3- Leg Extension Machine: the leg extension can me found in almost every gym, it’s a staple. Unfortunately it’s a staple which can cause serious injury to the knees. The problem when using the leg extension is that the movement combined with weights creates great shearing forces at the knees. While one may not injure themselves after one use, there is a cumulative effect each time the machine is used causing injury sooner or later. In addition to this, it’s not a very functional piece of equipment and a person would be better served on other things.
Alternative: there are a couple of great alternatives. One would be to perform square. Squats are great for the quads while also being a very functional exercise which works everything. A machine alternative would be to use the Leg Press with one leg. This is a great multi joint exercise which works the quads with little stress on the knee.
4- Weight lifting belts. Weight lifting belts are becoming less and less common with very good reason. The idea is that the belt will assist it’s user in being more stable. This added stability, then, will cause the person to lift heavier weights. Proponents also say that the belt had the added psychological benefit of making it’s user feel more support. The problem with the weight lifting belt is that it’s use slows the development of the core muscles. The muscles in our core are meant to provide support. They need to be loaded with weight in order to get stronger. By using a belt, these muscles have no need to be engaged and so the core is not properly developed. What happens is that the surrounding muscles get stronger but the core doesn’t leaving the very strong possibility for injury when not using the belt.
Alternative: A great alternative can be to wear an elastic band around the waist. While this will not provide support, it will force the user to engage the core and develope those important muscles.