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 RCI ) scores for oxygen uptake (V̇O 2 ) values associated with estimated lactate threshold (θ LT ), respiratory compensation point (RCP), and peak oxygen uptake (V̇O 2peak ) 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 2 at θ LT , RCP, and V̇O 2peak . Using MMC RCI ∆V̇O 2 scores of ±3.9 mL·kg −1 ·min −1 , ±4.0 mL·kg −1 ·min −1 , and ± 3.6 mL·kg −1 ·min −1 for θ LT , RCP, and V̇O 2peak , respectively, patients were classified as "positive" (Δθ LT , ΔRCP, and/or ΔV̇O 2peak ≥ +MMC RCI ), "non-" (between ±MMC RCI ), or "negative" responders (≤ -MMC RCI ). Results Mean RCP ( n = 86) and V̇O 2peak ( n = 303) increased ( p < 0.05) from 19.4 ± 3.6 mL·kg −1 ·min −1 and 18.0 ± 6.3 mL·kg −1 ·min −1 to 20.1 ± 3.8 mL·kg −1 ·min −1 and 19.2 ± 7.0 mL·kg −1 ·min −1 at exit, respectively, whereas θ LT ( n = 140) did not change (15.5 ± 3.4 mL·kg −1 ·min −1 versus 15.7 ± 3.8 mL·kg −1 ·min −1 , p = 0.324). For changes in θ LT , 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 2peak , 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 LT , RCP and V̇O 2peak .