© 1997 Oxford University Press
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Baroreflex function in sedentary and endurance-trained elderly people
1Departments of Pharmacological Sciences The University Newcastle upon Tyne NE2 4HH, UK
2Departments of Medicine The University Newcastle upon Tyne NE2 4HH, UK
3Physiological Sciences, The University Newcastle upon Tyne NE2 4HH, UK
Regional Medical Physics Department, Freeman Hospital Newcastle upon Tyne, UK
Address correspondence to: G. A Ford. Fax: (+44) 191 232 3613. Email: g.a.ford{at}ncl.ac.uk
Objective: to determine the differences associated with age and endurance exercise training on the baroreflex function of healthy subjects.
Design: cross-sectional study.
Setting: university research department.
Participants: 26 (10 female) sedentary, healthy, normotensive elderly subjects (mean age 67 years, range 62–81), eight (two female) elderly endurance-trained athletes (66 years, 62–69) and eight (two female) young (30 years, 25–34) subjects.
Measurements: baroreflex sensitivity was quantified by the a-index, at high frequency (HF, 0.15–0.35 Hz) and mid frequency (MF, 0.05–0.15 Hz), derived from spectral and cross-spectral analysis of spontaneous fluctuations in heart rate and blood pressure.
Results: resting heart rate was significantly lower in endurance-trained athletes than sedentary elderly people (58 ± 12 versus 68 ±11 min–1, P < 0.05) but not different to that in healthy young subjects (63 ± 9min–1). 
HF in sedentary elderly subjects (8.1±4.2 ms.mmHg–1) was lower than both endurance-trained elderly athletes (14.8 ±4.8 ms.mmHg–1, P < 0.05) and healthy young subjects (28.3 ± 21.8 ms.mm Hg–1 P < 0.05) and was not significantly different between endurance-trained elderly athletes and healthy young subjects (P = 0.10). µF in healthy young subjects (15.4 ± 8.8 ms.mm Hg–1) was greater than in sedentary elderly subjects (6.5 ± 3.2 ms.mm Hg–1, P < 0.01)and endurance-trained elderly athletes (6.9 ± 2.0 ms.mmHg–1, P < 0.01), while there was no significant difference between the two elderly groups (P = 0.66).
Conclusions: both components of the barorefiex measured by the a-index show a decrease with age. Elderlyendurance-trained athletes have less reduction in the high, but not mid, frequency component of the a-index compared with sedentary elderly subjects. Some of the age-related changes in baroreflex sensitivity may be related to physical fitness and activity levels.
Received November 15, 1996;
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