Risk factors and injury prevention strategies for hamstring injuries: a narrative review

Abstract

• Hamstring injuries are a significant concern in high-speed running and kicking sports, contributing to a high incidence and recurrence rate among athletes.

• Anatomical and biomechanical properties of the hamstrings, especially the biceps femoris long head, make them susceptible to strain, contributing to the high injury rate observed in athletes.

• Key risk factors, including prior injury history, neuromuscular deficiencies, excessive load, and muscle–tendon architecture, have been identified as contributors to injury prevalence.

• Eccentric strengthening exercises, particularly the Nordic hamstring exercise, are highlighted for their effectiveness in reducing the incidence of hamstring injuries.

• Stretching protocols, when combined with strengthening exercises, have shown potential in enhancing muscle flexibility and reducing injury risk, although their standalone effectiveness remains a subject of ongoing research.

Introduction

Hamstring injuries are a prevalent concern in both amateur and professional sports, representing a significant burden on athletes, teams, and healthcare systems worldwide. These injuries not only result in substantial time loss from training and competition, but also often lead to long-term sequelae, compromising an athlete’s performance and overall well-being (1, 2). Understanding the risk factors associated with hamstring injuries and implementing effective prevention strategies are paramount in mitigating their occurrence and improving athlete outcomes.

In recent years, there has been a growing interest in elucidating the multifactorial nature of hamstring injuries. While muscular imbalances, poor flexibility, and previous injury have historically been implicated as primary risk factors, contemporary research has revealed a more nuanced interplay of factors contributing to injury susceptibility (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14). These factors encompass biomechanical, anatomical, physiological, and environmental elements, highlighting the complex aetiology of hamstring injury. The role and anatomical position make it particularly susceptible to injury. The hamstrings’ dual function in knee flexion and hip extension, combined with their composition of type 1 fibres and innervation by different nerves during specific movements, increases the hamstrings’ vulnerability.

Various mechanisms of action have been implicated in the risk of hamstring injuries, most associated with dynamic movements often seen in high-level sports. Injuries typically occur during movements that involve a combination of extensive hip flexion and knee extension, which are commonly observed in high-speed sprinting and sports that involve stretching to extreme joint positions. This includes sagittal kicks (dance and gymnastics), high kicks (ballet and martial arts), overhead kicks seen in soccer, decathlon, and pole vaulting (15).

Moreover, the economic ramifications of hamstring injuries are substantial, with direct medical costs, rehabilitation expenses, and indirect costs associated with decreased productivity and potential long-term disability (3, 4, 5, 6, 7). Consequently, there is a pressing need to develop comprehensive injury prevention programs tailored to address the diverse risk factors predisposing individuals to hamstring injuries.

This review aims to evaluate the current literature on the risk factors contributing to hamstring injuries and assess the efficacy of existing injury prevention programs. By consolidating evidence from epidemiological studies, biomechanical analyses, and clinical trials, this article seeks to provide a comprehensive overview of the modifiable and non-modifiable risk factors associated with hamstring injuries. Ultimately, the goal is to inform clinicians, sports medicine practitioners, coaches, and athletes about evidence-based strategies for mitigating the risk of hamstring injuries and optimising athletic performance.

Risk factors for hamstring injuries

Neuromuscular control

Neuromuscular control is a significant risk factor for proximal hamstring injury, especially during high-speed activities. According to Roussiez et al. (16), imbalances in lumbar–pelvic mechanisms, such as pelvic asymmetry and excessive anterior tilt, can lead to increased tension on the hamstrings and affect the hamstring unit during functional activities. Furthermore, psychological factors observed in conditions such as competitive anxiety can alter the neuromuscular function of the hamstrings, potentially leading to dysregulations in muscle activity and stiffness, subsequently increasing the risk of injury.

A lack of neuromuscular control has also been implicated in hamstring injury recurrence due to factors such as persistent neural inhibition, leading to chronic eccentric hamstring weakness, selective hamstring atrophy, and shifts in the torque-joint angle relationship (17). This inhibition limits voluntary muscle activation, particularly during eccentric actions and at longer muscle lengths, impacting recovery and potentially contributing to injury recurrence.

