Strain Injury Research Articles

Hamstring activation deficits in different jumping directions in athletes with a history of hamstring strain injuries: a cross-sectional laboratory study

ABSTRACT This study aimed to investigate the hamstring onset time and recruitment level during jumping tasks in athletes with chronic hamstring strain injuries. Thirteen hamstring injured athletes and thirteen matched healthy athletes were recruited. Activation onset time and muscle recruitment (median frequency of the EMG) of the lateral hamstring (LH) and medial hamstring (MH) was measured during double leg jumps in vertical and horizontal directions on the force platforms. The peak vertical ground reaction force and loading rate were obtained for all jumps. The injured group showed a delayed onset time (p = 0.029) and a lower recruitment of the LH during the landing (p = 0.018) than the control group. Activation deficits in the injured group led to a higher landing force and loading rate. Additionally, the LH and MH were lesser recruited in the vertical direction than the horizontal directions in the landing. In conclusion, athletes with hamstring injuries show hamstring activation deficits of the injured leg during jumping leading to degrading jump-landing performance. Also, jumping in different directions play a role to modify the recruitment of the hamstrings in the injured athletes. Therefore, movement plane is suggested to be considered in clinical rehabilitation for the hamstring injury.

Does a history of childbirth impact injury prevalence and mental health in female military members?

The effect of parity status on the prevalence and impact of musculoskeletal injury (MSKi) among female Canadian Armed Forces (CAF) members is unknown. This study aims to identify whether a history of childbirth and pregnancy-related complications are associated with MSKi occurrence among female members of the CAF. From September 2020 to February 2021, data were collected via an online questionnaire that assessed MSKi, reproductive health, and barriers to recruitment and retention in the CAF. Actively serving, female members were included in this analysis stratified by parous (n=313) or nulliparous (n=435) status. Descriptive analysis and binary logistic regressions were used to identify prevalence and adjusted odds ratios (aOR) of repetitive strain injuries (RSI), acute injuries, and body regions affected. Covariates included in aOR: age, body mass index, and rank. A p valueof <0.05 was considered significant and 95% confidence intervals (CI) were reported. Female members with a history of childbirth were more likely to report an RSI (80.9%vs. 69.9%, OR = 1.57, CI: 1.03 to 2.40), and when stratified by body region, were more likely to have an RSI of the wrist (30.0%vs. 20.5%, aOR = 1.62, CI: 1.09 to 2.40), and foot (39.3%vs. 24.1%, aOR = 1.79, CI: 1.24 to 2.59). When compared to the nulliparous group, parity did not influence prevalence of acute injuries. MSKi and mental health perceptions were different for females who experienced postpartum depression, miscarriage, or preterm birth. Childbirth and pregnancy-related complications impact prevalence of some RSI among female CAF members. Thus, specific health and fitness support may be needed for parous female CAF members.

Speed Matters in Nordic Hamstring Exercise: Higher Peak Knee Flexor Force during Fast Stretch-Shortening Variant Compared to Standard Slow Eccentric Execution in Elite Athletes.

Hamstring strain injuries are prevalent in many sports. Research has demonstrated that the Nordic hamstring exercise (NHE), a knee-dominant exercise addressing the posterior chain muscles, can aid in reducing the risk of hamstring injuries in athletes. However, most research on hamstring injury prevention has focused on performing the eccentric version of the NHE (NHEECC). In contrast, in sports, it is quite frequent for athletes to use an eccentric-concentric version of the NHE. Additionally, eccentric NHE is typically performed using a slow, controlled tempo. The effect of a fast stretch-shortening cycle NHE (NHESSC) compared to standard slow NHEECC on peak knee flexor force has not been investigated. The aim of the study was therefore to investigate fast NHESSC vs. standard slow NHEECC. Our hypothesis posited that peak knee flexor force would be greater for fast NHESSC compared with standard slow NHEECC. The study involved 22 elite athletes (actively competing in both national and international events) consisting of female (n = 10) and male (n = 7) track and field athletes and male football players (n = 5), aged 17-31 years. The participants performed maximum trials of slow NHEECC and fast NHESSC repetitions in which measurement of bilateral peak knee flexor force was conducted at the ankle with the use of a load cell. During the NHEs, a linear encoder was used to measure both the position where the peak knee flexor force was recorded and the average eccentric velocity. SSC contributed to an enhanced NHE performance, where bilateral absolute peak knee flexor force was 13% higher for fast NHESSC vs. standard slow NHEECC (822 vs. 726 N, p < 0.01, ES = 0.54). Participants achieved a 32% greater forward distance at the breakpoint stage during NHEECC compared to the coupling phase for NHESSC (54 vs. 41 cm, p < 0.001, ES = 1.37). Eccentric average velocity was more than three times higher for NHESSC compared with NHEECC (0.38 vs. 0.12 m/s, p < 0.001, ES = 3.25). The key findings of this study were that SSC contributed to an enhanced NHE performance, where absolute peak knee flexor force was 13% greater for fast NHESSC compared to standard slow NHEECC. The fast NHESSC could therefore be an interesting alternative to the standard slow NHEECC execution, as it may offer potential advantages for sprint performance, as well as hamstring injury prevention and rehabilitation.

