Federer vs. Djokovic—How do they measure up?

We thought we would compare the two players. Both are about the same size and weight. Djokovic is 6'2", 176 lbs., while Federer is 6'1" and 187. Federer, 27, is considered to be the best tennis player of all time with 15 Grand Slam titles and the longest run in history as the #1 ranked tennis player. Djokovic is 22, currently ranked #4 in the world, and has beaten Federer four times.

Stride Angle

Stride Angle is the maximum opening between the front and back leg as the player runs across the court. We have found that for every degree you increase the Stride Angle in an athlete, they cover 2% more ground when running.

Since Djokovic's Stride Angle is 5° larger than Federer's, he can cover 10% more ground with each stride. This means he can cover the court faster with fewer strides, or more speed with less fatigue.

Roger Federer Stride Angle 

Novak Djokovic Stride Angle 

External Arm Rotation Angle

We have found that for every degree we increase the External Arm Rotation Angle, a player can add 1 mph to their serve.

Federer and Djokovic both serve about 130 mph tops.

Djokovic should have a 40 mph advantage, but he doesn't. We'll show you why later. The reason is quite amazing.

Roger Federer EAR angle Novak Djokovic EAR angle

Why would just a one-degree increase in the External Arm Rotation Angle add a mile-an-hour to the serve? Does it make the arm more ëpowerfulí?

Obviously not. But it does allow more time and distance for the racquet head to get up to speed prior to impact. Service speed is all about racquet head speed at impact. Players with a bigger External Arm Rotation Angle have more time and distance to get their racquet head up to speed before impact.

You can compare Federer and Djokovic to two drag racers. Federer has 1/8th of a mile to get his car up to speed; Djokovic has a quarter mile. Djokovic does not have to exert as much effort to reach the same top speed.

Djokovic's External Arm Rotation Angle is exceptionally good. We have found only one other comparable player, Andy Roddick. But Roddick's serve has been clocked at 155 mph. So why is Djokovic's serve topping out at only 130 mph?

Roger Federer EAR angle Novak Djokovic EAR angle

Hip Rotation During the Serve

During the serve and groundstrokes, tennis players are putting the racquet head in an orbit around their body. We normally put satellites into orbit with a multi-stage rocket. A tennis player can be considered a five-stage rocket consisting of the legs, hips, shoulders, arm and hand. As with a rocket, the most powerful stages are at the bottom, and the smaller, less powerful stages at the top. Also, as with a rocket, it is most effective to fire each stage in sequence from the bottom up. Otherwise, a satellite would not be able to go into a useful orbit, and just end up in the ocean. In the case of tennis, poor sequence means the ball goes into the net, out of bounds or returned for a winner.

Much of the power for the serve and groundstrokes is generated by the rotation of the hips. For example, a tennis player who increased his hip rotation speed with just a thirty-minute workout on the Power Hip Trainer, immediately increased his racquet head speed from 50 to 80 mph, as measured by a laser unit.

Here is Federer's hip rotation from toss to impact.

Federer Toss Federer Impact

During his toss, Federer has rotated his hips about 120° away from the baseline. At impact, his hips are turned away about 70° from the baseline. In other words, Federer has rotated his hips only 50° during his serve.

Djokovic is another story entirely.

Djokovic Toss Djokovic Impact

Djokovic has rotated his hips away from the baseline 135°. With his 40° advantage in External Arm Rotation Angle and greater rotation away from the baseline, he should have a much faster serve than Federer.

But, as you can see, at impact his hips are still rotated away from the baseline 135°. In other words, he has not rotated his hips at all during his serve.

Since hip rotation is the main source of power during the serve, Djokovic is relying entirely on his upper body to power his serve. Instead of using his legs to quickly rotate his hips (and generate a tremendous torque that will be transmitted by his arm to the racquet), Djokovic uses his legs exclusively to jump up at the ball.

Tennis players do this for two reasons. One, they think that jumping up gives them more height so that they can hit down on the ball. Research with high-speed cameras, however, shows that the racquet is actually traveling up as it impacts the ball. This upward motion imparts topspin to the ball, which makes it curve down over the net and into the service court. Tennis players, regardless of how they feel, are not hitting down on the ball.

The second reason is that tennis players, along with all other athletes, associate effort with winning, even though research shows that efficiency is more associated with winning than effort. Efficient athletes put out less effort, but win more often.

Using your legs to launch your body up toward the ball feels very effortful and gratifying, but is actually a very weak move, and cannot impart much speed to the ball. You can demonstrate this for yourself by tossing a tennis ball up in the air and then jumping up and hitting with your head. It wonít go very far or very fast.

The psychological benefits of launching your body into space during the serve are far outweighed by the fatigue to your legs. Not so much while jumping up, but in landing. As gravity pulls you back down to earth, you have to stop your fall with your legs, especially the quads. As your knee bends to absorb the shock, your quads have to stretch and contract simultaneously. Anytime a muscle has to contract and stretch at the same time, many of the tens of thousands of individual muscle fibers that make up each quad muscle get torn. You then have to run around the court with torn muscle fibers. Not a great recipe for tennis success.

Tennis players would be better off to use their legs to generate hip rotation speed during the serve. It wouldnít look so attractive to the spectators (they would think you were lazy because you are not jumping into the air like everyone else), but your opponents will be impressed with your service speed as they swing too late to return the ball.

Hip Rotation on the Forehand

As with the serve, the hips and shoulders should rotate well before the arm in order to generate maximum groundstroke speed with the least amount of effort. Federer is more efficient on his forehand. You can see in the photos below that both players rotate their hips the same on the forehand, but Federerís shoulders are rotated more open long before impact, giving him more effortless speed on the forehand side.

