Shoulder pain is common among athletes, both due to direct traumas, such as collisions in contact sports, and due to repetitive movements above shoulder height (“overhead”), that occur in racket sports (Anderson & Alford, 2010; Hulstyn & Fadale, 1997). The risk for an athlete to develop shoulder pain is closely related to the character of the sport and is highest in sports with overhead shoulder loading (Doyscher et al., 2014). Also, in throwing sports, such as baseball, shoulder pain is commonly occurring. During a season, half of young baseball pitchers had experienced shoulder pain (Lyman et al., 2002).

Badminton includes many repetitive overhead motions and previous studies have shown that up to 30% of players on both the highest elite level (Fahlström et al., 2006) and at recreational level (Fahlström & Söderman, 2007) suffer from shoulder pain that affects daily life. Young female elite badminton players have an imbalance in strength and mobility in the shoulder muscles (Couppé et al., 2014), which can contribute to painful subacromial conditions. Under-17 badminton players with a shoulder internal rotation range of motion of 55⁰ or less, were shown to have increased risk of shoulder pain one year later (Cejudo, 2022) A study performed on 62 female overhead athletes on elite level and recreational level among different sports has shown larger acromio-humeral distance in the dominant side than in the non-dominant side. In addition, the elite level athletes had a larger dominant side acromio-humeral distance than the recreational level athletes (Maenhout et al., 2013). A larger acromio-humeral distance in overhead athletes means that the shoulder is less stable and the risk for pathologies in the area due to repeated subluxation is increased (Chambers & Altchek, 2013). It has also been suggested in a recent study on Danish elite badminton players that greater shoulder external rotational strength is strongly associated with an increased acromio-humeral distance. This suggests hypertrophy of the supraspinatus tendon which could lower the risk of injury (Schmidt et al., 2021).

Wrestling is among the oldest sports known to man (Martin & Margherita, 2021), it puts high demands on the shoulders, and wrestlers have a different type of loading on their shoulders compared to athletes with repetitive overhead shoulder loading. The wrestlers´ shoulder is affected by twisting and leverage, as well as falls, with sudden contact with the carpet. Shoulder injuries can occur when a wrestler is trying to escape a hold, which can force the shoulder joint past its normal range of motion (Halloran, 2008). An American study that followed 458 male high school wrestlers, aged 14-19 years, for a season found an incidence of 52 injuries/100 wrestlers/season. The most injured body part was the shoulder (rotator cuff, glenohumeral joint and AC-joint) (24%), followed by the knee (17%). The injured wrestlers were older on average and had been wrestling longer than other wrestlers participating in that study. The most common mechanisms of injury were found to be direct forces or blows (42%) and twisting forces (23%), while only 6% of all injuries were due to overuse or repetitive activity (Pasque & Hewett, 2000). A study comparing the prevalence of shoulder injuries for different sports at high school level found wrestling to have the second highest incidence for shoulder injuries behind American football. Wrestlers had more shoulder injuries than soccer, basketball and volleyball players (Bonza et al., 2009).

In badminton it is known that shoulder pain is common and affects sports performance (Fahlström et al., 2006). Imbalance in shoulder strength and a large acromio-humeral distance seems to be associated with a higher risk to develop shoulder pain in badminton players (Couppé et al., 2014; Chambers & Altchek, 2013). In wrestling fewer studies have been performed with the focus on shoulder pain compared to badminton. The knowledge about what consequences wrestlers suffer from their shoulder pain and how it affects their performance is not extensive. A direct comparison between badminton and wrestling, where the shoulder loading is of different character, has not been made.

The prevalence and the severity of injuries should be studied with the aim to prevent sports injuries (Van Mechelen, 1997). Therefore, comparing two sports with different injury mechanisms to the shoulder; repetitive overhead motion in badminton, and twisting, leverage and other direct forces for the wrestlers’ shoulder could result in interesting findings.

The aim of this study was to study painful conditions in the shoulders among badminton players and wrestlers, to describe them and make a comparison between both sports.

123 athletes were asked to participate in the study of which 119 (97%) accepted. Sixty-three of the participants (53%) were badminton players (50 male, 13 female) and 56 of the participants (47%) were wrestlers (32 male, 24 female).

