Cardiorespiratory adaptation with short term training in older men

The purpose of this study was to assess the rate of training-induced cardiorespiratory adaptations in older men [mean (SD), 66.5 (1.2) years]. The eight subjects trained an average of 4.3 (0.3) times each week. The walk/jog training was in two phases with 4 weeks (phase 1) at a speed to elicit 70% of pre-training maximal oxygen consumption ( \(\dot VO_{2\max } \) ), and 5 weeks (phase 2) at 80%. Maximal exercise treadmill tests and a standardized submaximal protocol were performed prior to training, at weekly intervals during the training programme, and after training. \(\dot VO_{2\max } \) (ml·kg⁻¹·min⁻¹) increased significantly over both phases: 6.6% after the first 4 weeks, and an additional 5.2% after the final 5 weeks. The weekly changes in \(\dot VO_{2\max } \) over phase 1 were well fitted by an exponential association curve (r=0.75). The half-time for the rate of adaptation was 13.8 days, or 8.3 training sessions. Over phase 2, the change in \(\dot VO_{2\max } \) did not plateau and a time course could not be determined. Submaximal exercise heart rate (f _c ) was reduced a significant 10 beats · min⁻¹ after the first 4 weeks, and a further 6 beats · min⁻¹ over the final 5 weeks. Thef _c reductions showed half-times of 9.1 days (phase 1) and 9.8 days (phase 2) (or 5-6 training sessions). The anaerobic ventilation threshold was increased 13.9% over the 9 weeks of training and the respiratory exchange ratio during constant load heavy exercise was significantly reduced; however, these changes could not be described by an exponential time course. Thus, short-term exercise training of older men resulted in significant and rapid cardiorespiratory improvements.