, 1992; Faulkner et al., 1997; Pakkala selleck chemical et al., 2005; Vassalle et al., 2013). Furthermore, the HRrest and HRmax may or may not change in response to an increased VO2max (An et al., 2006; Cornelissen et al., 2010; Ekblom, 1968; Oliveira et al., 2013; Raczak et al., 2006; Uusitalo et

al.,1998). Therefore, the purpose of this study was to determine if the HRindex Method was accurate for tracking changes in VO2max following 8-weeks of endurance training among collegiate female soccer players. Based on the previous findings in non-athletic men (Esco et al., 2011; Haller et al., 2011), it was hypothesized that the HRindex Method would provide an accurate assessment of VO2max at baseline and following training among the entire group (i.e., no significant mean differences between predicted and observed values), but that it would result in a wide range of individual

error at both time points. Material and Methods Subjects Fifteen female soccer players (age = 21.5 ± 1.8 years; body height = 167.2 ± 6.0 cm; body mass = 64.2 ± 7.4 kg) from the National Association of Intercollegiate Athletes (NAIA) participated in this study and provided written informed consent. The study was approved by the Institutional Review Board at the Auburn University at Montgomery for research involving human subjects. All subjects were free from cardiovascular, pulmonary, and metabolic diseases. Pre- and post-training data collection was conducted within an exercise physiology laboratory in the morning hours

between 7 am and 11 am on any weekday as close as possible to awakening from sleep. Before each day of testing, the athletes were required to refrain from the consumption of food or caffeine for at least 8 hours prior and to avoid strenuous exercise and alcohol consumption for 24 hours prior. Maximal Graded Exercise Test Each subject performed a maximal graded exercise test using a Trackmaster treadmill (Full Vision, Inc., Carrollton, TX) and a calibrated ParvoMedics TrueOne® 2400 metabolic cart (ParvoMedics Inc., Sandy, UT). The Bruce protocol was employed, which began at 1.7 mph at 10% grade Entinostat with increasing speed and grade (i.e., 2.5 mph at 12%, 3.4 mph at 14%, 4.2 mph at 16%, 5.0 mph at 18%, etc.) every 3 minutes until test termination. Observed VO2max (aVO2max) was achieved if two of the following criteria occurred: a plateau in VO2 (< 2.0 mL·kg−1·min−1) with an increasing work rate; the respiratory exchange ratio equal to or greater than 1.15; the HR within 10 beats of age predicted maximum (220 – age); or volitional fatigue. Heart Rate Measures Heart rate data was collected with a Polar F11 HR Monitor (Polar Electro Oy, Kemple, Finland). Before the GXT, the subjects assumed a supine position for 5-minutes in a quiet, climate controlled, dimly lit exercise physiology laboratory.