Basic characteristics of the participants are shown in Table 1. The male participants were older, had a higher BMI, were stronger and had a higher total Constant Score in both shoulders than the females. Apart from the difference in shoulder strength between male and female, the only difference in strength of same-sex participants was between male badminton players and male wrestlers in the dominant shoulder [15.8±4.4, 16 points vs 17.9±4.9, 18 points (p=0.035, r=0.23)].

Previous or on-going shoulder pain was reported by 29 (46%) of the badminton players - 24 (48%) male and 5 (38%) female and by 30 (54%) of the wrestlers - 20 (63%) male and 10 (42%) female.

A comparison of differences between badminton players with previous or on-going pain and other badminton players can be seen in Table 2. There were no differences in shoulder strength or mobility between the two groups of badminton players.

A comparison of differences between wrestlers with ongoing or previous pain and other wrestlers can be seen in Table 3.

In badminton players the shoulder pain was located to subacromial structures in the dominant shoulder, while the distribution of shoulder pain in wrestlers was widespread and included both dominant and non-dominant side on various locations, (Figures 1a and 1b).

In Figure 1 a and 1 b the right side represents dominant side and the left side non-dominant side. Each participant may have marked more than one location for pain.

On-going shoulder pain was more frequent in wrestlers; 18 of the wrestlers (32%) had ongoing shoulder pain, while three badminton players (5%) had ongoing shoulder pain (p=<0.001, φ-0.36). Ongoing shoulder pain was registered by 14 (44%) of the male wrestlers, compared to three (6%) of the male badminton players (p=<0.001, φ=-0.45). More male than female wrestlers had ongoing shoulder pain, [14 (44%) vs 4 (17%), (p=0.032, φ=0.29)].

A comparison of differences between male wrestlers with ongoing pain and other male wrestlers can be seen in Table 4. Male wrestlers with ongoing shoulder pain had a higher body mass index compared to male wrestlers without ongoing shoulder pain [25.2±2.6, 25 kg/m² vs 23±2.3, 23 kg/m² (p=0.011, r=0.44)]. Similar differences as those presented in Table 4 could be seen comparing female wrestlers with ongoing pain and other female wrestlers, except for body mass index, where female wrestlers with ongoing pain had a lower body mass index compared to pain-free female wrestlers [19.4±2, 18.9 kg/m² vs 21.7±2.1, 22.2 kg/m² (p=0.045, r=0.41)].

No significant differences were found between badminton players and wrestlers with ongoing or previous pain regarding type of debut of pain (sudden or gradual). Also, no differences between the sports whether the pain affected competition and training habits were found.

Eight of the male wrestlers with ongoing pain (57%) had experienced a sudden onset of pain, while for female wrestlers none had experienced a sudden onset of pain (p=0.055, φ=0.48). Furthermore, seven (50%) of the male wrestlers with ongoing pain were forced to change their training- or competition habits, while for female wrestlers with ongoing pain there were none (p=0.070, φ=0.43). Four of the male wrestlers with ongoing pain (29%) experienced that their pain affected activities of daily life, while for female wrestlers with ongoing pain, one (25%) experienced affected activities of daily life (p=0.888, φ=0.033). Disturbed sleep due to ongoing pain was experienced by four of the male wrestlers (29%), and by one of the female wrestlers (25%) (p=0.888, φ=0.033). Looking at wrestlers with ongoing pain, eight male wrestlers (57%) had sought medical advice, while no female wrestlers had done so (p=0.043, φ=0.48).

The aim of this study was to study painful conditions in the shoulders among badminton players and wrestlers, to describe them and make a comparison between both sports.

Previous or on-going shoulder pain was common in both studied groups of badminton players (46%) and wrestlers (63%), even though more wrestlers than badminton players were found to suffer from on-going shoulder pain. Previous studies performed on competitive and recreational badminton players have shown that shoulder pain is a common problem with about 30% of players suffering from on-going shoulder pain (Fahlström et al., 2006; Fahlström & Söderman, 2007). Surprisingly few badminton players in this study (5%) suffered from on-going shoulder pain. This might be because they were relatively young and did not practice as much as the players in the previous studies. The badminton players’ prevalence of shoulder pain in this study is comparable to the prevalence of shoulder pain in 9-12% among people aged 19-44 years old in the normal population (Urwin et al., 1998).

