There’s no secret that tennis is demanding. How demanding? That's tough to say. I mean, how do we measure the intensity and stress of a practice or match? Traditionally, time on court has been the go to method - but does this sole metric give us enough info? Is a 3-set tennis match 'hard' because it goes the distance? Naturally, many of us would assume that a 3-set match is taxing. But what if the scoreline was 6-1, 2-6, 6-2 and finished in about 1.5 hours? Contrast that to a scoreline of 6-4, 6-7, 7-6 - a match that lasts for over 3 hours? Surely these 2 scenarios aren’t the same. We have a similar dilemma in practice settings. What if player A is playing all out during a session while player B brings the intensity down a notch?
You may be wondering why this is important anyway? Well, knowing the stress that practices and matches have on players can provide useful information for the coach. It may help the design of future sessions - i.e. you don’t want to plan a tough session full of movement drills if a payer has had consecutive hard training days. Further to that, gaining more insight into the stress & intensity of a session can perhaps help mitigate injury, overtraining and possible burn-out. In this post, we’ll outline how to measure training intensity using a simple tool - called the rating of perceived exertion (RPE). This tool has HUGE implications when it comes to monitoring training load. We’ll find out how to measure it and then how coaches can apply the tool when working with players.
Why is monitoring training load important?
First off, it’s impossible for players to practice at full intensity every time they step on the court. It’s actually a bit frustrating to see coaches yelling at players to have more intensity - not only from a physical standpoint, but mentally and emotionally, this constant high-intensity training is exhausting...and as we’ll see later, exhaustion should never be the goal of a practice session.
This is probably why a linear approach to training doesn’t work (and has been thrown to the waist side by most elite coaches). Although periodization - dividing training into different phases - has gained popularity in mainstream fitness, the textbook approach doesn’t hold true in modern sport (that doesn’t mean periodization - or planning - doesn’t have merit.) There are simply too many competitions and too much at stake in each outing to plan to peak only a few times a year - read more about that here. That said, science (and high performance coaches) consistently tell us that some sort of variation in training load DOES in fact lead to elite performances. This is likely due to it's effects on recovery (needed for a training adaptation to occur), the management of fatigue and it's influence on preventing stagnation & overtraining.
There are a number of theories that attempt to explain the adaptation process. One that seems to resonate well with me is the fitness-fatigue model (Zatsiorsky 1995). This theory proposes that an athlete's preparedness for their sport is the summation of fitness and fatigue - as both occur as a result of training. But this interaction must be managed appropriately (by accelerating recovery) so that fitness outweighs fatigue - otherwise training is all for not. This is perhaps why many players get burnt out, or incur an injury - they, along with their coaches, believe that more training & competition is the answer, when in fact, it’s likely the variation in training load that will lead to the elite performances, not the number of hours spent on court.
How to monitor training load?
Many team sports have, in recent years, adopted global positioning satellite systems (GPS), accelerometers and other tracking devices to monitor (and help prescribe) training loads. These are considered external-load measures. The opposite, called internal-load measures, would include such physiological markers as salivary blood, heart rate and oxygen consumption measurements. Although many studies have reported that these measures (both external and internal) are reliable and valid, they are often expensive and impractical - especially in tennis settings where many weeks of travel are involved.
Traditionally, tennis coaches have used weekly or daily court time as a measure of training load. Even the ITF (International Tennis Federation) provides hour based recommendations for players & coaches based on the training phase (preparation or competition). However, this form of monitoring is inadequate. Why? It does in NO WAY account for session intensity. Is a 1 hour training session where a player stands in a corner and hits balls the same as a 1 hour session where a player runs through multiple high-intensity drills? Hardly. What about a 30 min serving session that focuses on speed versus a 30 min serving session that focuses on technique? Not the same either. These are just examples of scenarios that place vastly different physical stressors on a player….and should therefore be accounted for.
Enter the RPE (rating of perceived exertion) scale - aka the CR-10 (Category Ratio) RPE Scale. You may have heard of the RPE scale in other settings (running being one of them). Once you finish a run, you’re asked, ‘how hard was that run for you” and the athlete responds with a rating between 1 and 10. Here’s what it looks like:
Rating Descriptor
0 = Rest
1 = Very, very easy
2 = Easy
3 = Moderate
4 = Somewhat hard
5 = Hard
6 = -
7 = Very Hard
8 = -
9 = -
10 = Maximal
Beyond 10 would be absolute physical exhaustion - probably what some players feel like after playing Nadal. In training, it is never recommended to take an athlete to this point. But this is another issue altogether - learn more here.
So now that we have a measure of intensity, we can combine a session rating with the total duration of that session to get a measure of training load. For example, if I practice for 120 minutes and my RPE rating was 7 I would simply multiply the 2 results (120 x 7 = 840). This score of 840 would be called the ‘Session RPE’ and the actual values are recorded as ‘arbitrary units’ (AU). Again this provides a training load for that particular session. This can be taken one step further to look at the training load across an entire week, simply by adding all the session RPE’s for that week. Over the course of a year you’ll get a pretty good idea of the training load imposed on your athlete.
