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. 2025 Oct 21;7(6):101295. doi: 10.1016/j.asmr.2025.101295

Increased Incidence of Hamstring Injuries in the United States From 2015 to 2024 and Projected Growth Through 2030

Samuel A Florentino a,∗, Parshva Sangvhi b, Jeremy M Adelstein a, Alexander N Berk a, Logan M Good a, Jacob G Calcei a, James E Voos a, Michael J Salata a
PMCID: PMC12800840  PMID: 41541515

Abstract

Purpose

To evaluate the epidemiology of hamstring tendon injuries in the United States from 2015 to 2024 and to project incidence trends through 2030.

Methods

Patients diagnosed with hamstring strains between 2015 and 2024 were identified using International Classification of Diseases, 10th Revision code S76.31. Data were collected using the TriNetX US Collaborative Research Platform, which includes over 120 million deidentified patient records. Incidence proportion was calculated annually. Demographic substratification by age and sex was performed, and linear regression was used to project incidence through 2030.

Results

A total of 118,197 patients with hamstring injuries were identified, with a mean age of 48.7 years; 49% were female. In 2024, hamstring injury incidence was 42.79 per 100,000 (95% confidence interval, 42.01-43.98), a significant increase from 11.61 per 100,000 (95% confidence interval, 11.28-11.94) in 2015 (P < .001). A bimodal distribution was noted, with the highest total number of injuries in adults aged 60 to 64 years and the highest incidence proportion in those aged 15 to 19 years. Under age 35 years, males had higher injury rates, while over age 35 years, females had higher rates. Projections estimate that incidence will rise to 56.2 per 100,000 by 2030 (R2 = 0.83), reflecting a 6.7% average annual increase through 2030.

Conclusions

There is a rising burden of hamstring injuries in the general population, with the highest incidence among older adults and young people. Projections based on current trends estimate that the annual incidence of these injuries will continue to rise.

Level of Evidence

Level IV, descriptive epidemiologic study.

Hamstring strains are common muscle injuries, accounting for 12% to 29% of injuries in athletes, with recurrence rates exceeding 30%.1, 2, 3, 4, 5 The hamstring muscle includes the semimembranosus, semitendinosus, and biceps femoris, which comprises both long and short heads. Injury typically occurs during the terminal swing phase of the gait cycle while sprinting, often presenting with an acute onset of posterior thigh pain.6

Diagnosis is primarily clinical, supported by findings including ecchymosis, localized tenderness, swelling, a palpable defect, and weakness with resisted hip extension or knee flexion.7,8 Radiographs are useful for detecting avulsion injuries, while magnetic resonance imaging is preferred for evaluating the extent and location of soft tissue injury.9, 10, 11 Management depends on severity: mild to moderate strains are typically treated nonoperatively with rest, ice, physical therapy, and a gradual return to activity, whereas high-grade injuries may benefit from surgical intervention to restore function and minimize long-term deficits.9,10,12,13

Contemporary literature on hamstring tendon injuries has predominantly focused on athletic and physically active populations, with studies showing hamstring tendon injuries constituting 10% to 24% of all injuries in field-based team sports.2,3,12,14,15 Furthermore, studies among athletic populations have found a rising annual incidence as these injuries become more recognized. Specifically, in men’s professional football, hamstring injury rates have increased by 6.7% annually from 2001 to 2022.2,15 However, the broader epidemiology of hamstring injuries among recreational and nonathletic populations remains poorly defined. These patterns highlight the importance of examining epidemiologic trends in the broader US population, beyond competitive athletes. The purpose of this study was to evaluate the epidemiology of hamstring tendon injuries in the United States from 2015 to 2024 and to project incidence trends through 2030. We hypothesized that our findings would show a continued rise in the annual incidence of hamstring injuries, with projections indicating further increases through 2030.

Methods

Study Design

The TriNetX US Collaborative Research Platform was used to conduct a retrospective, multicenter study examining trends in hamstring injuries in the United States. The platform has access to over 70 health care organizations and 121 million electronic patient records, comprising almost one-third of the US population. The data are entirely deidentified in accordance with §164.514(b)(1) of the Health Insurance Portability and Accountability Act Privacy Rule, using expert-certified methods such as obfuscation and minimum thresholds, guaranteeing that each query includes at least 10 individuals. As a result, it does not qualify as Protected Health Information and is not subject to Health Insurance Portability and Accountability Act or institutional review board regulations. All data in the platform are accessed through the use of insurance billing codes, including the International Classification of Diseases, 10th Revision (ICD-10) and Current Procedural Terminology codes.

