Joanne B. Krasnoff

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 (VO2) of 614 healthy, sedentary men and women aged 16-65 yr were measured during three cycle ergometer exercise tests. The HR associated with 55, 65, 70, and 75% of each subjects pretraining VO2max was used to prescribe exercise intensity. Subjects exercised three times a week, beginning at a HR associated with 55% VO2max for 30 min. Duration and intensity was gradually increased over 20 wk of training. The duration and HR of each training session were controlled by a computer. RESULTS Using the linear relationship between HR, VO2 and power output (PO), PO were predicted for each of 60 training sessions at the respective programmed HR. The average ratio of the actual training HR to programmed HR was 0.99. It was hypothesized that participants whose actual training PO exceeded their predicted PO would improve VO2max more than those whose actual PO was less than their predicted PO. Using the ratio of actual/predicted PO determined after the training was over, participants were arbitrarily assigned to three groups: 128 participants had low (LO) ratios (0.65-0.84), 408 had average (AV) ratios (0.85-1.14), and 78 had high (HI) ratios (1.15-1.34). Secondary analysis showed that the training program significantly increased mean VO2max of all three groups. Those who had a smaller increase in training PO (LO) had significantly less increase in VO2max than those with larger increases in PO (HI). CONCLUSION People who exercise at a HR associated with the same %VO2max can vary substantially in their training PO, in their rate of increase in PO over a 20-wk training program, and in improvement of their VO2max.

A comparison of 24-h average blood pressures and blood pressure load following exercise

Although the use of 24-h ambulatory blood pressure monitoring has been recommended in the study of blood pressure and exercise, consistent results have not been found for average 24-h systolic or diastolic blood pressures. Systolic load and diastolic load (the percentage of pressures >140/90 mm Hg during daytime hours and >120/80 mm Hg during sleep) have recently been identified as an important variable, but has had limited use with exercise. The purpose of this study was to compare the average systolic and diastolic pressures to systolic and diastolic loads from 24-h data recorded after a 50-min treadmill walk at 50% VO2max to data from a nonexercise control day. Subjects were 36 normotensive (116.9 +/- 10.7/77.0 +/- 8.9 mm Hg) and 25 hypertensive (141.0 +/- 13.7/96.6 +/- 9.0 mm Hg) adults. No significant differences were found for systolic and diastolic pressures or loads between the control and exercise days for normotensives. Even though no significant changes were found for any of the average systolic and diastolic pressures between the control and exercise days for the hypertensives, significant reductions were found in systolic load for 24-h (-25.7%), day (6 AM to 10 PM, -23.1%), work (6 AM to 5 PM, -22.9%), and leisure (5 PM to 10 PM, -26.7%) periods; and in diastolic load for the work (-22.5%) period. Thus, the measurement of systolic and diastolic load may be more sensitive than average systolic and diastolic blood pressures for the detection of 24-h ambulatory blood pressure changes with exercise in borderline hypertension.

Physical Functioning In Patients With Chronic Kidney Disease: 1228 Board #83 2:00 PM ??? 3:30 PM

BACKGROUND Patients with chronic kidney disease (CKD) treated with dialysis have reduced levels of physical functioning. Little is known of the physical functioning in patients prior to initiation of renal replacement therapy (RRT). The purpose of the study was 2-fold: (i) to document physical functioning of patients with CKD not requiring RRT, using objective laboratory tests, physical performance measures and self-reported functioning; and (ii) to determine the correlations between these measures of physical functioning and renal function. METHODS Thirty-two patients with CKD (mean estimated glomerular filtration rate [eGFR] 29.9 +/- 17.0) were recruited for the study. Subjects completed symptom-limited treadmill test (peak oxygen uptake [VO2peak]), physical performance measures (gait speed, sit-to-stand and 6-minute walk) and the SF-36 Health Status Questionnaire (physical functioning scale [PF] and physical composite scale [PCS]). Descriptive and correlational analyses were performed on the data. RESULTS VO2peak (O2 17.8 +/- 6.7 ml/kg body weight per minute), physical performance measures and self-reported functioning were reduced compared with sedentary age-predicted norms. Significant correlations were found between VO2peak and all other physical functioning measures; however, only maximal gait speed and PCS correlated significantly with eGFR. CONCLUSIONS Patients with CKD have reduced physical functioning as measured using objective laboratory tests (VO2peak), physical performance measures and self-reported functioning. Given that low physical functioning predicts outcomes in dialysis patients, interventions to maintain or improve physical functioning are warranted prior to initiation of dialysis.