Changes in Amplitude of Hamstring Electromyographic Activity and Its Peak Location During Nordic Hamstring Exercise by Adding External Load

This crossover trial aimed to investigate whether additional loading of unilateral Nordic hamstring exercise on a sloped platform would increase the biceps femoris long head electromyographic activity. Participants were randomly allocated to unilateral Nordic hamstring exercise under three conditions: bodyweight only (BW) or BW with an added weighted ball of 3 kg (BW + 3 kg) or 6 kg (BW + 6 kg), respectively. The biceps femoris long head electromyographic activity was significantly higher for BW + 6 kg (p &lt; .001) than for BW and BW + 3 kg (p &lt; .01). Therefore, adding a load to unilateral Nordic hamstring exercise on a sloped platform might be effective for rehabilitation and prevention of hamstring strain injury recurrence.

The effects of hip- vs. knee-dominant hamstring exercise on biceps femoris morphology, strength, and sprint performance: a randomized intervention trial protocol

BackgroundThe hamstrings are an important muscle group that contribute to horizontal force during sprint acceleration and are also the most injured muscle group in running-based sports. Given the significant time loss associated with hamstrings injury and impaired sprinting performance following return to sport, identifying exercises that drive adaptations that are both protective of strain injury and beneficial to sprint performance is important for the strength and conditioning professional. This paper describes the study protocol investigating the effects of a 6-week training program using either the hip-dominant Romanian deadlift (RDL) or the knee-dominant Nordic hamstring exercise (NHE) on hamstring strain injury risk factors and sprint performance.MethodsA permuted block randomized (1:1 allocation) intervention trial will be conducted involving young, physically-active men and women. A target sample size of 32 will be recruited and enrolled participants will undergo baseline testing involving extended-field-of-view ultrasound imaging and shear wave elastography of the biceps femoris long head muscle, maximal hamstrings strength testing in both the RDL and NHE, and on-field sprint performance and biomechanics. Participants will complete the 6-week training intervention using either the RDL or NHE, according to group allocation. Baseline testing will be repeated at the end of the 6-week intervention followed by 2 weeks of detraining and a final testing session. The primary outcome will be regional changes in fascicle length with secondary outcomes including pennation angle, muscle cross sectional area, hamstring strength, and maximal sprint performance and biomechanics. An exploratory aim will determine changes in shear wave velocity.DiscussionDespite extensive research showing the benefits of the NHE on reducing hamstring strain injury risk, alternative exercises, such as the RDL, may offer similar or potentially even greater benefits. The findings of this study will aim to inform future researchers and practitioners investigating alternatives to the NHE, such as the RDL, in terms of their effectiveness in reducing rates of hamstring strain injury in larger scale prospective intervention studies.Trial RegistrationThe trial is prospectively registered on ClinicalTrials.gov (NCT05455346; July 15, 2022).