Cohort Creation

All patients with hamstring tendon injuries in the research platform were identified using the ICD-10 code S76.31. Only patients in the United States were considered for analysis, and the study period was restricted from 2015 to 2024. Patients without ICD-10 code S76.31 and those outside the United States were excluded from analysis. Patients were substratified by demographic characteristics, including sex and age.

Outcomes Evaluated

The primary epidemiologic outcome evaluated was incidence proportion (IP), which was defined as the number of new hamstring strain cases diagnosed in a given year divided by the total population at risk that year. We define the total population at risk for each year as the number of unique individuals who had at least 1 health care encounter recorded in the database during that year.16 Diagnoses prior to 2015 were excluded from the analysis due to a substantial reduction in the number of health care organizations contributing data to the TriNetX platform before that year. General information on the cohort was also collected, including demographic information, comorbidities, and geographic distribution. A linear regression was performed to project the incidence of hamstring strains to 2030. This time frame was selected to maintain predictive accuracy and avoid excessive uncertainty associated with longer-term extrapolations. Model fit was assessed using R2.

Statistical Analysis

The incidence proportion was calculated using the epidemiologic tools within the TriNetX platform. A Poisson distribution was assumed to generate a 95% confidence interval (CI) for the incidence proportion values. Rates between years and demographic categories were compared using a χ2 test. A P value of less than .05 was considered significant.

Results

Cohort Characteristics

From 2015 to 2024, a total of 118,197 patients were diagnosed with a hamstring strain (Table 1). The mean age of the cohort was 48.7 ± 21.2 years. Females accounted for approximately 49% of the cohort, while males comprised 46%. Most patients were White (70%), followed by African American patients (12%). Essential hypertension was the most common comorbidity, affecting one-third of patients. Geographically, most diagnoses occurred in the Northeast (33%), closely followed by the South (30%).

Table 1.

Hamstring Strain Cohort Characteristics (n = 118,197)

Characteristic Value
Age, y 48.7 ± 21.2
Sex
 Male 51,182 (46)
 Female 54,825 (49)
 Unknown 5,600 (5)
Race
 White 77,827 (70)
 Unknown 12,288 (11)
 Black or African American 13,912 (12)
 Asian 2,590 (2)
 Other 3,883 (3)
Body mass index 28.5 ± 7.12
Comorbidities
 Nicotine dependence 8,302 (7)
 Diabetes mellitus 13,242 (12)
 Essential (primary) hypertension 34,559 (31)
 Overweight, obesity, and other hyperalimentation 21,602 (19)
 Chronic lower respiratory disease 20,999 (19)
 Acute kidney failure and chronic kidney disease 7,132 (6)
 Iron-deficiency anemia 5,344 (5)
 Metabolic syndrome 327 (<1)
Geographic distribution
 Northeast 39,835 (33)
 Midwest 27,729 (23)
 South 35,126 (30)
 West 14,992 (13)
 Unknown 1,388 (1)
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NOTE. Values are presented as n (%) or mean ± standard deviation.

Overall Trends in Hamstring Injuries

In 2024, the IP was 42.8 (95% CI, 42.0-44.0) cases per 100,000 patients, which was significantly higher than in 2015, when the IP was 11.6 (95% CI, 11.3-11.9) cases per 100,000 patients (P < .001). The IP observed a sharp increase from 2015 to 2016 (92.4%), followed by a gradual increase from 2016 to 2019. A marked decline occurred in 2020 (24.8% decrease), but values rebounded in 2021 to levels similar to 2019 and continued to rise through 2024 (Fig 1).

Fig 1.

Fig 1

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Epidemiology of hamstring strain incidence proportion per 100,000 individuals in the United States from 2015 to 2024.

Hamstring Injuries by Sex and Age

From 2015 to 2024, males had a significantly higher IP of hamstring injuries than females (P < .01). In 2024, males had an IP of 49.9 (95% CI, 48.8-51.1) cases per 100,000 patients, and females had an IP of 37.6 (95% CI, 36.6-38.6) cases per 100,000 patients (Fig 2).

Fig 2.

Fig 2

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Epidemiology of hamstring strain incidence proportion per 100,000 individuals in the United States by sex from 2015 to 2024.

When stratified by age, IP was significantly increased among all age groups when comparing values between 2015 and 2024 (P < .01). Regarding IP, the 15- to 19-year age group experienced the highest IP, with 78.8 (95% CI, 74.7-82.9) cases per 100,000 patients, followed by the 65- to 69-year age group, which had an IP of 57.8 (95% CI, 54.8-60.8) cases per 100,000 patients (Fig 3).

Fig 3.

Fig 3

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Epidemiology of hamstring strain incidence proportion per 100,000 individuals in the United States from 2015 to 2024 by age group.

