Background While Nordic hamstring exercise(NHE)training has been shown to reduce hamstring strains,the muscle-specific adaptations to NHE across the 4 hamstrings remain unclear.This study investigates architectural an...Background While Nordic hamstring exercise(NHE)training has been shown to reduce hamstring strains,the muscle-specific adaptations to NHE across the 4 hamstrings remain unclear.This study investigates architectural and microstructural adaptations of the biceps femoris short head(BFsh),biceps femoris long head(BFlh),semitendinosus(ST),and semimembranosus(SM)in response to an NHE intervention.Methods Eleven subjects completed 9 weeks of supervised NHE training followed by 3 weeks of detraining.Magnetic resonance imaging was performed at pre-training,post-training,and detraining to assess architectural(volume,fiber tract length,and fiber tract angle)and microstructural(axial(AD),mean(MD),radial(RD)diffusivities,and fractional anisotropy(FA))parameters of the 4 hamstrings.Results NHE training induced significant but non-uniform hamstring muscle hypertrophy(BFsh:22%,BFlh:9%,ST:26%,SM:6%)and fiber tract length increase(BFsh:11%,BFlh:7%,ST:18%,SM:10%).AD(5%),MD(4%),and RD(5%)showed significant increases,but fiber tract angle and FA remained unchanged.After detraining,only ST showed a significant reduction(8%)in volume,which remained higher than the pre-training value.While fiber tract lengths returned to baseline,AD,MD,and RD remained higher than pre-training levels for all hamstrings.Conclusion The 9-week NHE training substantially increased hamstring muscle volume with greater hypertrophy in ST and BFsh.Hypertrophy was accompanied by increases in fiber tract lengths and cross-sections(increased RD).After 3 weeks of detraining,fiber tract length gains across all hamstrings declined,emphasizing the importance of sustained training to maintain all the protective adaptations.展开更多
The maximal force a muscle can exert depends on its length,which has been explained by the sliding filament theory on the sarcomere level.1 A longer muscle can act over a greater range of motion and has more sarcomere...The maximal force a muscle can exert depends on its length,which has been explained by the sliding filament theory on the sarcomere level.1 A longer muscle can act over a greater range of motion and has more sarcomeres in series,which increases its capacity to produce force at a specific muscle contraction velocity because each sarcomere contracts at a lower velocity.展开更多
Background Eccentric training,such as Nordic hamstring exercise(NHE)training,is commonly used as a preventive measure for hamstring strains.Eccentric training is believed to induce lengthening of muscle fascicles and ...Background Eccentric training,such as Nordic hamstring exercise(NHE)training,is commonly used as a preventive measure for hamstring strains.Eccentric training is believed to induce lengthening of muscle fascicles and to be associated with the addition of sarcomeres in series within muscle fibers.However,the difficulty in measuring sarcomere adaptation in human muscles has severely limited information about the precise mechanisms of adaptation.This study addressed this limitation by measuring the multiscale hamstring muscle adaptations in response to 9 weeks of NHE training and 3 weeks of detraining.Methods Twelve participants completed 9 weeks of supervised NHE training,followed by a 3-week detraining period.We assessed biceps femoris long-head(BFlh)muscle fascicle length,sarcomere length,and serial sarcomere number in the central and distal regions of the muscle.Additionally,we measured muscle volume and eccentric strength at baseline,post-training,and post-detraining.Results NHE training over 9 weeks induced significant architectural and strength adaptations in the BFlh muscle.Fascicle length increased by 19%in the central muscle region and 33%in the distal muscle region.NHE also induced increases in serial sarcomere number(25%in the central region and 49%in the distal region).BFlh muscle volume increased by 8%,and knee flexion strength increased by 40%with training.Following 3 weeks of detraining,fascicle length decreased by 12%in the central region and 16%in the distal region along with reductions in serial sarcomere number.Conclusion Nine weeks of NHE training produced substantial,region-specific increases in BFlh muscle fascicle length,muscle volume,and force generation.The direct measurement of sarcomere lengths revealed that the increased fascicle length was accompanied by the addition of sarcomeres in series within the muscle fascicles.展开更多
Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientifi...Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientific community.This study aimed to explore the correlation between the diameter of autologous tendon grafts and age in anterior cruciate ligament reconstruction(ACLR).Methods:A retrospective review of 388 patients who underwent arthroscopic ACLR with hamstring autografts was performed.Patients were grouped by age to analyze differences in hamstring autograft dia-meter and tendon cross-sectional area(CSA).We explored the correlations between age and graft diameter and between age and the CSA of the popliteal tendon while controlling for the influence of other pertinent variables.Results:Compared with female patients,male patients presented significantly greater autograft diameters and hamstring tendon CSAs(P<0.05).Notably,graft diameter and hamstring tendon CSA varied significantly across different age groups(P<0.05);patients aged>32 years were substantially more likely to have a graft diameter exceeding 8 mm and a CSA surpassing 18.5 mm^(2) than their≤32-year-old counterparts were(P<0.05).Conclusion:This study revealed that graft diameter varies across different age groups,with age independently influencing graft diameter.展开更多
Background: The size of Hamstring autograft of less than 8.0 mm in ACL re-construction is one of the key factors that may contribute to the failure of the graft. In this study, we are going to assess the correlation o...Background: The size of Hamstring autograft of less than 8.0 mm in ACL re-construction is one of the key factors that may contribute to the failure of the graft. In this study, we are going to assess the correlation of pre-operative MRI measurement of Hamstring tendons with the intra-operative ACL graft. Thus, it may help surgeons to anticipate the needs for graft augmentation should the final graft size be smaller than expected. Methods: We retrospectively re-viewed 41 cases of ACL reconstructions in which MRI were done pre-operatively, in Hospital Pakar Sultanah Fatimah (HPSF), Muar between January 2019 until December 2022. MRI measurements of Hamstring tendon (semitendinosus: ST, and gracilis) were done by a radiologist, and the in-tra-operative notes were reviewed for the final graft size. Pearson’s correlation coefficients were calculated to determine the relationship between graft size and tendon cross-sectional area. The intraclass correlation (ICC) by using two-way mixed model with type consistency, the reliability based on average measure was 0.41 (95% CI: ?0.10, 0.69). A p-value < 0.05 was considered sig-nificant. Results: Of 105 patients with primary ACL reconstruction done be-tween January 2019 to December 2022, only 41 patients were included in this study. There was fair correlation (p = 0.048) between pre-operative MRI measurement and the graft diameter intra-operatively. The mean of 17.0 mm of combined diameter of ST and gracilis tendon in MRI may results in graft diameter of 8.3 mm. There was also positive correlation between patients’ height and the intra-operative graft size. Conclusion: These results showed good correlation between pre-operative MRI measurement of Hamstring ten-don size with the intra-operative graft size, hence it is a reliable tool to predict the Hamstring autograft size in ACL reconstruction.展开更多