Additive Manufacturing and Upper-Limb Orthoses: A Scoping Review

ABSTRACT Introduction Additive manufacturing has the potential to revolutionize the orthotic fabrication process for health professionals. Although there is evidence to suggest the benefits of additive manufacturing in rehabilitation-related fields, there is still fairly limited evidence supporting the use of 3D-printed orthoses as an effective and feasible alternative to manually fabricated devices used for the upper limb (UL). The purpose of this scoping review was to examine how 3D printers are currently being used in UL orthotic fabrication within the scope of rehabilitation professionals. Methods A literature search was conducted using five databases from 2011 to 2021. Two independent researchers reviewed the abstracts and full text of the articles. The PRISMA process was used to report findings, and data extraction and charting were completed according to the JBI-suggested scoping review protocol. Results Thirty-three studies were reviewed as determined by inclusion criteria from various disciplines and countries. Eight diagnostic categories identifying indications for use were derived from the studies including arthritic conditions, burns/contractures and wound care, finger deformities, neurological and neuromuscular disorders, and traumatic, strain, and nerve injuries. Both benefits and challenges are identified with the use of 3D-printed orthoses. Conclusions The scope of the 3D-printed orthoses produced in this review is broad and internationally widespread. More evidence is needed to determine the effectiveness of 3D-printed orthoses for each of the identified conditions, but the benefits outside of healing are obvious. The current state of the evidence suggests that this technology remains exploratory in respect to UL orthoses and is therefore not yet ready to be implemented in clinics. With appropriate supports and more evidence, 3D printing still has the potential to revolutionize the UL orthotic fabrication process. Clinical Relevance It may be unrealistic for rehabilitation professionals to design and fabricate 3D-printed orthoses without the proper education or time, but it is important for health care professionals to have an emphasized presence in this conversation, as it is their responsibility to treat the patients. This suggests that co-design, combining professionals' expertise, might be the best approach to fabricating these devices for patients.

Work-related musculoskeletal symptoms among Saudi radiologists: a cross-sectional multi-centre study

BackgroundMusculoskeletal disorders are common health problems worldwide. Several factors cause these symptoms, including ergonomics and other individual considerations. Computer users are prone to repetitive strain injuries that increase the risk of developing musculoskeletal symptoms (MSS). Radiologists are susceptible to developing MSS because they work long hours analysing medical images on computers in an increasingly digitalised field. This study aimed to identify the prevalence of MSS among Saudi radiologists and the associated risk factors.MethodsThis study was a cross-sectional, non-interventional, self-administered online survey. The study was conducted on 814 Saudi radiologists from various regions in Saudi Arabia. The study's outcome was the presence of MSS in any body region that limited participation in routine activities over the previous 12 months. The results were descriptively examined using binary logistic regression analysis to estimate the odds ratio (OR) of participants who had disabling MSS in the previous 12 months. All university, public, and private radiologists received an online survey containing questions about work surroundings, workload (e.g., spent at a computer workstation), and demographic characteristics.ResultsThe prevalence of MSS among the radiologists was 87.7%. Most of the participants (82%) were younger than 40 years of age. Radiography and computed tomography were the most common imaging modalities that caused MSS (53.4% and 26.8%, respectively). The most common symptoms were neck pain (59.3%) and lower back pain (57.1%). After adjustment, age, years of experience, and part-time employment were significantly associated with increased MSS (OR = .219, 95% CI = .057–.836; OR = .235, 95% CI = 087–.634; and OR = 2.673, 95% CI = 1.434–4.981, respectively). Women were more likely to report MSS than males (OR = 2.12, 95% CI = 1.327–3.377).ConclusionsMSS are common among Saudi radiologists, with neck pain and lower back pain being the most frequently reported symptoms. Gender, age, years of experience, type of imaging modality, and employment status were the most common associated risk factors for developing MSS. These findings are vital for the development of interventional plans to reduce the prevalence of musculoskeletal complaints in clinical radiologists.

