Question:
Yesterday, a friend and I went skydiving. It was his level three tandem. He has done great on all of his previous jumps. He did great on his skydive and opened his chute at the right altitude. (5000 ft.) He said he last looked at his altimeter at 3000 ft. After this, his hands started going numb. Then everything started getting black around the edges til it closed in on him and he blacked out. He came to after his instructor had already gotten them both safely on the ground. He is 27 years old, 180 lbs., and in good health. He has never had a problem like this before. He had not eaten before the jump. He said the leg straps seemed overly tight. Has anyone else heard of this happening? This could have been really bad if he had been by himself. Should he give up skydiving? Any comments on these items would be appreciated.

Answer: Might have been, but here is what happens with leg straps that are too tight. On opening, blood is 'sloshed' to the lower extremities. Blood return from the legs is relatively poor and the leg straps act like a tourniquet (diminishing venous return to the core without directly impeding arterial flow) and 'captures' or 'pools' blood in the legs that cannot now be used for things like perfusing the brain. Contrary to popular belief, return of blood from the lower extremeties is not primarily due to the pumping action of the heart (while in a more or less upright position) but from muscle contraction of the legs. If you dissect one of the large veins in the leg you will see a series of 'pouches' in the vein wall, with the open end toward the torso. Each time you contract your lower leg muscles, you force the blood upward. When the muscles relax, the blood falls back into the pouches until the next muscle contraction, when it is squeezed higher. This is one of the reasons you see varicose veins in people who have jobs where they spend a lot of time standing (not walking) and women who wear high heals (it's also a big reason for their upper thighs and asses turn to flab, but's that another subject). Not having regular muscle contraction to promote return, the blood 'pools' in the pouches which loose their elasticity over the years and start to bag out resulting in varicose veins and clot formation. So what does all this have to do with skydiving??? In addition to properly fitting leg straps, you can help promote blood return (and thereby help to stay conscious) by strongly contracting your leg muscles several times in about 1-2 second intervals.