Background: Netball is a popular sport. Due to high impact and quick movement, there is an enormous load on the lower extremities which increases the risk for injury. Aim: The aim of this study was to investigate the ...Background: Netball is a popular sport. Due to high impact and quick movement, there is an enormous load on the lower extremities which increases the risk for injury. Aim: The aim of this study was to investigate the relationship between the quadricep and hamstring strength and the prevalence of lower extremity injuries in netball players. Setting: Twenty-five female netball players (age: 20.8 ± 1.4 years) voluntarily participated. Methods: The Cybex Isokinetic dynamometer was used to determine concentric knee torques. Quadriceps:hamstring strength ratio was determined. Occurrence of lower extremity injuries was documented bi-weekly. Results: Medium effect sizes were noted for flexion torque:work for the left leg and for the quadriceps:hamstring ratio (≥60%) for the right leg. All the other measured variables have a small effect size. 18.75% of lower extremity injuries and ConQ:ConH of Conclusion: Injuries to the ankle and knee are especially common among netball players. Hamstring and quadriceps muscle asymmetry (>10%) were found to be a potential indicator of lower extremity injury. Contribution: This study highlights awareness on lower extremity injuries and the strength ratio between the quadriceps and hamstrings. This can aid coaches and netball players to lower the risk for injuries and thus improve individual- and team performance.展开更多
Background:The effect of hamstring flexibility on the peak hamstring muscle strains in sprinting,until now,remained unknown,which limited our understanding of risk factors of hamstring muscle strain injury(hamstring i...Background:The effect of hamstring flexibility on the peak hamstring muscle strains in sprinting,until now,remained unknown,which limited our understanding of risk factors of hamstring muscle strain injury(hamstring injury).As a continuation of our previous study,this study was aimed to examine the relationship between hamstring flexibility and peak hamstring muscle strains in sprinting.Methods:Ten male and 10 female college students participated in this study.Hamstring flexibility,isokinetic strength data,three-dimensional(3D)kinematic data in a hamstring isokinetic test,and kinematic data in a sprinting test were collected for each participant.The optimal hamstring muscle lengths and peak hamstring muscle strains in sprinting were determined for each participant.Results:The muscle strain of each of the 3 biarticulated hamstring muscles reached a peak during the late swing phase.Peak hamstring muscle strains were negatively correlated to hamstring flexibility(0.1179 ≤ R2≤ 0.4519,p = 0.001) but not to hip and knee joint positions at the time of peak hamstring muscle strains.Peak hamstring muscle strains were not different for different genders.Peak muscle strains of biceps long head(0.071 ± 0.059) and semitendinosus(0.070 ± 0.055) were significantly greater than that of semimembranosus(0.064 ± 0.054).Conclusion:A potential for hamstring injury exists during the late swing phase of sprinting.Peak hamstring muscle strains in sprinting are negatively correlated to hamstring flexibility across individuals.The magnitude of peak muscle strains is different among hamstring muscles in sprinting,which may explain the different injury rate among hamstring muscles.展开更多
Hamstring strains are one of most common sports injuries.The purpose of this literature review is to summarize studies on hamstring strain injury rate,mechanism,and risk factors in the last several decades with a focu...Hamstring strains are one of most common sports injuries.The purpose of this literature review is to summarize studies on hamstring strain injury rate,mechanism,and risk factors in the last several decades with a focus on the prevention and rehabilitation of this injury.Hamstring injury commonly occurs in sporting events in which high speed sprinting and kicking are frequently performed,such as Australian football. English rugby,American football,and soccer.Basic science studies have demonstrated that a muscle strain injury occurs due to excessive strain in eccentric contraction instead of force,and that elongation speed and duration of activation before eccentric contraction affect the severity of the injury.Hamstring strain injury is likely to occur during the late swing phase and late stance phase of sprint running.Shortened optimum muscle length,lack of muscle flexibility,strength imbalance,insufficient warm-up,fatigue,lower back injury,poor lumbar posture,and increased muscle neural tension have been identified as modifiable risk factors while muscle compositions,age,race,and previous injuries are non-modifiable risk factors.The theoretical basis of some of these risk factors,however,is lacking,and the results of clinical studies on these risk factors are inconsistent.Future studies are needed to establish the cause-and-effect relationships between those proposed risk factors and the injury.展开更多
Background:Hamstring injury is one of the most common injuries in sports involving sprinting.Hamstring flexibility and strength are often considered to be modifiable risk factors in hamstring injury.Understanding the ...Background:Hamstring injury is one of the most common injuries in sports involving sprinting.Hamstring flexibility and strength are often considered to be modifiable risk factors in hamstring injury.Understanding the effects of hamstring flexibility or strength training on the biomechanics of the hamstring muscles during sprinting could assist in improving prevention strategies and rehabilitation related to these injuries.The purpose of this study was to determine the effects of altering hamstring flexibility or strength on peak hamstring musculotendinous strain during sprinting.Methods:A total of 20 male college students(aged 18-24 years)participated and were randomly assigned to either a flexibility intervention group or a strength intervention group.Each participant executed exercise training 3 times a week for 8 weeks.Flexibility,sprinting,and isokinetic strength testing were performed before and after the 2 interventions.Paired t tests were performed to determine hamstring flexibility or strength intervention effects on optimal hamstring musculotendinous lengths and peak hamstring musculotendinous strains during sprinting.Results:Participants in the flexibility intervention group significantly increased the optimal musculotendinous lengths of the semimembranosus and biceps long head(p<0.026)and decreased peak musculotendinous strains in all 3 bi-articulate hamstring muscles(p<0.004).Participants in the strength-intervention group significantly increased the optimal musculotendinous lengths of all 3 hamstring muscles(p<0.041)and significantly decreased their peak musculotendinous strain during sprinting(p<0.017).Conclusion:Increasing hamstring flexibility or strength through exercise training may assist in reducing the risk of hamstring injury during sprinting for recreational male athletes.展开更多
