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Abstract
Objective To analyse injuries of water polo players reported during four Summer Olympic Games (2004, 2008, 2012, 2016) and four Federation Internationale de Natation World Championships (2009, 2013, 2015, 2017).
Methods Injuries during training and matches were reported daily by the team physicians and the local medical staff at the sports venues using an established surveillance system.
Results A total of 381 injuries were reported, equivalent to 14.1 injuries per 100 players (95% CI ±1.42). The most frequent diagnoses were laceration (12.7%) and contusion (10.9%) of head, followed by (sub-)luxation/sprain of hand (9.5%) and contusion of trunk (6.5%) or hand (6.2%). More than half of the injuries (57.0%) occurred due to contact with another player. A quarter of the injuries (25.4%) were expected to result in absence from training or match; 10 (2.9%) resulted in an estimated time-loss of 3 or more weeks. About three-quarters of injuries (75.6%) occurred during matches, 86 during training. The incidence of match injuries was on average 56.2 injuries per 1000 match hours (95% CI ±6.74). The incidence of time-loss match injuries (14.7; 95% CI ±3.44) was significantly higher in men than in women.
Conclusions A critical review of water polo in-competition rules and the implementation of a Fair Play programme may help to mitigate the high incidence of contact injuries incurred during matches. A water polo-specific concussion education programme including recognition, treatment and return to play is recommended. Finally, a prospective injury surveillance programme would help to better define water polo injuries outside of the competition period.
- water polo
- aquatic sports
- sports injury
- injury prevention
- top-level athletes
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What are the findings?
Location, type, cause and severity of injuries were similar in male and female water polo players.
Male water polo players incurred about twice as many time-loss match injuries as female.
The average incidence of all match injuries was similar during the Federation Internationale de Natation World Championships (FINA WCh) and the Olympic Games (OG) but the incidence of time-loss match injuries was 1.7-fold higher at the OG than at the FINA WCh.
Match injuries at the OG and the FINA WCh differed significantly in location, type, cause and severity.
How might it impact on clinical practice in the future?
Water polo team physicians should be trained and prepared to manage contact trauma during competition, especially during men’s matches.
Water polo should develop sport-specific concussion education programmes including concussion recognition and return to play guidelines.
A review of water polo competition rules and the strict application of these rules may result in a decrease in water polo injuries.
Team physicians should consider advocating that water polo sport organisations to develop and implement a Fair Play programme.
Introduction
History of water polo
Water polo originated in Britain in the 1870s, fashioned after rugby, and further developed in Scotland in the 1890s adopting football style rules. Water polo was played with a hard ball manufactured in India called a ‘pulu’, which was pronounced ‘polo’, which influenced the name of the game.1
The rules and governance of international water polo are under the oversight of the Federation Internationale de Natation (FINA), which was founded in 1908 and consists of 209 members federations. Water polo is the oldest team sport in the Olympic programme, first debuted at the Olympic Games (OG) in 1900 in Paris. Women’s water polo joined the Olympic programme in the 2000 OG in Sydney. The OG tournament consists of 8 women’s and 12 men’s teams. Men’s water polo was first introduced to the FINA World Championships (WCh) in 1973 in Belgrade, and women’s water polo joined the WCh in 1986 in Madrid; both genders have a 16-team tournament. In addition to the OG and the FINA WCh, the water polo international programme includes World Cups (since 1979), World Leagues (men since 2002; women since 2004), the Development Trophy (since 2007) and junior tournaments.2
Physiological demands of water polo
Water polo demands a unique blend of skills including swimming, throwing and physical contact. Physiologically, players undergo bursts of high-intensity effort amid moderate-intensity to high-intensity swimming. Athletes must train for both aerobic and anaerobic fitness, flexibility and neuromuscular strength, in addition to water polo-specific swimming, throwing and egg beater skills.3 4 The egg beater kick, an alternating, one-legged whip kick, enables the athlete to be hands-free in a stable, vertical position in the water. Water polo shots have been measured up to speeds of 70 km/hour demonstrating the need for strength, power and neuromuscular coordination.5 The nature of the game of water polo is outlined in box 1.