Altered muscle recruitment patterns in individuals with related musculoskeletal disorders may contribute to increased hamstring muscle activation and predispose proximal hamstring strain. Sole et al. (18) focused on athletes participating in running and sprinting sports who are at risk of hamstring injuries. These individuals often exhibit changes in how their muscles are recruited to compensate for pain, weakness, or instability in certain areas of the body. For instance, in the presence of low back pain, the body may recruit the hamstrings differently to provide additional support and stability to the lumbo–pelvic region. This altered recruitment pattern can lead to increased activation of the hamstrings, possibly exceeding their normal load-bearing capacity and increasing the risk of strain or injury.

Individuals with knee osteoarthritis may also experience changes in muscle activation patterns as the body adapts to protect the affected joint. In this case, increased hamstring activation can be a compensatory mechanism in response to instability or reduced function in the knee joint. In addition, individuals with glutaeal weakness may experience compensatory activation of the hamstrings due to shared attachments at the ischial tuberosity and sacrotuberous ligament (19). This heightened activation of the hamstrings, particularly in tasks such as walking, stair climbing, or running, can potentially strain the muscle and predispose it to injury due to the excessive recruitment demands placed upon it.

Hamstring micro-architecture

Variations in the muscle–tendon architecture of the hamstring muscles, specifically the biceps femoris long head (BFLH), may influence the risk of hamstring injuries during activities such as running (20). A study conducted by Huygaerts et al. looked at a cohort of young healthy individuals, and the researchers evaluated the BFLH composition in vivo. The muscle samples were taken from the mid-section, approximately 50% of thigh length. The investigation revealed a balanced muscle fibre composition in the BFLH, with type I fibres accounting for 47.1% ± 9.1% and type II fibres for 52.9% ± 9.1%. The BFLH muscle exhibits non-uniform architectural features, with differences in the pennation angle and fascicle length between its proximal, middle, and distal sections. These variations in architecture could affect stress and strain distribution within the muscle, potentially increasing injury risk.

Bourne et al. (21) assessed muscle forces and movements in different groups of participants including healthy adults, National Collegiate Athletics Association (NCAA) Division I sprint and jump athletes, and recreational level athletes in field and court sports. The study found that variability in hamstring muscle sizes, anatomical cross-sectional areas (ACSAs), and moment arms can impact the power outputs and force generation capacities of the hamstrings. These factors can influence the risk of hamstring injuries. Individuals with larger ACSAs may have greater force generation capacities, enabling them to produce higher forces during activities such as sprinting or jumping. On the other hand, individuals with smaller muscle sizes may have a reduced capacity to generate forces, potentially increasing the risk of overloading the hamstrings during explosive movements. This may subsequently increase the risk of hamstring injuries.

Structural fascial length, which refers to the physical length and elasticity of the hamstring muscles and their surrounding fascia, plays a crucial role in eccentric movement, function and preventing injury (22, 23). Timmins et al. (24) conducted a prospective cohort study including 152 elite soccer players and demonstrated that possessing BFLH fascicles shorter than 10.56 cm (RR = 4.1; 95% CI: 1.9–8.7) significantly increased the risk of hamstring injury. Importantly, it was determined through logistic regression for multivariate data that the heightened risk of future hamstring injuries in older players or those with a previous injury is reduced when they have longer BFLH fascicles.

Biceps femoris aponeurosis

According to Bourne et al. (21), a narrow proximal BF aponeurosis and a high muscle to aponeurosis width ratio have been suggested as potential risk factors for hamstring injuries. Biomechanical modelling has shown that the geometry of the aponeurosis, which is the connective tissue that transmits force from the muscle fibres to the tendon, strongly influences the location and magnitude of stress within the BF muscle.

A study by Evangelidis et al. (25), consisting of 30 healthy recreationally active participants, demonstrated that individuals with a relatively small BFLH tendon relative to muscle size or knee flexor strength might be more prone to proximal hamstring injuries. This relationship suggests that a smaller aponeurosis could lead to increased mechanical stress on the muscle tissue surrounding it, which could potentially predispose individuals to hamstring injuries. The study revealed that the BFLH proximal aponeurosis area displayed a weak correlation with the proximal BFLH/SM tendon cross-sectional area (CSA) (r = 0.36, P = 0.049), but was not significantly related to muscle size, muscle strength, or tendon CSA. This finding implies that individuals with disproportionately small aponeurosis compared to their muscle size or knee flexor strength may experience a concentration of forces on the muscle tissue, potentially overloading it and increasing the risk of hamstring injuries. Figure 1 demonstrates an example of a British athletics muscle injury classification (BAMIC) 4C injury of the proximal long head of biceps femoris tendon (26).