Risk factors for hamstring strain injury in male college American football players -a preliminary prospective cohort study-

BackgroundGiven the frequency of hamstring strain injuries (HSI) among male college American football players, several studies have attempted to determine whether certain risk factors can predict their occurrence. However, no consensus on modifiable risk factors for HSIs in male college American football players has yet been reached to prevent these injuries. This study aimed to clarify risk factors for HSI prospectively in college male American football players.MethodsA total of 78 male college American football players, whose positions were limited to skill positions, were medically assessed for potential risk factors of HSI. The preseason medical assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability.ResultsHSI occurred in a total of 25 thighs from 25 players (32.1%). Injured players had significantly lower hamstring flexibility (p = 0.02) and hamstring to quadriceps strength ratio (H/Q) (p = 0.047) compared to uninjured players. Additionally, injured players had significantly lower general joint laxity scores, especially for the total (p = 0.04), hip (p = 0.007), and elbow (p = 0.04) scores, compared to uninjured players.ConclusionsLower hamstring flexibility, lower hamstring to quadriceps strength ratio, and lower general joint laxity score were identified as risk factors for HSI in male college American football players placed in skill positions. The muscle flexibility and H/Q ratio could be useful in preventing HSI in such players.

Industrial Ergonomic Application of Preventing Repetitive Strain Injury to Optimize Work Productivity

Working with excessive repetitive motions experiencing pain is called repetitive strain injury (RSI). Pain is the result of over-moving muscles, nerves, ligaments and tendons. With the occurrence of pain it makes work productivity not optimal. To prevent repetitive strain injuries, it is necessary to make ergonomic adjustments at work. This scientific writing method uses descriptive literature studies. The main purpose of this paper is to understand the ergonomic requirements so as to prevent repetitive strain injury. With repetitive strain injury (RSI) can be prevented with an ergonomic approach, then productivity will be optimal

Descriptive and temporal trend analysis of LER/DORT Cases in Brazil from 2012 to 2021

The Repetitive Strain Injury (RSI) or Work-related Musculoskeletal Disorders (WMSDs) are labor misfortunes that affect thousands of workers in Brazil, capable of causing irreversible sequelae, depending on the severity of the accident and the conditions in which the work is performed. In this context, this research aims to conduct a quantitative descriptive study to evaluate the most incident cases of work-related musculoskeletal disorders in Brazil from 2012 to 2021. The proposed method was based on a descriptive analysis along with a linear regression model to capture the trend of major occupational ICDs over ten years. The cases of work-related musculoskeletal disorders analyzed showed a reduction throughout the period, and the most common pathologies are upper limb injuries, especially back pain, which resulted in an average of 24.7 thousand accidents per year. Thus, it is recommended to adopt more effective preventive measures in order to reduce the statistics of accidents caused by work-related musculoskeletal disorders in the country.

Biceps Femoris Fascicle Behavior during Submaximal and Maximal Slow Speed Contractions.

The present study compared the effects of contraction intensity (submaximal vs maximal) and mode (concentric vs eccentric) on biceps femoris long head (BFlh) fascicle lengthening, rotation, and architectural gear ratio at long and short muscle lengths. Data were captured from 18 healthy adults (10 men and 8 women) without history of right hamstring strain injury. BFlh fascicle length ( Lf ), fascicle angle (FA), and muscle thickness (MT) were assessed in real time using two serially aligned ultrasound devices while submaximal and maximal concentric and eccentric isokinetic knee flexions were performed at 30°·s -1 . Ultrasound videos were exported and edited to create a single, synchronized video, and three fascicles were analyzed through the range of motion (10° to 80°). Changes (Δ) in Lf , FA, MT, and muscle gear at long (60° to 80° knee angle; 0° = full knee extension) and short (10° to 30°) muscle lengths and across the full knee flexion range were measured and compared. Greater Δ Lf was observed at long muscle length ( P < 0.001) during both submaximal and maximal eccentric and concentric contractions. When the full length range was analyzed, a slightly greater ΔMT was observed in concentric contractions ( P = 0.03). No significant differences between submaximal and maximal contractions were observed for Δ Lf , ΔFA, or ΔMT. No changes were detected in the calculated muscle gear between muscle lengths, intensities, or conditions ( P > 0.05). Although gear ratio ranged ~1.0 to 1.1 under most conditions, the increased fascicle lengthening observed at long muscle lengths might influence acute myofiber damage risk but also speculatively play a role in chronic hypertrophic responses to training.

Relationship between shear elastic modulus and passive muscle force in human hamstring muscles using a Thiel soft-embalmed cadaver.

