A standardized approach to evaluate effectiveness of aerobic exercise training interventions in cardiovascular...

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 (V̇O₂) 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.

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 V̇O₂ at θ_LT, RCP, and V̇O_2peak. Using MMC_RCI ∆V̇O₂ 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).

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.

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.