Metabolic equivalents during the 10-m shuttle walking test for post-myocardial infarction patients

OBJECTIVE: Comorbidities are found to affect metabolic equivalents (METs). Therefore the main objective of this study was to compare METs (1 MET: oxygen uptake (Vo(2)) 3.5 ml/kg/min) during an incremental shuttle walking test (SWT) between non-cardiac and post-myocardial infarction (MI) men, and secondly to determine any differences in Vo(2) (ml/kg/min) between flat treadmill walking and the turning during the shuttle walking in non-cardiac subjects. DESIGN: Comparative study. SUBJECTS: Thirty one post-MI (mean (SD) age 63.5 (6.5), range 53-77 years) from phase IV cardiac rehabilitation and 19 non-cardiac (64.6 (7.5), range 51-76 years) men participated. METHODS: All subjects performed an SWT, and non-cardiac subjects a treadmill test of similar protocol. Throughout both, the subject's Vo(2) was measured. RESULTS: Analysis comparing lines of regression showed METs at 1.12 to 4.16 mph were higher (p<0.001) for post-MIs versus non-cardiac subjects. For non-cardiac subjects, there were no differences between the treadmill test and SWT (p>0.9) and LoA showed acceptable agreement in METs between treadmill vs SWT, mean difference -1.1 (8.8) (1.96SD). CONCLUSION: It would appear that for asymptomatic individuals it is appropriate to apply established METs for flat walking to the SWT. However, the significantly higher METs for the post-MI compared with the non-cardiac subjects indicates the need for caution when using METs derived from healthy subjects in the prescription of exercise for myocardial patients.