Submaximal oxygen uptake kinetics, functional mobility, and physical activity in older adults with heart failure and reduced ejection fraction.
BACKGROUND
Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction.


METHODS
Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA).


RESULTS
Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA.


CONCLUSIONS
Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF.
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
Scott L
SL
Hummel
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
John
J
Herald
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA.
Craig
C
Alpert
School of Nursing, University of Wisconsin-Madison, Madison, WI, USA.
Kimberlee A
KA
Gretebeck
William Beaumont School of Medicine, Oakland University, Royal Oak, MI, USA.
Wendy S
WS
Champoux
School of Kinesiology, University of Minnesota, Minneapolis, MN, USA.
Donald R
DR
Dengel
Aspirus Health System, Ontanagon, MI, USA.
Peter V
PV
Vaitkevicius
Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA; VA Ann Arbor Healthcare System, Ann Arbor, MI, USA.
Neil B
NB
Alexander
Aging; Congestive heart failure; Mobility; Oxygen uptake; The elderly