PRESCRIBING EXERCISE INTENSITY FOR OLDER WOMEN

OBJECTIVE: For the purpose of prescribing exercise intensity, the Amer ican College of Sports Medicine (ACSM) provides guidelines for relatin g the perceived level of exertion and the heart rate (HR) response dur ing exercise, expressed either as a percentage of maximal HR or of HR reserve, to a percentage of maximal aerobic power ((V) over dot O(2)ma x). However, because maximal HR and (V) over dot O(2)max decline with age, it is possible that these guidelines are not appropriate for an o lder population. The purpose of this study was to evaluate in 60-to 72 -year-old women the relationships among the common methods of prescrib ing exercise intensity. DESIGN: Participants were 112 healthy but sede ntary women, aged 66 +/- 4 years, who performed treadmill walking at f our speeds. SETTING: Subjects were recruited from the community, and e xercise tests were performed at a university laboratory facility. MEAS UREMENTS: (V) over dot O(2)max and maximal HR were determined during t readmill walking. The HR and (V) over dot O-2 responses to walking 6 m inutes at each of four speeds ranging from 67 to 107 m/min, along with ratings of perceived exertion (RPE) and plasma lactate levels, were d etermined on a separate day.RESULTS: The exercise bouts required an av erage of 55 +/- 10%, 64 +/- 12%, 77 +/- 12%, and 91 +/- 9% (V) over do t O(0)2max. Corresponding HR values were 64 +/- 8%, 70 +/- 9%, 81 +/- 10%, and 92 +/- 7% of maximal HR, and they were within the expected ra nges based on ACSM guidelines. HR values as a percentage of HR reserve were much lower than expected based on the guidelines. RPE values wer e lower than expected at a given %(V) over dot O(2)max, and plasma lac tate levels were also relatively low, suggesting that older women are able to exercise at a higher percentage of (V) over dot O(2)max than l evels currently recommended. CONCLUSIONS: The results indicate that HR expressed as a percentage of maximal HR is an appropriate method of p rescribing exercise intensity in healthy, sedentary 60-to 72-year-old women. The HR reserve method is not recommended in this population bec ause it will likely result in the exercise being performed at a higher than expected percentage of (V) over dot O(2)max.