Metabolic Equations Significantly Over Estimates Fitness Levels In Adults Between 60 And 80 Years Of Age.

Metabolic equations are used to estimate oxygen consumption and caloric expenditure when there is a lack of equipment or contraindications for maximal exercise testing for specific populations. Fitness levels decrease with age as does the ability to perform maximal testing. Thus, metabolic equations often determine fitness levels and guide intensity levels for exercise prescription. Therefore, the need to determine the extent to which metabolic equations differ from measured VO2 in older adults is warranted. PURPOSE: Determine the difference between measured VO2 and estimated VO2 in older adults. METHODS: Adults between the ages of 60 and 80 years old were recruited for the investigation. Height, weight, body fat percentage, resting and peak blood pressure, and appendicular skeletal muscle index(ASMI) (FFM kg/m2) were collected. VO2peak testing was performed via modified Bruce protocol until the participants reached volitional fatigue. VO2, blood pressure, heart rate, and oxygen-pulse (O2-pulse) were collected during the test. VO2 estimations were calculated with thefollowing equation VO2 = (0.1 · S) + (1.8 · S · G) + 3.5 RESULTS: Twenty-six adultssuccessfully completed the fitness test (age = 72.6 ± 5.1 yrs, body mass = 71.9 ± 13.3 kg, BMI =27.4 ± 5.0 kg/m2, body fat = 40.6 ± 9.5%, VO2peak = 21.4 ± 6.1 ml·kg-1·min-1). The prediction equation significantly overestimated (9.2 ± 6.0 ml·kg-1·min-1, P < 0.001) the VO2 of the participants compared to the measured VO2peak. As VO2peak increased O2-pulse also increased(r = 0.74, P < 0.001). As BMI and BF% increased VO2peak decreased (r = -0.43, P = 0.02; r = -0.54, P = 0.004), respectively. Interestingly, as ASMI increased so did O2-pulse (r = 0.43, P = 0.02). CONCLUSION: The metabolic equation for walking significantly overestimates the cost of peak treadmill walking in adults between 60 and 80 years old. BMI, and particularly BF% have a negative relationship with fitness level, whereas a higher ASMI appears to positively affect fitness in this aging population.