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.