Owing to players such as Maria Sharapova, Serena Wiliams, Rafael Nadal and Roger Federer,
tennis has generated a lot of public interest. Tennis players have become superstars,
their names being mentioned alongside those of popular musicians and actors. Behind
the glamour, however, a lot of hard work is going into improving the quality of the
game. The high level of tennis did not happen overnight. Sporting excellence is supported
by scientific research in all aspects of the sport. What are the major scientific
advances of the past 10 years and what is their impact on the game of tennis?
Player analysis technology
Specialised equipment (‘smart’ devices) are now available that have the ability to
measure the way the player performs or interacts with his equipment.1 This gives objective
information that was previously only available from a subjective analysis by the coach.
These devices include the KITRIS-KIT, the Babolat Play racket and the PlaySight smart
Players now have access to sophisticated coaching information at low cost, even if
they have no coach, and this is having a major impact on the sport. The information
is of real time (or very close to real time) and is much more detailed than was previously
possible. It is also possible to relay this analytical information to spectators and
the media which could significantly change the way that these groups interact with
The development of this player analysis technology is evolving so rapidly that the
2014 Rules of Tennis have been amended to permit International Tennis Federation (ITF)-approved
devices to be used during play. The use of the technology is restricted in accordance
with the Coaching Rule, which means that players cannot access any coaching information
generated by their equipment when coaching is not permitted.
A particularly noticeable scientific recent advance has been the introduction of an
electronic line-calling system in tennis (Hawk-Eye).2 This complex system uses 10
high-performance cameras to track the ball and determine where it lands on the court,
which is displayed using computer graphics. With the court layout (lines) programmed
into the system, Hawk-Eye accurately records the ball impact area. This information
can be provided to players, spectators and match umpires in close to real time and
is accepted as a definitive answer to the eternal question ‘in or out’.
This has had a major impact on the sport with reduced pressure on officials and rapid
closure for the players involved in contested points and decisions. Most importantly,
it prevents erroneous calls from deciding the outcome of matches.
Biomechanics and video analysis
Biomechanics has helped tennis coaches to understand the mechanical characteristics
of the tennis stroke and to unlock the complex mechanisms by which players develop
power and control. While most of the early research involved the tennis serve, recently
ground strokes have been analysed.3
Important discoveries in this area are (the timing of) the stretch-shortening cycle,
the kinetic chain and variability in stroke production (and therefore coaches should
vary pace, spin, direction and height of the ball). This has, in turn, enabled coaches
to understand the techniques necessary to develop players, and has led to the marketing
of a plethora of video analysis systems for tennis to aid this process (eg, Dartfish,
Coaches have always asked for information on stroke development and it is pleasing
to see investigations into which techniques change over time (variant) and those that
are similar for the young high-performance players and the professionals (invariant).
Low compression tennis balls
The introduction of low-compression tennis balls has fundamentally changed the way
children and adults learn to play tennis. These are essentially lightweight balls
that are easy to hit. As players become more familiar with the basic strokes, they
progress to normal-sized balls that are ‘soft’ (inflated to a lower pressure than
normal—coloured red, orange or green) so that the ball flight is slower and the bounce
is lower. This gives the intermediate player longer to return the ball, lengthens
the rallies and improves the overall experience of the individual in a positive way.
Very young players (under 10) can also use smaller rackets and play on a smaller court
in addition to using the soft balls (eg, the Tenniskids programme in the Netherlands).
Using modified courts and balls has a positive effect on increasing the technical
proficiency and number and success of shots and facilitates the learning experience
of young players.4
Major strides have also been made in the field of sport psychology. There is now high
awareness of the importance of parents of junior tennis players, and parent education
programmes have been developed. For coaching beginners and intermediate players, there
is much more focus on the motivational climate, as this is highly relevant. High-performance
tennis players use a variety of emotional control strategies, as this has been shown
to affect performance in a positive way. It has been acknowledged that tennis can
play a significant role for social inclusion of players with special needs. And, finally,
the health and psychosocial benefits of tennis play a large role for long-term tennis
General knowledge of tennis injuries has increased over the years, but the reported
incidence, severity and nature of injuries show great variation between studies. Although
some of this variation can be accounted for by different sample populations and conditions,
the main reasons are related to the significant variation in injury definition and
the disparate methodologies employed by the separate studies. A consensus statement
has now been published on the definitions and methodology for recording injuries and
illnesses during tennis activities and this should lead to greater consistency in
future studies.5 The first study that used the standardised definitions and methodology
was published in 2012—a 25-year analysis of injury data from the US Open.6
Recently, research has explored the links between loading and tennis injuries, although
much more work is needed in this area before definite conclusions can be reached.