The game of water polo
The field: the playing area is 30 m×20 m and the pool must be a minimum of 2 m deep.
Teams: teams have 13 players, with a goalkeeper and six field players participating at any one time.
Players’ code: players tread water the entire game and cannot touch the bottom or side of the pool. No player except the goalkeeper may handle the ball with more than one hand.
Duration of play: the game is separated into four quarters of 8 min at elite level, with a 2-min interval between quarters.
Start of play: each quarter is started with teams lined up on opposite goal lines. The referee’s whistle is the signal for teams to sprint towards the centre of the pool, where the ball has been placed or dropped.
Time clock: a possession—or shot—clock controls time. Each team has 30 s to shoot the ball at the goal. If no shot is taken, a free throw is awarded to the opposing team. A separate game clock times the passing of each quarter.1
Injuries in water polo
Injury surveillance is the cornerstone to effectively managing injury risk in sport,6–9 and is the first step of the Translating Research into Injury Prevention Practice model.10 Protecting athletes’ health through the prevention of injuries is mandated for all international sport organisations by the Olympic Charter11 and Olympic Movement Medical Code.12 Water polo injury incidence has been studied at many tournaments.13–19
There are few epidemiological data published on injuries in water polo.20 21 All data on water polo injuries during elite tournaments at the FINA WCh and OG will be summarised in this paper. Of concern, at the OG, the injury rate of all and of time-loss injuries has doubled from 2008 to 2016 (figure 1). At the Rio OG 2016, water polo ranked fifth in the proportion of injured athletes (after BMX cycling, boxing, mountain bike cycling and taekwondo) before all other team sports such as rugby, football and handball.19
Water polo injuries incurred during the time period of the Olympic Games in 2008, 2012 and 2016.17–19
This increasing injury rate trend is alarming and raises the question as to whether water polo is becoming more dangerous over time. Given that FINA’s strategic plan (2017–2021) identifies the objective to ‘Ensure well-being of our athletes and our sport…to educate athletes and coaches, officials and National Federations to ensure their well-being (FINA Strategic Plan 2017–2021, unpublished)’, and that water polo is undergoing an evaluation of its competition regulations in 2018 (FINA Water Polo Reform ‘21, unpublished), the objective of this study is to analyse the collective database of water polo injuries reported during four Summer OG (2004, 2008, 2012, 2016) and four FINA WCh (2009, 2013, 2015, 2017) to learn of opportunities for mitigating athlete risk of injury in water polo.
Methods
The present study analysed all water polo injuries reported during four Summer OG (2004,16 2008,17 2012,18 201619 and four FINA WCh (2009,13 2013,14 2015,15 2017). The study design, study implementation, injury definition, data collection and analysis procedures were similar at all tournaments, and have previously been described in detail.13–19
Definition and reporting of injury
An injury was defined as ‘any musculoskeletal complaint or concussion newly incurred due to competition and/or training that received medical attention regardless of the consequences with respect to absence from competition or training’.22 Injuries during training and matches were reported daily by the team physicians and the local medical staff at the sports venues using the IOC injury surveillance system for multisport events,22 except for the 2004 OG. At the 2004 OG, solely match injuries were reported daily by the team physicians using the same injury definition but an earlier version of the injury report form.16
Number of players and exposure
At the OG 2004–2016, 12 men’s and 8 women’s water polo teams and at the FINA WCh 2009–2017, 16 men’s and 16 women’s water polo teams participated. Each water polo team consisted of 13 players. Thus, 260 (156 males, 104 females) water polo players participated in each OG and 416 (208 females, 208 males) in each FINA WCh totalling 2704 players.
A total of 636 water polo matches (360 by men, 276 by women) were played in the eight tournaments: 96 matches (48 by each men and women) at each of the FINA WCh 2009, 2015 and 2017, 88 (44 by each men and women) at the FINA WCh 2013, 64 matches (44 by men and 20 by women) at the each of the OG 2004 and 2008 and and 66 matches (42 by men and 24 by women) at the each of the OG 2012 and 2016.
