Both Dynamic and Static Stretching Play a BIG Role During the Tennis Warm-Up
This is the third part of this 3-part series on mobility & flexibility training for tennis. The first post was an introductory post that defined what mobility truly is (read that here) and highlighted some of the problem areas for tennis players - with a special emphasis on the hip and shoulder. The second part went into more specifics regarding the science of stretching and it's role in the overall development of flexibility (we also dispelled the myth that flexibility is only attainable by the special few). And it included detailed info on how to improve both range of motion (ROM) and strength while presenting a shoulder internal rotation stretch example. You can read that article here.
In this post, we'll primarily be looking at the differences between dynamic and static stretching. More specifically, we'll outline what role dynamic stretching (DS) and static stretching (SS) play in the warm-up of the tennis player and how to effectively implement each type of stretching into your pre-match/practice routine. Let's go!
Dynamic vs Static Stretching - Definitions and Performance Implications
We’ve already outlined static stretching (SS) in the previous post (full article) and looked at it's effect on injury prevention (if you haven't read that post, spoiler alert, traditional static stretching WON'T prevent injury). Just to refresh your memory, SS implies holding a particular position for a period of time with no movement of limbs, joints, muscles etc. An example being bending your torso to touch your toes and holding that position.
Dynamic stretching (DS) on the other hand, involves moving a joint or muscle group through a particular range of motion and in a particular direction. Examples of this can come in the form of forward lunges, leg swings or hip rotations. Although still a relatively new phenomenon (with regards to the literature), most research has supported the use of DS as part of an effective warm-up because of it's good correlation with various performance measures (Behm 2011).
Dynamic Stretching, Static Stretching and Performance
Although some research has pointed to the benefits of DS for performance enhancement, a recent systematic review by Behm et al (2016) revealed that neither DS nor SS had any significant effects on performance. Meaning, both types of stretching didn’t seem to either hinder or improve subsequent measures of strength, power or speed. Many of the studies in this review DID NOT incorporate a warm-up routine...so it's practical effectiveness is definitely in question.
When it comes to SS stretching in combination with a warm-up, performance either decreases or there’s no real impact. The stretch duration plays a role here. In other words, most studies that had participants hold a stretch for longer than 30 seconds noticed a decrease in performance while less than 30 seconds had small, insignificant changes in performance. The bottom line here (based on the review study) is that SS just prior to training or competition won’t help performance and depending on intensity and duration, could actually impede it.
On the other hand, when performing DS as part of a complete warm-up routine, IMPROVEMENTS, in a variety of performance outcomes, have been observed on numerous occasions. These include shuttle run times, medicine ball throws for distance and vertical jump heights (Behm 2011). Why is this the case? One reason being that most dynamic stretches have similar movement patterns to those encountered during sport AND at similar movement velocities. DS also seems to affect muscle & body temperature and has a role in stimulating the nervous system, providing further evidence for their implementation in a thorough tennis warm-up.
Stretching During the Warm-Up and Tennis Performance
The ITF (International Tennis Federation) recommends that static stretching be replaced with dynamic stretching. This is a good recommendation...to an extent. Let me explain.
Three studies on tennis serve performance and stretching have been conducted. Knudson et al (2004) saw no effect on tennis serve performance (in terms of both serve speed and serve accuracy) following a SS protocol. In other words, there was no increase or decrease in these measures. Gelen et al (2012) had elite players perform 4 different warm-up protocols on 4 different days and analyzed serve performance after each warm-up. The 4 methods were 1) No warm-up, 2) a static stretching routine, 3) a dynamic stretching routine and 4) a ballistic plyometric routine. Figure 1 shows a detailed description of the study and includes the 4 warm-up methods:
What were the results? You probably guessed it - the MOST effective outcome occurred after the ballistic plyometric protocol with a serve speed increase of 3.3%. The second highest was the dynamic exercise method (a 1.23% increase) followed by the no warm-up and static stretching protocols. SS had the lowest serve speeds out of all groups. So based on these results, the ITF has a point, static stretching should probably be replaced by dynamic stretching (and ballistic activities...but more on this later in the post).
Finally, Ayala et al (2016) conducted a very interesting study. They investigated the effects of static stretching and dynamic stretching on a variety of performance measures (20m sprint, countermovement jump [CMJ] and serve speed/accuracy) at 3 different time points - just prior to tennis play, 30 minutes into tennis play and 60 minutes into tennis play. It’s important to note that both warm-ups included light aerobic exercise as well as a variety of ballistic movements AND all players performed both protocols (on different days). Four things you need to know about the results of this study:
Overall, in terms of performance in all tasks (sprint, jump, serve), dynamic stretching was superior compared to static stretching.
