Reliability and validity of responses to submaximal all-extremity semirecumbent exercise in older adults.

Although popular in clinical settings, little is known about the utility of all-extremity semirecumbent exercise machines for research. Twenty-one community-dwelling older adults performed two exercise trials (three 4-min stages at increasing workloads) to evaluate the reliability and validity of exercise responses to submaximal all-extremity semirecumbent exercise (BioStep). Exercise responses were measured directly (Cosmed K4b2) and indirectly through software on the BioStep. Test-retest reliability (ICC2,1) was moderate to high across all three stages for directly measured METs (.92, .87, and .88) and HR (.91, .83, and .86). Concurrent criterion validity between the K4b2 and BioStep MET values was moderate to very good across the three stages on both Day 1 (r = .86, .71, and .83) and Day 2 (r = .73, .87, and .72). All-extremity semirecumbent submaximal exercise elicited reliable and valid responses in our sample of older adults and thus can be considered a viable exercise mode.