-In one study involving asthma, people using a placebo inhaler did no better on breathing tests than sitting and doing nothing. But when researchers asked for people’s perception of how they felt, the placebo inhaler was reported as being as effective as medicine in providing relief.
-In another study, people were given a placebo and told it was a stimulant. After taking the pill, their pulse rate sped up, their blood pressure increased, and their reaction speeds improved. When people were given the same pill and told it was to help them get to sleep, they experienced the opposite effects.
Several studies revealed an effect of caffeine on maximal strength. For instance, studies that have tested percent muscle activation and maximal muscle strength of the knee extensors under isometric conditions have shown that caffeine is capable of increasing voluntary activation and strength. A 2014 study reported that caffeine can increase not only concentric (i.e. lifting the weight) and eccentric (i.e. lowering the weight) maximal strength, indicating that caffeine increased maximal strength regardless of the contraction mode.
Caffeine seems to work especially well for increasing performance in the gym. For example, 13 resistance-trained men ingested a caffeinated (179 mg) energy drink or placebo solution 60 minutes before completing a bout of the following exercises: bench press, deadlift, prone row, and back squat exercise to failure at an intensity of 60% 1-repetition maximum. Subjects who consumed the caffeinated beverage performed more repetitions to failure in all exercises. Another study had 15 women consume caffeine (6 mg/kg) or placebo (PL) seven days apart. Sixty min following supplementation, participants performed a one-repetition maximum (1RM) barbell bench press test and repetitions to failure at 60% of 1RM. They discovered that 1-RM strength was greater during the caffeine condition in these resistance-trained women.
4) Told placebo, given caffeine.
Maximal voluntary concentric force and fatigue resistance of the knee flexors and extensors was measured using isokinetic dynamometry. So we have a interesting study which compared the direct effects of caffeine vs the placebo effect. At the end of the study, a significant and equal improvement in peak concentric force was found in the told caffeine, given caffeine subjects and told placebo, given caffeine trials. Despite participants believing caffeine would evoke a performance benefit, there was no effect of told caffeine, given placebo. Caffeine caused an improvement in some aspects of muscle strength, however there was no additional effect of expectancy. Performance was poorer in participants who believed caffeine would have the largest benefit, which highlights a link between expected ergogenicity, motivation, and personality characteristics.