A water polo match is played by two teams with seven players on the field of play each, with 32 min of active play (four periods of 8 min). Thus, 8904 player matches were played (5040 by men, 3864 by women) in the eight tournaments, which is equivalent to 4748.8 match hours (2688 by men, 2060.8 by women).
Calculation of incidence
The incidence of all injuries—including both match and training injuries, was calculated per 100 players. The incidence of match injuries was also calculated per 1000 player match hours and per match.
Data analysis
All data were processed using Excel and SPSS (V.23). Statistical methods applied were frequencies, percentages, cross-tabulations, incidences with 95% CIs and Χ2 test. Significance was accepted at p<0.05.
Results
The team physicians and local medical staff reported a total of 381 injuries, 254 injuries at the four FINA WCh, and 127 at the four OG. Injuries in male players (224; 59.4%) were more frequent than in female players (153; 40.6%) (Χ2=13.3; p<0.001; four missing values). About three-quarters of the injuries (267; 75.6%) were incurred during matches and 86 (24.4%) during training (28 missing values).
Incidence of injuries
On average, 14.1 injuries per 100 players (95% CI ±1.42) were reported at the eight tournaments, of which 3.2 injuries per 100 players (95% CI ±0.67) were expected to result in time-loss from sport. The injury rate per 100 players was 2.85 times higher in matches (9.87; 95% CI ±1.18) than in training (3.52; 95% CI ±0.74; p<0.001); the rate of time-loss injuries was almost five times higher in matches (2.59; 95% CI ±0.61) than in training (0.53; 95% CI ±0.29; p<0.001).
The incidence of match injuries was on average 56.2 injuries per 1000 match hours (95% CI ±6.74) and did not differ significantly between men and women. It was slightly higher during FINA WCh (61.6; 95% CI ±9.18) than during the OG (48.4; 95% CI ±9.78). The incidence of time-loss match injuries was on average 14.7 (95%CI ±3.44) per 1000 match hours, and significantly higher in men (19.0; 95% CI ±5.21) than in women (9.22; 95% CI ±4.15; p<0.01), and higher at the OG (19.6; 95% CI ±6.23) than at the FINA WCh (11.4; 95% CI ±3.95; p<0.05). Gender difference in (time-loss) match injuries were more pronounced at the OG than at the FINA WCh (for details, see table 1).
Exposure time, number and incidence of injuries and time-loss (TL) injuries at the FINA World Championships (FINA WCh) and the Olympic Games (OG)
On average 3.5 training injuries per 100 players (95% CI ±0.74) were reported during the eight tournaments, of which 0.5 per 100 players (95% CI ±0.29) resulted in time-loss from sport. No gender difference in the rate of all or of time-loss training injuries was observed. The incidences of training injuries were not compared between the FINA WCh and the OG because of the different length of the water polo competitions.
Characteristics of injuries
More than a quarter of the injuries affected the head (97; 25.6%). Other frequent injury locations were the hand/finger (61, 16.1%), trunk (48; 12.7%) and shoulder (43; 11.3%). The most frequent types of injuries were contusion (91; 24.3%) and subluxation/sprain (85; 22.7%), followed by skin lesion (55; 14.7%). For further details, see table 2.
The most frequent diagnoses were laceration (35; 9.3%) and contusion (30; 8.0%) of the head, followed by (sub-)luxation/sprain of the hand (26; 9.6%) and contusion of trunk (18; 4.8%) or hand (17; 4.5%) (table 3). The most frequent diagnoses of time-loss injuries were laceration of the head (8; 9.4%) as well as fracture (7; 8.2%) and (sub-)luxation/sprain of the hand (7; 8.2%).
