If volleyball is your chosen sport then you will need to make sure you have extremely strong quad and lower leg muscles in order to both support you during your jumps as well as to prevent injuries.
One of the key skills you will call upon when playing volleyball is jumping up towards the net in order to spike the ball. Having a lot of force and power in your legs is going to enable you to not only jump higher, thus increase the chances that you hit the ball but also allow you to transfer some of this force to actually hitting the ball with your arms.
To develop strong quad muscles for volleyball really focus on strength training exercises such as low squats, wall squats, jump lunges and leg extensions. Jump lunges are particularly good because this will work your quad muscles as well as improve your rebounding abilities. To perform them get into a lunge position and then jump off the ground changing leg positions mid-air. Finally land with the opposite leg forward back in the lunge position.
Next for the lower leg, perform both calf raises and band-resisted ankle pulls. Band-resisted ankle pulls are done by looping a resistance band over the top of your foot while tying the other end to a chair or something sturdy far enough away from you so that the band is tight. Then, sitting on the floor with legs straight out in front of you pull your toes in the direction of your body while resisting the tension in the band. Perform 15-20 repetitions and then switch legs. This exercise will be quite effective at preventing shin splints or the ankle injuries that are very common amongst these athletes.
Make sure to include these two particular exercises in your workout next time you are the gym so you can be sure you are maximizing your performance ability on the court.