Assessing muscle flexibility and architecture is important for hamstring strain injury (HSI) prevention. We investigated the relationship between shear modulus and passive force in hamstring muscles at different sites and the effect of muscle architecture on the slope of the shear modulus-passive force using shear wave elastography (SWE). The biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) muscles were dissected from nine Thiel-embalmed cadavers and fixed to a custom-made mechanical testing machine. Calibrated weights (0-1800g) were applied gradually in 150-g increments. The shear modulus and anatomical cross-sectional area (ACSA) were measured at proximal, central, and distal points using SWE. The muscle mass and length were measured before the loading test. The shear modulus-passive load relationship of each tested muscle region was analyzed by fitting a least-squares regression line. The increase in shear modulus slope per unit load was calculated and compared between the muscles before and after normalization by the muscle mass, length, and ACSA. The shear modulus and passive force for all hamstring muscles in each region showed a statistically significant linear correlation. Furthermore, the increase in shear modulus slope was greater for BFlh and ST than for SM (P < 0.05), but after normalization by the muscle length and ACSA, there were no significant differences among the muscles. The local mechanical properties of individual hamstring muscles can be indirectly estimated using SWE, and the slope of increase in shear modulus reflects characteristics of the muscle architecture.

SCS 5th Annual Conference. São Paulo, Brazil, 2022

On behalf of the Strength and Conditioning Society (SCS) and the Nucleus of High Performance in Sport (NAR), we are pleased to present the abstracts of the SCS 5th Annual Conference, which, for the first time, took place outside of Europe. The event was held at NAR's state-of-the-art facilities in São Paulo, Brazil, on 3-5 November 2022, and comprised several invited sessions from international and national speakers on a variety of topics related to strength and conditioning practices and their application to health, injury prevention and sports performance. These included strength training in high-performance sports and older adults, sleep and recovery in elite athletes, performance optimization of the female athlete, high-intensity interval training, velocity-based resistance training, and running and cycling biomechanics, among others. The Conference also included different practical workshops conducted by renowned academics and practitioners on post-competition recovery strategies, plyometric training, hamstring strain injuries in soccer, and resisted sprint training. Finally, the event disseminated up-to-date strength and conditioning research by providing practitioners and researchers with the opportunity to present their most recent findings. In this regard, all abstracts of the communications presented at the SCS 5th Annual Conference can be found in this Conference Report.

Low Pre-Season Hamstring-to-Quadriceps Strength Ratio Identified in Players Who Further Sustained In-Season Hamstring Strain Injuries: A Retrospective Study from a Brazilian Serie A Team

A common pre-season injury prevention assessment conducted by professional football clubs is the hamstring-to-quadriceps (H:Q) strength ratio calculated by peak torque (PT). However, it is debatable whether players that present low pre-season H:Q ratios are more susceptible to further sustaining in-season hamstring strain injuries (HSI). Based upon retrospective data from a Brazilian Serie A football squad, a particular season came to our attention as ten out of seventeen (~59%) professional male football players sustained HSI. Therefore, we examined the pre-season H:Q ratios of these players. H:Q conventional (CR) and functional (FR) ratios, and the respective knee extensor/flexor PT from the limbs of players further sustaining in-season HSI (injured players, IP) were compared to the proportional number of dominant/non-dominant limbs from uninjured players (UP) in the squad. FR and CR were ~18-22% lower (p < 0.01), whereas quadriceps concentric PT was ~25% greater for IP than UP (p = 0.002). Low scores of FR and CR were correlated (p < 0.01) with high levels of quadriceps concentric PT (r = -0.66 to -0.77). In conclusion, players who sustained in-season HSI had lower pre-season FR and CR compared to UP, which appears to be associated with higher levels of quadriceps concentric torque than hamstring concentric or eccentric torque.

