Does age attenuate aerobic conditioning response in postmenopausal women? Response

Abstract

Dr. Roy Shephard recently commented on our article examining the age-attenuated response of aerobic power in women participating in a monitored exercise program (Earnest et al. 2010). While we do not totally disagree with his comments, we feel that Dr. Shephard has missed several key points regarding our investigation. Critical to this discussion is that our paper should be taken in the context of its main hypothesis. Our current article is an ancillary report to a parent NIH trial known as the Dose Response of Exercising Women (DREW) trial. Women participating in DREW were recruited based on age, body mass (overweight and obese), elevated blood pressure, and being sedentary. As previously reported in a Methods paper, followed by our primary outcomes paper, the principal aim of DREW was to examine the a priori question of whether there is ‘‘minimal,’’ ‘‘threshold,’’ or ‘‘optimal’’ dose of exercise needed to improve fitness and health by examining the effects of exercise at 50, 100, and 150% of the NIH Consensus Panel physical activity recommendation on cardiorespiratory fitness (NIH Consensus Development Panel on Physical Activity and Cardiovascular Health 1996; Church et al. 2007; Morss et al. 2004). As Dr. Shephard did not cite these papers he may not have read these prior to his critique. Unfortunately, in the era of large clinical trials examining exercise training with multiple outcomes of potential interest the ability to report on the findings of these trials is a two-edged sword that is blunted by the inability to list every methodological detail within every paper given page and/or word count restrictions for most journals. Admittedly, while Methods papers help by providing greater detail than one might have room for in future publications, it is conceivable that some of these details are lost should a reader take each ancillary paper onto itself. For this inconvenience, we apologize and hope that future critiques will consider the body of work surrounding the DREW study; specifically, the design, intent, and primary outcomes for the study. With regard to exercise testing, we used a standardized testing protocol based on three criteria following in the following order of importance: (a) a plateau of VO2 (\100 ml/ min) accompanying a 2 min stage protocol—not a ramp as Dr. Shephard asserts—that increased in small increments (i.e., 20 W/2 min) (b) an RER exceeding 1.10, and (c) and the attainment of a max heart rate within 10 beats of 220— age. An issue within Dr. Shephard’s critique extends to the heart rate response of our older age group. Yet, when one examines the heart rate response of this group (mean age 64.9 years) and our stated criteria, their heart response puts them pretty much spot on for our third criteria. Moreover, Gulati et al. (2010) have recently reported the potential error in using the 220-age equation, thus advocating the prediction of maximal heart rate using 206-0.88 (age), which better estimates the actual maximal heart associated with exercise testing in asymptomatic women (Gulati et al. 2010). Following the latter criteria, our expected maximal heart rate for the[60 years group would be 149 b/min. Given our 10 b/ min allowance for the statistical error surrounding prediction equations, our current report not only matches nicely with this revised equation, but also lies well within the 95% confidence limits also proposed by (Gulati et al. 2010). Communicated by Susan Ward.