Date of Award


Degree Type


Degree Name

Doctor of Philosophy




Dr. Donald H. Paterson


A reduced maximal O2uptake (V02max) and a slower rate ofadjustment for V02during the exercise on-transient have been demonstrated in older individuals compared to their younger counterparts. Endurance-exercise training elicits cardiovascular adaptations in older individuals, resulting in age-dependent limitations being reduced. The mechanisms explaining the improvements in cardiorespiratory fitness have been proposed to be sex- related. However, there is a gap of information in terms of the mechanisms and time- course of changes occurring in response to short-term endurance training. Additionally, there are few studies directly comparing physiological responses to endurance training in older and young men and women. This thesis examined the mechanisms explaining the changes in VC^max and the VO2 time constant (xV02) occurring in older compared with young men and women in response to a 12-week endurance training program.

The main findings were that: 1) a short-term training program with progressive increases in exercise intensity resulted in significant increases in VC^max in older and young men and women; 2) the time-course of increases in VC^max in response to a 12- week endurance training program was similar in older men and young men and women with changes in both maximal cardiac output and arterial-venous O2 difference explaining the increases in VC>2max; however, older women showed a plateau-like response in VC^max during the last 3 weeks of training and marked reliance on peripheral changes related to increased O2 extraction throughout the training program; 3) the decrease in pulmonary tVC>2 (tV0 2p) in older and young men and women occurred within the first 3 weeks of training with no subsequent changes observed thereafter; 4) microvascular O2 delivery to the active muscle sites o f O2 utilization seems to be an important constraint for the initial


slower rate of adjustment in tV02Pin older and in young men and women and, although the fundamental control of VC^p kinetics may take place intracellularly, by factors that were not measured in these studies, O2 delivery appears to be a major constraint in participants with “slow” VO2 kinetics.

In conclusion, an increase in V02max and speeding of V02kinetics in older adults can be achieved with a short-term exercise training program.



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