However, the localization of shoulder pain was very similar among the badminton players in this study and those in previous studies (Fahlström et al., 2006; Fahlström & Söderman, 2007), which indicates that the type and mechanism of injury is of a similar character. If this study had been conducted on badminton players who practiced more and competed at a higher level, it is likely that the prevalence of on-going shoulder pain would have been more similar to what has been found in previous studies.

The prevalence of on-going pain was especially high among male wrestlers, where 44% suffered from on-going pain. Despite the on-going pain, the wrestlers were still participating in competitions and training sessions. Wrestling with on-going shoulder pain seems likely to inhibit the performance of the wrestler and may force them to utilize different techniques compared to if they weren’t suffering from shoulder pain. This might contribute to the development of other injuries.

The male and female wrestlers in this study perform different styles of wrestling, the male Greco-Roman wrestling and the female Freestyle wrestling. In Greco-Roman wrestling it is only allowed to grapple the opponent from waist and above, while in Freestyle it is also allowed to grapple the opponent’s legs. A previous study that compared the injuries of the two wrestling styles during a 2006 US national junior tournament, found that the overall injury rate was higher in Freestyle wrestling (7.0 injuries/1000 athlete-matches) than in Greco-Roman wrestling (4.6 injuries/1000 athlete-matches). Knee injuries were more common in freestyle while elbow and head/face/neck injuries were more common in Greco-Roman wrestling. Shoulder injuries in Greco-Roman wrestlers were found to be caused from being driven into the mat (70%) and by other physical contacts (30%) (Yard & Comstock, 2008).

Looking at the localization of pain, wrestlers had a more widespread localization than badminton players. This difference in localization of pain indicates that the shoulder loading within badminton and wrestling are of different characters, and that different mechanisms are responsible for causing shoulder pain in badminton players and wrestlers. This gives better insight in participants shoulder pain and is a strength of this study.

Male wrestlers with on-going pain had a higher BMI than other male wrestlers, while female wrestlers with on-going pain had a lower BMI than other female wrestlers. Perhaps in Greco-Roman wrestling, having a higher BMI (being relatively heavier) is a factor that increases the load on the shoulders that might result in pain. For the female wrestlers with pain, having a lower BMI might be related to less stabilizing musculature for the shoulder. No female wrestler in this study with on-going pain had experienced a sudden debut of pain, that might indicate that different mechanisms of injury occur in Greco-Roman and Freestyle wrestling.

In this study eight (57%) of the male wrestlers (who performed Greco-Roman wrestling) with on-going shoulder pain had experienced a sudden debut of their pain. Taking this together with the mechanisms of shoulder injuries found earlier by Yard & Comstock (2008) into consideration, it seems likely that many Greco-Roman wrestlers with shoulder pain have a sudden debut of their pain due to direct trauma.

Wrestlers with on-going or previous pain had lower scores in several directions of shoulder mobility compared to other wrestlers. (Table 3). This may be due to them suffering from shoulder pain during the testing (those with ongoing pain), or it may be because they, due to decreased mobility, were more susceptible to acquiring shoulder pain. It is generally not known if it is beneficial for wrestlers regarding shoulder pain and injuries to have a flexible or a more rigid shoulder. One previous study, however, showed that wrestlers with at least one positive test for general ligamentous laxity had only half the number of shoulder injuries compared to the other wrestlers in that study (Pasque & Hewett, 2000). Comparatively, for badminton players it is known that instability in the shoulder and an imbalance in shoulder strength for internal- and external rotation may contribute to painful conditions (Couppé et al., 2014; Chambers & Altchek, 2013; Stausholm et al., 2021).

Wrestlers seemed to suffer from more severe consequences from their shoulder pain compared to badminton players. Male wrestlers also seemed to suffer from more severe consequences of their pain compared to female wrestlers. For wrestling, the different prevalence of pain for male and female wrestlers and its consequences might be related to the difference in wrestling styles by male and female wrestlers.

Although this study was performed on badminton players and wrestlers, similar shoulder problems can be expected in athletes who participate in other types of sports with shoulder loading of similar character.

Constant Score is an established method to assess shoulder function, it can be performed in a short amount of time, which was important in this study, since testing of each athlete was performed in a limited timeframe. The mobility and strength tests are measured in intervals that are translated into points. This does not give an exact measurement but on the other hand it is easier and quicker to conduct the tests.