Player track systems could be used in longitudinal cohort studies to investigate the
association between risk factors (such as training and match load) and tennis injuries.
Randomised controlled trials are needed that examine the effect of injury prevention
measures in tennis.
Recent advances in nutrition have mainly focused on sports with high-energy demands
such as cycling and marathon running, but awareness of the benefits of proper nutrition
in tennis has increased. Nowadays, most professional players have a well thought out
diet before, during and after play that includes fluids, carbohydrates and protein
in the right combination for optimal performance and enhanced recovery.
A number of studies have been performed to investigate the thermoregulatory response
of tennis players to heat stress.7–9 These show that core body temperature (CBT) can
be maintained at a safe level across a wide range of environmental conditions and
is determined mainly by the intensity of the exercise and the resulting metabolic
rate. When the cooling mechanisms of the body (sweating and cutaneous vasodilation)
work normally, thermal equilibrium is reached and maintained after approximately 40 min
of tennis match play.10
However, in hot ambient conditions, CBT is determined not only by the metabolic rate,
but also by the environmental heat load.3 Work by Périard et al, who studied male
tennis players during tennis match play in cool (∼19°C WBGT (wet bulb globe temperature),
22°C) and hot weather (∼34°C WBGT, 37°C), showed mean CBTs of ∼38.7°C under cool and
∼39.4°C under hot conditions.8 In addition, adverse environmental conditions (eg,
high air temperature, high humidity, solar radiation and no wind) will result in a
high skin temperature and increased thermal discomfort (irrespective of the actual
As thermal discomfort increases, players decrease the pace of the match, which results
in a drop in metabolic rate: an excellent example of autoregulation. Additional measures
that players may take to cool their bodies are the use of ventilators, fans, parasols,
ice vests, ice towels and cold water. However, the player may be at risk if he is
ill (cytokines raise the temperature set point), is severely dehydrated (less circulating
blood to the skin and less cooling) or has autonomic dysfunction (high spinal cord
injury, less sweating). In these situations, great care needs to be taken to protect
the players from potentially life-threatening heat illness.
When to stop play?
Although biological risk is a continuous variable, the reality of sport means that
the decision to play or not to play will be dichotomous. Medicine often puts continuous
variables into ‘cut-offs’ (ie, treatment thresholds for most conditions such as cholesterol,
blood pressure, osteoporosis by dual-energy X-ray absorptiometry). Currently, it is
up to the tournament referee to decide when to stop play but there is no predetermined
Evidence from the recent Australian Open indicated that there should be an upper limit
above which play should be suspended, even for healthy athletes. This upper limit
seems to be around an air temperature of 41–43°C or a WBGT of 32°C, if not for the
players, at least for the long-suffering spectators!
It is important that the available scientific information gets disseminated to the
right people. The ITF has developed a sophisticated website for tennis coaches, players
and all tennis enthusiasts. This includes information that translates scientific research
into plain language and practical information that is readily available. In particular,
the Tennis iCoach section (http://tennisicoach.com) contains technical, tactical,
physical, mental and medical information.
The Society for Tennis Medicine and Science (STMS) is an international organisation
whose mission is to disseminate practical, scientific, tennis-related information
in order to optimise the health and performance of tennis players worldwide. They
have a website (http://www.stms-web.org), a journal that is published three times
a year, and organise biannual conferences.
The International Tennis Performance Association (iTPA) offers research-based tennis-specific
performance education and three levels of certification (http://itpa-tennis.org).
Recent advances in many areas of science have directly impacted the way in which tennis
is played nowadays and it is anticipated that scientific research will be a major
driver for future developments.
Evolution is evident throughout the modern game of tennis and Charles Darwin would
undoubtedly be an avid enthusiast of the sport!