Successful Repair of M. obliquus Internus Abdominis Avulsion at the Iliac Crest—Operative Technique in Professional Soccer Players

Sports related injuries to the anterolateral abdominal wall have been described as side strain injuries or hip pointer. So far, only a few cases of avulsion injuries of the m. obliquus internus abdominis muscle from the iliac crest have been described. All were treated conservatively. The aim of this study is to present the surgical technique. This report presents three cases of professional soccer players who were treated surgically with transosseous reattachment to the iliac crest. These male players were 23, 25, and 29 years old. Two of them suffered a direct contusion and one an indirect injury. The diagnosis was suspected based on the patient's history and clinical examination and confirmed by MRI. In each case, the fibrocartilaginous layer of the m. obliquus internus was separated 2cm from the iliac crest. All three players were operated by aponeurotic m. obliquus internus refixation to the lateral iliac crest (three transosseous drill holes). Return to play was 55, 60, and 122 days postoperatively. Functional limitations, symptoms, sports/recreational activities, and quality of life in terms of occupational, social, emotional, and lifestyle concerns were measured using the iHOT 12 instrument at 11.1 and 9.7 years postoperatively. Six weeks postoperatively, sport-specific training was started. After 2 to 4 months, all three patients were fully reintegrated into their elite sports and unrestricted sports ability was achieved. Long-term follow-up was performed using the German version of the iHOT-12 questionnaire and 92.7% and 99.9% were calculated for the two German speaking soccer players. Our cases demonstrate that transosseous suture reattachment was a successful procedure that allowed a safe and predictable return to sport. Full performance and excellent, long lasting treatment results were achieved.

Prevalence of vertical movement asymmetries at trot in Standardbred and Swedish Warmblood foals.

Many horses, just before and during their athletic career, show vertical movement asymmetries, to the same degree as clinically lame horses. It is unknown whether these asymmetries are caused by pain or have alternative explanations, such as inherent biological variation. In the latter case, movement asymmetries would be expected to be present at a very young age. This study aimed to investigate the prevalence of movement asymmetries in foals. Motion analysis, using an inertial measurement unit-based system (Equinosis), was performed on 54 foals (31 Swedish Warmbloods, 23 Standardbreds) during straight-line trot. The foals were between 4-13 weeks old and considered sound by their owners. Differences between the vertical minimum and maximum values recorded for the head (HDmin, HDmax) and pelvis (PDmin, PDmax) between left and right stance were calculated for each stride and an average was computed for each trial. Thresholds for asymmetry were defined as absolute trial mean >6 mm for HDmin and HDmax, and >3 mm for PDmin and PDmax. These thresholds were exceeded for one or several parameters by 83% of Standardbred foals and 45% of Swedish Warmblood foals, demonstrating surprisingly high prevalence of asymmetries in young foals, although the risk of repetitive strain injuries and cumulative risk of trauma injuries was expected to be low in this age group. Standardbred foals showed similar prevalence of asymmetries to that reported previously for yearling Standardbred trotters, so relatively higher prevalence of movement asymmetries may be expected among trotters as a breed. In general, vertical head and pelvic movement asymmetries can be anticipated among foals considered sound by their owners. A better understanding of the aetiology of asymmetries is needed for correct interpretation of objective symmetry measurements in different populations of horses.

Prevalence of Contralateral Internal Oblique Strain in Recreational Fast Bowlers

Background:Side strain injuries in cricketers have increased in recent years. An internal oblique strain occurs most commonly in fast bowlers and is the second most common injury among them. Young bowlers are more prone to internal oblique strain injury. The aim of this research was to investigate the prevalence of contralateral internal oblique strain in recreational fast bowlers. Method:Random sampling method was used in this study which consisted of 43 participants who were selected on the basis of inclusion and exclusion criteria. The collected data included demographic data and responses to a questionnaire. Result: Based on the statistical analysis, it was found that contralateral internal oblique strain is prevalent among recreational fast bowlers and was considered extremely significant (p &lt; 0.0001). Overall, 45.56% of the respondents were aware of this injury. Conclusion: We found a high prevalence of contralateral internal oblique strain in recreational fast bowlers in this study.

Short-term Effectiveness of High-intensity Laser Therapy in De Quervain Tenosynovitis: A Prospective, Randomized, Controlled Study.

