Table 3.

Neurolab autonomic nervous system protocol

	Experimental session
Activity	∼72 days pre-flight	Mission days 12 or 13	Landing day
Instrumentation	90	85	90
Trial upright tilt		—
Handgrip to determine maximum
voluntary contractions
Baseline cardiac outputs*		—
Blood sampling
Breathing protocol	25	25	25
Noradrenaline infusion	7	7	—
Valsalva manoeuvres	8	8	—
Static handgrip	10	10	10
Cold pressor	9	9	—
Lower body negative pressure	24	24	—
Upright tilt	15	—	15
Deinstrumentation	10	10	10

Instrumentation includes placement of electrodes and sensors, intravenous catheter insertion, and microneurography. Breathing protocol: uncontrolled, 5 min; random frequency, 6 min; controlled frequencies, 9 min, including hyperventilation followed by apnoea (for as long as possible). Static handgrip includes baseline measurements, 1 min; 40% maximum voluntary contraction to fatigue, ∼ 2 –3 min; blood pressure cuff inflation, 2 min; and recovery, 5 min. Cold pressor includes baseline measurements, 1 min; exposure to cold, 2 min; and recovery, 5 min. Lower body negative pressure and blood draws includes baseline measurements, 10 min; and −15 and −30 mmHg, 7 min each. *Cardiac outputs were also measured before and during upright tilt. Each intervention was followed by a recovery period (1–6 min duration) to allow measurements to return to baseline levels.