Short-Term Changes in Cardiorespiratory Fitness in Response to Exercise Training and the Association with Long-Term Cardiorespiratory Fitness Decline: The STRRIDE Reunion Study

Background: Substantial heterogeneity exists in the cardiorespiratory fitness (CRF) change in response to exercise training, and its long-term prognostic implication is not well understood. We evaluated the association between the short-term supervised training-related changes in CRF and CRF levels 10 years later. Methods and Results: STRRIDE (Studies of a Targeted Risk Reduction Intervention Through Defined Exercise) trial participants who were originally randomized to exercise training for 8 months and participated in the 10-year follow-up visit were included. CRF levels were measured at baseline, after training (8 months), and at 10-year follow-up as peak oxygen uptake (Vo₂, mL/kg per min) using the maximal treadmill test. Participants were stratified into low, moderate, and high CRF response groups according to the training regimen–specific tertiles of CRF change. The study included 80 participants (age: 52 years; 35% female). At 10-year follow-up, the high-response CRF group had the least decline in CRF compared with the moderate- and low-response CRF groups (−0.35 versus −2.20 and −4.25 mL/kg per minute, respectively; P=0.02). This result was largely related to the differential age-related changes in peak oxygen pulse across the 3 groups (0.58, −0.23, and −0.86 mL/beat, respectively; P=0.03) with no difference in the peak heart rate change. In adjusted linear regression analysis, high response was significantly associated with greater CRF at follow-up independent of other baseline characteristics (high versus low [reference] CRF response: standard β=0.25; P=0.004). Conclusions: Greater CRF improvement in response to short-term training is associated with higher CRF levels 10 years later. Lack of CRF improvements in response to short-term training may identify individuals at risk for exaggerated CRF decline with aging.