More than 200 injuries (208; 57.0%) were incurred due to contact with another player, 50 (13.7%) by contact with an object. Sixty (16.7%) injuries were classified as overuse. Non-contact trauma (21; 5.8%), recurrence of previous injuries (10; 2.7%) and other reasons (16; 4.4%) were rare. The injury mechanism was not reported in 16 cases.
Three-quarters of the injuries (255; 74.6%) were not expected to result in absence from training or match. The large majority of time-loss injuries were classified as mild (72; 82.8%), eight as moderate and seven as severe based on the estimate duration of absence of 4 weeks or greater. In 39 cases, no estimate of time-loss was reported. The 10 injuries (2.9%) with an estimated time-loss in sport of 3 or more weeks were: a concussion, a facial fracture, a rupture of ear drum, a nerve injury of the cervical spine, a fracture of sternum, a ligamentous rupture in the thoracic spine, a groin strain, a dislocation of shoulder, a tendon rupture in the elbow and a fracture of the hand. Eight of these most severe injuries affected men, two women. All these injuries, except one, were incurred during matches and due to contact with another player. Seven of these 10 injures were incurred during OG, 4 during the 2016 Rio OG.
No statistically significant gender differences in location, type, cause and severity of all or match injuries were observed. Men and women differed just in the type of training injuries (Χ2=22.5; p<0.05). Training and match injuries differed significantly in location (Χ2=31.1; p<0.01), type (Χ2=44.0; p<0.001) and cause (Χ2=69.3; p<0.001) but not in severity of injuries nor between men and women. Significant differences between the FINA WCh and the OG were observed in location (Χ2=22.2; p=0.05), type (Χ2=26.3; p=0.05), cause (Χ2=12.3; p<0.05) and severity (Χ2=17.2; p<0.01) of match injuries, as well as in location (Χ2=28.5; p<0.01) of training injuries. For details, see table 2.
Discussion
This is the first study focussing on water polo injuries during international tournaments. Summarising the injuries from eight tournaments with a total of 8904 player matches, it presents a comprehensive overview on injury incidence and characteristic in top-level players.
Injury patterns
About three-quarters of all injuries in this study were incurred during matches, with significant differences in location, type and cause between training and match injuries. These findings identify the need to develop different interventions to reduce injury risk for training during the competition period, than during the match, with an emphasis on match injury mitigation given the larger risk.
The incidence of time-loss match injuries was significantly higher in men than in women, and 8 of the 10 most severe injuries were incurred by male athletes. This finding could be the result of greater strength, speed and contact in the men’s game in comparison with the women’s. This information demonstrates the importance of considering gender injury risk patterns in competition injury prevention programming.
Another unique finding was the difference between WCh and OG in location, type, cause and severity of match injuries, as well as the higher incidence of time-loss match injuries at the OG. The reason for this finding is likely due to the perceived importance of the OG being greater in terms of financial gain and reputation than the WCh. Likewise, tailoring prevention interventions to incorporate this finding is recommended.
Injury location
Head
More than a quarter of the injuries affected the head; however, only seven concussions were reported during the study period. The most frequent diagnoses to the head include contusions (31.3%) and lacerations (36.5%). In contrast, a survey by Blumenfield et al 23 of over 2060 water polo players found that 36% respondents reported having suffered at least one concussion, with the average per player of 2.14 career concussions. Concussion rates in other athletes in the US Collegiate system ranged from 23.2% in men’s soccer to 29.2% in women’s ice hockey.24 It is therefore likely that concussions are under-reported in our present study, or wrongly reported as contusions or lacerations. Athletes’ under-reporting of concussion symptoms are reported to be as high as 59% in a cohort of US Collegiate athletes, with various reasons for under-reporting such as ‘fear of being pulled from the game’, ‘wishing to tough it out’ and ‘afraid to lose future playing time’.25 Water polo-specific education addressing recognition, treatment and return to play guidelines are needed. Education of the team physician and/or trainer to identify the signs and symptoms of concussion from either a direct or indirect blow to the head during training and competition is recommended. The inclusion of a video monitoring system, or a dedicated head injury assessor, as used in the National Hockey League, should be explored.26
The FINA injury surveillance methodology lists dental injuries under the heading of ‘head injury’ and specifies it under type of injury.27 In the present study, five dental injuries were reported. Hersberger et al 28 published a retrospective survey of 415 Swiss water polo players finding that 21% of all respondents had suffered a dental injury during play over their career. It is likely that dental injuries are also under-reported in this study. Consideration should be given to making mouth guards mandatory as are ear protective caps,29 since only 7.7% wore a mouth guard during play, with the stated reason for not wearing a mouth guard as ‘not necessary’, and ‘impedes with the tough image of sport’.28
Hand
The second most common injury location in this study was the hand/finger (16.1%). The water polo ball has a larger circumference relative to other throwing sports (68–71 cm for men; 65–67 cm for women),29 resulting in an increase in abduction of the fingers during play for water polo athletes. This hand positioning, in addition to the ball handling, ball velocity, shooting, blocking and aggressive play renders the hand vulnerable to injury.30 31 Consideration should be given to studying the effects of varying ball sizes on injury rates to improve this injury location pattern.
