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Help tennis players cope with the physiological demands
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Physiological demands of tennis match play
Tennis is an intermittent (stop-start) sport, characterised by short bouts of activity, which are usually between 4 – 10secs, interspersed with short, around 10 – 30secs, and longer passive recovery bouts of 60 – 90secs(1). Yet for the exquisite simplicity of the game there are many biological and technical components that influence match play. The physiological demands of tennis are varied and depend upon complex interactions between the type of equipment being used, the tactics employed by players, and environmental factors. Indeed, the type of court surface, playing style (serve and volley, baseline player), rally duration, ambient temperature and humidity combine to influence physiological demands. These interactions can be quantified and used to inform tennis-specific training and nutritional practices.
Physical characteristics of tennis players
Table 1 shows typical anthropometric characteristics and aerobic capacities of tennis players. It should be noted that tennis players are well-developed athletes in a range of physical components and do not excel in any particular area unlike other individual sport athletes such as endurance runners who may have an exceptional aerobic capacity but poorly-developed anaerobic capacity. This is most likely due to the varied physical demands of tennis training and competition evident in figure 1.
Time-motion demands of tennis match play
Tennis is most frequently competed on three different types of court surface: 1) hard, 2) clay and 3) grass. The type of surface typically determines the physiological demands of competitive match play as the way players deal with the ball speed and bounce determines the characteristics of the rally thus physical demands. The demands of tennis match play can be described in several ways; one way is to determine the mean duration of rallies. This statistic provides scientists, coaches and players with information regarding time-motion characteristics. Since it can be assumed that rallies are contested at a high to very high relative intensity given the need to win points to avoid defeat, this method provides an indirect way to assess physiological demands. Research studies have used different methods to assess the mean average rally duration on different court surfaces but typically rallies are longest on clay courts and shortest on grass courts. On clay courts, mean rally times last between 8-9secs, on hard courts 6-7secs and grass courts around 4secs. It should be noted that these data are mostly collected from male competitions. Although these time differences seem very small, over the duration of an entire match they can add up. Indeed, some studies suggest that there are larger percentage playing times on clay courts when compared to hard courts (25% vs 21%) (2). As well as court surface, individual playing style also influences rally duration. Research indicates that players who prefer to adopt a baseline playing style are likely to have longer rallies than those who prefer to serve and volley (4). This means that players who choose baseline tactics on clay courts, which is typically the preferred style, are more likely to be involved in longer duration rallies than players who choose to serve and volley on grass courts.
Physiological demands of tennis match play
Physiological assessments closely reflect the assumed demands from time- motion studies. For example, players who adopt baseline tactics on clay tend to have higher peak blood lactate responses (2). This is likely because rallies are on average (mean) longer and due to the highintensity nature require considerable activation of anaerobic energy systems. Despite this assertion, mean blood lactate concentrations are within the region of 3 mmol•L-1 irrespective of the courttype (2). Research also suggests that cardiovascular demands are different depending on the type of court surface played on. Mean heart-rate tends to be higher on clay (approximately 148 bpm) than on hard courts (approximately 140 bpm) (2). This may also be related to the choice of playing style as a higher rate of oxygen uptake has been observed during baseline compared with serve and volley tactics. The general consensus from the published research is that mean oxygen uptake during a match is around 55% of peak aerobic capacity indicating that the aerobic energy system plays a considerable part in the supply of energy during tennis matches. Using this data, it is possible to estimate the likely energy expenditures of different length of matches based upon mean responses reported in the scientific literature (table 2).
Additional physiological demands may come in the form of environmental factors. Tennis is often played outdoors in summer months, which coincide with high ambient temperatures and can influence the intensity of match play. This is unlikely to be because players reach critical body temperature limits or attain dangerous levels of dehydration, but more than likely because players anticipate a future level of heat strain and pace their efforts to prevent an excessive rise in body temperature. Research(5) has shown that rally duration is positively correlated to deep body temperature, which means that when players feel they are hot rally duration is shortened. This could be because players are choosing their ‘battles’ more carefully or because of poor shot selection/skill execution because of perceived heat strain and/or exertion. Players’ sweat rate will vary depending on the intensity of the match and the environmental conditions. In a typical 90-minute match played in hot conditions, female players’ sweat rates have been estimated at around 1.5 litres per hour and males around 2.2 litres per hour(2).