Roger Federer Novak Djokovic

Hip Rotation on the Backhand

It seems from their impact position that both players rotate their hips the same on their backhand side, as you see in the photos below.

Roger Federer Novak Djokovic

But if we look at their sequence prior to impact, we see a different story. Federer does not use his hips at all during his backhand. They remain in the same position throughout his stroke, even after impact.

Roger Federer Backhand Sequence--No Hip Rotation! 

By contrast, Djokovic rotates his hips back about 45° on his cross-court backhand (frame #3 below, first sequence) while taking his racquet back. He then actively rotates his hips to about 30° open prior to impact (frame #1, second sequence). So we estimate that Djokovic rotates his hips 75° more than Federer prior to impact on his backhand.

Novak Djokovic Backhand Sequence--75° Hip Rotation Prior to Impact 

This is not the result of a two-hand backhand. Djokovic is actively using his hips on his backhand, whereas Federer is not using his hips at all. There is nothing in the single-arm backhand that prevents a player from rotating his hips prior to impact. It is just a matter of choice or instruction. There are, for instance, plenty of two-handed players who do not rotate their hips back prior to impact. Djokovic is making more effective use of the mass of his hips on his backhand. As we know, Force = Mass x Acceleration. Djokovic and Federer have similar mass, but Djokovic is accelerating his hip mass more effectively. Federer has what we call a 'balletic' backhand--beautiful to watch, but not effective at generating ball speed.

Eyes On the Ball

The eyes, of course, do not generate any ball speed, but are important for ball contact, helping to make sure the player gets the ball on the sweet spot in the center of his racquet.

If the player hits the ball off-center, some of the energy generated by his hips will be lost. Both players do equally well keeping their eyes on the ball.

Roger Federer Novak Djokovic

What Have We Learned?

Federer does not rotate his hips on his backhand and Djokovic does not rotate his hips on his serve. Both players are needlessly throwing away ball speed. Federer could be effortlessly generating more backhand winners, and Djokovic could be easily generating 150+ mph serves. It seems amazing that neither they nor their coaches allow this sad state of affairs to continue--but it is quite common. We have never found a tennis player who rotates their hips equally well on the serve, forehand and backhand. This means that there is plenty of room for improvement in tennis performance. Players who learn to forcefully rotate their hips will have an unnoticed advantage over their competitors.

While Federer rotates his hips 70° prior to impact on his serve, there is no reason why he cannot rotate them 135°. Instead of using his legs so much for jumping up during his serve, he could use them more to drive his hip rotation. This would add miles per hour to his serve, putting more pressure on his opponents.

Djokovic, of course, would serve faster with even a little hip rotation, but would be extraordinary with 135° of hip rotation and 130° of external arm rotation. His serves would be almost un-returnable.

As with most tennis players, Federer would measurably benefit from more flexibility in his shoulder, back and hips. If he increased his external arm rotation and back extension, he would have an External Arm Rotation Angle much greater than 90°, which would add speed to his serves while reducing his effort. Increasing the flexibility in his hips would increase his Stride Angle, making him faster on court, again with less effort. As he ages, increasing these two Angles would keep him physically young.

Stretching Doesn't Help

As most tennis players know, stretching is not very effective at measurably increasing flexibility.

This is because tennis players lose flexibility from the stress of playing tennis. Stopping and abruptly changing direction on court, endlessly practicing serves and forehands from a very young age, all tear some of the tens of thousands of individual tiny muscle fibers that make up each muscle. As these muscles repair, they do become stronger, but microfibers (scar tissue) also develop between the muscles. These microfibers accumulate over time, making players stiffer with age. Because they are scar tissue, microfibers cannot be released by stretching or conventional therapy.

This process of microfibrosis is accelerated when tennis players lift weights, as weight lifting also tears the individual muscle fibers. In fact, this is why players increase their muscle mass from lifting. As the torn fibers repair, they become bigger. Tear and repair--the Neanderthal's method to increase strength.

Regardless of whether they lift or not, tennis players have short careers because of the accumulation of microfibers that gradually makes them stiffer in their legs, shoulders and hips as they age.

Normally, the connective tissue membranes (white) between the muscles (red) are smooth. They allow the muscles to slide past each other, which they have to do in order to stretch.

But when you have even a mild injury (falls on court), overuse (lifting weights, running) or stress , microfibers form as part of the healing process to immobilize the area. Microfibers are nature’s internal cast.

Unfortunately, once the area has healed, the microfibers not only do not go away, they tend to accumulate over time, making athletes stiffer with age.

By releasing microfibers with Microfiber Reduction, Somax can measurably improve tennis performance. The client below increased his external arm rotation 20∞ in just four weeks. Radar gun tests with tennis players with the same improvement showed that they added 20 mph to their serve.

External Arm Rotation before Somax

External Arm Rotation after Somax 

Federer can also easily improve his court speed by releasing microfibers that have accumulated in his hips from decades of playing tennis. Our client below increased his adductor range almost 300%, again in just four weeks.

Before Microfiber Reduction 

After Microfiber Reduction 


Federer can improve his already great court performance by improving his flexibility in tennis-specific ranges. Rafael Nadal is not the only threat to his career, as Novak Djokovic, another very flexible player, has already defeated him four times. Increasing his flexibility will increase his serve and court speed. Actively rotating and strengthening his hips will add speed to his backhand and serve. Combined with his skill level and experience, he will be able to continue to win titles into his 30's and 40's. It will also reduce his chances of having to play another 29-game set to win at Wimbledon.

If Djokovic wants to advance beyond #4 in the world, he can start by rotating his hips on his serve. Some rotation would be better than nothing.