Todd Ellenbecker, D.P.T., chairman of the USTA Sport Science Committee and co-author of Complete Conditioning for Tennis, answers your tennis health questions.

I have often experienced painful cramps in my legs, mostly the calf area, while playing. This normally happens during a tournament after three or so matches in the heat. I know that it could be caused by heat and excess sweating, but I drink plenty of Gatorade and water. Is there anything you know about this as far as supplements, stretches and training?—Hassan Rashid

Cramping as you describe it is likely due to an electrolyte imbalance and improper hydration practices. Even though you are drinking Gatorade and water, you may be starting matches dehydrated and not able to keep up with the fluid loss while you’re playing despite your efforts. Some players sweat excessively and really lose a lot of fluid and electrolytes while playing (especially sodium). A physiologist can evaluate you for this to determine if you need to take extra steps to combat this problem.

Some things I would recommend include weighing yourself before and after play in the heat. This will allow you to know how much fluid loss you have encountered while playing and also ensure that you drink enough to regain your pre-match weight ensuring that you replace the fluid you lost before you play the next day. Also, research has shown that many players are dehydrated before they even step out on the court. Monitoring the color of your urine can help as well. If it is yellow or dark colored, you are still dehydrated and need to keep drinking fluids (though if you take supplements, it may never be clear). Gatorade allows you to get extra electrolytes by adding the contents of electrolyte packages to your drink. Stretching is always a good idea but likely will not help if you are cramping due to a fluid imbalance.

What is the best way to build stamina for tennis?—Nicole Ross

By studying physiology in tennis, scientists have shown us that fitness in tennis requires bursts of activity known as anaerobic fitness, as well as aerobic fitness due to the long matches and the repetitive nature of the game. Given that, players need both explosive power and aerobic endurance to be successful. So, for the stamina aspect, you should try to supplement your training with some aerobic training. Research has shown that players with higher levels of aerobic fitness recover better between points. To build your aerobic fitness level, the American College of Sports Medicine recommends you perform steady exercise for periods of 20–30 minutes at least three to four times per week at an intensity of 60–80 percent of your maximum heart rate. To do this you could use a stationary bike, elliptical trainer or Stairmaster and use your heart rate as a guide to get optimal benefit out of our workout. Go here to learn to calculate your target heart rate.

Since you love tennis, you could also try enrolling in a cardio tennis program—any type of sustained exercise as mentioned above would be a great choice. If you have had any types of knee or leg issues, running would be my last choice since the pounding of tennis along with the pounding of running may be an overload in your training.

I partially tore my ACL in February 2008. I’ve seen a couple of ortho docs and some physical therapists and I’m really confused. My knee feels OK now, but it starts to hurt after an hour or so, especially when I serve. But I can still play and move. If I elect to have surgery, which is better for a tennis player? One doctor wants to do a hamstring autograft and the other doctor wants to do a cadaver/allograft. One P.T. I saw said I shouldn't get the surgery because it gives you arthritis in 10 years! He said just play with a brace. So, I’m really confused. Help!—Joe Polito

Injury to the ACL in a tennis player is a significant functional problem. With the weight-bearing, loading and twisting that occurs when you play tennis, not having the surgery in a knee that is unstable can lead to arthritis due to increased translation between the femur bone and tibia. You have done the right thing in consulting with numerous orthopedic surgeons and physical therapists as they can give you the specifics of the surgery and rehabilitation following the procedure.

Recent research following patients for as long as 10 years after surgery has not shown a superior graft choice. Patients using their own tissue (autograft) as well as a cadaver graft (allograft) both can return to function following reconstruction. Failure to have the ACL reconstructed can lead to continued meniscal (cartilage) tears which can lead to accelerated rates of arthritis in the knee.

Regardless of the graft and procedure chosen, a steady course of rehabilitation is required following surgery to retrain the muscles in the lower extremity and core to allow for an optimal result. Unfortunately, there is no best surgery, but by consulting the top sports-medicine physicians in your area and asking them the key questions you have outlined will likely guide you to the best procedure for your specific knee injury. Either way, making sure you regain the strength in your quads and hamstrings will help to stabilize the knee, no matter what you decide.

