Generally speaking, any conditioning (done properly) is better than none at all. So long slow jogs are strictly better for your tennis game than sitting on the couch. But if you are serious about your conditioning, and serious about improving your tennis game, there are certain functional exercises that you can do in order to improve, and there are some exercises you may want to avoid.
In tennis, the key to everything is having a solid foundation. This means having strong legs and a strong base from which to begin your hitting motion.
Probably the most important thing to remember when it comes to strength conditioning is that YOU DO NOT WANT TO GET INJURED. If you ever think that the weight might be too high, or you kind of egg yourself on to quit wimping out and just PUSH THROUGH IT, stop, and carefully consider the risks. If you injure yourself, you can be out of tennis for 6 months to a year, and have to rebuild your skillset from the ground up. So injuries are very counter-productive, and you should take maximum care to get stronger slowly and steadily with good technique. Make it a regular routine, and do not try to do too much too fast.
Running is good for your match endurance and overall fitness – I would recommend running a maximum of 5 miles, and when you get comfortable with that distance, then work on progressing to faster times rather than longer distances. It can be hard on your knees, so make sure you have high quality running shoes, and run on softer surfaces like grass or track whenever possible. Also try to avoid running on uneven surfaces as this can also lead to funky pronation of your foot, and knee issues.
Wall sits, or Jackie-Chan sits are great for getting used to staying low. It will condition your hips, quads, and full body to keep that position and remain balanced. It also helps to strengthen your shoulders. Try doing this for 40 seconds, then work your way up to a minute, then 1.5 minutes, etc. When you get comfortable holding for more than 2 minutes, take a break at the 2 minute mark, rest for 1 minute, and then do another 2 minutes.
Squat Lunges are good for tennis because it gets your body used to getting nice and low. You’ll be doing this motion on a lot of shots. The dynamic scissor kicking motion is good for activating your fast twitch muscles and explosive power from the lunge as well.
Squats are generally a good exercise as long as you have proper form. Unfortunately a lot of people injure themselves by trying to use too much weight and unknowingly using poor form. If you are going to squat more than half your own body weight, have a friend or fitness trainer watch you to make sure your form is correct. You do not want a lifelong injury, bulging disk, torn muscle, etc. from doing squats.
Skipping – great for your calves and will help you stay on your toes for the whole match.
Vertical Jumps for explosive power (helpful on serve).
Don’t neglect your core – it’s the main power source and stabilizer for your body. All the usual workouts apply – crunches, leg raises, v sits, Russian twists, all are good.
The key here is to make sure that your muscles develop evenly. Work all muscle groups and don’t neglect a particular area. Vary your exercises to target different parts of each muscle group, and reduce the likelihood of a muscle imbalance. Muscle imbalances can cause injury, slowness, bad posture, and hindrances for fluid tennis technique.
Make sure to stretch after your workouts to maintain good flexibility. You will actually develop more tennis power from having long flexible muscles than tight lumped up muscles, as there will be more elasticity and energy buildup.
Chin-ups, push-up varieties, shoulder raises, curls, tricep extensions, dips, rowing, etc. are all good exercises that will help you in tennis.
One particularly useful exercise for tennis players is to work your rotator cuffs lightly. It is a tiny muscle so you do NOT want to over-work it with too much weight. It’s not a strength building exercise but rather just for injury prevention. Use small weight, and move slowly.
This is probably the area where most people have to work at to substantially improve their tennis game. The average tennis point lasts only 15 seconds, and ranges generally from 1 second to perhaps 30. Between points you have 30 seconds rest, so you want to condition your body to getting used to 15-20 seconds of high energy dynamic work, followed by 20-30 seconds of rest. You need to be able to blast hard at each point, then recover quickly so you’re not winded when the next point begins.
Wind-sprints, or intervals on the bicycle are good for this. Sprint as hard as you can for 20 seconds, then jog until your heart-rate comes down. Try to get to keep reducing your recovery time and the number of sprints you do.
Skipping is a fantastic cardio workout and it works your legs and court movement.
Shadow boxing, or boxing classes are also good, as they teach you balance, movement, coordination, core strength, body rotation, and the kinetic chain. It’s also a great cardio workout – try shadowboxing for 3 minutes non-stop as hard as you can, then take a 1 minute break, and repeat.
10 Stutters and a sprawl – keep your body low, legs bent, and feet moving as fast as you can. When you’ve done 10 stutters, sprawl and get back up. Continue for a set of 5 sprawls and then take a break.