The research presented within this article is from varied sources which used different methods of data collection, levels of athletes and genders. Although it’s possible to get an idea of how the demands of tennis differ depending on court surface it would be more useful for players and coaches to get an idea of the specific time-motion demands of their own competition. This may sound complex, but it’s actually a lot simpler to do than it sounds. There are some easy-to-use free analysis tools that can help you to do this in both desktop and mobile formats. The general idea behind these software programmes is ‘tagging’; if you can identify a behaviour, which could be as simple as defining a rally or as complex as shot selection in specific areas of the court, then it’s possible to ‘tag’ that behaviour and quantify its frequency and duration. To assess the time-motion demands of tennis match play, you will need to record the match, once the match has been recorded it needs to be downloaded or transferred into a video analysis programme. Most of the research studies that have determined the time-motion profile of tennis match play have assessed the following variables:
- Duration of each rally
- Duration of each game
- Duration of rest intervals between serves
- Duration of rest intervals between games
- Duration of rest intervals between changeover breaks
- Number of shots per rally
- Total duration of matches
- Rally duration
- Rest time between rallies
- Rest time between first and second serve
- Effective playing time (expressed as a percentage of total match time)
- Work-to-rest ratio (ratio of duration of rallies to rest time)
- Number of strokes per rally
As a single observational analysis tool, this approach might inform you about the time-motion characteristics of a snap shot in time, but this would be highly dependent on the quality of your opponent. If you are able to collect data over time, a clearer picture of the real time-motion demands will emerge. This type of analysis could also form the basis for tactical analysis and overtime, it may be possible to correlate tactical variables or phases of play with the most effective means of winning points (less physiological demand). Assessing opposition that you play most frequently will also provide you with an advantage as you’ll be able to quantify their strengths, areas of weakness and pacing strategies and exploit these areas during the match.
Heart-rate monitoring –As energy requirements in tennis are predominantly supported by the aerobic energy system, heart-rate assessment will provide a good indication of the cardiovascular and energetic demands of a tennis match. This is particularly important in matches lasting longer than 90 minutes as performance impairment may be offset by appropriate and planned nutritional strategies.
Rating of perceived exertion (RPE) – In conjunction with the previously mentioned approaches to assessing the physiological demands of tennis, it may also be useful to assess players’ RPE using the Borg CR-10 scale. Assessment of RPE after each match or, if possible, each set, game and point along will provide coaches and players with perceptual data regarding the intensity of match play. This can be used to plan and assess training intensity and volume using the session RPE method by using analysis of matches as an intensity baseline. For example, if immediately after a single game a player rates the game as a 7 out of 10 (very hard) and the duration of the game was 4 minutes the perceived demand (volume) would be 7 x 4 = 28 AU (arbitrary units). Coaches could use this knowledge to plan and monitor training intensities and loads with reference to the demands of match play.
Methods of physiological assessment
Once the specific movement and physiological demands of tennis match play have been identified, it is important to consider using performance tests that isolate these components so that they can be assessed. Ultimately, the coach should make a decision about the choice of test but some examples of tennis-specific tests that have been used in the literature are included in table 3. Note that this is not a definitive list but it may offer some guidance.