Figure 1.

Coronal STIR MRI of BAMIC 4C injury of the proximal long head of biceps femoris tendon.

Furthermore, Kayani et al. (8) conducted a case study focussing on the surgical repair of distal musculotendinous T junction injuries of the BF, an example of which is illustrated in Fig. 2. This study found that the distal T junction of the BF is particularly prone to injury due to its complex anatomical structure and the mechanics of muscle contraction. This junction is formed by the convergence of the long and short heads of the BF, which creates a narrow and elongated aponeurosis. This design leads to poor dissipation of forces from the muscle belly to the tendons, making the proximal and distal musculotendinous junctions susceptible to injury. In addition, the asynchronous activation of the long and short heads during muscle contraction generates different force vectors, further increasing the risk of strain at these interfaces. The intricate coalition of the epimysial surfaces at the T junction, combined with the high tensile forces experienced during athletic activities, contributes to the vulnerability of this region to acute injuries.

Figure 2.

Coronal (A) and sagittal (B) STIR MRI of a distal T-junction hamstring injury.

Hamstring:quadriceps muscle strength ratio

An imbalance in strength between the hamstrings and quadriceps, particularly when considering the hamstrings-to-quadriceps ratio, can potentially elevate the risk of proximal hamstring strain injuries. Coratella et al. (5) assessed peak joint torque angle changes recorded with an isokinetic test before and after fatiguing muscle with a simulated soccer match. The study included 22 healthy male amateur soccer players with an average age of 20.1 years, and findings were calculated at three different angular velocities: 1.05, 3.14, and 5.24 radian/s. These velocities were used during the maximal isokinetic strength tests for both hamstrings and quadriceps muscles. Overall, the study found that when the quadriceps exert a greater force than the hamstrings, especially during activities that involve rapid knee extension (such as sprinting or kicking), the hamstrings are subjected to excessive load. This is particularly concerning because the hamstrings play a crucial role in decelerating the knee joint during such movements, predisposing the hamstring to injury.

This is supported by a study conducted by Lee et al. (6) which found that professional soccer players with a concentric hamstring-to-quadriceps ratio below 0.505 during preseason isokinetic strength testing had a 3.14-fold higher risk of sustaining hamstring strain injuries at an angular velocity of 60 degrees/s during preseason isokinetic strength testing. This finding suggests that a poor ratio between hamstring and quadriceps strength is significantly associated with an increased likelihood of experiencing acute hamstring injuries during the competitive season. Another study conducted on competitive sprinters emphasised that a preseason hamstring:quadriceps muscle peak torque ratio of less than 0.6 at 180 u/s was a significant risk factor for hamstring muscle injury. Athletes with this lower ratio were found to have a 17-fold increased risk of sustaining a hamstring injury (7).

Decreased muscle flexibility

Increased muscle tightness, particularly in the hamstring and quadriceps muscles, is associated with a higher risk of developing musculoskeletal lesions, as discussed by Witvrouw et al. (27). The study conducted on 146 male professional soccer players found that players with hamstring injuries (31 individuals) or quadriceps injuries (13 individuals) displayed significantly lower flexibility in these muscles before their injuries compared to the uninjured group. Specifically, the injured group exhibited significantly lower mean flexibilities in both the quadriceps (P = 0.047) and hamstring (P = 0.02) muscles. These findings suggest a strong correlation between decreased flexibility in the hamstring and quadriceps muscles and the risk of subsequent muscle injuries in male professional soccer players. Decreased flexibility may impair the muscles’ ability to elongate and contract effectively during dynamic movements involved in sport, increasing the likelihood of strains, sprains, or overuse injuries. This finding is consistent with those of Gabbe et al. (9), which looked at 126 community-level Australian football players who completed a musculoskeletal screen to inform a baseline. Overall, it was found that decreased quadriceps flexibility was identified as a statistically significant predictor of the time to sustain a hamstring injury.

