The placebo effect on aerobic fitness test results is preserved following a multidisciplinary intervention program for treating childhood obesity

Background: The aim of the study was to examine the placebo effect on fitness test results in trained and untrained overweight and obese children. Methods: Twenty pre-pubertal overweight children performed two pairs of progressive treadmill exercise tests before and 12 weeks into a multidisciplinary program for the treatment of childhood obesity. In each test pair, at random order, participants received different types of information regarding a water drink consumed prior to testing—standard information (water) vs deliberate positive information (presumed energy drink, placebo). Results: The intervention led to a significant change (P <.05) in BMI%ile (95.6 ± 4.4 vs 93.6 ± 6.9), % fat (35.4 ± 6.0 vs 31.6 ± 5.8), baseline heart rate (104.2 ± 11.6 vs 94.0 ± 7.0 bpm), total leisure activity score—Godin (9.3 ± 8.8 vs 41.5 ± 15.2), total screen time (6.9 ± 5.8 vs 3.1 ± 1.4 h/d), and a significant improvement in fitness. Following the placebo drink, both groups achieved a significantly higher peak heart rate (untrained: 176.1 ± 13.7 vs 167.5 ± 16.8; trained: 170.7 ± 11.6 vs 166.2 ± 11.4 bpm) and longer running time (untrained: 559.9 ± 151.0 vs 434.4 ± 140.3 seconds; trained: 728.3 ± 177.3 vs 667.1 ± 176.1 seconds). Despite longer exercise duration and higher peak exercise heart rate, average, and peak RPE were lower after the placebo drink (untrained: 12.1 ± 2.3 vs 13.6 ± 2.1; trained:10.0 ± 1.8 vs 11.6 ± 2.1), recovery time was shorter (untrained: 119.2 ± 25.3 vs 133.2 ± 23.7 seconds; trained: 92.6 ± 18.9 vs 102.7 ± 18.3 seconds). The placebo-induced change in running time and peak RPE were significantly greater prior to training. Conclusion: The significant information placebo effect is preserved in trained overweight children. Information, as well as other motivating aids and fatigue distractors may be useful in enhancing physical performance in obese children.