vertical velocity = up and down movement..you may fly off the bike at 100fps, but your vertical decent may only be 30fps

cumulative velocity = vertical velocity + horizontal velocity + depth velocity.

basalar injury = what the HANS device now prevents in NASCAR.

G's = magnification of weight..you should know this marine man...

exert = force applied.

physiologist = someone who studies physiology...the science of the body i believe.