Adaptation to a standardized training program and changes in fitness in a large, heterogeneous population: the HERITAGE Family Study

Purpose: This paper describes the variations in response to a standardized, computer-controlled training program. Methods: Steady-state heart rate (HR ) and oxygen intake ((V) over dot O-2) of 614 healthy, sedentary men and wo men aged 16-65 yr were measured during three cycle ergometer exercise tests . The HR associated with 55, 65, 70, and 75% of each subject's pretraining (V) over dot O(2)max was used to prescribe exercise intensity. Subjects exe rcised three limes a week, beginning at a HR associated with 55% (V) over d ot O(2)max for 30 min. Duration and intensity was gradually increased over 20 wk of training. The duration and HR of each training session were contro lled by a computer. Results: Using the linear relationship between HR, (V) over dot O-2 and power output (PO), PO were predicted for each of 60 traini ng sessions at the respective programmed HR. The average ratio of the actua l training HR to programmed HR was 0.99. It was hypothesized that participa nts whose actual training PO exceeded their predicted PO would improve (V) over dot O(2)max more than those whose actual PO was less than their predic ted PO. Using the ratio of actual/predicted PO determined after the trainin g was over, participants were arbitrarily assigned to three groups: 128 par ticipants had low (LO) ratios (0.65-0.54), 408 had average (AV) ratios (0.8 5-1.14), and 78 had high (HI) ratios (1.15-1.34). Secondary analysis showed that the training program significantly increased mean (V) over dot O(2)ma x of all three groups. Those who had a smaller increase in training PO (LO) had significantly less increase in (V) over dot O(2)max than those with la rger increases in PO (HI). Conclusion: People who exercise at a HR associat ed with the same %(V) over dot O(2)max can vary substantially in their trai ning PO, in their rate of increase in PO over a 20-wk training program, and in improvement of their (V) over dot O(2)max.