The main purpose of this study patients undergoing a single bundle anterior was to compare the clinical outcomes of cruciate ligament reconstruction (ACL-R) of using quadrupled hamstring (4HT)autografts and two-strand...The main purpose of this study patients undergoing a single bundle anterior was to compare the clinical outcomes of cruciate ligament reconstruction (ACL-R) of using quadrupled hamstring (4HT)autografts and two-strand tibialis anterior (2TA) aUografts,and to find out the rate of graft failure and possible causes.We hypothesized that there would be no difference in the clinical outcome,and graft failure would be associated with the use of small sized allograft in young active males with high demand of sports activities.We retrospectively evaluated 222 patients (male,n=167,female,n=55) undergoing ACL-R between January 2010 and July 2014.Of 222 patients,115 were included in the 4HT autograft group and 107 patients in the 2TA allograft group.Inclusion criteria were primary unilateral ACL-R with a minor MCL (<grade Ⅱ)injury with or without meniscus tear and had at least 2.5 years of follow-up.Subjective evaluation was performed using Tegner-Lysholm score,modified Cincinnati knee score,and IKDC knee form.Anteroposterior laxity was assessed using ADT and Lachman test whereas rotational laxity was assessed using pivot shift test.Similarly,functional assessment was performed using range of motion (ROM),Daniel's one-leg hop test,and overall IKDC score.Clinical outcomes were satisfactory and comparable in both groups with no statistically significant difference in all the respective parameters.No statistically significant difference was observed in graft re-rupture rate.However,most graft failures occurred in young active males with high demand of sports activities,graft size smaller than 8 mm,and use of allograft.An autograft with at least 8 mm diameter should be considered in a young active male with high demand of sports activities to avoid graft failure.展开更多
Objective:Both ligament-advanced reinforcement system(LARS)and hamstring tendon autograft can serve as grafts for posterior cruciate ligament(PCL)reconstruction.However,few studies have compared the effectiveness of t...Objective:Both ligament-advanced reinforcement system(LARS)and hamstring tendon autograft can serve as grafts for posterior cruciate ligament(PCL)reconstruction.However,few studies have compared the effectiveness of these two approaches.This study therefore aimed to compare the clinical efficacy of arthroscopic reconstruction of the PCL using either the LARS or hamstring tendon autograft.Methods:A total of 36 patients who underwent PCL reconstruction were retrospectively analyzed.Within this cohort,15 patients received a reconstruction using the LARS(LARS group)and 21 using the hamstring tendon autograft(HT group).Results:The pre-and post-operative subjective scores and knee stability were evaluated and the patients were followed up for a period of 2 to 10.5 years(4.11±2.0 years on average).The last follow-up showed that functional scores and knee stability were significantly improved in both groups(P<0.05).Six months after operation,Lysholm scores and IKDC subjective scores were higher in the LARS group than in the HT group(P<0.05).Nonetheless,the last follow-up showed no significant differences in the functional scores or the posterior drawer test between the two groups(P>0.05).In the LARS and HT groups,12 and 9 patients,respectively exhibited KT1000 values<3 mm,with the difference being statistically significant(P<0.05).In the HT group,the diameter of the four-strand hamstring tendon was positively correlated with height(P<0.05),which was 7.37±0.52 mm in males and 6.50±0.77 mm in females(P<0.05).Conclusion:Both LARS and hamstring tendon approaches achieved good efficacy for PCL reconstruction,but patients in the LARS group exhibited faster functional recovery and better knee stability in the long term.LARS is especially suitable for those who hope to resume activities as early as possible.展开更多
Rupture of the anterior cruciate ligament(ACL)is a common orthopedic injury.Various graft options are available for the reconstruction of ruptured ACL.Using the hamstring muscle as an autograft was first described in ...Rupture of the anterior cruciate ligament(ACL)is a common orthopedic injury.Various graft options are available for the reconstruction of ruptured ACL.Using the hamstring muscle as an autograft was first described in 1934,and it remains a commonly harvested graft for ACL reconstruction.Hamstring autografts can be harvested using the traditional anteromedial approach or the newer posteromedial technique.An isolated semitendinosus tendon can be used or combined with the gracilis tendon.There are numerous methods for graft fixation,such as intra-tunnel or extra-tunnel fixation.This comprehensive review discusses the different hamstring muscle harvesting techniques and graft preparation options and fixation methods.It provides a comprehensive overview for choosing the optimal surgical technique when treating patients.展开更多
Objective To measure the tensile strength of the normal medial patellofemoral ligament(MPFL),and evaluate the biomechanics of different fixation methods of the hamstring tendon graft on the patella.Methods Eight fresh...Objective To measure the tensile strength of the normal medial patellofemoral ligament(MPFL),and evaluate the biomechanics of different fixation methods of the hamstring tendon graft on the patella.Methods Eight fresh cadaver knees were prepared by isolating the patella,leaving only the MPFL as its attachment to the medial condyle of femur.The MPFL was reconstructed by three different methods:four-suture fixation,anchors-single suture fixation,and anchors-double suture fixation.The tensile strength and the elongation of the normal MPFL and the tendon grafts were measured.Results The tensile strength of the four-suture fixation group(234.86±49.02 N)was stronger than that of the normal MPFL(146.91±25.30 N,P=0.0014)and the anchors-single suture group(159.17±49.07N,P=0.0077),while weaker than that of the anchors-double suture group(314.74±78.46 N,P=0.0052)Conclusions With regard to the tensile strength,the four-suture fixation method is reliable for clinical use.Compared with the anchor-suture method,the four-suture fixation method which has no specific implants is more economical,convenient and efficient.展开更多
