UNASSIGNED: A disadvantage of using hamstring tendon autograft consisting of the semitendinosus and gracilis tendons for anterior cruciate ligament reconstruction is pain from tendon harvesting and persistent hamstring weakness. In the tendon-sparing all-inside technique, a quadrupled semitendinosus graft and adjustable-loop cortical fixation are suggested to give less postoperative flexion deficits while displaying overall similar clinical results to the traditional hamstring technique. However, there are a limited number of high-quality studies comparing these techniques with inconsistent results.
UNASSIGNED: To investigate differences between the all-inside (quadrupled semitendinosus) and traditional hamstring (double-stranded semitendinosus and gracilis) technique regarding (1) self-reported function, (2) hamstring strength, and (3) knee laxity.
UNASSIGNED: Randomized controlled trial; Level of evidence, 1.
UNASSIGNED: A total of 98 patients were randomized to either the all-inside or the traditional hamstring technique. Perioperatively, duration of surgery and graft size were obtained. The International Knee Documentation Committee 2000 Subjective Knee Form score, Knee injury and Osteoarthritis Outcome Score, Tegner Activity Scale score, knee laxity (KT-1000 arthrometer side-to-side difference and pivot shift), range of motion, isokinetic knee strength, and hop test score were collected preoperatively and 2 years postoperatively. Return-to-sport readiness was evaluated 9 months postoperatively.
UNASSIGNED: A total of 89 patients completed 2-year follow-up, 45 patients with the all-inside technique and 44 patients with the traditional hamstring technique. There were no significant differences between groups in any of the outcome measures 2 years after surgery, but there was a tendency in the all-inside group toward having increased anterior translation (mean, 3.6 mm vs 2.7 mm), a higher number of revision surgeries (5 patients vs 2 patients), and more patients having +1 and +2 pivot-shift values (29 vs 18 patients) when compared with the traditional group.
UNASSIGNED: The all-inside technique yields equivalent results to the traditional hamstring technique 2 years after surgery and should be considered a reliable technique to use for ACL reconstruction. Sparing the gracilis tendon does not lead to less persistent hamstring weakness. Long-term follow-up is needed to further determine whether the tendency of increased anterior translation seen at 2 years postoperatively will lead to a higher risk of graft failure.

UNASSIGNED: Muscular strength deficits are common after ACL injury. While the Limb Symmetry Index (LSI), using the uninvolved limb as a reference, is widely used, negative strength adaptations may affect both limbs post-injury. It is uncertain how the strength of the uninvolved limb in those with an ACL injury compares to uninjured individuals, making it unclear whether it is appropriate as a benchmark for determining sufficient strength.
UNASSIGNED: To compare the strength of key lower extremity muscles of the uninvolved limb in those with history of ACL injury (ACL-I) to the dominant limb in individuals with no history of ACL injury (control).
UNASSIGNED: Cross-sectional study. Methods: A total of 5,727 military cadets were examined, with 82 females and 126 males in the ACL-I group and 2,146 females and 3,373 males in the control group. Maximum isometric strength was assessed for six muscle groups measured with a hand-held dynamometer. Separate two-way ANOVAs with limb and sex were performed for each muscle group.
UNASSIGNED: Significant main effects for limb were observed with the uninvolved limb in the ACL-I group displaying greater strength compared to the dominant limb in the control group for the quadriceps, hamstrings, and gluteus medius, but effect sizes were small (Cohen\'s d <0.25). Significant main effects for sex were observed with greater male muscular strength in all six muscle groups with small to large effect sizes (Cohen\'s d 0.49-1.46). No limb-by-sex interactions were observed.
UNASSIGNED: There was no evidence of reduced strength in the uninvolved limb in those with a history of ACL injury compared to the dominant limb in those with no prior ACL injury. This finding suggests that, after clearance to return to activities, the uninvolved limb can be used as a standard for comparison of sufficient strength, including when using the LSI. Level of Evidence: Level 3.

Professional soccer players typically perform regular training sessions and match play for most of the yearly macrocycle with limited time focused on solely developing physical development. The COVID-19 outbreak in 2020 caused mass disruption to professional soccer but provided an opportunity for an alternative approach to training in attempt to develop professional soccer players physical fitness levels. In a non-randomised and non-controlled study, we aimed to assess the effectiveness of a 13-week remote based physical training programme on physical fitness levels in elite professional soccer players. Twenty professional soccer players undertook body composition assessments, a countermovement jump (CMJ) test, eccentric hamstring strength test and a submaximal 30-15 intermittent fitness test (IFT) pre- and post-remote based training programme. Body mass (79.3 ± 6.7 vs. 80.0 ± 7.3 kg), skinfold thickness (54.1 ± 14.8 vs. 56.7 ± 15.2 mm), maximum CMJ height (38.4 ± 3.4 vs. 40.9 ± 4.1 cm), eccentric hamstring strength (1035 ± 158 vs. 1009 ± 140 n) and percentage max heart rate reached in submaximal 30-15 IFT (81.3 ± 5.2 vs. 82.3 ± 7.3%) were maintained (all P > 0.05) from pre- to post training programme, respectively. Although team-based soccer specific training load was removed, and the training programmes prescribed had an increased physical focus, fitness levels were maintained. This suggests that alternative modes of training can potentially be used in instances where team-based soccer specific training load isn\'t required or is unavailable, without negatively impacting physical development.