An analysis of male and female rates stratified by age from 2015 to 2024 observed that female patients between the ages of 60 and 64 years experienced the highest total number of hamstring injury cases (208.8 cases per 100,000 patients; 95% CI, 203.4-214.2), followed by males between the ages of 10 and 14 years (198.6 cases per 100,000 patients; 95% CI, 193.1-204.0). In contrast, among females, patients between the ages of 20 and 24 years experienced the lowest number of hamstring strains (49.6 cases per 100,000 patients; 95% CI, 47.3-51.9), while males older than 85 years experienced the lowest rate of hamstring strains (55.6 cases per 100,000 patients; 95% CI, 48.3-63.2) (Fig 4).

Fig 4.

Fig 4

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Epidemiology of hamstring strain by total number of hamstring strains per 100,000 individuals in the United States from 2015 to 2024 by age and sex.

Projected Incidence of Hamstring Injuries

A linear regression model was used to project the incidence of hamstring strains through 2030 and was shown to have a coefficient of determination of R2 = 0.83. Based on the projected model, the incidence of hamstring injuries will rise to 56.2 (95% CI, 48.6-63.8) cases per 100,000 patients, an increase of 6.7% on average annually from 2024 (Fig 5).

Fig 5.

Fig 5

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Linear regression model projecting the incidence of hamstring injuries through 2030. (CI, confidence interval; IP, incidence proportion; SE, standard error.)

Discussion

From 2015 to 2024, the incidence proportion of hamstring injuries in the United States rose from 11.6 to 42.8 cases per 100,000 patients, with males consistently experiencing higher rates than females and marked variation by age. The incidence of hamstring injuries showed a consistent upward trend over the study period. In 2024, the IP was 42.8 per 100,000 (95% CI, 42.0-44.0), significantly higher than values 10 years prior. Projections based on current trends estimate that the annual incidence of these injuries will continue to rise, reaching an incidence of 56.2 per 100,000 (95% CI, 48.6-63.8) by 2030. These findings identify a growing burden of hamstring injuries across the general population and also underscore the need for widespread awareness, recognition, and the implementation of effective treatment and prevention strategies at the population level.

A key finding of this study was the marked increase in the incidence proportion of hamstring injuries across the US population between 2015 and 2024. Specifically, IP increased by an average of 18% annually. Similarly, Laszlo et al.17 reported a nationwide increase in hamstring injury incidence in Sweden, from 2.2 to 7.3 per 100,000 person-years between 2001 and 2020, alongside a growing proportion of operatively treated cases. While their study focused on surgically managed injuries within the Swedish health care system, our findings build on this trend by capturing both operative and nonoperative cases across a broader US population. This reinforces the notion that hamstring injuries are not simply becoming more common but are also increasingly recognized and treated in diverse clinical settings. In further support of our findings, additional studies, limited to athletic populations, have also documented rising injury rates, with reported annual incidence increases of 6.7% from 2001 to 2022. In prior studies analyzing hamstring injuries in athletes, the increased incidence of hamstring injuries was attributed to increases in athlete strength, muscle mass, and sprinting speed across all levels of competition.2,12 Given that our study includes a more generalized population, capturing injuries across a wider spectrum of ages and activity levels, the observed increase in injuries may reflect several contributing factors. Rather than an isolated rise in the biological incidence of hamstring injuries, it is likely that improvements in clinical recognition, greater awareness among both patients and providers across demographic groups, and advancements in diagnostic tools such as magnetic resonance imaging and musculoskeletal ultrasound have played a substantial role.18 These tools, in combination with clinical suspicion, have made it easier to detect injuries that may have previously gone unrecognized or been misattributed to other causes of posterior thigh pain.11,18,19 Additionally, evolving treatment paradigms and documentation practices may contribute to increased coding and reporting, further contributing to the apparent incidence in large data sets.20,21 Taken together, these trends suggest that what may appear to be a rise in hamstring injuries could reflect our growing ability to detect and report them.

