Considering the variability in the V'o2response (regarding age, sex, genetics, etc.), is there any minimal percent value of improvement which one can consider significant for a successful intervention?
1 met (i.e 3,5 mL.min-1.kg-1) is generally used in cardiac rehabilitation. See ASCM recommandation or Publication of Meyers.
The best method is calculation of the statistical significance. However, you have a 10% improvement that can be considered statistical relevant improve. For example if you are working with a heart failure patient and deterioration start under 20ml/kg/min - 10% is 2ml/kg/min. So if the patient would improve from 16ml/kg/min towards 18ml/kg/min that should be than a "relevant" improve. Significance is a statistical definition, therefore I should not use this term in this context
Dear Julian, if we consider the variability as the typical error of measurement (noise), we could define the follow: many studies have reported a typical error around 3-4% for VO2max assessment (by test-retest analysis). Will Hopkins suggests that about 1.5–2.0 times the typical error could be used as a threshold above which any individual change would be interpreted as “real” following an intervention. Thus, at least an increase around 4.5% (TE= 3% + 1.5x) should be consider.
Dear Julian, this is an interesting question. Others have responded in relation to determining a statistically significant change (or real change) using VO2max assessment to evaluate the impact of an exercise intervention. Depending on the cohort and the context you are working within, a statistically significant change may not be clinically important; the clinically significant change following an intervention might be quite different. For example, Myers et al. (2002) report that an increase in 1 MET (3.5 mL.min-1.kg-1) was associated with a 12% improvement in survival. The study (https://www.researchgate.net/publication/11469274_Exercise_capacity_and_mortality_among_men_referred_for_exercise_testing) includes an informative discussion on clinically significant MET (and VO2) values, which may be of interest.
Article Exercise Capacity and Mortality among Men Referred for Exerc...
Tom's excellent answer above references the seminal Myers 2002 paper - and 1 MET (3.5ml/kg/min) has become commonly used (by me too!). However, reviewing this topic recently, I came across a surprising number of papers that report much lower differences that are still associated with improvements in hard outcomes (e.g. survival). How about this one: a difference of only 0.4ml/kg/min or 6% increase in VO2 max over three months improved outcome (composite primary endpoint of time to all-cause mortality or all-cause hospitalization) by 5%! See the HF-ACTION heart failure trial: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3732187/ . Perhaps we need to lower our minimum important difference for VO2 max to 1 ml, which would have major implications for powering future studies..........
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