Limited research has reported the reliability of rapid force generation characteristics during isometric assessments of the hamstrings. Therefore, the purpose of the present study was to determine the between-session reliability of rapid force generating characteristics of the hamstrings and relationship to maximal force production. Twenty-three female soccer players (age: 20.7 ± 4.7 years; height: 168.7 ± 5.9 cm; body mass: 64.4 ± 6.7 kg) performed three unilateral trials of the 90-90 isometric hamstring assessment, on two separate occasions, separated by 7 days. Peak force, force at 100- and 200 ms and average rate of force development (aRFD) over 100- and 200 ms epochs were calculated. Absolute and fair-good reliability was observed for peak force and all rapid force generating measures (<8.33CV%, ICC >0.610). Significant and meaningful relationships (p < 0.001, r > 0.802) were observed for all rapid force generating measures and peak force. The 90-90 isometric assessment can be used to assess peak and rapid force generating reliably to enable practitioners to confidently track changes in performance over time as part of fatigue monitoring and management.

BACKGROUND: Different resistance exercise determinants modulate the musculotendinous adaptations following eccentric hamstring training. The Nordic Hamstring Exercise (NHE) can be performed 2-fold: the movement velocity irreversibly increases toward the end of the range of motion or it is kept constant.
METHODS: This cross-sectional study aimed to investigate if the downward acceleration angle (DWAangle) can be used as a classification parameter to distinguish between increasing and constant velocity NHE execution. Furthermore, the kinetic and kinematic differences of these 2 NHE execution conditions were examined by analyzing the DWAangle in relation to the angle of peak moment.
METHODS: A total of 613 unassisted NHE repetitions of 12 trained male sprinters (22 y, 181 cm, 76 kg) were analyzed.
RESULTS: The majority of analyzed parameters demonstrated large effects. NHEs with constant velocity  (n = 285) revealed significantly higher impulses (P < .001; d = 2.34; + 61%) and fractional time under tension (P < .001; d = 1.29; +143%). Although the generated peak moments were significantly higher for constant velocity (P = .003; d = 0.29; +4%), they emerged at similar knee flexion angles (P = .167; d = 0.28) and revealed on average just low relationships to the DWAangle (Rmean2=22.4%). DWAangle highly correlated with the impulse (Rmean2=60.8%) and δ (DWAangle-angle of peak moment; Rmean2=83.6%).
CONCLUSIONS: Relating DWAangle to angle of peak moment assists to distinguish between significantly different NHE execution, which will potentially elicit different musculotendinous adaptations. These insights are essential for coaches and athletes to understand how to manipulate eccentric hamstring training to change its purpose.

UNASSIGNED: Kinesio tape has been proposed to improve the muscle extensibility. However, there are contradictory results in the literature.
UNASSIGNED: To investigate the effect of Kinesio tape on hamstring muscle lengthening and on hamstring and quadriceps muscle strengthening in university students with hamstring muscle tightness.
UNASSIGNED: In this pre-post experimental study, 96 female students with hamstring muscle tightness were recruited from Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia, and randomly assigned to Kinesio tape, sham tape, or control groups (32 in each group). The inhibition technique was used for the Kinesio tape application, with the tape being applied from the muscle insertion to the origin. Measurements were taken before and 15 min after the intervention. Outcome measurements included active knee extension test to measure the hamstring muscle length, and isometric strength measurements of hamstring and quadriceps muscles using a handheld dynamometer.
UNASSIGNED: A significant increase in the immediate hamstring muscle length was found in both the Kinesio (P = 0.001) and sham (P = 0.004) tape groups, while no difference was noted in the control group (P = 0.066). The muscle lengthening was significantly greater in the Kinesio tape group than the sham tape (P = 0.001) and control (P = 0.001) groups. There was no difference in the pre- and post-measurements in the quadriceps and hamstring muscle strengths in all three groups.
UNASSIGNED: These results demonstrate that applying Kinesio tape has an immediate effect on hamstring muscle extensibility, but has no effect on the quadriceps and hamstring muscle strengths.
UNASSIGNED: NCT03076840.

This study sought to investigate post-game hamstring strength recovery of 26 Australian Football League (AFL) players with a previous hamstring strain injury (HSI) across an AFL season. Maximal unilateral isometric knee flexion strength was assessed using an externally fixed dynamometer, and inter-session reliability was measured during the pre-season period. Linear mixed effects models investigated the influence of numerous variables on post-game hamstring strength decrement (relative change between initial weekly test and individual baseline) and individual within-week strength change following gameplay. The test demonstrated good inter-tester reliability (ICC = 0.81-0.88; CV = 6.73-7.33), and an acceptable level of error (MAE = 5.77-7.14%). Player as a random effect strongly influenced post-game strength decrement and within-week strength change (marginal R2 = 0.185-0.407; conditional R2 = 0.455-0.654). Within-week hamstring strength change was strongly determined by post-game strength decrement alone (estimate = 0.51, 95% CI = -0.66- -0.36 ; η2 = 0.32; P=<0.001) and in interaction with number of days post-game (estimate = 0.43, 95% CI = 0.20-0.66; η2 = 0.096; P=<0.001). This study shows the importance of early individual assessment of post-game hamstring strength in players with prior hamstring injury and could be valuable to inform post-game hamstring recovery in future applications.

