From a recent review:
Although treadmill exercise testing can provide an assessment of cardiorespiratory fitness, which serves as an independent prognostic indicator, numerous studies now suggest that usual gait speed, time, or distance covered during walk performance tests and weekly walking distance/time are powerful predictors of mortality and future cardiovascular events in selected patients. This review summarizes the relation between these variables and their association with cardiovascular and all-cause mortality, with specific reference to potential underlying mechanisms and implications for the clinician. Contemporary health care providers have escalating opportunities to promote lifestyle physical activity using pedometers, accelerometers, and smartphone-based health and wellness applications. In conclusion, fitness and/or ambulatory indexes should be considered a “vital sign” in middle-aged and older adults.