Aim: The aim of the study was to examine the effect of information placebo on fitness test results in normal weight, overweight and obese children.
Methods: Twenty-four pre-pubertal children with overweight or obesity and 24 age- and maturity-matched normal weight children performed a progressive treadmill exercise test, twice. Different types of information were randomly provided regarding a water drink consumed prior to testing; standard (water) versus deliberate positive (presumed energy drink, placebo) information.
Results: Following the placebo drink, both groups demonstrated a significantly higher peak heart rate (overweight 165.8 ±16.7 versus 174.2±14.8bpm and normal weight 177.9±13.6 versus 189.8±12.2bpm) and longer time to exhaustion (overweight 396.9±161.9 versus 521.5±182.5 sec; normal weight: 700.1±155.2 versus 893.3±150.1seconds). Despite the longer exercise duration and higher peak heart rate, the average and peak rate of perceived exertion were significantly lower after the placebo drink (overweight 14.1±2.5 versus 12.5±2.5; normal weight 12.1±1.4 versus 10.7±1.5), with a significantly shorter recovery time (overweight 132.2±28.5 versus 118.4±31.6; normal weight: 106.7±18.6 versus 96.7±17.8 seconds).
Conclusion: Our results demonstrate a significant effect of information placebo on fitness test results that is unrelated to body weight. Children with obesity may enhance their physical activity levels and energy expenditure if properly encouraged.