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Estimating cardiorespiratory fitness in older adults using a usual‐paced 400‐m long‐distance corridor walk

2021; Wiley; Volume: 69; Issue: 11 Linguagem: Inglês

10.1111/jgs.17360

1532-5415

Reagan E. Moffit, Yujia Qiao, Kyle Moored, Adam J. Santanasto, Brittney S. Lange‐Maia, Peggy M. Cawthon, Bret H. Goodpaster, Elsa S. Strotmeyer, Anne B. Newman, Nancy W. Glynn,

Heart Rate Variability and Autonomic Control

Cardiopulmonary exercise testing (CPET) is the gold standard measure of aerobic fitness (oxygen uptake, VO2peak), a powerful indicator of older adults' capacity to perform daily and recreational activities (VO2peak > 18 ml/kg/min indicative of functional independence).1 However, maximal effort during CPET performance may be limited by functional status and is not always feasible in epidemiologic studies due to rigorous staff training, equipment requirements, participant burden, and potential inconsistency across clinical centers. Subsequently, a fast-paced overground long-distance corridor walk (LDCW), a safer and less expensive alternative for older adults, was validated against treadmill CPET.2 But, many clinical and epidemiologic studies include a usual-paced 400-m LDCW in lieu of a fast-paced walk.3 With increasing frailty and age, even a usual-paced 400-m LDCW may be challenging and elicit ones' maximal capacity, as evidenced by comparable performance on fast-paced and usual-paced 400-m LDCW tests for those older and lower functioning.4 Therefore, the usual-paced LDCW may estimate CPET performance, although this has not been previously shown. This report examined whether a usual-paced 400-m LDCW was related to VO2peak measured from treadmill CPET. Community-dwelling older adults (N = 36) aged 70–89 years were enrolled in the cross-sectional Study of Energy and Aging – Pilot (SEA-P), the pilot to the Study of Muscle, Mobility, and Aging (SOMMA).5 Institutional Review Boards at the University of Pittsburgh and California Pacific Medical Center approved SEA-P, and written informed consent was obtained. Participants were instructed to complete the 400-m LDCW at their "usual or normal walking pace" down a long hallway marked with traffic cones spaced 20-m apart with time to completion (seconds) recorded. VO2peak was determined using a modified Balke protocol following the American College of Sports Medicine criteria,6 with strong encouragement to reach a respiratory exchange ratio > 1.05 and Borg Rating of Perceived Exertion (RPE) > 16.5 Treadmill speed was held constant at the participants' fastest of two usual-paced gait speed 6-m walks. Treadmill grade began at 0% and increased by 2% every 2 min until volitional exhaustion.5 Covariates examined were age, sex, and physical fatigue (Situational Fatigue Scale7). Two participants completed the usual-paced 400-m LDCW, but were unable to finish CPET; the final analytic sample included 34 participants. We generated Pearson correlations between VO2peak and covariates. Linear regression analysis estimated VO2peak (outcome) and usual-paced 400-m LDCW time (independent variable), adjusted for covariates. Statistical analyses were conducted using SAS v9.4 (SAS Institute, Inc., Cary, NC). The SEA-P participants were mean age of 78.2 ± 5.1 years, predominantly male (59%), and white (94%), with a mean physical fatigue score of 6.4 ± 4.2 (scale range: 0–20) and usual Short Physical Performance Battery score of 10.9 ± 1.3 (test range: 0–12), indicating higher function. Participants had a mean VO2peak of 22.1 ± 5.6 ml/kg/min (range: 7.8–33.4 ml/kg/min). Time to complete the usual-paced 400-m LDCW was 339.6 ± 60.4 s (range: 252.5–536.0 s). VO2peak was strongly inversely correlated (r = −0.64, p < 0.0001; Figure 1) with the usual-paced 400-m LDCW time and moderately inversely correlated with age (r = −0.41) and physical fatigue score (r = −0.42), both p < 0.02. Every 30 s longer (i.e., slower) time to complete the usual-paced 400-m LDCW was associated with a 1.5-ml/kg/min lower measured VO2peak adjusted for age and physical fatigue score (p = 0.0002), explaining 41% of the 57% total model variance in VO2peak (Table S1). Age (8%) and physical fatigue (8%) also contributed to the explained variance in VO2peak (both p = 0.03). Adding sex did not improve the estimation of VO2peak (p = 0.27). We established that the usual-paced 400-m LDCW time strongly estimated cardiorespiratory fitness in older adults after age and physical fatigue adjustment. As expected, age was associated with VO2peak, but usual-paced 400-m LDCW time explained >5-fold more of the model variance than age. Physical fatigue score also explained some variance in VO2peak, supporting the existing evidence that higher fatigue was related to poorer exercise capacity.8, 9 All participants completed the usual-paced 400-m LDCW, but two were unable to finish the CPET, highlighting the utility for an alternative measurement of VO2peak. Limitations include small sample size and using a less sensitive measure of one's perception of fatigue.9, 10 Furthermore, the SEA-P sample was relatively high functioning, hence more research is needed to confirm our findings in lower functioning older adults. A strength was measuring VO2peak with the well-established, standardized modified Balke protocol. Our findings demonstrate the initial support for using a usual-paced 400-m LDCW as a viable alternative for measuring cardiorespiratory fitness in older adults, thus providing another low-cost, safer option for research and clinical settings. The ability to identify at-risk older adults with poor walking endurance indicative of prevalent or impending mobility limitations is important for early interventions. Future research in SOMMA may confirm and extend this work, as its large sample will allow for subgroup analyses by age, sex, physical function, and fatigability severity. The authors declare that they have no conflicts of interest. Ms Reagan E. Moffit and Dr Nancy W. Glynn had full access to all of the data in the study and take responsibility for the integrity of the data and accuracy of the data analysis. All authors were involved in the interpretation of data and critical revision of the manuscript for important intellectual content. All authors read and approved the submitted manuscript. None. This work was supported by the National Institutes of Health, National Institute on Aging, American Recovery and Reinvestment Act grant RC2 AG036594, and the National Institute on Aging, University of Pittsburgh Claude D. Pepper Older Americans Independence Center Research Registry P30 AG024827. Additionally, the National Institute on Aging Epidemiology of Aging training grant T32 AG000181 at the University of Pittsburgh supported Kyle D. Moored and Brittney S. Lange-Maia. Adam J. Santanasto was supported by National Institute on Aging grant K01 AG057726. Table S1. Final model for estimating cardiorespiratory fitness (VO2peak, ml/kg/min) using a usual-paced 400-m long-distance corridor walk: Study of Energy and Aging – Pilot (N = 34). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.