Relative flexibility between the hamstring and lumbar extensor muscles, which can be evaluated using lumbopelvic curvature during active knee extension in sitting, can sometimes be assessed in physical therapy. Howeve...Relative flexibility between the hamstring and lumbar extensor muscles, which can be evaluated using lumbopelvic curvature during active knee extension in sitting, can sometimes be assessed in physical therapy. However, reliability for its quantitative measure has not been established yet and its establishment was the aim of the current study. Twenty-seven individuals with clinically tight hamstring muscles were recruited. On two separate sessions, the lumbopelvic curvature was evaluated in sitting when the right knee was moved from 90° flexion to 10° flexion on 15 occasions using a flexible ruler by two examiners on Day 1 and one on Day 2. Lines drawn tangential to the lumbopelvic curvature were traced at T12 and S2 vertebral levels and the angle between the two vertical lines was calculated. Using Day 1 data, the minimum number of repetitions and inter-examiner reliability were assessed. Inter-session reliability was also examined. As a result, there was no statistical difference (P?> 0.05) in the mean absolute difference between the mean value of N-1 and N repetitions (6 ≤ N ≤ 15) in the lumbopelvic curvature angle, indicating that five was considered the minimum number of repetitions. Intraclass correlation coefficient (ICC)(1, 5)?for the inter-session reliability and ICC(2, 5)?for the inter-examiner reliability was 0.97 and 0.93, respectively, indicating excellent reliability. The measure for the lumbopelvic curvature during active knee extension in sitting, which was established in the current study, will be a foundation for further research regarding the relative flexibility of the lumbar and adjunct regions.展开更多
Hamstring muscle strain injury is the most common and prevalent injury in sports involving high-speed running,such as American football,Australian football,English rugby,soccer,track and field,and cricket.1Hamstring m...Hamstring muscle strain injury is the most common and prevalent injury in sports involving high-speed running,such as American football,Australian football,English rugby,soccer,track and field,and cricket.1Hamstring muscle strain injury also has a high recurrence rate of up to 48%.2The average practice and game time loss due to hamstring injury is between17 and 60 days,contingent on the grade of injury.2Severe hamstring muscle strain injuries,and associated recurrent inju-展开更多
The Four-Strand Hamstring Tendon Autograft has been long established as the gold standard for surgical reconstruction of the Anterior Cruciate Ligament. Some studies have suggested wider grafts, such as a Five-Strand ...The Four-Strand Hamstring Tendon Autograft has been long established as the gold standard for surgical reconstruction of the Anterior Cruciate Ligament. Some studies have suggested wider grafts, such as a Five-Strand hamstring graft, may provide greater strength and a larger scaffold for incorporation of the graft into the bone tunnels, leading to greater postoperative anterior stability of the knee. 28 (n = 18 Four-Strand and n = 10 Five-Strand) patients with planned ACL reconstructive surgery by a single surgeon were recruited for this study. The KT-1000 Arthrometer (MED metric, CA, USA) was used to quantify AP translation in the subjects’ knees before (T0) and after surgery at 6 (T1) and 12 (T2) weeks. At 12 weeks there was significantly higher (p = 0.01) mean anterior laxity on Maximum Manual Test in the Five- Strand group (9.1 ± 1.7 mm) than the Four Strand Group (6.9 ± 2.3 mm). Further, there were significantly higher mean side-to-side differences (p = 0.01) on Maximum Manual Test in the Five-Strand cohort (5.1 ± 3.5 mm) compared to the Four-Strand cohort (1.9 ± 2.2 mm). A significantly larger positive mean change in anterior laxity (p = 0.02) from 6 - 12 weeks was evident in the Five-Strand group (1.4 ± 0.9) than the Four-Strand group (-0.3 ± 1.9 mm). No significant correlations were seen between graft widths and measures of anterior stability on KT-1000. This study illustrated that there was no benefit to using a Five-Strand Hamstring Tendon Autograft when compared to the gold standard Four-Strand Repair specifically with regards to anterior stability of the knee.展开更多
Background:Injuries to the hamstring are relatively common in professional cricketers(as they are in many team sports) and have increased in incidence in the "T20 era"(introduction of 20-over matches) of cri...Background:Injuries to the hamstring are relatively common in professional cricketers(as they are in many team sports) and have increased in incidence in the "T20 era"(introduction of 20-over matches) of cricket since 2006.Methods:This study analyzed incidence of hamstring injury in the various elite male match types over a 20-year period(1995–1996 to 2014–2015seasons).Risk factors for hamstring strain were assessed using a multivariate logistic regression analysis technique.Results:There were 276 match time-loss hamstring injuries recorded over a 20-year period at the Australian state or national player level,of which170 occurred in one of 40,145 player match sets.The overall rate of match onset rate was 22.5 hamstring injuries per 1000 team days.Fast bowling onset injuries were the highest subcategory at a rate of 10.9 injuries per 1000 team days,although batting onset injuries were particularly common in 50-over(one day) international matches.Significant risk factors in logistic regression analysis,in addition to hamstring injury history,were being a fast bowler relative risk(RR) 2.5(95% confidence interval(CI):1.3–4.5) and playing a match in Australia RR 2.3(95%CI:1.3–3.9).Conclusion:Fast bowlers suffer more hamstring injuries than other playing roles in cricket,particularly in First Class(multi-day) cricket.Batsmen are more likely to get injured in 50-over(one day) cricket.Playing in Australia(compared to overseas venues) leads to increased risk of hamstring injury.展开更多
Context and Objective: Hamstring strain is a common injury in football and it causes a significant amount of time lost from competition and training. Since poor flexibility is thought to predispose to muscle strain, s...Context and Objective: Hamstring strain is a common injury in football and it causes a significant amount of time lost from competition and training. Since poor flexibility is thought to predispose to muscle strain, stretching is routinely recommended during warm-up routines by coaches to prevent injuries. However, available evidence suggests that pre-exercise stretching (PES), especially static stretching, has no benefit on injury rates and may even reduce performance in explosive type activities. We designed this study to assess the attitudes, beliefs and practices of football coaches regarding stretching in the prevention of hamstring strains. Design: A cross-sectional survey. Setting: Mauritius Football Association (MFA). Participants: 26 football coaches registered with the MFA. Intervention: Questionnaires were distributed to football coaches of the MFA via sports officers. Questionnaires were then collected two weeks after distribution. Main Outcome Measures: Attitudes, beliefs and practices of football coaches regarding stretching in the prevention of ham-string strains. Results: MFA coaches held generally positive attitudes and beliefs towards stretching. 88% of coaches felt that PES is beneficial and 93% believed that PES prevents hamstring strains. The majority of coaches recommended stretching after warming up (81%) and after the training session (93%). 76% of coaches also advised stretching outside the training sessions. 96% of coaches used static stretching to stretch the hamstrings. The hamstrings were stretched on average for 4 times at each training session and the mean duration of a static stretch was 12 seconds. Conclusions: Nearly all coaches believed that PES prevents hamstring strains although evidence is limited. Some of the coaches’ beliefs and practices were not in line with current recommendations. Coaches reported that their stretching practices would be most likely influenced by scientific research. Thus there is an urgent need to devise awareness and training programmes in this area.展开更多
