Need for population specific validation of a portable metabolic testing system: a case of sedentary pregnant women.

Commercially available portable metabolic systems have been validated with samples of young, healthy, and well-fit subjects, but use of these systems with a special population, such as healthy but sedentary pregnant women, requires a unique set of considerations. These include a woman's limited testing time necessary for fetal safety, relatively low oxygen consumption, and the unique physiology of pregnancy (woman, the placenta, and the fetus). The purpose of this study was to validate a portable metabolic testing system (VO2000) with healthy sedentary pregnant women. A total of 9 sedentary pregnant women who averaged 30 years of age (SD = 3), 93 kg (SD = 19) weight, 163 cm (SD = 7) height, and at 19 weeks' gestation (SD = 5) volunteered to participate. Submaximum fitness tests using the Cornell protocol were conducted once with two systems (VO2000 and CPX/D, a reference) simultaneously, and then subsequently twice with one system (VO2000). The VO2000 consistently overestimated VO^sub 2^ measurement, compared to the same manufacturer's reference system, by 4.4 +/- 3.6 (SD) ml/kg/min, and when VO2000 was used twice, the mean difference was statistically significant (1.0 +/- 1.8 [SD] ml/kg/min; t^sub (45)^ = 3.9, p Keywords: fitness test; VO2000; inactivity; metabolic testing; reliability; gestation Increasing physical activity among sedentary adults is a major public health goal in the US and many other industrialized countries. A recent Surgeon General's report notes the ever-increasing prevalence of obesity particularly among women (U.S. Department of Health and Human Services [USDHHS], 1999). Pregnancy is a milestone for obesity in later life for women. But many pregnant women receive conflicting advice as to how much exercise is good for them and safe for their fetuses (American College of Obstetricians and Gynecologists, 2002). Conflicting advice is due in part to lack of accurate and precise methods to assess their aerobic fitness. Accurate assessment is the key to effective and safe exercise. Existing aerobic fitness assessment systems are quite costly and require routine calibration and maintenance by trained staff. As such, few clinicians who provide care for pregnant women have access to such systems. A few portable systems that require much less space and technical care are available at substantially less cost. If these portable systems provide reliable and valid measure of aerobic fitness with sedentary pregnant women, as they do with young athletic subjects (Byard & Dengel, 2000; King, McLaughlin, Howley, Bassett, & Ainsworth, 1999; McLaughlin, King, Howley, Bassett, & Ainsworth, 2001; Melanson, Freedson, Hendelman, & Debold, 1996), pregnant women can safely receive tailored exercise regimes during pregnancy based on individual's aerobic fitness level. The purpose of this study was to evaluate the appropriateness of a commercially available portable metabolic testing system with a group of healthy but sedentary pregnant women. One commercially available portable system, the VO2000 (Medical Graphics Corporation, 2000), was tested with pregnant women. BACKGROUND Research demonstrates that people who exercise daily report better mood and fewer physical symptoms (Brown, Goldstein-Shirley, Robinson, & casey, 2001; Sculco, Paup, Fernhall, & Sculco, 2001). The benefits of physical activity for chronic disease and mental well-being have been recognized as the scientific consensus in the U.S. Surgeon General's report on physical activity and health (Dishman, Washburn, & Heath, 2004). What is not well known is how much exercise is sufficient to bring about positive health outcomes without causing adverse effects. …