If you are a beginning lifter it is best to use lighter weights. You want to focus on perfect technique and reaching full range of motion. You want to challenge yourself, but not so much where you compromise technique and reduce range of motion just in order to say you lifted more weight. This happens frequently, not just to beginners, but to those that have been lifting for years. In class we might squat for a heavy set of 3-5 reps and occasionally a heavy set of 10. We will stress that heavy is not a max. What do we usually see? Often times athletes will fail on rep 2-3 on a set of 5. I’ve seen an athlete fail on rep 9 on a set of 20. Our first few reps might look and feel good and the rest look and feel awful. I’ve been there. We like pushing ourselves as CrossFitters. That’s a great thing. The downside to failing and compromising technique is threefold:
1) We ingrain bad motor patterns. Better put, we teach ourselves poor technique and whether we know it or not, this becomes acceptable to us during workouts and other lifts. It has carry over to our performance. Our goal should be, whenever possible, perfect technique and perfect range of motion. Professional weightlifters max lifts don’t look much different from their 60-70% efforts. I like to compare CrossFit/Weight-lifting to hitting a ball off a tee (baseball). The goal is for every swing to be the same. Come game-time, know matter where the ball is pitched or how fast it comes, the motor pattern is the same. With proper technique and range of motion achieved comes strength gains down the road.
2) Compensation patterns. This is closely related to bad motor patterns. There is a time and place to grind our reps. An experienced lifter that has worked out for years knows how to grin d our reps and to focus on technique when they get fatigued. Beginners-Novice lifters will often find themselves compromising technique in order to finish sets, when they would be better off stopping or dropping the weight. Compensation means other muscle groups hop on board to do more work in order to successfully complete a task. The stronger the athlete is, the better they are at compensating. NFL players are a great example. Guys have played at that level with fractures, torn biceps, and other ligaments. They are so strong around those joints they can still perform. Sure, not all the time. A good example of a compensation pattern is found on the front squat. An athlete can often squat to full depth with their elbows up during a set of 3 at 70%. Get up to 85% and the elbows are dropping on the way down and more on the way up. We call it a good morning squat. The upper back muscles are working overtime to compensate.
3) Injury. Failure for beginning lifters will more often than not result in injury. Sometimes a compensation injury and at other times from technique issues. Failure for an advanced lifter pushing themselves for a max or aiming for a heavy set of 3-5 and missing due to a mis-guess for the day isn’t too big of a deal. It becomes an issue when the athlete tries over and over again.
Athletes will progress and get stronger lifting to their threshold for the day. Pushing beyond their threshold will be counter productive in the long-run and hinder progress. Most strength gains are found in the 75%+- area of 3-5 reps.