The need for lifting weights with a "spot" or "spotter" can be best illustrated by the following story. Three years ago, I was on duty in the Emergency Room of a local hospital when an ambulance came in with a thirty four year old gentleman who sustained a rather large laceration on the right side of his forehead. The laceration was deep enough to reveal the deeper tissues of the man's forehead. Thankfully, his injury was not life threatening, but he required twenty stitches How did he sustain the injury? Doing something he'd done a couple of times a week for years- lifting weights.
Make no mistake, anyone who has read my blogs over the past year will know that I'm a huge advocate of incorporating weightlifting into any fitness regimen. However, there are certain weight lifting exercises that absolutely require the assistance of a workout partner or "spot". The spot need not be someone you do your whole workout with. Often, it is someone who happens to be working out right next to you. The spot is the person who can hand you the weights you need to use for an exercise and, moreover, stand over or behind you to help guide your weight lifting motion, provide assistance if you struggle, or grab the weight(s) should something unexpected happen.
That unfortunate gentleman who sustained the laceration was doing dumbbell presses on a bench when his right shoulder gave out, and the weight that was over his head landed on the right side of his forehead causing the laceration- and it could have been much worse. That guy was not using a spotter. If he were, it is likely that the spot could have grabbed the weight before it did any harm.
Bench presses, especially with heavy weights (specifically barbells) require the help of a spot. Moreover, there are many other exercises that require one as well, such as the shoulder press, squats and dead lifts. The latter two are especially critical as they can very seriously hurt the lifter.
Many, especially those who consider themselves "veteran" weight lifters, often deny that these mishaps can happen to them. The lifter with the laceration had been lifting weights for over ten years! A slip, cramp, or unexpected pain can happen to anyone, whether you're a first timer or Mr. Universe.
Some guys are "embarrassed" to ask for help and others feel like they're inconveniencing the other person who may be working out next to them. That's just nonsense. Most are more than happy to help, and, in turn, will look forward to asking you for some help as well. It's a pretty small price to pay when you consider the alternatives.
If you are having a particularly tough time finding someone to help (i.e. you late night or early morning types) or the gym is empty, don't chance it. If something happens then, you're really out of luck. In that case, pass on the free weights, and go to the machines. Usually, machines such as Nautilus, Cybex, Hammer Strength, and others, allow you to work any muscle a free weight can, but are a lot safer and easier to control.
Furthermore, the spotter can often provide encouragement on those last grueling reps and really allow you to fatigue your muscles- without the danger of the weight crashing down on you. As with most things, it's more fun to share your accomplishments with someone else. Besides, now you'll have a witness to your fabulous performance.