How can I avoid a bruise on the heel of my hand where the racquet rests? I use a [K] Three Wilson raquet.—Sharon Ortega

This problem is most likely not due to the racquet but rather how you grip it. Each racquet has an enlarged end (butt cap) to keep the hand from sliding downward on the racquet when playing. Having your grip and hand position checked by certified teaching professional is likely the best line of defense for this issue, as your hand might be too far down on the racquet. Additionally, if you have your hand positioned in a grip so increased loads are transmitted to certain parts of the hand, like the bones in your wrist, this may cause more discomfort. Sometimes an overgrip can give additional cushioning to your hand, but I would first consult the teaching professional to be sure your grip is proper and best suited for your game.

I am 53 years old and starting to develop knee pain after playing for 30 minutes, is there a certain type of knee support that would offset the discomfort. I really don’t want to give up tennis, I use it as an encouragement to keep getting in better shape.—Jim Cielma

Without examining your knee is difficult to determine what is best for you as there are many options. Knee supports can consist of simple sleeves with a cut-out around the knee cap to support the kneecap when you play. These can be particularly effective if you don’t have really good quadriceps strength and need that support. If your knee pain is caused by an alignment issue (such as if you are bow-legged), then there are specific braces that can be used to unload your knee and relieve compressive type pain in the knee from early arthritis. The best advice for making sure you have the correct support and exercise program for you ailing knee is to see an orthopaedist to examine the knee and determine the source of the discomfort, then perhaps a physical therapist to get the right exercises. The combination of the right brace and exercise regimen will hopefully keep you out on the courts for a long time to come.

I’m trying to train my sister and get her as fit as possible. I want to do some stuff but I’m not sure if they’re a little bit too extreme for her since she’s only 9. Can you please give me some advice on what things she could do?—Erik Angamarca

At that age, working on basic athletic skills is very helpful. Lifting weights and other typical training methods are not as effective and could be dangerous without the supervision of a trained professional. However, doing general calisthenics and body-weight exercises like squat and lunges, sit-ups and push-ups can be used to tone the muscles and gain coordination. Often, exercises that promote body awareness and balance, such as agility drills and kicking (soccer) can be very helpful for general coordination. Many tennis drills can be used or altered for young players to keep it fun and promote overall athletic fitness at that early age, which can go a long way in a player’s development.

I’m 21 years old, and I haven’t played tennis for six or seven years. I started playing again, but now when I play I feel some pain in my wrist. What kinds of exercises can I do to prevent the pain and to strengthen my wrist?—José Dias

Great question. Since you have taken some time off from tennis, you may not have as much strength in your forearms and wrist as you once had when you were playing more regularly. I would recommend doing some wrist exercises to increase your strength to get you back in playing shape. These would involve using 3–5 pounds (I don’t know how large you are, how strong you are etc, so starting out with just a few pounds would likely be the best choice) and doing wrist curls both with your palm facing upward (flexion curls) as well as palm facing downward (extension curls).

In addition to the curls, you can squeeze a ball, holding for five seconds and repeating 10–15 times per session. The curls can be done moving the weight slowly in an upward and downward direction for 3 sets of 15–20 repetitions. These exercises should not be done right before playing or practicing as it will tire out your muscles before you play. Do these several times a week and in 4–6 weeks your wrists will be stronger.

I am 55 years old and play mostly men’s doubles at a 4.5 level. I have a ruptured disc in the lower lumbar spine area. The pain dictates when I can play and for how long. Should I stop doing what I love, consider surgery or try and live with the pain? I have had decent results with Z-pak steroids (a small dose for 6 days straight). Would this be OK to help me keep playing?—Ron Eddy

Injuries to the spine are common in tennis players of all ages and ability levels. Typically the best treatment for tennis players with back problems is to improve their core stability. The core consists of the muscles of the lower back, abdomen and hips. All players need to have a strong core to perform the rotational movements required in tennis. There are many ways to strengthen the core, and for tennis players, exercises with rotation are most specific to the movements you do in tennis. Using a physio ball adds a lot to the exercise by providing an unstable base, which works muscles of the core even more. Doing sit-ups with rotation, as well as exercises for the lower back such as the superman and pointer exercise can be especially helpful as research has shown that elite tennis players actually have fairly strong abdominal muscles, but have relatively weak low back muscles. Injections and surgery should be resorted to after physical therapy and exercise have not remedied the problem. Go here for a core workout from TENNIS. Adopting a comprehensive core training program would be a great step to playing with greater core strength.