Rationale: Previous studies have demonstrated that the placebo effect may significantly enhance objective measures of exercise performance. Given that increased exercise intensity is associated with increases in the incidence of cardiovascular complications in patients with cardiovascular disease, knowledge of how placebos might effect exercise intensity in this population is needed.

Objectives: This study was designed to test the hypothesis that total distance completed in the 6-minute walk would be improved and characterized by a faster early pace in the presence of a placebo.

Methods: Ten participants in an exercise-based rehabilitation program (age range = 57-75 years) performed three 6-minute walk tests (practice, placebo, and control). They had been shown a brochure designed to induce the expectation that the placebo agent would enhance performance. The 6-minute walk performance was measured by total distance completed and by distance in each 30 s segment, HR was measured via radiotelemetry, and RPE by the Borg scale.

Results: There were no significant (P < .05) differences in placebo vs control for 6-minute walk total distance (1,797 +/- 304 vs 1,773 +/- 293 ft), in walking speed over the first (5.13 +/- 0 vs 5.04 +/- 0.71 ft s^-1) or second (4.99 +/- 0.83 vs 4.88 +/- 0.78 ft s^-1) 30 s segments of the trial, in the maximum HR achieved (107 + 16 vs 104 + 16 bpm) or in RPE at the end of the 6-minute walk (9.1 +/- 1.3 vs 9.3 +/- 1.3).

Conclusions: In view of the nonsignificant differences in 6-minute walk performance, the experimental hypothesis is rejected. The results suggest either that there is not a placebo effect on 6-minute walk performance or that the methods used to induce increased expectations of improved performance were inadequate in this population.