如果是减脂肪，主要还是cardio，如果是练肌肉和线条，最常用的就是Squats和Lunges

Squats:
Why They Rock: Most trainers agree that squats are one of the best exercises you can do. Squats work your glutes, quads, hamstrings and calves all at once.
How to Do it: Stand with feet wider than shoulders with barbell resting on meaty part of shoulders. Bend knees and, keeping chest up, lower into a squat. Keep abs in and the knees behind the toes. Push through the heels to raise back up and repeat.

Lunges:
Why They Rock: Like squats, lunges work most of the muscles in your legs including your quads, hamstrings, glutes and calves.
How to Do It: Using barbell or dumbbells (or no weight) stand with feet apart, toes forward. Slowly lower into lunge position, keeping body erect and abs in, knees at 90 degree angles. Push through the front heel, squeeze butt and slowly lift up to starting position (without locking knees). Repeat for one set and switch legs.

还有一个Straight Leg Glute Extensions:
Using ankle weight (or no weight), balance on hands and knees, abs in and back flat. Straighten one leg and slowly lift up, squeezing the glute. Lower back down allowing toes to barely touch the floor. Repeat and then switch legs.

可以的。做lunges的时候手抓哑铃自然下垂，或者空做两手叉腰都可以。Squats最好还是用barbell，这个是锻炼全身最大muscle group的，负重应该尽量大一些，如果拿哑铃的话，两手要放在胸前，重量大的可能握不住，上身也可能前倾。这个动作要保证重心在脚后跟上，膝盖弯曲程度不要超过脚趾。

重量就要自己调整了，海延mm的帖子里提过，如果练线条，小重量多次数，如果练肌肉，大重量少次数，这个也一样的。我一般连续5分钟各种速度各种下蹲程度，当cardio做的，用的10公斤的barbell，如果当weight training，应该用重一些的，没试过。