基金financial support from the general electric (GE) healthcareAustralian Research Council Discovery Project (DP200101476)+5 种基金in parts by National Institutes of Health (NIH) grants (R01 AR077604, R01 EB002524, R01 AR079431, P41 EB02706)Stanford Graduate FellowshipThe University of Queensland Graduate ScholarshipNational Health and Medical Research Council of Australia Fellowship (#1194937)Wu Tsai Human Performance Alliance at Stanford Universitythe Joe and Clara Tsai Foundation
文摘Background While Nordic hamstring exercise(NHE)training has been shown to reduce hamstring strains,the muscle-specific adaptations to NHE across the 4 hamstrings remain unclear.This study investigates architectural and microstructural adaptations of the biceps femoris short head(BFsh),biceps femoris long head(BFlh),semitendinosus(ST),and semimembranosus(SM)in response to an NHE intervention.Methods Eleven subjects completed 9 weeks of supervised NHE training followed by 3 weeks of detraining.Magnetic resonance imaging was performed at pre-training,post-training,and detraining to assess architectural(volume,fiber tract length,and fiber tract angle)and microstructural(axial(AD),mean(MD),radial(RD)diffusivities,and fractional anisotropy(FA))parameters of the 4 hamstrings.Results NHE training induced significant but non-uniform hamstring muscle hypertrophy(BFsh:22%,BFlh:9%,ST:26%,SM:6%)and fiber tract length increase(BFsh:11%,BFlh:7%,ST:18%,SM:10%).AD(5%),MD(4%),and RD(5%)showed significant increases,but fiber tract angle and FA remained unchanged.After detraining,only ST showed a significant reduction(8%)in volume,which remained higher than the pre-training value.While fiber tract lengths returned to baseline,AD,MD,and RD remained higher than pre-training levels for all hamstrings.Conclusion The 9-week NHE training substantially increased hamstring muscle volume with greater hypertrophy in ST and BFsh.Hypertrophy was accompanied by increases in fiber tract lengths and cross-sections(increased RD).After 3 weeks of detraining,fiber tract length gains across all hamstrings declined,emphasizing the importance of sustained training to maintain all the protective adaptations.
文摘The maximal force a muscle can exert depends on its length,which has been explained by the sliding filament theory on the sarcomere level.1 A longer muscle can act over a greater range of motion and has more sarcomeres in series,which increases its capacity to produce force at a specific muscle contraction velocity because each sarcomere contracts at a lower velocity.
基金supported by the Australian Research Council Discovery Project(DP200101476)in part by National Institute of Health grants(R01 AR077604,RO1 EB002524,RO1 AR079431,and P41 EB02706)+1 种基金Stanford Graduate Fellowship,The University of Queensland Graduate Scholarship,National Health and Medical Research Council of Australia Fellowship(#1194937)by Wu Tsai Human Performance Alliance at Stanford University and the Joe and Clara Tsai Foundation。
文摘Background Eccentric training,such as Nordic hamstring exercise(NHE)training,is commonly used as a preventive measure for hamstring strains.Eccentric training is believed to induce lengthening of muscle fascicles and to be associated with the addition of sarcomeres in series within muscle fibers.However,the difficulty in measuring sarcomere adaptation in human muscles has severely limited information about the precise mechanisms of adaptation.This study addressed this limitation by measuring the multiscale hamstring muscle adaptations in response to 9 weeks of NHE training and 3 weeks of detraining.Methods Twelve participants completed 9 weeks of supervised NHE training,followed by a 3-week detraining period.We assessed biceps femoris long-head(BFlh)muscle fascicle length,sarcomere length,and serial sarcomere number in the central and distal regions of the muscle.Additionally,we measured muscle volume and eccentric strength at baseline,post-training,and post-detraining.Results NHE training over 9 weeks induced significant architectural and strength adaptations in the BFlh muscle.Fascicle length increased by 19%in the central muscle region and 33%in the distal muscle region.NHE also induced increases in serial sarcomere number(25%in the central region and 49%in the distal region).BFlh muscle volume increased by 8%,and knee flexion strength increased by 40%with training.Following 3 weeks of detraining,fascicle length decreased by 12%in the central region and 16%in the distal region along with reductions in serial sarcomere number.Conclusion Nine weeks of NHE training produced substantial,region-specific increases in BFlh muscle fascicle length,muscle volume,and force generation.The direct measurement of sarcomere lengths revealed that the increased fascicle length was accompanied by the addition of sarcomeres in series within the muscle fascicles.
基金This work was supported by the Fundamental Research Funds for the Central Universities(WK9110000143)the USTC Research Funds of the Double First-Class Initiative(YD9110002060)the Health Research Program of Anhui(AHWJ2022b060)。
文摘Objective:While age has been recognized as a noteworthy factor in preoperative graft selection,the correlation between age and hamstring autograft diameter has been the subject of continued debate within the scientific community.This study aimed to explore the correlation between the diameter of autologous tendon grafts and age in anterior cruciate ligament reconstruction(ACLR).Methods:A retrospective review of 388 patients who underwent arthroscopic ACLR with hamstring autografts was performed.Patients were grouped by age to analyze differences in hamstring autograft dia-meter and tendon cross-sectional area(CSA).We explored the correlations between age and graft diameter and between age and the CSA of the popliteal tendon while controlling for the influence of other pertinent variables.Results:Compared with female patients,male patients presented significantly greater autograft diameters and hamstring tendon CSAs(P<0.05).Notably,graft diameter and hamstring tendon CSA varied significantly across different age groups(P<0.05);patients aged>32 years were substantially more likely to have a graft diameter exceeding 8 mm and a CSA surpassing 18.5 mm^(2) than their≤32-year-old counterparts were(P<0.05).Conclusion:This study revealed that graft diameter varies across different age groups,with age independently influencing graft diameter.
