Ageing is associated with a decline in cardiorespiratory function. However, in many older people lifestyle factors, particularly physical inactivity, may account for a significant proportion of this decline. To eliminate this confounder and investigate the inherent ageing process, healthy physically active people should be studied (Lazarus and Harridge 2010). Most studies of human ageing are cross-sectional and confounded by the natural heterogeneity in levels of function that exist between different individuals. To overcome both limitations a longitudinal study of a subset of highly active master cyclists (Pollock et al., 2015) was performed. The cyclists were retested to determine how cardiorespiratory function has changed over 9 years. The overarching hypothesis is that with a maintenance of health and exercise levels, any changes observed could be attributed to the biological ageing process unaffected by negative lifestyle factors.
Fifteen healthy master cyclists (men n = 14; female n = 1), now aged 64–85 years (74±6 years) returned for testing. Body composition was measured using dual-energy X-ray absorptiometry (DEXA). Resting blood pressure and heart rate were measured after 10 minutes of supine rest. R function (Forced Vital Capacity, FVC, Forced Expiratory volume, FEV1 and Peak Expiratory Flow, PEF) was assessed in accordance with ATS guidelines. An incremental exercise test on a cycle ergometer was used to determine maximal aerobic power (VO2max) and ventilatory threshold (VT). Oxygen uptake kinetics were also determined. All data are presented as mean±SD and compared pre and post 9 years using a paired t-test.
After 9 years, cycling volume was unchanged (585±388 vs. 570±407 km/month; p = 0.88). Body mass (70±7.0 vs. 67±6.8 kg; p = 0.009) and fat free mass ((FFM); 55±4.6 vs. 50±4.1 kg; p< 0.001) were reduced by 3% and 8%, respectively, whilst fat mass increased 15% (14.4±3.5 vs. 16.5±3.7 kg; p < 0.005). Resting systolic blood pressure (128.7±13.8 vs. 129.9±22.1 mmHg; p = 0.80), and diastolic blood pressure (69.4±8.9 vs. 64.1±13.5 mmHg; p = 0.08) were unchanged after 9 years. FVC (5.6±1.1 vs. 4.0±1.0 L; p < 0.001), and FEV1 (3.6±0.6 vs. 2.9±0.6 L p < 0.001) declined by 28% and 19%, respectively whilst PEF remained unchanged (8.2±2.3 vs. 8.1±1.5 L/s; p = 0.76). The FEV1/FVC ratio increased by 13% (64.9±8.8 vs. 73.1±7.4; p < 0.001). VO2max declined by 18% (47.3±3.5 vs. 38.9±4.7 ml kg−1 min−1; p < 0.001), but less so (12%) when normalised to FFM (59.4±3.9 vs. 52.1±5.5 ml (kg FFM)−1 min−1; p < 0.001).  There was a decline in maximum heart rate (165.1±10.9 vs. 157.9±14.3 bpm; p = 0.02). VT decreased by 11% (35.7±3.7 vs. 31.9±4.5 ml/kg/min; p = 0.001), and by 6% when normalised to FFM (44.8±3.9 vs. 42.2±5.2 ml mls/kg/min; p = 0.03). O2 kinetics did not change (tau; 22.2±8.3 vs. 24.3±3.3 s; p = 0.30).
These data show a decline in many indices of cardiorespiratory function in master cyclists over a nine-year period, which in the context of a maintenance of both their health status and exercise training can be interpreted as being a result of the inherent ageing process.