SS had a negative impact on serve and jump height when tested just prior to tennis play and at the 30 minute interval.
When tested again at the 60 minute mark, serve and jump height performance seemed to level off - i.e. there was no longer a negative effect.
The DS protocol seemed to produce consistent results across all performance tasks just prior, 30 minutes after and 60 minutes post tennis play.
Should the Tennis Warm-Up Focus Only on Dynamic Stretching and Eliminate Static Stretching Altogether?
Ok so by this point we’re not that surprised that DS was more effective than SS as a warm-up modality but what's interesting about the study by Ayaya et al (2016) is that the negative effects of SS started to subside around the 30min mark and were back to ‘normal’ at the 60min mark. This study isn’t the only example. Others have seen decreases in strength after static stretching with normal levels returning between that 30min-60min range. Many authors have suggested that this is due to both mechanical and neural factors but the exact mechanisms are not yet known. In any case, from a flexibility perspective, this has important implications - especially for players with mobility restrictions. Let's use the hip to illustrate this point:
An Example: The Tennis Hip
Let's say you or your player, like many tennis players, have hip restrictions. You probably want your hips to function more effectively during tennis play. From a movement perspective, the muscle groups around the hips are our biggest power generating areas. When it comes to the production of power in serves and groundstrokes, without the ability to effectively disassociate the hips from the lower and upper body, power will be limited. Remember the concept of the kinetic chain...well it’s optimized when joints can act like joints and move independent of one another.
The research on the hip joint in tennis, however, is unclear. Three main studies exist but all 3 are descriptive. Below you'll find a summary of the results from all 3 studies - 2 of the 3 included male and female players (all competitive, ranging from junior to pro [ATP/WTA]) while the 3rd study analyzed WTA female players only.
Note - All values are in degrees
The same measurement technique was used to assess internal/external active ROM of the hips in all 3 studies (prone active internal & external hip ROM). Couple things you should notice when analyzing the charts above. First, when comparing males to females, the gaps aren’t as big as you’d expect. Females do however have better internal range of motion compared to males. Furthermore, Young (2014) only looked at females in the top 200 and the results for total range of motion are quite poor (60 in the dominant leg and 65 in the non-dominant leg - the lowest out of all 3 studies). What’s concerning is the range in results (from 22-83 in the dominant hip and 41-110 in the non-dominant hip).
From my experiences working with players along with the large discrepancies found within these studies, we can almost safely assume that most players have hip ROM restrictions. And as Dr. Andreo Spina concluded, most ROM studies reflect results of participants who generally have poor ROM to begin with. Furthermore, Young (2014) reported that there may exist a link between poor hip ROM and a host of other problems, including low back pain, shoulder/elbow tendinopathy and abdominal strains. This makes sense as decreased function in one area of the body can cause a chain reaction in other areas that are now assuming more of the forces.
"Most studies reflect results of participants who, generally speaking, have poor range of motion to begin with."
So let's say you do have hip (or shoulder, or spinal) restrictions. What should you do?
Warm-Up & Stretching Recommendations
1. Static Stretch at Least 60min Before Playing
If you or your athlete have particular range of motion restrictions - like internal rotation deficit in the hip - I would highly recommend performing static stretches prior to training or competing (similar to the video above). That said, these stretches should be performed at least 60 minutes before stepping onto the court. Although 30 minutes might work, stick to a safe range as your aim is for tissue function and strength to fully recover.
Also, the intensity of stretch, along with isometric contractions (refer to the previous post for details) need to be appropriately assigned. If intensity is too great, it could lead to a longer delay in strength recuperation as well as some enhanced muscle fatigue.
2. Perform a 15-20 Minute Warm-Up Before Touching a Racquet
Once you've finished your static stretches, rested for at least 30min, you'll begin the full pre-match warm-up. This will include some light jogging/court movements to begin with, then progressing to dynamic stretches (especially in patterns that are similar to what you’ll experience during tennis).
Lastly, before hitting some balls, I recommend performing both upper and lower body ballistic movements. These usually come in the form of low load plyometric drills and can include ball throws & band work to prep the shoulder along with some lower-body plyos to prep for explosive movements.
Please note, if mobility/flexibility is an issue, perform dedicated training sessions to target these qualities. These can be more vigorous and intense compared to pre-match routines.