Objective: To test the hypothesis that aerobic, but not strength, training would lead to attenuated reactivity to and more rapid recovery from cognitive and orthostatic challenge and that deconditioning would reverse this effect.
Methods: We conducted a randomized controlled trial contrasting the effects of aerobic versus strength training on heart rate, four indices of RR interval variability, and blood pressure reactivity to and recovery from psychological and orthostatic challenge in 149 healthy, young, sedentary adults. Subjects were randomized to 12-week aerobic or strength training programs and studied before and after training and again after 4 weeks of sedentary deconditioning. The data were analyzed by performing a Group (aerobic versus strength) by Session (study entry, post training, and deconditioning), by Period (baseline, speech, Stroop, math, tilt) three-way analysis of variance with prespecified contrasts of the effect of group assignment on reactivity and recovery.
Results: Aerobic capacity increased in response to conditioning and decreased after deconditioning in the aerobic, but not the strength, training group. However, the two groups did not differ on heart rate, RR interval variability, or blood pressure reactivity to or recovery from laboratory challenge.
Conclusions: These findings, from the largest randomized controlled trial to address this matter to date, raise doubts about attenuation of reactivity or enhancement of recovery as a putative mechanism underlying the cardioprotective effects of aerobic exercise.
Trial registration: ClinicalTrials.gov Identifier: NCT00365196.