文摘Background: The size of Hamstring autograft of less than 8.0 mm in ACL re-construction is one of the key factors that may contribute to the failure of the graft. In this study, we are going to assess the correlation of pre-operative MRI measurement of Hamstring tendons with the intra-operative ACL graft. Thus, it may help surgeons to anticipate the needs for graft augmentation should the final graft size be smaller than expected. Methods: We retrospectively re-viewed 41 cases of ACL reconstructions in which MRI were done pre-operatively, in Hospital Pakar Sultanah Fatimah (HPSF), Muar between January 2019 until December 2022. MRI measurements of Hamstring tendon (semitendinosus: ST, and gracilis) were done by a radiologist, and the in-tra-operative notes were reviewed for the final graft size. Pearson’s correlation coefficients were calculated to determine the relationship between graft size and tendon cross-sectional area. The intraclass correlation (ICC) by using two-way mixed model with type consistency, the reliability based on average measure was 0.41 (95% CI: ?0.10, 0.69). A p-value < 0.05 was considered sig-nificant. Results: Of 105 patients with primary ACL reconstruction done be-tween January 2019 to December 2022, only 41 patients were included in this study. There was fair correlation (p = 0.048) between pre-operative MRI measurement and the graft diameter intra-operatively. The mean of 17.0 mm of combined diameter of ST and gracilis tendon in MRI may results in graft diameter of 8.3 mm. There was also positive correlation between patients’ height and the intra-operative graft size. Conclusion: These results showed good correlation between pre-operative MRI measurement of Hamstring ten-don size with the intra-operative graft size, hence it is a reliable tool to predict the Hamstring autograft size in ACL reconstruction.
文摘Background: Netball is a popular sport. Due to high impact and quick movement, there is an enormous load on the lower extremities which increases the risk for injury. Aim: The aim of this study was to investigate the relationship between the quadricep and hamstring strength and the prevalence of lower extremity injuries in netball players. Setting: Twenty-five female netball players (age: 20.8 ± 1.4 years) voluntarily participated. Methods: The Cybex Isokinetic dynamometer was used to determine concentric knee torques. Quadriceps:hamstring strength ratio was determined. Occurrence of lower extremity injuries was documented bi-weekly. Results: Medium effect sizes were noted for flexion torque:work for the left leg and for the quadriceps:hamstring ratio (≥60%) for the right leg. All the other measured variables have a small effect size. 18.75% of lower extremity injuries and ConQ:ConH of Conclusion: Injuries to the ankle and knee are especially common among netball players. Hamstring and quadriceps muscle asymmetry (>10%) were found to be a potential indicator of lower extremity injury. Contribution: This study highlights awareness on lower extremity injuries and the strength ratio between the quadriceps and hamstrings. This can aid coaches and netball players to lower the risk for injuries and thus improve individual- and team performance.
基金supported by the National Natural Science Foundation of China(No.81572212)the Fundamental Research Funds for the Central Universities of China(No.2016BS013)
文摘Background:The effect of hamstring flexibility on the peak hamstring muscle strains in sprinting,until now,remained unknown,which limited our understanding of risk factors of hamstring muscle strain injury(hamstring injury).As a continuation of our previous study,this study was aimed to examine the relationship between hamstring flexibility and peak hamstring muscle strains in sprinting.Methods:Ten male and 10 female college students participated in this study.Hamstring flexibility,isokinetic strength data,three-dimensional(3D)kinematic data in a hamstring isokinetic test,and kinematic data in a sprinting test were collected for each participant.The optimal hamstring muscle lengths and peak hamstring muscle strains in sprinting were determined for each participant.Results:The muscle strain of each of the 3 biarticulated hamstring muscles reached a peak during the late swing phase.Peak hamstring muscle strains were negatively correlated to hamstring flexibility(0.1179 ≤ R2≤ 0.4519,p = 0.001) but not to hip and knee joint positions at the time of peak hamstring muscle strains.Peak hamstring muscle strains were not different for different genders.Peak muscle strains of biceps long head(0.071 ± 0.059) and semitendinosus(0.070 ± 0.055) were significantly greater than that of semimembranosus(0.064 ± 0.054).Conclusion:A potential for hamstring injury exists during the late swing phase of sprinting.Peak hamstring muscle strains in sprinting are negatively correlated to hamstring flexibility across individuals.The magnitude of peak muscle strains is different among hamstring muscles in sprinting,which may explain the different injury rate among hamstring muscles.
文摘Hamstring strains are one of most common sports injuries.The purpose of this literature review is to summarize studies on hamstring strain injury rate,mechanism,and risk factors in the last several decades with a focus on the prevention and rehabilitation of this injury.Hamstring injury commonly occurs in sporting events in which high speed sprinting and kicking are frequently performed,such as Australian football. English rugby,American football,and soccer.Basic science studies have demonstrated that a muscle strain injury occurs due to excessive strain in eccentric contraction instead of force,and that elongation speed and duration of activation before eccentric contraction affect the severity of the injury.Hamstring strain injury is likely to occur during the late swing phase and late stance phase of sprint running.Shortened optimum muscle length,lack of muscle flexibility,strength imbalance,insufficient warm-up,fatigue,lower back injury,poor lumbar posture,and increased muscle neural tension have been identified as modifiable risk factors while muscle compositions,age,race,and previous injuries are non-modifiable risk factors.The theoretical basis of some of these risk factors,however,is lacking,and the results of clinical studies on these risk factors are inconsistent.Future studies are needed to establish the cause-and-effect relationships between those proposed risk factors and the injury.
基金by a research grant from the National Natural Science Foundation of China(Grant No.81572212)the Fundamental Research Funds for the Central Universities of China(Grant No.2019PT015).
