Medicine & Science in Sports & Exercise:
B-14 Thematic Poster - Breast Cancer (Clinical Exercise Physiology Association): JUNE 1, 2011 1:00 PM - 3:00 PM: ROOM: 101
Kirkham, Amy A.; Campbell, Kristin L.; McKenzie, Donald C.
The University of British Columbia, Vancouver, BC, Canada.
(No relationships reported)
It is unknown how intensities achieved by different aerobic exercise intensity prescription methods compare in any population. This complicates the interpretation and comparison of studies necessary to create evidence-based exercise guidelines, which are currently a high priority for the cancer population. The accuracy of prescription methods in achieving the prescribed intensity is also unknown for the cancer population. Methods that are inaccurate could be unsafe or ineffective.
PURPOSE:To compare the achieved intensity (AI) and accuracy (AC) of four common methods of intensity prescription within and between breast cancer patients recently finished chemotherapy (n=10), survivors finished treatment (n=10) and healthy controls (n=10).
METHODS: In randomized order, 1) the ACSM's metabolic equation for treadmill walking (MET equation), 2) heart rate reserve (HRR), 3) direct heart rate (direct HR) and 4) rating of perceived exertion (RPE) methods were used to prescribe an intensity of 60% of oxygen consumption reserve (VO2R) in separate 10-minute treadmill bouts with expired gas analysis to measure AI, AC was defined as: [60%VO2R - AI]. Comparisons of AI and AC within each group were made with one-way ANOVA. The interaction between group and AC was analyzed with 3 x 4 ANOVA.
RESULTS: In ranked order from most accurate, the average AI (%VO2R), and AC (+/- percentage points (pp)) in the patient group were: HRR: 61%, 3 pp; MET equation: 56%, 4 pp; direct HR: 60%, 8 pp; RPE: 53%, 9 pp. RPE differed significantly from the HRR method in both AI (p=.02) and AC (p=.05), and the direct HR method in AI (p<.01). In the survivor group results were: MET equation: 59%, 3 pp; HRR: 63%, 5 pp; direct HR: 64%, 5 pp; RPE: 47%, 13 pp. RPE differed significantly in AI (all at p<.01) and AC (all at p<.01) from all three methods. There was a significant interaction effect (p=.04) between group and AC.
CONCLUSIONS: The four methods of intensity prescription do not achieve equivalent intensities, and vary in AC in prescribing 60 %VO2R within the 3 groups. The AC of the four methods is not equivalent among breast cancer patients, survivors and healthy controls. These results have implications for selecting an aerobic exercise intensity prescription method in this clinical population.
Supported by CIHR & MSFHR.