I’m a weightlifter (Olympic-style) and have had some troubles with blacking out or getting light headed when I come up with heavy (90 to 100 percent) efforts in the Clean. I have been told that this is due to a blood pressure change during the lift and that increasing my fitness level should help with the problem. I don’t feel any less cardio fit than when I was not having this problem. Are you able to shed some light on this?
Holding one’s breath during a heavy exertion, especially with a near maximum load resting across the neck, may close off the glottis and create what is called a Valsalva maneuver. Here you are basically choking yourself. For more details, check the book Essentials of Strength Training and Conditioning (Human Kinetics).
Most lifters take and hold a breath before beginning a Clean. They exhale a bit at the most powerful part of the pull and as they rise past the “sticking point” in the recovery phase. Elite weightlifters punch the barbell several inches off their shoulders at the top of the Clean (while again exhaling a bit). They absorb the descending weight on slightly bent knees, then standing ready to Jerk. This is not an attempted Jerk but merely a strong leg drive to get the weight off of their shoulders, partially in order to avoid blacking out. The technical rules for the Clean-and-Jerk allow for repositioning of the lifter’s hands or the barbell after the Clean and before the Jerk.
Avoidance of both holding the breath and having the barbell across the throat prevents lightheadedness and/or blacking out.
As mentioned in my book Explosive Lifting for Sports (page 100), the bar position after the Clean and before the Jerk is important. It is best to create a shelf to support the bar without the bar impeding breathing, which means the weight of the bar is ideally spread across both deltoids and the clavicles. With the shoulders protracted slightly forward and upward, the lifter can continue to breathe without difficulty.
Don’t worry about “increasing your fitness level,” whatever that may mean. Competitive weightlifters are not necessarily “fit” beyond the specific needs of their sport.