A standardized approach to evaluate effectiveness of aerobic exercise training interventions in cardiovascular disease at the individual level.

Background: Reliable change indices can determine pre-post intervention changes at an individual level that are greater than chance or practice effect. We applied previously developed minimal meaningful change (MMC) scores for oxygen uptake (V̇O) values associated with estimated lactate threshold (θ), respiratory compensation point (RCP), and peak oxygen uptake (V̇O) to evaluate the effectiveness of exercise training in cardiovascular disease patients.

Methods: 303 patients (65 ± 11 yrs.; 27% female) that completed a symptom-limited cardiopulmonary exercise test (CPET) before and after 6-months of guideline-recommended exercise training were assessed to determine absolute and relative V̇O at θ, RCP, and V̇O. Using MMC ∆V̇O scores of ±3.9 mL·kg·min, ±4.0 mL·kg·min, and ± 3.6 mL·kg·min for θ, RCP, and V̇O, respectively, patients were classified as "positive" (Δθ, ΔRCP, and/or ΔV̇O ≥ +MMC), "non-" (between ±MMC), or "negative" responders (≤ -MMC).

Results: Mean RCP (n = 86) and V̇O (n = 303) increased (p < 0.05) from 19.4 ± 3.6 mL·kg·min and 18.0 ± 6.3 mL·kg·min to 20.1 ± 3.8 mL·kg·min and 19.2 ± 7.0 mL·kg·min at exit, respectively, whereas θ (n = 140) did not change (15.5 ± 3.4 mL·kg·min versus 15.7 ± 3.8 mL·kg·min, p = 0.324). For changes in θ, 6% were classified as "positive" responders, 90% as "non-responders", and 4% as "negative" responders. For RCP, 10% exhibited "positive" changes, 87% were "non-responders", and 2% were "negative" responders. For ΔV̇O, 57 patients (19%) were classified as "positive" responders, 229 (76%) as "non-responders", and 17 (6%) as "negative" responders.

Conclusion: Most patients that completed the exercise training program did not achieve reliable improvements greater than that of chance or practice at an individual level in θ, RCP and V̇O.