When a player’s strength and areas of improvement have been identified through physiological testing, training aimed at improving specific areas can be implemented. On-court drills such as the ones depicted in Figure 2(6) can be manipulated by changing the work to rest ratio to suit the desired physical component. The effectiveness of tennisspecific conditioning was evidenced in a recent study published in the Journal of Strength and Conditioning Research(7). Thirty-one nationally ranked male tennis players took part in a 6 week training study. After initial physiological testing, each player was randomly assigned to one of the following training groups: 1) High-intensity interval training (HIIT); 2) repeated sprint (RST); and 3) control (CON). The HIIT and RST group both undertook 18 on-court training sessions, which were planned to include three intensive exercise bouts (either HIIT or RST) interspersed by a 2-on-1 tennis specific game. The HIIT group performed 3 x 90secs (180secs recovery) court runs at an intensity that elicited 90-95% maximum heart-rate (HRmax). The RST group performed 3 x (10 x 22m (15secs recovery)) maximum intensity shuttle sprints. The control group maintained their normal training tennis programme. All groups also undertook 1-2 low-intensity injury prevention training sessions per week. The main findings were that both the HIIT and RST groups improved their peak aerobic capacity by 6 and 4.9% respectively, whereas little change occurred in the control group (-0.4%). Similarly, both the HIIT and RST improved their performance in a tennis specific endurance test by 28.9% and 14.5% respectively. Only the RST group improved performance in a repeated sprint test (3.8%) and neither training programme improved jumping or sprinting performance. The authors concluded that both types of training were effective but recommended that ‘RST provides a time-efficient stimulus for simultaneous improvement of general and tennisspecific aerobic fitness’.
The afore mentioned assessment of the physiological demands of tennis match play indicate that players must alternate between anaerobic energy production, which places demands on intramuscular phosphate stores and glycolysis, and aerobic demands via oxidative phosphorylation to restore homeostasis between bouts of high intensity activity. It seems prudent that players should develop their ability to perform repeated high intensity activities and be able to rapidly recover from these bouts. Tennis players should therefore include both high intensity and aerobic training methods within their preparation. Each player has unique strengths and weaknesses and favourable styles of play which influence their physiological demands. Training should be tailored and targeted to develop the systems that provide energy for these unique physiological demands. The choice of training focus should depend upon the past and present conditioning of the player as well as immediate and mid-to-long-term training and competition demands. Dr Mark Kovacs of the International Tennis Performance Association (ITPA) provides the following energy-system specific conditioning recommendations for training tennis players (3):
- All players should have a good level of conditioning in areas specified in figure 1. What determines ‘good level’ should be determined by coaching staff. As guidelines, maximum aerobic fitness should be > 50 ml•kg•min-1 for males and > 42 ml•kg•min-1 for females. Estimates of aerobic capacity can be obtained from 30:15 intermittent running test/YoYo intermittent tests.
- Despite this recommendation, players should look to develop high-intensity intermittent performance and be discouraged from spending time undertaking long-slow distance training.
- If you are an attacking player it is likely that you will play shorter points. You should place greater emphasis on speed and power activities.
- To develop tennis-specific speed and agility, work-to-rest ratios should range between 1:25 and 1:40. For example, maximal 6secs sprints could be interspersed with 2.5-min passive recovery periods.
- If you are a defensive player, it is likely that you will play longer points. You should place greater emphasis on training muscular and aerobic endurance.
- To develop tennis-specific endurance drills, a work-to-rest ratio of between 1:3 and 1:5 may be sufficient to simulate match demands. For example, a 30secs tennis-specific drill could be interspersed with 90secs recovery periods.
- To stress tennis-specific energy pathways whilst maintaining high technical output players could cluster drills into small bouts with short recovery periods. For example, 3-5 seconds of rest for every 1 second of tennis-specific exercise.
Alan Ruddock MSc, CSCS, YCS is a researcher in exercise physiology at Sheffield Hallam University, UK
Intramuscular phosphate: Immediate energy source
Glycolysis: Intermediate energy pathway
Oxidative phosphorylation: Oxygen-dependent energy pathway
References 1. Br J Sports Med, 2006, 40(5): 387-391. 2. J Sports Sci Med, 2013, In Press. 3. Sports Med, 2007, 37(3): 189-198. 4. Med Sci Sports Exerc, 2001, 33(6): 999-1005. 5. Br J Sports Med, 2008, 42(8): 679-685. 6. J Strength Cond, 2004, 26(5): 10-13. 7. J Strength Cond Res, 2012, 26(1): 53-62.
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