Date of Award

Summer 8-2023

Document Type


Degree Name

Master of Science (MS)


Human Movement Sciences


Exercise Science

Committee Director

Patrick Wilson

Committee Member

Leryn Reynolds

Committee Member

Hunter Bennett


Previous research has shown that placebos can impact medical conditions such as irritable bowel syndrome and depression as well as elicit analgesic effects and improvements in certain exercise performances. These placebo responses occur from a variety of alterations to the placebo itself or through verbal suggestion of how helpful the placebo will be. This study aimed to observe whether changing the color and quantity of capsules can induce improvements in both vertical jump and hand grip strength. This deceptive, parallel study consisted of 28 participants, with a mean age of 24.9 (±4.3) years old, that were randomly assigned to receive either two bright red and yellow capsules or a single white capsule, which all contained rice flour powder. Participants were informed that there was a 50% chance of receiving an herbal-amino acid blend or a placebo and were asked to perform two assessments of strength and neuromuscular performance. Both groups attended one session, that started with obtaining informed consent, completing a background questionnaire, performing a body composition test in the BodPod, a 5- minute seated rest with resting heart rate measured, the completion of visual analogue scales of fatigue (VAS-F) and energy (VAS-E), and a warm-up on a Monarch cycle ergometer. Participants then completed familiarization trials for both vertical jump and hand grip dynamometry using the Lode contact mat and Jamar hand dynamometer, respectively, followed by a baseline assessment for both the vertical jump and single hand grip dynamometer consisting of three attempts with 30-60 seconds of rest between attempts. Subsequently, participants received their randomized treatment along with a standardized script, which was followed by a 15-minute incubation period before repeating the VAS-F, VAS-E, and vertical jump and maximal strength tests. Before debriefing, participants were shown four images and asked to rate the perceived stimulatory properties of each on a 100-mm VAS (VAS-S); the first image was a single white capsule, the second was two red/yellow capsules, the third was two white capsules, and the fourth was a single red/yellow capsule. The primary outcome variables were assessed via mixed analysis of variance (group x time). Results suggested no significant differences between groups for any of the primary outcome variables: vertical jump, grip strength, VAS-F, VAS-E, and change of heart rate over time. However, participants perceived two red/yellow capsules (61.4±4.6) to have a greater stimulatory effect than a single white capsule (26.6±4.1) via the VAS-S (p < 0.05). The results agree with previous research that individuals associate higher pill quantity and red-yellow as having stimulatory effects. That said, no effects on physical performance or perceived fatigue or energy were detected. Future research should consider using a combination of aerobic and anaerobic exercise.


In Copyright. URI: This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).