cardiac blood pool imaging and echocardiography. Maximal O2 uptake (VO2max) was 50.4 +/- 1.7 mL.kg-1 x min-1 in the MA and 29.6 +/- 1.4 mL.kg-1 x min-1 (P = .0001) in controls. Systolic and mean blood pressures at rest and during exercise were not different in the two groups. Left ventricular systolic function at peak exercise was higher in the MA than in sedentary controls as evidenced by (1) a higher left ventricular functional reserve (delta EF: 12.4 +/- 2 versus 5.6 +/- 2.5, P = .05), (2) a large decrease in end-systolic volume during exercise (MA: 56 +/- 4 mL at rest and 42 +/- 5 mL at peak exercise, P = .007; controls: 43 +/- 2 mL at rest and 42 +/- 6 mL at peak exercise, P = .35) with no differences in systolic blood pressure, (3) a higher left ventricular fractional shortening at peak exercise (MA: 52 +/- 2.6%; controls: 45 +/- 1%, P = .046) at comparable values for end-systolic wall stress (MA: 56 +/- 12 g/cm2; controls: 53 +/- 7 g/cm2, P = .50), and (4) a greater decrease in end-systolic diameter at peak exercise in the MA than in controls (MA: -1.2 +/- 0.16 cm versus -0.57 +/- 0.13 cm, P = .014) despite no significant differences between the changes in end-systolic wall stress during exercise (MA: -15.5 +/- 7.5 g/cm2, controls: -11.0 +/- 9.0 g/cm2, P = .6). MA had a larger end-diastolic volume at rest (153 +/- 6 versus 132 +/- 4 mL, P = .009) with a normal wall thickness-to-radius ratio (0.34 +/- 0.02). Peak exercise stroke volume was higher (P = .023) in the MA (132 +/- 6 mL/min) than in the sedentary controls (111 +/- 6 mL/min). Changes in stroke volume correlated strongly with changes in ejection fraction in the MA (r = .80, P = .010) but not in sedentary controls (r = .59, P = .097). Further, changes in stroke volume from rest to exercise correlated strongly with changes in end-diastolic volume in both MA (r = .78, P = .013) and sedentary controls (r = .73, P = .026), suggestive of reliance of stroke volume on end-diastolic volume and preload. However, for a given increase in end-diastolic volume, the rise in stroke volume during exercise was significantly larger in the MA than in controls, which, in the absence of differences in mean blood pressures, indicates that enhanced left ventricular systolic function independent of preload plays an additional role in maintaining a higher stroke volume at peak exercise in the highly trained older men.nnnCONCLUSIONSnCardiac adaptations in older endurance trained men are characterized by volume-overload left ventricular hypertrophy and enhancement of left ventricular systolic performance at peak exercise. These adaptive responses contribute to enhanced stroke volume at peak exercise in older endurance trained men.

Left ventricular dysfunction after prolonged strenuous exercise in healthy subjects

To determine whether depressed left ventricular (LV) contractile function can occur after prolonged and strenuous exercise, 12 healthy men, 26 +/- 1 years old (mean +/- standard error of the mean) were studied. The subjects exercised on a treadmill at 69 +/- 1% of maximal O2 uptake until exhaustion (170 +/- 10 minutes). Hemodynamic variables were measured before and 10 minutes after exhausting exercise. Baseline systolic blood pressure decreased from 124 +/- 2 to 113 +/- 3 mm Hg (p less than 0.001) after exhausting exercise. LV end-diastolic diameter, measured by echocardiography, decreased from 51 +/- 1.0 to 47 +/- 1.0 mm (p less than 0.005) but LV end-systolic diameter did not change (34 +/- 1.0 vs 34 +/- 1.0 mm). Both LV fractional shortening and the mean velocity of circumferential fiber shortening decreased (33 +/- 1 vs 28 +/- 1%; p less than 0.01 and 1.09 +/- 0.4 vs 0.97 +/- 0.05 circ/s; p less than 0.025) despite a lower end-systolic wall stress (sigma es = 88 +/- 4 vs 82 +/- 5, X 10(3) dynes/cm2; p less than 0.05) after prolonged exhausting exercise. A repeat bout of exercise of the same intensity but brief in duration (10 minutes) resulted in increases in LV fractional shortening (p less than 0.001) and mean velocity of circumferential fiber shortening (p less than 0.001), and a decrease in LV end-diastolic diameter (50 +/- 1.0 to 48 +/- 1.0 mm; p less than 0.05) at heart rates comparable to those attained after prolonged exhausting exercise. The results suggest that prolonged strenuous exercise may result in impaired LV function in healthy young subjects.

Elevated High-Density Lipoprotein Cholesterol Levels in Older Endurance Athletes

To ascertain whether older (masters) athletes exhibit a more favorable plasma lipoprotein/lipid profile than sedentary men of similar age, 14 endurance-trained masters athletes (mean age 60 +/- 2 years [+/- standard error of the mean]), 12 older, untrained-not lean men (mean age 62 +/- 1 years), 9 older untrained-lean men (mean age 61 +/- 2 years), 15 young endurance-trained athletes (mean age 26 +/- 1 years) and 15 young untrained men (mean age 28 +/- 1 years) were studied. The athletes had higher values for maximal oxygen uptake and lower levels of body fatness compared with the untrained men, regardless of age (p less than 0.05). High-density lipoprotein (HDL) cholesterol was markedly higher in the masters athletes than in the other groups (66 vs 42 to 55 mg/dl, p less than 0.05). The total cholesterol (TC) and low-density lipoprotein cholesterol concentrations of the masters athletes generally were higher than those of the younger groups, similar to those of the older lean men, and lower than those of the older-not lean men (p less than 0.05). The TC/HDL cholesterol ratios were similarly low (2.8 to 3.4) for the athletes and the young untrained men compared with the older untrained men (4.0 to 5.6) (p less than 0.05). Thus, some older endurance athletes exhibit markedly higher HDL cholesterol levels and lower TC/HDL cholesterol ratios compared with their sedentary peers. This favorable plasma lipoprotein profile may indicate a reduced risk of developing coronary artery disease for older men who exercise regularly.