Shoulder
The shoulder was the fourth most commonly reported location and accounted for 11.3% of all injuries. Sallis et al 21 found a similar injury incidence (11.5%) of shoulder injuries in water polo in the Collegiate sport system in the USA. In contrast however, two systematic review papers showed a range of shoulder injury incidence in water polo from 24% to 80%31 and 24% to 51%.32 However, comparing incidence studies is difficult due to different observation periods, methodologies and injury definitions. Miller et al 33 found that risk for shoulder injury in water polo was multifactorial varying with volume of shooting, range of motion, scapular dyskinesis, strength imbalance, proprioceptive deficits and altered throwing kinematics. A study by Wheeler et al 34 found that shoulder pain was correlated with the volume of goal shooting and less rest time between shots. These details are not captured in the current study methodology thus the need to implement prospective injury surveillance in the daily training environment to better define the nature of shoulder injuries in this population.
Injury cause
In this study, >57% of all injuries, and 90% of the 10 most severe injuries were reported to have occurred due to contact with another player. Water polo has higher rates of contact injuries than the other aquatic disciplines of swimming, diving, synchro and open-water swimming.13–15 During the 2016 Rio OG, water polo had the highest injury rates of all team sports.19 Water polo has a ‘machismo’ sport culture, and thus risk reduction interventions targeting contact injuries should address a cultural change with the water polo stakeholders. From a risk mitigation perspective, it behoves FINA to address the rules of play to minimise contact, and to implement a FINA Fair Play Programme, especially in the men’s game.6 7
The second most frequent (16.7%) cause of injury was overuse. This finding is consistent with a study by Wheeler et al 34 that identified the occurrence of shoulder injuries at squad selection training camps, outside of the competition period. As water polo players train 6 days per week with 3–4 swimming sessions at a distance of 2–5 km/session, weight training, skills training and at least one match per week, the risk of overuse injuries is significant. A retrospective survey at the 2013 WCh demonstrated that 41.9% of all responding water polo players had a physical complaint during the 4-week study period preceding the WCh; 43.8% reported that their training was affected, and only 31.3% were symptom free at the commencement of the WCh.14 This finding was confirmed at the 2015 WCh, which found that 27% of all responding water polo players had a physical complaint during the 4 weeks prior to the WCh; 68.1% of all aquatic athlete physical complaints during the study period were reported to have been caused by overuse injuries and 69.6% were still present at the beginning of the WCh.15 Thus, water polo athletes train and compete with injuries.14 15 35 As the injury surveillance system used in the present study only identifies new-onset injuries or an exacerbation of a pre-existing injury during competition or training during the WCh or OG time period, the overuse injuries reported in this study are likely only the ‘tip of the iceberg’, and prospective surveillance for athlete complaints during the training period is recommended.27
Injury severity
Almost three-quarters of the injuries were not expected to result in time-loss from sport, and 83.8% of time-loss injuries were classified as ‘mild’. While it is encouraging to learn that the majority of injuries are not considered to be serious, as defined by ‘time-loss’, any injury will ultimately affect athlete performance and well-being, and should be addressed. Time-loss injury patterns, while not the majority of injuries, are nonetheless important as these injuries indicate severity and negatively affect athlete health and performance the most. Male athletes suffered significantly more time-loss injuries during matches than female players, and 8 of the 10 injuries with 3 or more weeks expected time loss. This finding demonstrates the important need to evaluate and change the competition rules to minimise aggressive play, especially in the men’s game.