Dyk et al. (10) investigated the association of lower limb flexibility with the risk of hamstring injuries in 438 players. The study identified deficits in the passive hamstring and ankle dorsiflexion range of motion (ROM) as risk factors for hamstring injuries. The reduced passive knee extension ROM had a hazard ratio of 0.97 (95% CI: 0.95–0.99; P = 0.008), while the ankle dorsiflexion ROM had a hazard ratio of 0.93 (95% CI: 0.88–0.99; P = 0.02).

Age

Age has also been found to be a significant risk factor for proximal hamstring injuries. Gabbe et al. (11) focused on Australian football players and found that players aged over 23 years were significantly more at risk of sustaining hamstring injuries (RR = 3.8). The study highlighted age-related changes in body weight, hip flexor flexibility, and active hip internal rotation range of movement as factors contributing to the increased risk of hamstring injuries in older athletes.

Furthermore, Henderson et al. (12) conducted a study which aimed to model physical parameters affecting hamstring injury in English Premier League soccer players using multiple logistic regression analysis. The study found that older, more powerful, and less flexible soccer players are at increased risk of sustaining hamstring injuries. More specifically, the odds of sustaining a hamstring injury increased by 1.78 times for each additional year of age. This is also supported by consistent findings reported by Verrall et al. (13), which identified that the older the athlete, the higher the likelihood of sustaining a hamstring muscle strain injury, even when the confounding factor of a previous posterior thigh injury was excluded.

Acute load

A relationship between excessive acute load on the hamstrings and injury has been increasingly established, particularly observed in sports characterised by dynamic movements such as the jackling position in rugby (28). A study by Schache et al. (29) involved the collection of full-body kinematics and ground reaction force data from five males and two females while they sprinted on an indoor running track. It found that acute injuries to the hamstring muscles are prevalent during high-speed running, particularly during the terminal swing phase of the stride cycle. The study found that during this phase, the biarticular hamstrings (specifically the SM, ST, and BFLH) experienced peak musculotendon strain, produced peak force, and performed significant negative work (energy absorption). This suggests that the high acute loads experienced by the hamstrings during terminal swing may increase the risk of injury, as the muscles are subjected to substantial strain and eccentric contractions at this time.

This is supported by a study by Chumanov et al. (30) which assessed whole body kinematics, electromyographic (EMG) activities, and ground reactions which were recorded as participants ran on an instrumented treadmill at varying speeds (80% to maximum). Twelve participants (nine male and three female) took part with a mean age of 24.5 years. The study found two distinct loading peaks for the hamstrings: one during late swing (between 85 and 95% of the gait cycle) and another during early stance (between 0 and 15% of the gait cycle). The hamstrings were found to undergo a lengthening contraction during the late swing phase, which is associated with negative work. This negative work increases with speed, suggesting that the hamstrings are more susceptible to injury during this phase due to the high inertial loads experienced. The results indicated that the biomechanical demands placed on the hamstrings during the swing phase are more consistent with muscle injury mechanisms compared to the stance phase, highlighting the importance of eccentric loading in injury risk.

Previous hamstring injury

Several studies have demonstrated that athletes with a previous hamstring injury have an increased risk of re-injury, especially in the early period after returning to sports activities (3, 14). The increased risk of recurrent injury may be due to factors such as incomplete healing, weakened muscle tissue, altered biomechanics, or inadequate rehabilitation, leading to ongoing weaknesses or imbalances in the affected muscle group. Iatropoulos et al. (3) focused on elite sprinters and jumpers in track-and-field disciplines. The overall incidence of hamstring injury in track-and-field disciplines was calculated at 0.5 cases per 1,000 athletes with previous injury.

In addition, a study by Brockett et al. (14) involved elite and sub-elite athletes, specifically 23 Australian Football League (AFL) players and four track-and-field athletes. Participants were screened for previous injuries and categorised into two groups: those with a history of unilateral hamstring strains and uninjured athletes. It was found that the incidence of re-injury is notably higher in athletes with a previous injury history, with a recurrence rate of 34% in the Australian Football League.

