Effects of Caffeine and Intermittent Hypoxia on Leg Function in Human Spinal Cord Injury

Subjects will ingest capsules containing caffeine (up to 6mg/kg). Experiments will begin 30min after consumption to approximately coincide with peak plasma concentrations.Throughout the 30min wait time and experimentation, blood pressure and heart rate will be monitored.

Participants will breathe intermittent low oxygen via air generators. The generators will fill reservoir bags attached to a non-rebreathing face mask. Oxygen concentration will be continuously monitored to ensure delivery of FIO2 (fraction of inspired oxygen) = 0.10±0.02 (hypoxia). Throughout experimentation, blood pressure and heart rate will be monitored.

This is a placebo counterpart to the caffeine drug. Subjects will ingest capsules containing dextrose. Experiments will begin 30min after consumption to mimic the caffeine drug protocol. Throughout experimentation, blood oxygenation, blood pressure and heart rate will be monitored.

This is a placebo counterpart to breathing intermittent low oxygen. Participants will breathe intermittent room air via air generators. The generators will fill reservoir bags attached to a non-rebreathing face mask. Oxygen concentration will be continuously monitored to ensure delivery of FIO2 (fraction of inspired oxygen) = 0.21±0.02 (normoxia). Throughout experimentation, blood pressure and heart rate will be monitored.