The effect of left ventricular systolic function on maximal aerobic exercise capacity in asymptomatic patients with coronary artery disease.

The purpose of this study was to examine the relationship between maximal O2 uptake (VO2max) and left ventricular systolic function in patients with coronary artery disease. We studied 27 patients, age 50 +/- 10 years (mean +/- SD), who were asymptomatic and able to attain true VO2max. VO2max was defined by the leveling-off criterion and/or a respiratory exchange ratio of 1.15 or greater. Left ventricular ejection fraction was determined by gated cardiac blood pool imaging. In patients whose ejection fraction decreased with exercise, VO2max was 21 +/- 4 vs 27 +/- 4 ml/kg/min in those whose ejection fraction increased (p less than .001). Systolic blood pressure/end-systolic volume relation was shifted upward and to the right in the former group in response to peak exercise. In contrast, the pressure-volume relation was shifted upward and to the left in patients whose ejection fraction increased with exercise. Ejection fraction at rest did not correlate with VO2max. There was a significant but weak correlation between peak exercise ejection fraction and VO2max (r = .43, p less than .025). Left ventricular exercise reserve, i.e., the change in ejection fraction from rest to exercise, correlated with VO2max (r = .77, p less than .0002), maximal O2 pulse (r = .50, p less than .005), and maximal heart rate during treadmill exercise (r = .61, p less than .001). Maximal heart rate during treadmill exercise correlated with VO2max (r = .70, p less than .0002).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of training on systolic time intervals at rest and during isometric exercise in men and women 61 to 64 years old

To determine whether regular exercise improves left ventricular (LV) contractile function in persons 60 years and older, systolic time intervals (STIs) were measured in 10 healthy men and women (mean age 62 +/- 1 year [+/- standard deviation]) before and after 6 months of intense endurance training. STIs, systolic and diastolic blood pressure (BP) and heart rate (HR) were determined at rest and in response to isometric handgrip exercise. Systolic BP, diastolic BP and HR increased acutely from rest in response to handgrip (p less than 0.002). The indexes of total electromechanical systole and LV ejection time (ET) index increased (p less than 0.01), preejection period (PEP) index increased (p less than 0.05) or remained unchanged and PEP/LVET did not change from values at rest in response to handgrip. Training resulted in an 18% increase in maximal oxygen uptake (p less than 0.01). After training, systolic and diastolic BP were reduced at rest (p less than 0.002) and, along with HR, were lower in response to handgrip (p less than 0.002). However, training did not alter STIs at rest or during handgrip. These findings indicate that healthy persons in their 60s have a normal LV response to isometric exercise. Prolonged, intense endurance training does not alter LV contractile function at rest or in response to isometric exercise. However, training can significantly reduce BP at rest, and markedly lower the HR-systolic BP product attained during acute isometric stress, even in normotensive older subjects.

[Vdot]O2 Max in Variable Type Exercise Among Well-Trained Upper Body Athletes

Abstract The purpose of this study was to determine the maximal oxygen consumption ([Vdot]O2 max) of well-trained upper body (WTUB) athletes and untrained individuals in four different types of exercise: arm cranking (AC), legs only cycling (LC), graded treadmill running (TM) and combined arm cranking and leg cycling (A + L). The subjects included 12 rowers, 10 gymnasts, 11 swimmers, 10 wrestlers and 12 non-WTUB individuals. Maximal oxygen uptake was measured via an open circuit system. The results of this study indicated that: (1) WTUB athletes attained a significantly (p<.05) higher [Vdot]O2 max in AC and A + L than non-WTUB individuals, (2) differences among various WTUB groups in AC were reduced when [Vdot]O2 max was expressed in ml · kg-1 · min-1, but became evident in A + L, (3) WTUB athletes attained 80–95% of their LC [Vdot]O2 max in AC whereas non-WTUB individuals attained 60-70%, (4) WTUB individuals attained 120-130% of their LC [Vdot]O2 max in A + L whereas non-WTUB individuals attained 110-11...

Endogenous digoxin-like immunoreactivity in blood is increased during prolonged strenuous exercise

Digoxin-like immunoreactive factors (DLIFs) in serum may represent endogenous cardiotropic agents. We determined if blood levels of these endogenous factors changed during prolonged strenuous exercise. Total and loosely protein-bound (LPB) DLIF were measured by radioimmunoassay in the serum of nine healthy subjects during prolonged exercise to exhaustion. Mean total and LPB serum levels of DLIF increased by 72% (580 to 945 pg/mL) and 63% (53 to 91 pg/mL) over baseline values in digoxin equivalents (p less than 0.01), respectively, after three hours of exercise at 70% of VO2max. The prevalent serum nonesterified fatty acids (arachidonic, linoleic, oleic, palmitic, and stearic acids) as well as hydrocortisone did not account for the observed elevations in DLIF. Percent left ventricular fractional shortening (%FS) and mean velocity of left ventricular circumferential fiber shortening (mVCF) measured echocardiographically were lower (-18.0% and -16.4%, respectively, p less than 0.05) after exercise as compared to prior to exercise. Cardiac left ventricular dysfunction as measured by %FS did correlate with blood levels of DLIF (r = -0.680, p less than 0.02). These observations may suggest a relationship between serum levels of DLIF and cardiac fatigue.