How do different athletic qualities fit into the program of a tennis player? This is a complex question but one that deserves an answer. With information being so readily accessible, there are countless videos of players doing all kinds of things off the tennis court. But just because a top 100 or 50 player is doing X or Y, does it mean it’s effective? Is it driven by some underlying scientific basis? Often times, it’s not. It’s a regurgitation of someone else’s training or a drill that was once seen before. If you’re a player, and someone is telling you to do squats on a stability ball…or ladder drills to develop footwork and speed...seek alternatives as these are merely gimmicks that have little transfer to elevated sporting performance.
How does a player increase power, explosiveness and racquet head speed? Before we can truly understand how these different abilities make their way into the training program of an elite tennis player, we must first understand a basic principle of sport science...the force-velocity (F-V) relationship - aka the F-V curve.
What follows is a brief description of the F-V curve, how it impacts tennis and what training methods have been proven to improve various components of the curve.
Strength & Conditioning Basics - The Force-Velocity Curve
The force velocity relationship underpins all muscle contractions and joint movements. It states that muscle force and velocity are inversely related. When contraction force is high, velocity is low and vice versa (Figure 1). For instance, lifting very heavy, like a 1RM back squat, produces very high forces and very low velocities. On the complete other end of the spectrum you have high velocity movements and low forces - like sprinting at max speeds. Hill (1938) has been attributed for the discovery of the force-velocity relationship, almost 80 years ago. Today, strength & conditioning coaches and sport scientists use the F-V curve to guide training programs, as an upwards shift in the curve will improve muscle function and athletic performance. How so? The basic premise is this - shift the curve upwards and at any given velocity, you can now produce more force. Or put another way - at any given force, you can produce more velocity.
In theory, this is what the curve looks like...along with associated training qualities:
Here’s an example in tennis. During the tennis serve, the shoulder internal rotators can have speeds up to 3000 degrees/s (that’s fast!). The internal rotators must produce up to 200 N (Newtons) of force to reach these speeds. Now, let’s say you’ve gone through specific velocity training (the velocity/low end of the F-V curve) of the rotators and have increased the velocity output of that motion. You’re now able to reach 3250 degrees/s for the same given force output. This is a velocity specific adaptation. What does this do? It increases your power output for that motion (basic physics, Power = Force x Velocity - in Figure 1, the blue curve represents the power curve; the peak of this curve being a blend of force and velocity).
How Does the Force-Velocity Curve Affect Tennis?
Every stroke and movement in tennis doesn’t fall perfectly into one specific part of the F-V curve. Remember, the F-V curve applies to muscles and joints. We should therefore look at it as part of a continuum. Within one tennis stroke, many (and perhaps all) parts of the curve could be involved as human movement is complex (contraction types, speeds & angles are different and are affected by many variables). In any case, here’s a brief breakdown of the various parts of the F-V curve and where certain movements in tennis fit in.
Maximum Strength & the F-V Curve
Maximum strength can also be referred to as absolute force or absolute strength. It’s concern is with maximum force generation of a muscle or muscle group. To develop maximum force, you need to lift maximum loads - this doesn’t mean doing a 1RM every time you're in the gym but it does mean lifting somewhere above 85% of your 1RM. You’ll find max strength at the very top of the F-V curve, where higher forces and low velocities are generated.
In tennis, max strength is critical to both absorb high forces and to generate high forces. When referring to the absorption of forces, the most common scenario in tennis is deceleration (Download a full research article on deceleration for tennis by Kovacs here). The higher the running speed before setting up for a ball, the faster will be the rate of deceleration and the more force the lower body must absorb. Eccentric strength is vital in this scenario. If you think about decelerating when tracking down a ball, you can associate that with the deceleration phase of a heavy squat. Strength adaptations are joint specific, contraction specific and speed specific. Believe it or not, deceleration in sport and the lowering phase of a squat have similar characteristics.
Another example of force absorption in tennis is landing after a serve. When serving, there are large forces and torques (another term for force but in a rotational manner) created. Kovacs & Ellenbecker (2011) observed that these forces can be as much as 2 times your bodyweight (which is a general recommendation of how much strength an athlete should possess anyway). To absorb these forces, we must land on one leg. If we don’t have the eccentric strength to land efficiently on our front leg after the serve, that force will crush us and impede the next movement - and that next movement must be an explosive recovery to organize oneself for the oncoming shot.
Next is the generation of high forces in tennis. Let’s run with the previous serve example. Once you absorb the landing forces after a serve, to initiate movement, high forces are required. There is a large inertia (or resistance) that’s acting on a player at this point, and the only way to move explosively is to generate high forces. Two other examples include the re-acceleration after a shot (especially when deceleration forces are high… like running for a tough wide ball) and the very early stages of a big groundstroke - planting the foot and using ground reaction forces.
It is critical to remember that the higher the inertia (or resistance) the more important max strength becomes. Research also suggests that you cannot have high levels of power without first being relatively strong! Stronger athletes have greater neuromuscular characteristics - greater size of type 2 muscle fibres, enhanced neural recruitment, superior inter & intra muscular coordination and so on. Because of these neural factors, max strength potentiates the remainder of the F-V curve. That means that at any given velocity, you’ll produce more force and hence, more power (remember...P = F x V).