A CASE STUDY USING SESSION RPE
A research group (Coutts et al 2010) wanted to test the session RPE theory in a tennis specific setting. In 2008, they recorded the session RPE of a top 80 ATP player leading up to, and during, Roland Garros (arguably the most physically gruelling tournament of the calendar year). Table 1 below reflects the session RPE ratings for both the player AND the coach the week prior to the event.
Table 1 - Athlete vs. Coach Session RPE
This was deliberately done to see if a discrepancy existed between what the coach prescribed and what the athlete actually perceived. As you can see, there’s only 1 training day where both the coach and the athlete had a similar assessment of the session intensity - the duration of practices was of course constant so the different scores can only be attributed to intensity. If we assume that day 1 of training (Monday), they performed a 120 minute session, then the discrepancy in intensity is 2 levels from one another (6 for the athlete and about 4 for the coach). This is quite significant, as 6 represents close to ‘very hard’ while 4 is only ‘somewhat hard’.
This is not an uncommon occurrence. Murphy et al (2014) - a research group that works closely with Tennis Australia - found that coaches significantly underestimate an athlete's session RPE. If this is a trend across many settings, then perhaps as coaches, we're placing too much stress on athletes without even knowing it!
Furthermore, look at table 2. This is the session RPE of the top 80 player during Roland Garros. The general trend seems to point to increased duration equaling increased perceived difficulty. This is not always the case, as I can attest to from experience, but having this info can help coaches and players with their future practice planning.
Table 2 - Session RPE During Competition
WHY IS SESSION RPE SUCH A VALUABLE TOOL?
As a coach, whether you prescribed a tough session or not, knowing how your player perceived that session provides extremely useful information in designing and planning subsequent sessions. In the above example, if the coach thought the session was only a 4/10 and didn’t know that the athlete perceived it as harder than that, he may plan more and more difficult sessions as the week progresses. While we don’t know if this was planned or not, there appears to be a variation in either intensity, duration or both in the subsequent sessions for that athlete.
This info also gives the coach an indication of the intensity of matchplay. Many sport scientists have written over the years about maximal intensity in training versus maximal intensity in competition. While it’s possible to work extremely hard in practice, according to these pioneers (and I tend to agree), nothing can compare to the intensity of competition. The tension, stressors and heightened focus/awareness are just a few factors that contribute to the equation and nothing but competition can relate. Practice matches might come close, which is why they’re so vital in the preparation of an elite player, but not close enough.
THE DANGER OF ACADEMY SETTINGS
As we know, each individual recovers from training at different rates. This poses a problem in the academy setting as large groups of players are funnelled into similar training regimes. As coaches, what do we do? I mean, what if one player perceives a 2 hour session to be extremely intense while another perceives it as being moderately intense? Furthermore, what if player A is competing in an event while player B is off?
The week leading to the events, it’s probably best to pair players together that are competing. That said, if there isn't anyone playing an event, it’s still important to individualize as best as possible. This can be done by manipulating either the duration of a player’s practice or their intensity. For instance, if 2 players have been training hard and are scheduled for a ‘light’ session, put them together and prescribe a lower intensity hit. This is actually often what happens on tour. During tournaments, players try to find other players who are in the same boat as they are - whether that’s a light hit or a couple intense practice sets. If your setting doesn’t allow for this type of setup, it may be required to adjust a player’s practice duration. Instead of the 2 hours that was prescribed, have them play 1 hour with the group and then assign a number of recovery modalities (stretch, ice, light exercise etc) for the remaining hour.
OTHER PRACTICAL IMPLICATIONS
Adopting this type of monitoring approach might be easier in certain settings than others. For instance, a pro player has more flexibility in their training schedule versus a junior who plays in an academy. That said, getting some sort of training load value, in my opinion, is an absolute must!
Session RPE is by no means the only way to measure training load (I’ve used session RPE, along with a variety of other questionnaires in both one-on-one settings and group settings with good success). There are also specific mental questionnaires (like the ‘Mental Exertion Rating’) that are likewise extremely beneficial. More advanced GPS and tracking devices can also be useful, but like I mentioned previously, they aren't exactly practical. Questionnaires are a low cost, reliable, repeatable and valid way to get detailed info from players.
Although not the topic of this article, it’s worth mentioning that optimizing recovery (so players can train more frequently and with greater overall intensities) can be achieved through several specific recovery modalities - like stretching, contrast baths/showers, electrical stimulation etc. That said, before attempting these modalities, there are other, more important recovery strategies including proper nutrition, good sleeping habits and sound programming - this is where monitoring plays an integral role.