Nonexercise Model Fails to Predict Aerobic Capacity in College Students with High VO2 Peak
Kolkhorst, Fred W., Dolgener, Forrest A., Research Quarterly for Exercise and Sport
The benchmark of aerobic capacity is accepted as maximal oxygen uptake (V[O.sub.2]max), which is used as a measure of aerobic power ([Angstrom]strand & Rodahl 1986). Although laboratory testing using indirect calorimetry is the most accurate method to determine maximal aerobic capacity, the procedure is expensive, time-consuming, and requires a highly motivated subject exercising to voluntary exhaustion. Not all individuals have the motivation to perform a maximal test, and certain contraindications may prohibit maximal testing of some individuals. Consequently, tests to estimate aerobic capacity were devised based on the heart rate response at a submaximal workload. These methods, which commonly use bench-stepping, cycle ergometry, and walking/running protocols, can be used to quickly test large groups of individuals. Some of the more well-known prediction tests include the Harvard Step Test (deVries & Klafs, 1965), the Cooper 12-minute run (Cooper, 1968), 1.5-mile run (Cooper, 1970), and the [Angstrom]strand-Rhyming Nomogram ([Angstrom]strand & Rhyming, 1954).
Researchers also have investigated the relationship of physical work capacity with self-reported activity (Godin & Shephard, 1985; Jackson et al., 1990; Kohl, Blair, Paffenbarger, Macera, & Kronenfeld, 1988; Siconolfi, Lasater, Snow, & Carleton, 1985; Taylor et al., 1978). Aerobic capacity has been reported to be moderately correlated with self-reports of "strenuous exercise" (r=.35) (Godin & Shephard, 1985), physical activity (r=.59) (Jackson et al., 1990), and sweat-inducing physical activity (r = .46) (Siconolfi et al., 1985). A multiple correlation coefficient of .45 was reported between total treadmill time and responses from the Leisure Time Physical Activity Questionnaire (Taylor et al., 1978). Also, Kohl et al. reported a multiple correlation coefficient of .65 with nonexercise predictors of total treadmill time, which included age; an index of walking, jogging, and running; and frequency of sweat-induced activity.
Recently, Jackson and associates (1990) developed the University of Houston Non-Exercise Test (N-Ex), which uses a physical activity questionnaire (NASA/JSC physical Activity Scale; PA-R) to predict functional aerobic capacity (V[O.sub.2]peak) without exercise testing. Data were taken from 2,009 employees of the NASA/Johnson Space Center to develop two models for predicting aerobic capacity. These models used age, gender, and either percent body fat (%fat) from skinfold measurements or body mass index (BMI) for body composition. Their reported R values were .81 and .78 for the N-Ex %fat and N-Ex BMI models, respectively. Total error values ranged from 4.6 to 5.4 mL.[kg.sup.-1].[min.sup.-1]. The authors cross-validated these models with a randomly chosen cross-validation sample and concluded that the N-Ex models Provided an accurate estimate of V[O.sub.2]peak for adult females and males who had a V[O.sub.2]peak less than 55 mL.[kg.sup.-1].[min.sup.-1].
Such a nonexercise prediction test would be very useful in a wide variety of settings, including a university wellness or physical education class. If the N-Ex models prove valid for a college population, they could be used in place of more traditional tests. Therefore, the purpose of this study was to cross-validate the N-Ex models for prediction of aerobic capacity using a university student population.
Subjects in this study were healthy males and females who volunteered to participate in a semester-long university course in which they trained to participate in a 42.2-km marathon foot race and studied the psychological and physiological aspects of the endeavor. Subject characteristics are presented in Table 1.
Table 1. Subject characteristics
Characteristics Females Subjects (n) 41 Age (years) 21.1 [plus or minus] 1. …