Test-retest reliability of the aerobic power index submaximal exercise test in cancer patients

The purpose of this study was to investigate the reliability of the Aerobic Power Index (API) submaximal cardiorespiratory exercise test, as well as associated variables of oxygen uptake (ml·kg(-1)·min(-1)) and ratings of perceived exertion (RPE) in cancer patients who are generally unable to complete maximal or lengthy aerobic fitness tests. Twenty male and female participants (11 male; 9 female) aged between 18 and 70 y (mean = 53.28 ± 11. 82 y) were recruited with medical consent within 4 weeks of completing chemotherapy treatment for a lymphohaematopoietic cancer (LHC). Of the twenty recruited participants' 2 were excluded from analysis due to disease relapse or complications unrelated to testing occurring within the month following testing. Intra-class correlation coefficient (ICC) scores for power output (W·kg(-1)) and oxygen uptake (ml·kg(-1)·min(-1)) were highly reliable (R1 = 0.96 and 0.96, respectively) and the ICC for RPE was moderately reliable (R1 = 0.83). Technical error of measurement results for power output (W·kg(-1)), oxygen uptake (ml·kg(-1)·min(-1)) and RPE were 0.11W·kg(-1), 1.18 ml·kg(-1)·min(-1) and 1.0 respectively. A Pearson's product-moment correlation demonstrated a strong relationship between power output (W·kg(-1)) and oxygen uptake (ml·kg(-1)·min(-1)) for both trials (r = 0.93 and 0.89, respectively). Results demonstrate that the API test is a highly reliable protocol for use with a LHC population and can be considered a clinically feasible, safe and tolerable exercise test.