The effectiveness of high-intensity laser therapy (HILT) has been demonstrated in some musculoskeletal repetitive strain injury disorders. This study aimed to determine the short-term effectiveness of HILT in de Quervain tenosynovitis (DQT). Sixty-four patients with DQT diagnosis (32 males, 32 females; 18-65 years) were randomly divided into two groups. A short opponens splint was applied to both groups and HILT to the treatment group and sham HILT to the control group once a day, on alternate days, 3 days a week, for 5 weeks. Pre- and post-treatment evaluations were made using a visual analog scale (VAS); Quick Disabilities of the Arm, Shoulder, and Hand questionnaire; Short Form-36 Health Survey; and hand grip strength test. The demographic results (age, gender, duration of complaint, body mass index, occupational group) of both groups were similar (p>0.05). The pre-treatment measured values were similar in both groups (p>0.05). After a 5-week treatment, a significant improvement was observed in all parameters in both groups. Post-treatment, hand grip strength levels were statistically higher in the HILT group than in the sham therapy group, and VAS levels were significantly lower (p<0.001). HILT is a non-invasive and reliable method that increases grip strength and decreases pain in DQT.

Are Football Players More Prone to Muscle Injury after COVID-19 Infection? The “Italian Injury Study” during the Serie a Championship

Football was the first sport to resume competitions after the coronavirus disease 2019 (COVID-19) lockdown and promptly the hypothesis was raised of a potential relationship between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and musculoskeletal injuries in athletes. This study aimed to confirm the association between SARS-CoV-2 infection and muscle strain injury in a large population of elite football players and to investigate if the COVID-19 severity level could affect the risk of injury. A retrospective cohort study involving 15 Italian professional male football teams was performed during the Italian Serie A 2020-2021 season. Injuries and SARS-CoV-2 positivity data were collected by team doctors through an online database. Of the 433 included players, we observed 173 SARS-CoV-2 infections and 332 indirect muscle strains. COVID-19 episodes mostly belonged to severity level I and II. The injury risk significantly increased after a COVID-19 event, by 36% (HR = 1.36, CI95% 1.05; 1.77, p-value = 0.02). The injury burden demonstrated an 86% increase (ratio = 1.86, CI95% 1.21; 2.86, p-value = 0.005) in the COVID-19 severity level II/III versus players without a previous SARS-CoV-2 infection, while level I (asymptomatic) patients showed a similar average burden (ratio = 0.92, CI95% 0.54; 1.58, p-value = 0.77). A significantly higher proportion of muscle-tendon junction injuries (40.6% vs. 27.1%, difference = 13.5%, CI95% 0.002%; 26.9%, p-value = 0.047) was found when comparing level II/III versus Non-COVID-19. This study confirms the correlation between SARS-CoV-2 infection and indirect muscle injuries and highlights how the severity of the infection would represent an additional risk factor.

Should We Use the Men Load–Velocity Profile for Women in Deadlift and Hip Thrust?

Injuries are common in team sports and can impact both team and individual performance. In particular, hamstring strain injuries are some of the most common injuries. Furthermore, hamstring injury ratios, in number of injuries and total absence days, have doubled in the last 21 seasons in professional soccer. Weakness in hip extensor strength has been identified as a risk factor in elite-level sprinters. In addition, strength imbalances of the hamstring muscle group seem to be a common cause of hamstring strain injuries. In this regard, velocity-based training has been proposed to analyze deficits in the force-velocity profile. Previous studies have shown differences between men and women, since there are biomechanical and neuromuscular differences in the lower limbs between sexes. Therefore, the aim of this study was to compare the load-velocity profile between males and females during two of the most important hip extension exercises: the hip thrust and the deadlift. Sixteen men and sixteen women were measured in an incremental loading test following standard procedures for the hip thrust and deadlift exercises. Pearson's correlation (r) was used to measure the strength of the correlation between movement velocity and load (%1RM). The differences in the load-velocity relationship between the men and the women were assessed using a 2 (sex) × 15 (load) repeated-measures ANOVA. The main findings revealed that: (I) the load-velocity relationship was always strong and linear in both exercises (R2 range: 0.88-0.94), (II) men showed higher velocities for light loads (30-50%1RM; effect size: 0.9-0.96) than women for the deadlift, but no significant differences were found for the hip thrust. Based on the results of this study, the load-velocity equations seem to be sex-specific. Therefore, we suggest that using sex-specific equations to analyze deficits in the force-velocity profile would be more effective to control intensity in the deadlift exercise.