Strength-Speed & The F-V Curve
When compared to max strength, strength-speed refers to the generation of high forces at higher speeds. This is generally seen in explosive strength exercises like the clean & jerk or snatch (Olympic weightlifting movements). Again, here, the loads must be quite high (between 80%-90% of 1RM) which puts this quality just below max strength on the F-V curve.
In tennis, strength-speed qualities are important during various parts of groundstrokes and serves. More specifically, the leg drive and take off phases of these strokes. Another example is movement qualities. After the initial acceleration phase, high levels of explosive strength need to be generated to propel the body in the direction of the oncoming ball.
Strength-speed is primarily developed through Olympic weightlifting movements. These movements generate higher power outputs compared to traditional strength training exercises. This is true because the bar (and body) are propelled throughout the entire acceleration phase of a lift. In other words, there is no deceleration until you have to catch the bar (either on your shoulders in the clean OR overhead in the snatch). This deceleration helps the braking forces in tennis, especially when the requirement is to decelerate VERY quickly.
Furthermore, olympic weightlifting exercises have similar movement kinetics (joint angles, recruitment patterns etc) to movements that occur in sport. This includes jumping, accelerating and changing direction - all important qualities for tennis.
Speed-Strength & the F-V Curve
One quick thought before we move on to speed strength. To better understand the difference between strength-speed and speed-strength (I know it can be confusing), just remember that the first word in each of the terms is the quality that’s being emphasized a bit more AND both refer to what many people call, power. So strength-speed uses heavier load power training and the adaptations will be more on the strength side (because of higher forces). While speed-strength is more on the lighter side of power training and the adaptations are more speed focused (because of higher velocities). With speed-strength, we’re now starting to move our way down the F-V curve and into ranges of 30-60% of 1RM.
The acceleration phases of the tennis serve and groundstrokes require high levels of speed strength. In other words, you must be able to produce very high velocities under lighter resistances. Bigger shots and serves will be seen if one can produce higher velocities at a given force, which is the goal of this type of training. Speed-strength is primarily targeted through medicine ball (MB) exercises, loaded jumps, and other ballistic type movements.
Furthermore, speed-strength qualities are important during the use of elastic/reactive strength on most change-of-direction (COD) actions, strokes, split-steps etc. This is where our plyometric training and reactive abilities come into action. These exercises are seen further down on the F-V curve as there is no external resistance added (i.e. unloaded).
Again, the further down the curve you go, the more sport specific the exercises become - so when it comes to speed-strength, in some cases, there is still an added resistance to the exercise, but because it’s lighter, you’ll be able to produce more velocity. The adaptations are similar to those seen with strength-speed (neural) along with an increase in RFD (rate of force development).
Lastly, at the bottom of the F-V curve, we have maximum speed. This is emphasized during training drills that can generate very high speeds under very light loads. An example is throwing a javelin or running at maximum speed. Loads are generally less than 30% of 1RM - although generally this is difficult to quantify as movements here are more specific to sport, and occur at very high velocities.
In tennis, max speed can be seen through arm speed (and hence, racquet speed) on all serves and groundstrokes. The highest velocities occur just before contact. Also, high speeds can occur with the rotational components of these shots, especially during (and just after) the acceleration phases.
Max speed, to an extent, can also occur during sprinting movements in tennis. More specifically, when running down drop shots, serving & volleying, retrieving wide balls, on the run etc. It’s difficult to truly reach top speeds in tennis, but high running speeds still have a place in the training of elite players.
Furthermore, research has proven that increases in power and force in high-velocity movements occur with high-velocity training. Meaning that the F-V curve at the velocity end will shift upwards (Figure 3).
That was a lot to digest and it can be complicated...so I’m sure you’re now wondering how tennis players can train all these different qualities to improve on-court performance. Let’s take a closer look:
Maximum Strength In Tennis
Many coaches and players believe heavy weight training will make players slow. This is nonsensical, uneducated thinking. How many of these coaches/players have read hundreds of peer-reviewed research papers on the topic? I’d guess not very many. Perhaps they relate weight training to bodybuilding style workouts. But I hope by now we know that’s not what we’re referring to. What we’re saying, and what sport science has proven again & again, is that heavy weight training improves maximal force production. And why is this important? Remember Newton’s 3rd law? For every action, there is an equal (force) and opposite (direction) reaction. Therefore, the more force we apply to the ground, the more force will be exerted. So we’re not necessarily looking at increasing muscle size per se (there will be some increases and this is a good thing...to protect certain tissues like tendons, ligaments etc.) but rather, we're looking at increasing the force-generating capacity of the system. The system being the player.
How do we do this? The most effective exercises here are the big lifts. For lower body quad dominant strength, the squat. For lower body, posterior strength, the deadlift. For upper body anterior shoulder and chest strength, the bench press. For something which has a more similar movement pattern to the serve, the overhead press. For upper-back & trunk strength, pull-ups.