Prevention strategies for hamstring injuries

Nordic hamstring exercise (NHE)

NHE may help to reduce the risk of hamstring injuries. They are often assimilated into injury prevention protocols, such as FIFA11+ (31, 32). The programme involves the subject starting in the kneeling position, with their hip in an extended position to maintain the torso upright. With the heels secured, the participant proceeds to lower themselves, only moving at the knee joint, at a constant rate until floor level. The participant then returns to the starting position (33). There are several variations of the NHE altering in difficulty and eccentric strain imposed on the hamstring, which range from additional loading to lightly rocking – reducing the angle of extension at the knee joint (34, 35, 36, 37). The effectiveness of the NHE is demonstrated in the meta-analysis carried out by Van Dyk et al. highlighting, from the RCTs included, that NHE reduces primary HMI rates by 51% (RR = 0.49, 95% CI: 0.32–0.74, P < 0.001) (38). In addition, NHE demonstrates greater efficacy in those who have experienced recurrent hamstring injuries. Petersen et al. (39) observed an 85% reduction in the rate of recurrent hamstring injuries in 49 soccer players following the NHE protocol (RR = 0.137, 95% CI: 0.037–0.509, P = 0.003).

Al Attar et al. (40), following a systematic review, reported that benefit from the NHE positively correlates with higher compliance rates compared to lower compliance rates. Current literature suggests that compliance, greater than 50%, to a structured exercise plan significantly reduces the risk of HSI (40, 41). Avoidance of hamstring injuries, through the NHE, is explained by the consequent neural and structural changes. Electromyography tests, undertaken by Delahunt et al. (42), demonstrate that the semitendinosus and BFLH activation significantly increases following a 6-week NHE training programme. Opar et al. (43) theorise that dynamic neural activation is essential in preventing hamstring injuries via its role in torque generation in the hamstring. However, participants of Delahunt et al. (42) had no previous experience of eccentric conditioning, which in the scope of previously trained populations, creates a challenge of transferability as the rate of muscular adaptation plateau in trained individuals (44). Morphologically, NHE results in greater BFLH fascicle length and hypertrophy of the hamstring muscle group (33). Fascicle length is a key variable as it provides the sarcomeres with the ability to shorten swiftly, and thus generate greater power. In the RCT performed by Presland et al. (45), controlled detraining following an initial 6 weeks NHE intervention in 20 recreationally active males illustrated the importance of adherence, as fascicle length significantly reduced within 14 days (mean = −2.5 cm, 95% CI: −3.9 to 1.1 cm, P < 0.001). This finding highlights the importance of incorporating NHEs in structured hamstring injury prevention programmes.

Hip extensor exercises

Hip extensor exercises (HEE) are an alternative form of prevention that act by eccentrically contracting the hamstrings (46). Despite the popularity of NHE within the scope of literature, hip-focused eccentric exercises have demonstrated significantly positive effects on the morphology of the hamstring (33). HEEs are usually performed unilaterally or bilaterally with the hip in 45° extension with the knees fully extended, which engages the hamstrings more so than if the knees were flexed (47). The individual will then carefully flex their hip until 90° flexion, inducing eccentric contraction, and return to their original starting position (48). Whyte et al. (48) reviewed 24 collegiate athletes who were injury-free in the prior 6 months leading to the study and assessed the effects of HEE on hamstring strength. The 4-week HEE programme included both limbs, with total repetitions increasing each week. Following the intervention, HEE resulted in an increase in eccentric peak torque of 60°·s⁻¹ in both limbs compared to pre- and post-testing; dominant (200.4 ± 42.2 to 222.8 ± 33.9 Nm, P < 0.001) and non-dominant (189.6 ± 32.5 to 213.1 Nm ± 35.4, P < 0.0001). In addition, an improvement in the functional H:Q ratio on the dominant (4.6%, P = 0.03, η² = 0.21) and non-dominant (7.1%, P = 0.01, η² = 0.26) was observed, highlighting the applications of HEE in hamstring injury prevention. However, the study only reviewed 11 HEE participants, limiting the generalisability and warranting a prospective outlook on HEE impact on injury prevention.

Importantly, despite HEE improving hamstring strength, Whyte et al. (48) demonstrated that the NHE had greater effect on hamstring strength, hindering HEE’s clinical significance. However, Messer et al. (49), using a population of recreationally active females, observed a greater BFLH response in the HEE (25.45 ± 16.94, P < 0.001) compared to the NHE (25.39 ± 13.69, P < 0.001), using functional magnetic resonance imaging (fMRI). This is theorised to be dependent on the BFLH having a larger moment arm at the hip compared to the knee (50). In addition, the semitendinosus may have a greater moment arm at the knee, hence why it is preferentially activated during the NHE compared to the HEE (50). Considering the preference of the HEE to activate the BFLH compared to exercises such as the NHE, lumbo–pelvic exercises, and dynamic stretching, it prompts further research into its application in HSI prevention (46, 51, 52).