The comparison between the OG and the FINA WCh showed a 1.7-fold higher incidence of time-loss match injury in the OG, and 7 of the 10 most severe injuries occurred during the OG. This trend may be due to the difference in tangible and intangible secondary gains of financial or reputational success in the OG relative to the FINA WCh. Emphasis on rule application is therefore especially important during matches during the OG.
Study limitations
As the data analysed in this study are collected at either the OG or FINA WCh, the findings are not applicable to injury risk during out-of-competition training. In addition, given that the data were collected from team physicians and the local organising committee medical records, there is a potential bias from reporting inaccuracy. This method of data collection however, is the current gold standard for epidemiological study of injury incidence at larger sporting events.
Conclusion
Sport-specific guidelines on the identification, treatment and return to play for concussion in water polo are necessary given the under-reporting found in this study, and the known morbidity associated with concussion. Given the particular risk of injury to the head, the mandatory use of mouth guard is also recommended, and injury surveillance tools monitoring water polo athletes should be customised to differentiate head from facial, eye, ear and dental injuries.24 Prospective out-of-competition injury surveillance in water polo would help to better understand the overuse injury profile during the training period.
We speculate that the introduction of a Fair Play programme, including athlete, coach and referee education, consistency of rule application for brutality, in addition to branding and promotion, may mitigate the high rate of match injuries sustained by contact, especially in the men’s game. Finally, the in-competition rules, as well as the enforcement of those rules should be reviewed and modified to decrease contact injuries. Specifically, awarding a penalty foul for attacking from behind in the 6 m area in front of the goal would decrease contact injury. Increasing the roster size from 13 to 15 players would provide for more opportunity for substitution thus decreasing exposure and increasing athlete recovery time. In addition, the use of a Game Video Monitoring System to identify brutality during or after the match would act as a deterrent. Subsequently, in-competition injury surveillance should be conducted to evaluate for efficacy of the intervention strategies.
Water polo is an exciting game with speed, precision, team play and excitement. Improving athlete health through the reduction of injury risk will result in healthier athletes, longer sporting careers and a game that is stronger, faster and more entertaining.
Acknowledgments
The authors greatly appreciate the cooperation of the team physicians and the medical staff of the FINA World Aquatic Championships and of the Local Organising Committee of the Olympic Games who volunteered their time to collect the data for this project. The authors would like to thank Ms Gudrun Grasshoff, Ms Agnes Gaillard, Dr Sarah Benjamin, Ms Annika Prien, Mr Josh Slysz, Mr Johan Lefebvre, Kathrin Steffen, Torbjorn Soligard and Professor Lars Engebretsen for their valuable assistance in data collection.
References
Footnotes
Contributors MM: substantial contributions to the conception and design of the study, collection and interpretation of data, drafting, writing and revising of the manuscript and final approval of the version to be published. JM: substantial contributions to data collection and final approval of the version to be published. AJ: substantial contributions to the conception and design of the study, analysis and interpretation of data, drafting, writing and revising of the manuscript and final approval of the version to be published.
Funding The data collection was funded by the International Olympic Committee (IOC) and the Federation Internationale de Natation (FINA), Lausanne, Switzerland. No funding was received for the present study.
Competing interests None declared.
Patient consent Not required.
Ethics approval This study was approved by the McMaster University—Hamilton Integrated Research Ethics Board, Canada.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement No supplementary data.