文摘Background:Hamstring injury is one of the most common injuries in sports involving sprinting.Hamstring flexibility and strength are often considered to be modifiable risk factors in hamstring injury.Understanding the effects of hamstring flexibility or strength training on the biomechanics of the hamstring muscles during sprinting could assist in improving prevention strategies and rehabilitation related to these injuries.The purpose of this study was to determine the effects of altering hamstring flexibility or strength on peak hamstring musculotendinous strain during sprinting.Methods:A total of 20 male college students(aged 18-24 years)participated and were randomly assigned to either a flexibility intervention group or a strength intervention group.Each participant executed exercise training 3 times a week for 8 weeks.Flexibility,sprinting,and isokinetic strength testing were performed before and after the 2 interventions.Paired t tests were performed to determine hamstring flexibility or strength intervention effects on optimal hamstring musculotendinous lengths and peak hamstring musculotendinous strains during sprinting.Results:Participants in the flexibility intervention group significantly increased the optimal musculotendinous lengths of the semimembranosus and biceps long head(p<0.026)and decreased peak musculotendinous strains in all 3 bi-articulate hamstring muscles(p<0.004).Participants in the strength-intervention group significantly increased the optimal musculotendinous lengths of all 3 hamstring muscles(p<0.041)and significantly decreased their peak musculotendinous strain during sprinting(p<0.017).Conclusion:Increasing hamstring flexibility or strength through exercise training may assist in reducing the risk of hamstring injury during sprinting for recreational male athletes.
基金this study was supported by National Natural Science Foundation of China (No.81672166).
文摘The main purpose of this study patients undergoing a single bundle anterior was to compare the clinical outcomes of cruciate ligament reconstruction (ACL-R) of using quadrupled hamstring (4HT)autografts and two-strand tibialis anterior (2TA) aUografts,and to find out the rate of graft failure and possible causes.We hypothesized that there would be no difference in the clinical outcome,and graft failure would be associated with the use of small sized allograft in young active males with high demand of sports activities.We retrospectively evaluated 222 patients (male,n=167,female,n=55) undergoing ACL-R between January 2010 and July 2014.Of 222 patients,115 were included in the 4HT autograft group and 107 patients in the 2TA allograft group.Inclusion criteria were primary unilateral ACL-R with a minor MCL (<grade Ⅱ)injury with or without meniscus tear and had at least 2.5 years of follow-up.Subjective evaluation was performed using Tegner-Lysholm score,modified Cincinnati knee score,and IKDC knee form.Anteroposterior laxity was assessed using ADT and Lachman test whereas rotational laxity was assessed using pivot shift test.Similarly,functional assessment was performed using range of motion (ROM),Daniel's one-leg hop test,and overall IKDC score.Clinical outcomes were satisfactory and comparable in both groups with no statistically significant difference in all the respective parameters.No statistically significant difference was observed in graft re-rupture rate.However,most graft failures occurred in young active males with high demand of sports activities,graft size smaller than 8 mm,and use of allograft.An autograft with at least 8 mm diameter should be considered in a young active male with high demand of sports activities to avoid graft failure.
文摘Objective:Both ligament-advanced reinforcement system(LARS)and hamstring tendon autograft can serve as grafts for posterior cruciate ligament(PCL)reconstruction.However,few studies have compared the effectiveness of these two approaches.This study therefore aimed to compare the clinical efficacy of arthroscopic reconstruction of the PCL using either the LARS or hamstring tendon autograft.Methods:A total of 36 patients who underwent PCL reconstruction were retrospectively analyzed.Within this cohort,15 patients received a reconstruction using the LARS(LARS group)and 21 using the hamstring tendon autograft(HT group).Results:The pre-and post-operative subjective scores and knee stability were evaluated and the patients were followed up for a period of 2 to 10.5 years(4.11±2.0 years on average).The last follow-up showed that functional scores and knee stability were significantly improved in both groups(P<0.05).Six months after operation,Lysholm scores and IKDC subjective scores were higher in the LARS group than in the HT group(P<0.05).Nonetheless,the last follow-up showed no significant differences in the functional scores or the posterior drawer test between the two groups(P>0.05).In the LARS and HT groups,12 and 9 patients,respectively exhibited KT1000 values<3 mm,with the difference being statistically significant(P<0.05).In the HT group,the diameter of the four-strand hamstring tendon was positively correlated with height(P<0.05),which was 7.37±0.52 mm in males and 6.50±0.77 mm in females(P<0.05).Conclusion:Both LARS and hamstring tendon approaches achieved good efficacy for PCL reconstruction,but patients in the LARS group exhibited faster functional recovery and better knee stability in the long term.LARS is especially suitable for those who hope to resume activities as early as possible.
文摘Rupture of the anterior cruciate ligament(ACL)is a common orthopedic injury.Various graft options are available for the reconstruction of ruptured ACL.Using the hamstring muscle as an autograft was first described in 1934,and it remains a commonly harvested graft for ACL reconstruction.Hamstring autografts can be harvested using the traditional anteromedial approach or the newer posteromedial technique.An isolated semitendinosus tendon can be used or combined with the gracilis tendon.There are numerous methods for graft fixation,such as intra-tunnel or extra-tunnel fixation.This comprehensive review discusses the different hamstring muscle harvesting techniques and graft preparation options and fixation methods.It provides a comprehensive overview for choosing the optimal surgical technique when treating patients.
文摘Objective To measure the tensile strength of the normal medial patellofemoral ligament(MPFL),and evaluate the biomechanics of different fixation methods of the hamstring tendon graft on the patella.Methods Eight fresh cadaver knees were prepared by isolating the patella,leaving only the MPFL as its attachment to the medial condyle of femur.The MPFL was reconstructed by three different methods:four-suture fixation,anchors-single suture fixation,and anchors-double suture fixation.The tensile strength and the elongation of the normal MPFL and the tendon grafts were measured.Results The tensile strength of the four-suture fixation group(234.86±49.02 N)was stronger than that of the normal MPFL(146.91±25.30 N,P=0.0014)and the anchors-single suture group(159.17±49.07N,P=0.0077),while weaker than that of the anchors-double suture group(314.74±78.46 N,P=0.0052)Conclusions With regard to the tensile strength,the four-suture fixation method is reliable for clinical use.Compared with the anchor-suture method,the four-suture fixation method which has no specific implants is more economical,convenient and efficient.