Notice a pattern? These are big, compound lifts that target large muscle groups, require the recruitment of fast-twitch muscle fibres and have a big influence on maximal force production. When implementing them, we get a preferential shift in utilization of high threshold motor units, which are associated with powerful movements. That means the entire F-V curve shifts upwards - this is especially true for players who haven’t done much lifting in the past.
Strength-Speed in Tennis
Another big misconception in the tennis world is that Olympic weightlifting exercises are useless. I read on a forum once that Novak and Federer never did any weightlifting, so why would any other tennis player do them? Let’s set the record straight, you DO NOT have to do cleans and snatches to become a better tennis player but improving strength speed - in other words, the ability to produce high amounts of force in the shortest possible time (which Olympic weightlifting exercises target - video below), is paramount. That’s what allows players to move explosively to the ball, or use a big leg drive during open stance forehands. Whether Fed did any Olympic style weightlifting, I don’t know, but I guarantee his trainers worked on this quality in other ways.
And there are other ways. For example, a loaded barbell jump squat is one of those ways. Or a barbell bench press throw. As a coach, you have to weigh the pros and cons first. Olympic weightlifting movements are more technical than jump squats, so you’ll need to spend more time teaching those lifts. If you have time or you’re working with younger athletes, I highly advise it. If you have very little time and players have many events coming up, it may be better to implement jump squats. Regardless of your choice, strength-speed is an important quality to train.
Speed-Strength in Tennis
Speed-strength is more ballistic in nature. Loads are lighter and movements are faster. Consequently, power output should be higher. The acceleration phases of serves and groundstrokes require speed-strength qualities. Similar to strength-speed, Olympic lifts & loaded jumps work well here but at much lighter loads.
This is also where medicine ball work comes into play - which train more of the reactive/ballistic components (video below) of strokes, changes of direction and so on. Furthermore, this is where plyometrics play a large role. When the situation calls for fast reactions - like when a player is at net waiting for his/her opponent to drill the ball by them - reactive strength (a component of speed-strength), is vital. It may be the difference between a down the line winner by your opponent, or a stab volley into the open court. Remember, to train this quality, players must be able to first have good explosive abilities while utilizing the slow stretch-shortening cycle (SSC) and can then progress to fast SSC movements that are more often seen in elite tennis.
Maximum Speed in Tennis
Contrary to what many coaches in the tennis world believe, running 5, 10, 15 or even 20m will not develop speed qualities. And please, if you’re training speed, put the ladder away, it has absolutely nothing to do with speed development. There’s a minimum threshold where maximum speed is achieved for each athlete (and it’s usually around the 40m mark during an all-out sprint. To put that into perspective, a regulation court is about 37m long (from back drop to back drop). If that’s the case, why train max speed at all? It’s the adaptation we’re looking for - improving the ability to recruit, synchronize & fire type 2 fast-twitch muscle fibres. Also, because getting to maximum speed requires acceleration (supremely important for tennis players), training 40-60m sprints will have a carry over to acceleration qualities. Furthermore, the higher an athlete’s max speed capability (i.e., the more capacity the athlete holds in this quality), his/her type 2 fibres will be more resistant to fatigue.
In any case, max speed won’t take up the bulk of training for tennis players, as there are more important qualities to focus on. Arm - and subsequently, racquet head - speed is one of those qualities. In handball players, throwing velocity improved after heavy bench pressing (Hermassi et al 2011) - which is interesting when it comes to tennis. Perhaps there’s a reason Gil Reyes, Agassi’s former coach, had the retired American star benching over 300lbs later in his career. Or why Tsonga did some bench during post-activation potentiation training during his off-season. But maybe more interesting ways of improving racquet speed on serves and groundies is through overload and underload training. Examples of this include throwing drills to improve high velocity movements of the serving arm and overload/underload racquets. I see this as a simple progression:
Overhead press (max strength) → Push Jerk (strength speed) → Overhead MB Throw (speed strength) → Weighted Racquet Swing (max speed-overloaded) → Regular Racquet Swing (max speed)
You can even take it one step further and use an underloaded racquet - this would produce even more velocity compared to using one’s regular racquet. Although there hasn’t been any research (to my knowledge) on this topic in tennis, baseball has been using this concept with weighted balls and bats, for decades (read the full review here).
High-Performance Coach Eric Cressey does a really nice job of outlining the absolute strength to absolute speed continuum in this video - check it out!
Each area of the force-curve, starting from highest force and moving downwards, potentiates the subsequent area of the curve. Another reason why training every aspect of the curve is important. Look at the above figure - when training incorporates all areas of the curve, there's a shift upwards and to the right. That means, at any force, there will be an increased velocity response and vice versa. For sure, in tennis, more time will be spent on the bottom areas of the curve. But I believe, and the science is quite clear, athletes should be hitting all areas of the curve during training. When it comes to tennis players, this type of multi-faceted approach has yet to find it’s way into the training regimes of most players. From a performance perspective, failing to target specific areas of the curve may hinder a player’s ability to move more explosively, hit bigger shots and remain injury-free.