This study evaluates the effects of orally ingested, commercially available, coffee (3 mg/kg of caffeine) on the excitability of human spinal motoneurons of the lower leg.

Recently, it has been shown that human spinal motoneurons do not simply act as a binary control system. Instead, they are regulated by intrinsic properties that can elicit lingering effects on the descending motoneuron. Caffeine, one of the world's most popular over-the-counter supplements, can potentially augment these characteristics of motoneurons. Using decomposition software and non-invasive, high-density surface electromyography, it is possible to extract the characteristics of these motoneurons. This project will utilize a double-blind, inactive-placebo controlled, crossover design study to examine and quantify the effects of caffeine on motoneuron excitability.

Inclusion Criteria:

● Between 18 and 70 years of age

Exclusion Criteria:

• Significant neurological or orthopedic injuries, which may limit volitional torque generation in the tested muscles.
• Significant change in the subjects' health or treatment in the past month.
• Known history of cardiovascular pathology (to include: uncontrolled hypertension, cardiac arrhythmias) or medical restrictions to caffeine ingestion.
• Allergies or dislike of coffee.
• Women who are pregnant will be excluded due to potential forces at trunk from pelvic safety harness and due to potential adverse effects of caffeine on the developing child.
• Women who are breastfeeding will be excluded due potential adverse effects on the breastfeeding infant from caffeine administration.
• Adults unable to consent, minors, pregnant women, and prisoners will not be included.