文摘Relative flexibility between the hamstring and lumbar extensor muscles, which can be evaluated using lumbopelvic curvature during active knee extension in sitting, can sometimes be assessed in physical therapy. However, reliability for its quantitative measure has not been established yet and its establishment was the aim of the current study. Twenty-seven individuals with clinically tight hamstring muscles were recruited. On two separate sessions, the lumbopelvic curvature was evaluated in sitting when the right knee was moved from 90° flexion to 10° flexion on 15 occasions using a flexible ruler by two examiners on Day 1 and one on Day 2. Lines drawn tangential to the lumbopelvic curvature were traced at T12 and S2 vertebral levels and the angle between the two vertical lines was calculated. Using Day 1 data, the minimum number of repetitions and inter-examiner reliability were assessed. Inter-session reliability was also examined. As a result, there was no statistical difference (P?> 0.05) in the mean absolute difference between the mean value of N-1 and N repetitions (6 ≤ N ≤ 15) in the lumbopelvic curvature angle, indicating that five was considered the minimum number of repetitions. Intraclass correlation coefficient (ICC)(1, 5)?for the inter-session reliability and ICC(2, 5)?for the inter-examiner reliability was 0.97 and 0.93, respectively, indicating excellent reliability. The measure for the lumbopelvic curvature during active knee extension in sitting, which was established in the current study, will be a foundation for further research regarding the relative flexibility of the lumbar and adjunct regions.
文摘Hamstring muscle strain injury is the most common and prevalent injury in sports involving high-speed running,such as American football,Australian football,English rugby,soccer,track and field,and cricket.1Hamstring muscle strain injury also has a high recurrence rate of up to 48%.2The average practice and game time loss due to hamstring injury is between17 and 60 days,contingent on the grade of injury.2Severe hamstring muscle strain injuries,and associated recurrent inju-
文摘The Four-Strand Hamstring Tendon Autograft has been long established as the gold standard for surgical reconstruction of the Anterior Cruciate Ligament. Some studies have suggested wider grafts, such as a Five-Strand hamstring graft, may provide greater strength and a larger scaffold for incorporation of the graft into the bone tunnels, leading to greater postoperative anterior stability of the knee. 28 (n = 18 Four-Strand and n = 10 Five-Strand) patients with planned ACL reconstructive surgery by a single surgeon were recruited for this study. The KT-1000 Arthrometer (MED metric, CA, USA) was used to quantify AP translation in the subjects’ knees before (T0) and after surgery at 6 (T1) and 12 (T2) weeks. At 12 weeks there was significantly higher (p = 0.01) mean anterior laxity on Maximum Manual Test in the Five- Strand group (9.1 ± 1.7 mm) than the Four Strand Group (6.9 ± 2.3 mm). Further, there were significantly higher mean side-to-side differences (p = 0.01) on Maximum Manual Test in the Five-Strand cohort (5.1 ± 3.5 mm) compared to the Four-Strand cohort (1.9 ± 2.2 mm). A significantly larger positive mean change in anterior laxity (p = 0.02) from 6 - 12 weeks was evident in the Five-Strand group (1.4 ± 0.9) than the Four-Strand group (-0.3 ± 1.9 mm). No significant correlations were seen between graft widths and measures of anterior stability on KT-1000. This study illustrated that there was no benefit to using a Five-Strand Hamstring Tendon Autograft when compared to the gold standard Four-Strand Repair specifically with regards to anterior stability of the knee.
文摘Background:Injuries to the hamstring are relatively common in professional cricketers(as they are in many team sports) and have increased in incidence in the "T20 era"(introduction of 20-over matches) of cricket since 2006.Methods:This study analyzed incidence of hamstring injury in the various elite male match types over a 20-year period(1995–1996 to 2014–2015seasons).Risk factors for hamstring strain were assessed using a multivariate logistic regression analysis technique.Results:There were 276 match time-loss hamstring injuries recorded over a 20-year period at the Australian state or national player level,of which170 occurred in one of 40,145 player match sets.The overall rate of match onset rate was 22.5 hamstring injuries per 1000 team days.Fast bowling onset injuries were the highest subcategory at a rate of 10.9 injuries per 1000 team days,although batting onset injuries were particularly common in 50-over(one day) international matches.Significant risk factors in logistic regression analysis,in addition to hamstring injury history,were being a fast bowler relative risk(RR) 2.5(95% confidence interval(CI):1.3–4.5) and playing a match in Australia RR 2.3(95%CI:1.3–3.9).Conclusion:Fast bowlers suffer more hamstring injuries than other playing roles in cricket,particularly in First Class(multi-day) cricket.Batsmen are more likely to get injured in 50-over(one day) cricket.Playing in Australia(compared to overseas venues) leads to increased risk of hamstring injury.
文摘Context and Objective: Hamstring strain is a common injury in football and it causes a significant amount of time lost from competition and training. Since poor flexibility is thought to predispose to muscle strain, stretching is routinely recommended during warm-up routines by coaches to prevent injuries. However, available evidence suggests that pre-exercise stretching (PES), especially static stretching, has no benefit on injury rates and may even reduce performance in explosive type activities. We designed this study to assess the attitudes, beliefs and practices of football coaches regarding stretching in the prevention of hamstring strains. Design: A cross-sectional survey. Setting: Mauritius Football Association (MFA). Participants: 26 football coaches registered with the MFA. Intervention: Questionnaires were distributed to football coaches of the MFA via sports officers. Questionnaires were then collected two weeks after distribution. Main Outcome Measures: Attitudes, beliefs and practices of football coaches regarding stretching in the prevention of ham-string strains. Results: MFA coaches held generally positive attitudes and beliefs towards stretching. 88% of coaches felt that PES is beneficial and 93% believed that PES prevents hamstring strains. The majority of coaches recommended stretching after warming up (81%) and after the training session (93%). 76% of coaches also advised stretching outside the training sessions. 96% of coaches used static stretching to stretch the hamstrings. The hamstrings were stretched on average for 4 times at each training session and the mean duration of a static stretch was 12 seconds. Conclusions: Nearly all coaches believed that PES prevents hamstring strains although evidence is limited. Some of the coaches’ beliefs and practices were not in line with current recommendations. Coaches reported that their stretching practices would be most likely influenced by scientific research. Thus there is an urgent need to devise awareness and training programmes in this area.
