The present study discusses the usefulness of Lactate Threshold (LT) as a health indicator in carrying out an exercise program for middle-aged and elderly women.
The subjects were 16 middle-aged and elderly women aged 38 to 58 years (mean±SD=41±7 years).
In order to 1) measure LT and Onset of Blood Lactate Accumulation (OBLA), 2) study the change of sympathodrenal responsea in relation to changes of cardiovascular and metabolic responses, and 3) examine changes of sympathoadrenal, cardiovascular and metabolic responses during 60mins of exercise corresponding to LT, submaximal exercise tests were performed by the subjects.
The results obtained were as follows:
1) Heart rate (HR) and systolic blood pressure (SBP) at LT were 120±14 beats/min and 144±24mmHg, whereas at OBLA 153±12 beats/min and 171±20mmHg, respectively.
2) Plasma noradrenaline significantly increased above the HR level of 150 beats/min. And a significant relationship was found among the noradrenaline, SBP, pressure-rate product and lactic acid (LA).
3) During 60mins of exercise corresponding to LT, LA attained a peak level of 2.01±0.93mmol/l at 10min, and thereafter gradually decreased. On the contrary, there was a progressive increase in plasma free fatty acid and glycerol indicating an increase in lipolysis. Noradrenaline and adrenaline increased 50% and 90% respectively above the resting levels at 60min, at which time values of HR and SBP were 126±21 beats/min and 134±23mmHg, respectively.
In conclusion, it was suggested that LT is a superior indicator in terms of safety and efficiency for exercise prescriptions for middle-aged elderly women.