Stretching

Stretching remains a cornerstone of many prevention protocols, primarily targeting flexibility deficits and neuromuscular control, which may help to limit the effects of the aforementioned risk factors for hamstring injuries (53). The reported stretching modalities included static, dynamic, and proprioceptive neuromuscular facilitation (PNF) (54).

Classically, static and dynamic stretching have received the most insights and are understood to improve the flexibility of the hamstrings (55, 56, 57, 58). Bandy et al. (55) demonstrated that static stretching was twice as effective in increasing the flexibility of the hamstring (11.42° ± 6.52, P < 0.015), following 6-weeks of daily 30 s bouts of stretching, compared to dynamic stretching (4.27° ± 2.67, P < 0.015). Despite improvements in the ability of the hamstring to lengthen, acute effects of static stretching have been shown to transiently impair strength potentially compromising performance in sport (53). In contrast, dynamic stretching has been shown to improve eccentric hamstring strength and neuromuscular control (59). Therefore, dynamic stretching may be more suitable as a pre-participation intervention, as it preserves performance while promoting optimal muscle–tendon compliance (60).

PNF techniques, particularly contract-relax (CR) and contract-relax-antagonist-contract (CRAC), have demonstrated efficacy in improving chronic hamstring flexibility (61). CR PNF is performed with the subject laying in the supine position with an assistant lifting one leg until mild-stretch, at which point the subject must contract isometrically for 3–10 s (62) Following the isometric contraction, the straight leg is flexed further at the hip and the contraction is repeated several times (62). CRAC PNF is performed similarly to CR PNF; however, there is an additional contracture of the antagonist hip flexors during the elevation of the leg, demonstrated to amount in greater ROM to its counterpart CR (63). Similar to static stretching, highlighted by Bradley et al. (64), pre-participatory PNF may temporarily impair explosive muscular performance in metrics such as jumping (−5.1%, P < 0.001). Effects were observed 5 min following the PNF intervention, with metrics returning to normal within 15 min. Thus, when used in injury prevention after exercise, PNF programs of 4 weeks have shown to significantly increase hamstring flexibility (65, 66). Changes in flexibility, following PNF, are postulated to be a result of autogenic inhibition via Golgi tendon organs and stress relaxation within the musculotendinous units allowing for greater lengthening of the BFLH (67, 68). However, more research is necessitated to uncover whether PNF results in significant risk reduction in hamstring injury prevention (69).

Stretching alone may be insufficient as a standalone prevention strategy; therefore, combining dynamic stretching pre-activity and PNF post-activity may balance acute performance needs with chronic flexibility adaptations. However, adherence is critical as effects are dose-dependent and require consistent implementation. Its integration with other eccentric strengthening exercises, such as NHE, provide a more comprehensive solution for reducing hamstring injury incidence.

Neuromuscular training and core muscle strength

Considering the biomechanics during dynamic activity, such as running, involvement of the core muscles is anatomically described to influence the stressors imposed on the hamstring (70). The link is observed due to the articular nature of the hamstrings, specifically the BFLH tendon, which originates from the ischial tuberosity and the sacrotuberous ligament (71). In conjunction, the external oblique muscle of the abdomen transverses the lumbar spine and attaches to pelvis, along with the internal oblique and transversus abdominis (72). Thus, the interaction of the hamstring and the core muscles with the pelvis suggests that the enhancement of the core strength will optimize pelvic control, therefore reducing strain on the hamstring, and consequently reducing risk of HSI (73).

