Tracking Changes in Maximal Oxygen Consumption with the Heart Rate Index in Female Collegiate Soccer Players

The purpose of this study was to determine if the HRindex Method (VO(2max) = [6 x HRindex – 5] x 3.5, where HRindex = HRmax/HRrest) was accurate for tracking changes in VO(2max) following 8-weeks of endurance training among collegiate female soccer players. Predicted VO(2max) via the HRindex Method and observed VO(2max) from a maximal exercise test on a treadmill were determined for a group of female soccer athletes (n = 15) before and following an 8-week endurance training protocol. The predicted (pVO(2max)) and observed (aVO(2max)) values were compared at baseline and within 1-week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference between aVO(2max) before (43.2 ± 2.8 ml·kg·min(−1)) and following (46.2 ± 2.1 ml·kg·min(−1)) the 8-week training program (p < 0.05). However, pVO(2max) did not significantly change following training (pre = 43.4 ± 4.6 ml·kg·min(−1), post = 42.9 ± 4.1 ml·kg·min(−1), p = 0.53). Furthermore, the correlation between the change in aVO(2max) and the change in pVO(2max) was trivial and non-significant (r = 0.30, p = 0.28). The HRindex Method does not appear to be suitable for predicting changes in VO(2max) following 8-weeks of endurance training in female collegiate soccer players.