Inaccuracy of the HR Reserve vs. (V) over dotO2 Reserve Relationship during Prone Arm-paddling Exercise in Surfboard Riders

Previous studies have demonstrated that during lower-body exercise the percentage of heart rate reserve (%HRR) is equivalent to the percentage of the oxygen consumption reserve (%(V) over dotO(2R)) but not to a percentage of the peak oxygen consumption (%(V) over dotO(2peak)). The current study examined these relationships in trained surfboard riders (surfers) during upper-body exercise. Thirteen well-trained competitive surfers performed a stepwise, incremental, prone arm-paddling exercise test to exhaustion. For each subject, data obtained at the end of each stage (i.e., HR and (V) over dotO(2) values) were expressed as a percentage of HRR, (V) over dotO(2peak), and (V) over dotO(2R) respectively and used to determine the individual %HRR-(V) over dotO(2peak) and %HRR-%(V) over dotO(2R) relationships. Mean slope and intercept were calculated and compared with the line of identity (slope=1, intercept=0). The %HRR versus (V) over dotO(2R) regression mean slope (0.88+/-0.06) and intercept (20.82+/-4.57) were significantly different (p<0.05) from 1 and 0, respectively. Similarly, the regression of %HRR versus %(V) over dotO(2peak) resulted in a line that differed in the slope (p<0.05) but not in the intercept (p=0.94) from the line of identity. Predicted values of %HRR were significantly higher (p<0.05) from indicated values of (V) over dotO(2) for all the intensities ranging from 35% to 95% (V) over dotO(2R). Unlike results found for lower-body exercise, a given %HRR during prone upper-body exercise was not equivalent to its corresponding %(V) over dotO(2R). Thus, to ensure more targeted exercise intensity during arm-paddling exercise, individual HR-(V) over dotO(2) equations should be used. J Physiol Anthropol 29(6): 189-195, 2010 http://www.jstage.jst.go.jp/browse/jpa2 [DOI: 10.2114/jpa2.29.189]