Effects of Internal and External Cueing on Muscle Activation and Force Production

PURPOSE: The purpose of this study was to measure the effects of different attentional focus strategies (internal and external cueing) on muscle activation and force production during a maximal handgrip squeeze. METHODS: A total of 22 healthy adults between the ages of 18-25 years were recruited to participate. Participants were instructed to refrain from caffeine, alcohol, and exercise for 48 hr before testing. Anthropometric measures of height, weight, and body composition were taken when the participants first arrived. Researchers placed electrodes on participants’ brachioradialis and flexor digitorum superficialis muscles to measure muscle activity. Participants performed three maximal voluntary contractions (MVC) to record an average maximum force output. Electromyography was used to quantify muscle activation (MA), force production (FP), and rate of force development (RFD). Between each voluntary contraction was a 1 min rest. Participants were required to squeeze two times for each condition. The test conditions were categorized as internal condition (IC), external condition (EC), and control (C). An 8 min rest period separated each condition. HYPOTHESIS: It was hypothesized that internal cueing would increase muscle activation more than external cueing and that external cueing would increase force production and rate of force development more than internal cueing