Resting Oxygen Uptake Value of 1 Metabolic Equivalent of Task in Older Adults: A Systematic Review and Descriptive Analysis.
Level 1 - systematic review of randomized trials
Systematic review of observational studies measuring resting metabolic rate
PubMed 34417980 · doi:10.1007/s40279-021-01539-1
What was done
Authors conducted a systematic review across PubMed, Web of Science, Scopus, CINAHL, SPORTDiscus, and Cochrane Library from inception through July 2021. They included original studies measuring resting metabolic rate (RMR) via indirect calorimetry in adults aged 60 years or older and reporting values in mL O2 kg^-1 min^-1. Descriptive weighted averages were calculated for 1 metabolic equivalent of task (MET) across all included studies and among studies meeting methodological best practices.
What was found
Twenty-three studies comprising 1,091 participants (426 men) were analyzed. Twenty-one of the 23 studies reported RMR below the traditional standard of 3.5 mL O2 kg^-1 min^-1. The overall weighted average 1 MET value across all studies was 2.7 ± 0.6 mL O2 kg^-1 min^-1. Restricting the analysis to studies adhering to best-practice measurement standards yielded an average of 2.4 ± 0.3 mL O2 kg^-1 min^-1 (an 11% further reduction).
Why it matters
The conventional reference value of 3.5 mL O2 kg^-1 min^-1 markedly overestimates resting energy expenditure in adults aged 60 and older, distorting physical activity intensity classifications and caloric calculations. When direct indirect calorimetry is unavailable, assuming 2.7 mL O2 kg^-1 min^-1 provides a more accurate reference value for this population.
Limits
The review relies on aggregated study-level data rather than individual participant data, precluding detailed subgroup analyses by specific age strata, sex, body composition, or clinical comorbidities. Significant heterogeneity in indirect calorimetry protocols across the included studies likely contributed to variability in observed values.
Cited by
- supports One metabolic equivalent (MET) is defined as the resting oxygen consumption of 3.5 mL of oxygen per minute per kilogram of body mass.