# Injury Patterns and Frequency in Swimming: A Systematic Review
## 1 Introduction  
According to the 2022 Sports Habits Survey conducted by the Higher Sports Council [1], swimming ranked as the second most popular sport in Spain based on federative licenses, with 66,774 registered athletes. Its widespread practice across all age groups is attributed to its numerous health benefits, including its minimal stress on bones and joints, which make it a highly accessible activity for individuals of all ages [2]. Additionally, the survey reported that 57.35% of individuals over the age of 15 had participated in swimming during the last year. Competitive swimming involved consistently high training volumes and intensities, with some swimmers covering up to 110 km per week and performing thousands of shoulder revolutions per session, typically across 10-12 sessions per week [3]. Consequently, swimming was not exempt from injury risks, particularly overuse injuries affecting the shoulder, elbow, knee, ankle, and back [4; 5]. Among these, shoulder injuries were the most prevalent. A study by the National Collegiate Athletic Association (NCAA) revealed that 34.7% of injuries in collegiate male swimmers and 36.8% in female swimmers involved the shoulder [6]. Reported rates of shoulder injuries among competitive swimmers ranged from 40% to 91%, primarily due to repetitive overhead motions and the biomechanical demands of swimming [7]. Furthermore, overuse and non-contact injuries were more frequent in women, with 63.7% of injuries reported compared to 44.4% in men [6]. This difference was attributed to biomechanical factors, as female swimmers performed more arm revolutions per lap, thereby increasing their exposure to repetitive stress [8]. At the elite level, swimmers trained up to 14.5 km per day, completing more than 2500 shoulder revolutions daily, which significantly elevated their risk of musculoskeletal injuries [3]. Freeslyle (commonly known as \"crawl\") and butterfly strokes pose the highest injury risks among swimming styles, primarily due to the repetitive arm abduction and the elevation above the head required by these techniques [9; 10]. The repetitive nature of these strokes places significant stress on the rotator cuff and scapular stabilizers, often leading to fatigue, reduced dynamic stability, and impingement syndromes [11]. The shoulder joint, which plays a crucial role in swimming, is characterized by its extensive range of motion and is supported by ligaments such as the glenohumeral and coracohumeral [12]. Despite this support, muscular coordination is essential to maintaining joint stability. Research highlights the importance of shoulder range of motion (ROM), along with a balance between strength and flexibility, as deficits in these areas increase the risk of conditions such as scapular dyskines and \"swimmer's shoulder\" [13]. In contrast, breaststroke swimmers are more prone to knee injuries due to the valgus and rotational forces generated during the whip kick, commonly referred to as \"breaststrokeer's knee\" [14]. Both butterfly and breaststroke styles are also associated with an increased risk of lumbar spine injuries, as the hyperextension required to maintain a streamlined position places considerable load on the posterior structures of the lower back [15]. The cyclical nature of swimming, combined with high training loads, technical precision, and strength demands, further increase the risk of injury, particularly to the shoulder, knee, and lumbar spine [16; 17]. [PERSON] et al. [18] synthesized the findings from 22 studies on shoulder pain in competitive swimmers, highlighting the moderate evidence that associated competitive level training and altered muscle recruitment with pain, while factors such as range of motion and training frequency showed no significant association. Similarly, [PERSON] et al.