Furthermore, a bimodal distribution in hamstring injury incidence was identified, with the greatest burden observed in adolescent males and older adults. Our findings show that a substantial burden of injury occurs outside the traditional age range of high-level sports participation, despite most epidemiologic studies of hamstring strain injuries focusing on young athletes. Specifically, previous research has documented hamstring injury incidence in professional soccer, Australian football, rugby, and National Collegiate Athletic Association athletics.2,14,22, 23, 24, 25 However, our data show that individuals in their 20s and early 30s, ages typically associated with peak athletic performance, had among the lowest injury rates. Rather, this large population study showed that hamstring injury from 2015 to 2024 was most common among adults aged 60 to 64 years (205.5 per 100,000) and exceeded 150 per 100,000 in the age groups between 40 and 75 years, as well as among those aged 10 to 14 years. In addition, the 15- to 19-year age group had the highest incidence (78.8 per 100,000), followed by the 65- to 69-year age group (57.8 per 100,000). This distribution highlights 2 distinct vulnerable populations: highly active youth and aging adults, particularly those in the seventh decade of life. These findings are consistent with and expand upon prior work by Kuske et al.,26 who reported a similar bimodal pattern in a smaller cohort of 144 hamstring injuries, with elevated incidence among females younger than 15 years and individuals older than 40 years. The higher incidence of hamstring injuries among younger populations aged 10 to 19 years may in part be attributed to increasing participation in organized sports and the trend of sports specialization in this age group, which can place repetitive stress and elevate injury risk.27,28 Furthermore, an increase in activity levels among adults aged 65 years or older further supports an increasing incidence of sports-related orthopaedic injuries in the older population.29 Our nationally representative data set strengthens and expands upon the previously observed bimodal distribution across the broader population, offering a more robust epidemiologic understanding of hamstring injury patterns. Importantly, this dual peak in incidence calls for tailored prevention strategies, such as neuromuscular training and flexibility programs for youth athletes, and targeted interventions for older adults, including physical activity guidance and rehabilitation programs addressing age-related muscle imbalances.

In addition to the bimodal distribution observed, distinct age- and sex-specific patterns identified in this study further highlight important demographic considerations. Among individuals younger than 35 years, males consistently exhibited a higher incidence of hamstring injuries. This aligns with findings from a study of National Collegiate Athletic Association athletes, which reported a higher proportion of hamstring injuries in men.22 However, beyond age 35 years, this trend reversed, with females showing higher incidence proportions in older age cohorts. Supporting this pattern, a Swedish registry study of 7,268 patients similarly found that women aged 40 to 59 years had a higher proportion of hamstring injuries, although specific values were excluded.17 While not previously explored, this shift may reflect previously studied differences in physical activity patterns and health care-seeking behavior between sexes, as older women have been both more active and seek health care more frequently.29, 30, 31, 32

A marked decline in hamstring injury incidence was observed in 2020, likely due to multiple factors. First, widespread cancellations and modifications of organized sport at all levels of play due to the COVID-19 pandemic significantly reduced exposure to the high-intensity physical activities that typically precipitate hamstring injuries.33 Second, health care utilization patterns shifted during this period, with many individuals deferring or avoiding medical care for nonurgent conditions due to concerns about viral exposure or resource limitations.34 Third, reduced physical activity during lockdowns may have contributed to fewer activity-related injuries.35 Collectively, these factors likely contributed to the transient dip in hamstring injury incidence seen in 2020.

This study provides a comprehensive analysis of hamstring injury epidemiology and includes projections of future incidence. Our nationally representative data set strengthens the evidence base on age-specific injury patterns and enables the projection of future trends. Based on our logistic regression model, the incidence of hamstring injuries is expected to rise to 56.2 per 100,000 individuals by 2030 (95% CI, 48.6-63.8), underscoring a public health concern. Importantly, the rising incidence identified the need for targeted prevention strategies, such as neuromuscular training and flexibility programs for youth athletes, as well as physical activity counseling and age-specific rehabilitation for older adults.36,37

Limitations

The results of this study should be interpreted in the context of its limitations. As a retrospective database study using ICD-10 coding, our findings are subject to coding errors and misclassification bias, which may lead to under- or overestimation of true injury rates. The ICD-10 code S76.31 may encompass hamstring tendon tendinopathy, partial tears, or complete tears, which limits diagnostic specificity and may partly explain higher rates in older adults. Further, ICD coding does not allow any further specification of the anatomic site of the hamstring injury to directly determine the incidence of proximal versus distal injuries. Additionally, the database does not capture the entirety of the US population, which may limit the generalizability of the findings and potentially underestimate the national burden of hamstring injuries. Furthermore, while the data set provides insight into injury incidence, it lacks granularity regarding injury mechanism, severity, laterality, and activity at the time of injury. These factors are critical for deeper clinical interpretation. Demographic information, such as race and comorbidities, may also be inconsistently reported across contributing institutions.

Conclusions

There is a rising burden of hamstring injuries in the general population, with the highest incidence among older adults and young people. Projections based on current trends estimate that the annual incidence of these injuries will continue to rise.

Disclosures

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: J.G.C. is a consultant or advisor for Smith & Nephew. J.E.V. is a consultant or advisor for Johnson & Johnson AG Switzerland and Arthrex. M.J.S. is a consultant or advisor for Stryker. All other authors (S.A.F., P.S., J.M.A., A.N.B., L.M.G.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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