Improving core dysfunction can ameliorate neuromuscular control of the pelvis, as demonstrated by Schuermans et al. (74) in a population of amateur male footballers who were followed up for 1.5 seasons in a prospective cohort study. Using sEMG, an increase of 10% normalised activity of the truncal (OR = 0.99, 95% CI: 0.989–0.998, P = 0.007) and glutaeal (OR = 0.98, 95% CI: 0.963–0.997, P = 0.023) muscles resulted in a risk reduction of 6 and 20% in HSI, respectively. Despite the study only focussing on acceleration with no variability in movement, emphasis on lumbo–pelvic control was highlighted. In addition, hamstring injuries mainly occur during high-speed acceleration and deceleration, specifically during the terminal swing phase of the gait cycle, when the hamstrings are at maximal stretch (75, 76). Sherry et al. (77), proposed a progressive agility and trunk stabilisation programme, which significantly reduced reinjury rates 1-year after returning to play following an acute hamstring injury (P = 0.006). The programme included side bridges, single-leg windmill touches, and trunk rotation (77), targeting the core and glutaeal muscles which are shown to reduce anterior tilt and improve neuromuscular control of the pelvis (78, 79).

Mendiguchia et al. (79) implemented a 7-week neuromuscular training protocol including core and eccentric strengthening exercises. They observed improvements in both dominant and non-dominant limbs in terms of variables such as eccentric torque ((+15.2%, 90% CI: 12.0–18.5, P < 0.05) and (+13.0%, 90% CI: 10.1–15.9, P < 0.05), respectively), and H/Q ratio (+10.0%, 90% CI: 7.3–20.4, P < 0.05), which are known modifiable HSI risk factors. Considering the study only observed male amateur footballers suggests that generalisability to females and other levels of play is limited. Therefore, there is a need to address the paucity in literature looking at the effects of a focused lumbo–pelvic programme on HSI prevention, despite deficits being understood as a risk factor.

Study limitations

This study has some important limitations. First, since it is a narrative review, the list of risk factors found to be associated with proximal hamstring injuries is non-exhaustive. Second, it is difficult to include the various classifications of hamstring injuries as outlined in the BAMIC, demonstrated in Table 1 (26).

Table 1.

British athletics muscle injury classification (BAMIC) system for hamstring muscle and tendinous injuries, organised by MRI findings and architectural disruption (26). Grades are subclassified depending on site, although type ‘c’ (tendinous) is not applicable to grade 1 tears, and for complete tears (grade 4), the distinction is made only between tears involving muscle and those solely involving the tendon.

Grade	Site	MRI findings	Architectural disruption
0	a: Focal neuromuscular injury	Normal	Nil
	b: Generalised muscle soreness	Normal or consistent with DOMS	Nil
1: Small tear	a: Myofascial (peripheral)	High STIR signal <10% CSA; longitudinal length <5 cm	<1 cm fibre disruption
	b: Myotendinous junction/muscular
2: Moderate tear	a: Myofascial (peripheral)	High STIR signal 10–50% CSA; longitudinal length 5–15 cm	<5 cm fibre disruption
	b: Myotendinous junction/muscular
	c: Tendinous
3: Extensive tear	a: Myofascial (peripheral)	High STIR signal >50% CSA; longitudinal length >15 cm	>5 cm fibre disruption
	b: Myotendinous junction/muscular
	c: Tendinous
4: Complete tear	a/b: Myofascial, muscular, or myotendinous	Discontinuity of the muscle or tendon with retraction	Complete tear
	c: Tendinous

CSA, cross-sectional area; DOMS, delayed onset muscle soreness.

Summary

Hamstring injuries are prevalent in high-speed running and kicking sports, representing between 12 and 26% of all injuries in sporting activities, eventually posing significant challenges due to their relatively high incidence and recurrence rates. This review identifies key risk factors, including previous hamstring injury, neuromuscular deficits, muscle flexibility, H:Q ratio imbalances, age, and anatomical variations. Notably, neuromuscular control issues and altered muscle recruitment patterns significantly impact injury risk. Prevention strategies such as the NHE and HEEs have shown efficacy in reducing injury rates. Compliance with these programs is crucial for effectiveness. Future research should focus on validating these strategies across diverse populations and enhancing external validity to improve injury prevention and athlete safety.

ICMJE Statement of Interest

The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the study reported.

Funding Statement

This work did not receive any specific grant from any funding agency in the public, commercial, or not-for-profit sector.

Author contribution statement

AH helped in investigation, visualisation, and writing of the original draft. AAM helped in investigation, visualisation, and writing of the original draft. BK helped in conceptualisation, supervision, and writing of the review and editing. ATY helped in writing of the review and editing. FSH helped in conceptualisation and supervision.