Decreased exercise blood pressure in older adults after exercise training: contributions of increased fitness and decreased fatness

OBJECTIVE

To describe the contribution of changes in fitness and fatness resulting from exercise training on changes in submaximal exercise blood pressure (BP) during treadmill testing.

DESIGN AND SETTING

Prospective, randomised, controlled trial.

PARTICIPANTS

Sedentary older adults (n = 115) with untreated prehypertension or mild hypertension.

INTERVENTION

Six-month supervised aerobic and strength training.

MAIN OUTCOME MEASUREMENT

Systolic BP (SBP) was assessed at rest and during each stage of a maximal graded exercise test (GXT) that determined Vo(2)peak. General and regional fatness was assessed by anthropometry, dual-energy x-ray absorptiometry and MRI. BP changes were calculated for each GXT stage, and multivariate regression models were used to describe the association of changes in exercise BP with changes in fitness and fatness.

RESULTS

After training, exercisers versus controls had significantly increased Vo(2)peak and significantly lower measures of general and regional fatness. Also, stage-specific SBP was significantly lower at stage 3 (-9.4 vs -1.6 mm Hg, p = 0.03) and stage 4 (-7.9 vs -1.2 mm Hg, p = 0.03). Pooled regression analysis across all stages showed that exercisers had a 7.1 mm Hg reduction in SBP, but this reduction fell short of statistical significance (p = 0.12) compared with controls. A 1.0 ml/kg/min increase in Vo(2)peak and a 1.0 cm decrease in waist circumference independently predicted a 1.0 mm Hg decrease in exercise SBP (p = 0.04 and p = 0.001, respectively).

CONCLUSIONS

Decreased exercise SBP was independently associated with decreased waist circumference, a marker of abdominal obesity and increased fitness. These findings suggest that exercise training improves multiple factors that have an independent influence on SBP.

Exercise effects on cardiac size and left ventricular diastolic function: relationships to changes in fitness, fatness, blood pressure and insulin resistance

OBJECTIVES

To determine exercise training effects on cardiac size and left ventricular (LV) diastolic function and relationships of exercise induced changes in physiological and body composition parameters with cardiac parameters.

DESIGN

Prospective, randomised controlled trial.

SUBJECTS

Men and women (63.6 (5.7) years, body mass index 29.5 (4.4) kg/m(2)) with untreated hypertension (systolic blood pressure (BP) 130-159 or diastolic BP 85-99 mm Hg).

MAIN OUTCOME MEASURES

Cardiac size and LV diastolic function, peak oxygen uptake (Vo(2)), muscle strength, general and abdominal fatness, and insulin resistance.

INTERVENTIONS

6 months of exercise training versus usual care.

RESULTS

When analysed by group at six months, cardiac size and LV diastolic function did not differ between exercisers (n = 51) and controls (n = 53), whereas exercisers had significantly higher peak Vo(2) (28 v 24 ml/kg/min) and strength (383 v 329 kg), and lower fatness (34% v 37%), diastolic BP (73 v 75 mm Hg) and insulin resistance (quantitative insulin sensitivity check index 0.35 v 0.34) versus controls (all p <or= 0.05). By regression analysis, among six month changes, increased peak Vo(2) and reduced abdominal fat were associated with increased cardiac size. Increased peak Vo(2) and reduced abdominal fat, BP and insulin resistance were associated with improved LV diastolic function. r Values ranged from 0.20 to 0.32 (p <or= 0.05).

CONCLUSIONS

When examined by group assignment, exercise had no effect on cardiac size or LV diastolic function. When individual variations in six month changes were examined, participants attaining the greatest increases in fitness and reductions in abdominal fatness, insulin resistance and BP showed a modest trend towards physiological hypertrophy characterised by increased cardiac size and improved LV diastolic function. These results suggest that decreased abdominal fatness may have a role in improving cardiovascular health.

Exercise blood pressure response is related to left ventricular mass

An exaggerated SBP response to exercise has been associated with increased left ventricular (LV) mass in some but not all studies. A total of 43 women and 34 men, aged 55-75 years, without evidence of cardiovascular disease, with a mean resting BP of 142+/-9/77+/-8 mmHg had their BP measured at rest and during maximal treadmill exercise. LV mass was measured using magnetic resonance imaging. LV mass was adjusted for lean body mass, which was assessed by dual energy X-ray absorptiometry. LV mass was within the normal range for the majority of the subjects. Among the resting and exercise BP indices, maximal SBP was the strongest correlate of LV mass (r=0.41, P<0.05). In multivariate analysis, maximal SBP was independently associated with LV mass after adjustment for lean body mass and gender, explaining 3% of the variance (P<0.05). Maximal exercise SBP is a modest but still independent predictor of LV mass in older persons with normal LV mass. These results raise the possibility that the SBP response to maximal exercise is an early marker of LV hypertrophy.

Fitness, fatness and activity as predictors of bone mineral density in older persons

OBJECTIVES

To determine relationships of bone mineral density (BMD) with fitness, physical activity, and body composition and fat distribution.

DESIGN

Cross-sectional.

SETTING

General Clinical Research Center, Johns Hopkins Bayview Medical Center, Baltimore, Maryland.

SUBJECTS

Men (n = 38) and women (n = 46), aged 55-75 years with high normal blood pressure or mild hypertension but otherwise healthy.

METHODS

Aerobic fitness (oxygen uptake) on a treadmill, muscle strength by one-repetition maximum, activity by questionnaire, abdominal obesity by magnetic resonance imaging; anthropometrics, and body composition by dual energy X-ray absorptiometry (DXA) which measured total fat and lean mass, and BMD for the total skeleton, lumbar spine (L1-L4) and total hip.

RESULTS

Aerobic fitness did not correlate with BMD. Using multivariate analysis to ascertain independent contributions to the variance in BMD, in women, with adjustment for hormone replacement therapy (HRT), total skeleton BMD was independently related to muscle strength and abdominal total fat; total hip BMD to body weight; lumbar spine BMD to abdominal total fat. HRT also influenced BMD in the lumbar spine. In men, lumbar spine BMD was independently related to abdominal total fat physical activity and total hip BMD related to lower body strength. P < 0.05 for all of these correlations.

CONCLUSIONS

Abdominal obesity and muscle strength emerge as predominant correlates of BMD in older persons with stronger relationships seen in women. Body weight and HRT also explained portions of the variance in BMD in women. Whether abdominal obesity is simply a marker for general obesity or has independent protective effects on bone is yet to be determined.