How to use your legs on the tennis serve

Push the court first. It pushes back.

Key facts

1
Advanced servers produce about 1.5 times body weight of vertical ground force with a foot-back stance and about 2.1 times with a foot-up stance.
Bahamonde & Knudson
2
The rear foot's vertical ground reaction force correlates with racquet speed at r = 0.70, and the centre of gravity's vertical velocity at r = −0.94, in the acceleration phase.
Gorce & Jacquier-Bret, Frontiers, 2024
3
Knee flexion in the loading stage of the serve runs about 90–115°.
Kovacs & Ellenbecker, Sports Health, 2011
4
Higher-level players generate greater vertical ground reaction force on the serve.
Girard, Micallef & Millet, MSSE, 2005
5
By one physics estimate, a 4-inch jump widens the serve's vertical window by roughly 20 % for a 100 mph server.
Brody, Cross & Lindsey, The Physics and Technology of Tennis, 2002

Why it works

Push down and the court pushes up with the same force. That returned force is the whole budget for the kinetic chain. Your hips, trunk and arm spend it. The legs supply around half or more of the serve's kinetic energy.

A deeper, faster load returns more, but only if you get off the ground with it. A bend that pauses at the bottom loses the stretch-shortening cycle. Make the load one continuous move into the drive.

Your stance sets the dose. Feet together, the pinpoint stance, stack the push vertically. Feet apart, the platform stance, trade some of it for balance. Landing on your front foot inside the baseline tells you the drive went up and forward. If you land on the back foot, your arm paid for the shot.

The line to say on court
“Push the ground away.”

Drill: The load ladder

15 min · alone

Hit ten serves from a frozen trophy pose with no knee bend. Note where they land and how your shoulder feels.
Hit ten serves with a deliberate bend past 90° and a jump. Land on your front foot inside the baseline.
Hit twenty serves with your full motion. Count the front-foot landings inside the line.

Number to beat16 of 20 front-foot landings inside the baseline

More drills like this: warm-up and fitness

Faults and fixes

Arming the serve

There's no leg drive, so the shoulder supplies the speed and takes the load.

FixRebuild the loading stage: bend, then go up.

Landing on the back foot

The drive went nowhere and your weight stayed behind.

FixCue yourself to land inside the line.

Bending, then pausing

The stretch-shortening cycle is lost at the bottom.

FixMake one continuous load into the drive.

Treating the stance as balance only

Your feet are set for standing, not pushing.

FixChoose the stance for the push, then earn the balance.

Questions players ask

Should I bend my knees more on my serve?

Elite servers load to about 90–115° of knee flexion, but a bend only helps if you drive up out of it without pausing. Whether more knee bend gives club players more speed isn't settled.

Is pinpoint or platform stance better for the serve?

In one force-plate study, feet together (pinpoint) produced about 2.1 body weights of vertical force and feet apart (platform) about 1.5. Platform trades some push for balance.

What should I do when my legs are tired late in a match?

Keep the bend if you can still land inside the line, and cut it if you can't. Don't swing the arm harder, because the shoulder then absorbs what the legs stopped supplying.

Does the forehand use ground reaction force too?

Yes, though the force numbers here come from serve studies. In an open-stance forehand the outside leg loads into the court and the push comes back out as hip rotation.

What this doesn't cover

The force-plate numbers come from lab testing of advanced players. Video shows the motion, not the force, so any force arrow drawn on a clip is a model. Whether more knee bend gives amateur players more speed is not settled.

Sources

Bahamonde & Knudson, Ground reaction forces of two types of stances and tennis serves
Gorce & Jacquier-Bret, Frontiers (2024)
Girard, Micallef & Millet, Medicine & Science in Sports & Exercise (2005)
Kovacs & Ellenbecker, Sports Health (2011)
Brody, Cross & Lindsey, The Physics and Technology of Tennis (2002)

Serve and returnHow to serve in tennis: the service motion step by stepA good tennis serve is a throw that starts in your legs, passes through your trunk and shoulder, and reaches the racquet last. Legs and trunk supply about 51–55 % of the serve's kinetic energy, and shoulder internal rotation about 40 % of racquet-head speed. Load the knees, let the racquet drop edge-on, reach up to a straight-arm contact and land inside the baseline.StrikeHow to get racquet lag on your forehandYou get racquet lag on your forehand by keeping your hand soft while your body turns, so the racquet head trails your hand and then releases. Don't snap the wrist for power. In elite forehands, forearm pronation adds almost nothing to racquet speed, while the shoulder adds about 45 to 48%. The wrist's job is to get out of the way.StrikeHow to hit harder in tennis without swinging harderTo hit harder without swinging harder, start the swing from the ground and fire the body in order: legs, hips, trunk, arm, then racquet. Each link speeds up the next and then brakes, throwing momentum outward. On the serve, the legs supply an estimated half or more of the energy. The arm is the last and smallest contributor.Move and reactOpen vs closed stance forehand: when to use eachHit open stance when the ball is late and wide and you have little time, and step in with a neutral or square stance when it's slow and short. The swing barely changes between them. What open stance buys is the next ball: you're already facing the net at contact, so your first recovery step comes sooner.