among the hardest to do. However, for a complete physique you need to train your legs. You can even help build your upper body by weight training your leg muscles.
Nothing will build the legs like quadriceps workouts. The quadriceps, or quads, are the muscles on the front of the thighs. This large muscle group needs to be trained with high intensity for your legs to grow.
The most important exercise to do as part of a quadriceps workout is the squat. Squatting will not only work your quads, but also your hamstrings, lower back, and hips. There is probably not a better weight training exercise for improving your overall muscularity than the squat since you get a big testosterone boost when you perform them. It's best to do squats the old fashioned way during your quadriceps workouts but you can try smith machine squats for some variety.
Some exercises that you can do in your quadricep workouts after squats are hack squats and leg presses. These exercises also make great alternatives to the squat if you have lower back problems that stop you from doing them. Your back will be supported while doing either exercise. Make sure to put your feet in the proper position when you do hack squats or leg presses as improper placement could cause a knee injury.
Two other exercises that you can do during your quad workouts are lunges and front squats. Both will work the front and teardrop muscles of the quads. While you can do lunges from a fixed position or while walking forward and with either a barbell or dumbbell, the best option is probably walking dumbbell lunges. If you do them, make sure to put some wrist straps on so you keep your grip on the dumbbells throughout you sets. Front squats can be a bit uncomfortable at first due to where you have to place the bar on your body, but they are a great quadriceps workout exercise for building the muscles that don't do as much work when you do regular squats.
Leg extensions are one of the most popular exercises to do for the quads, but are best used as a finisher to a quadriceps workout. You can do high rep sets or drop sets to finish off your quad workouts with a nice pumped feeling in the muscles.
Here's a sample quadriceps workout that follows a light, medium, and heavy day scheme.
Light quadriceps workout (all sets done for 15-20 reps)
2-3 sets of squats
2-3 sets of hack squats or leg presses
1-2 sets of lunges or front squats
1-2 drop sets of leg extensions
Medium quad workout (10-15 reps on all sets)
3-4 sets of squats
2-3 sets of hacks or leg presses
2-3 sets of lunges or front squats
1-2 drop sets of leg extensions
Heavy quad workout (5-10 reps on all sets)
4-5 sets of squats
3-4 sets of hacks or leg presses
2-3 sets of lunges or front squats
1-2 leg extension drop sets
Try to do this quadricep workout routine every 5 to 7 days depending on your recovery ability. It doesn't a ton of sets during each workout to build your quads if you train hard, so this should be enough. Every workout or workout cycle you should switch between doing hacks and leg presses and doing lunges and front squats. This will keep your body guessing and your muscles growing.
When you put it all together, you should build up your legs and increase your overall muscularity when you perform quadriceps workouts.