A. J. Walker

Validity and reliability of combining three methods to determine ventilatory threshold.

PURPOSE This research was undertaken to validate a combination of methodologies to determine ventilatory threshold (VT). METHODS Three methods were used individually and then combined to determine VT as follows: 1) ventilatory equivalencies, 2) excess CO2 production, and 3) a modified V-slope method. Three groups of participants-endurance athletes (N = 132), healthy, aerobically active adults (N = 31), and healthy, sedentary/low-active adults (N = 22)-were independently evaluated for VT and compared with the criterion standard lactate threshold (LT) defined as the first rise in blood lactate with increasing intensity of exercise. RESULTS VT and LT were significantly correlated using the combined VT method within each study group (r = 0.98, 0.97, and 0.95, respectively; P < 0.001). Mean VO2 values at VT and LT were not significantly different between the three groups (P > 0.20). The combined method improved the determination rate of VT and reduced the standard deviation of the LT - VT difference by 80-170% over the individual methods. During test-retest procedures VO2lt and VO2vt determined by the combined method met criteria demonstrating further reliability. CONCLUSION The combined method to determine VT is valid and reliable across a wide fitness range in healthy individuals and improves the determination rate and accuracy of VT determination over the use of single methods.

Underwater Weighing Familiarization Program for Adults with Prader-Willi Syndrome

The purpose of the project was to evaluate an underwater weighing (UWW) and residual lung volume (RV) familiarization program developed for adults with Prader-Willi syndrome (PWS). UWW was conducted on 15 adults (10 men, 5 women) with PWS following a UWW familiarization program. Repeated measures ANOVA revealed no difference in percent body fat derived from UWW over the four sessions, F(3, 27) = 0.80, p = .505, with an intraclass reliability coefficient of R = .93. There was, however, a significant difference in RV, F(3, 27) = 5.25, p = .006, with an intraclass reliability coefficient of R = .65. The familiarization program is recommended for implementation prior to measuring percent body fat via UWW. However, predicting the RV may be an easier and more consistent alternative to measuring the RV in adults with PWS.