UNASSIGNED: Assessment of knee flexion torque is a relevant clinical measure following various injuries and surgeries to determine progress in rehabilitation and inform decision making. A variety of methods using hand-held dynamometry have been shown to be reliable in obtaining this measure, and typically require a means of external fixation or stabilization. Clinically efficient methods of reliable clinician-stabilization are sparse in the literature.
UNASSIGNED: Determine inter and intra-rater reliability of two clinically efficient methods of assessing isometric knee flexion torque using hand-held dynamometry with clinician-stabilization. The hypothesis was that each method would yield good to excellent reliability.
UNASSIGNED: Cross-Sectional Study.
UNASSIGNED: Twenty healthy individuals were assessed by two clinicians on two separate days. During each session, knee flexion torque was assessed with hand-held dynamometry with two methods: 1) in the seated position with the hip and knee flexed to 90 degrees while the clinician stabilized the dynamometer between the participant\'s leg and table and 2) in prone with the hip at 0 degrees and knee at 90 degrees while the clinician assumed a stride stance with elbows locked in extension to stabilize the dynamometer on the participant\'s leg. Inter and intra-rater reliability were determined for each method.
UNASSIGNED: ICC values were 0.88-0.94 and 0.77-0.90 for inter and intra-rater reliability respectively with the seated method. The prone method yielded ICC values of 0.84-0.96 and 0.89-0.94 for inter and intra-rater reliability respectively. MDC values ranged from 30-62% with the seated method and 21-40% with the prone method.
UNASSIGNED: Inter and intra-rater reliability were good to excellent for assessing knee flexion torque with hand-held dynamometry using both the seated and prone methods with clinically efficient clinician-stabilization approaches. The prone method may be more sensitive to detecting change over time due to lower MDC values.
UNASSIGNED: 2b.

BACKGROUND: The Nordic hamstring exercise (NHE) is commonly implemented to selectively improve eccentric knee-flexor strength. However, the standard version of the exercise (leveled shanks, extended hip joint) is too strenuous for most individuals, whose muscle activity rapidly decreases at extended knee angles. Hitherto, a gradual approach to the exercise has been missing. In this exploratory case study, we investigated elite performance to introduce a stepwise progression to the NHE.
OBJECTIVE: To determine the extent to which exercise modifications (shank inclination, additional load, hip flexion) altered NHE mechanics.
METHODS: One male long jumper (age = 33 years, height = 171 cm, mass = 69 kg) with high-level expertise in the NHE performed 20 exercise variations. The corresponding kinematics, kinetics, and electromyographic activity of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles were evaluated.
RESULTS: Exercise variations demonstrated gradually increased peak moments from 69% (zigzag pose) to 154% (inclined bent single-legged version) versus a standard NHE. Shank inclination and additional load elicited small to moderate effects on peak moments, BFlh, and ST (0.24 ≤ d ≤ 0.72), whereas hip flexion largely affected all tested variables (2.80 ≤ d ≤ 6.66), especially muscle activity (BFlh = -63%; ST = -55% of maximal voluntary isometric contraction).
CONCLUSIONS: These insights will help practitioners and scientists design multifaceted stepwise NHE progressions by creating differentiated stimuli that best match the strength capacities of individuals and address their specific needs.

OBJECTIVE: Avulsion of the proximal hamstring tendon origin can result in significant functional impairment, with surgical re-attachment of the tendons becoming an increasingly recognized treatment. The aim of this study was to assess the outcomes of surgical management of proximal hamstring tendon avulsions, and to compare the results between acute and chronic repairs, as well as between partial and complete injuries.
METHODS: PubMed, CINAHL, SPORTdiscuss, Cochrane Library, EMBASE, and Web of Science were searched. Studies were screened and quality assessed.
RESULTS: In all, 35 studies (1,530 surgically-repaired hamstrings) were included. Mean age at time of repair was 44.7 years (12 to 78). A total of 846 tears were acute, and 684 were chronic, with 520 tears being defined as partial, and 916 as complete. Overall, 92.6% of patients were satisfied with the outcome of their surgery. Mean Lower Extremity Functional Score was 74.7, and was significantly higher in the partial injury group. Mean postoperative hamstring strength was 87.0% of the uninjured limb, and was higher in the partial group. The return to sport (RTS) rate was 84.5%, averaging at a return of 6.5 months. RTS was quicker in the acute group. Re-rupture rate was 1.2% overall, and was lower in the acute group. Sciatic nerve dysfunction rate was 3.5% overall, and lower in the acute group (p < 0.05 in all cases).
CONCLUSIONS: Surgical treatment results in high satisfaction rates, with good functional outcomes, restoration of muscle strength, and RTS. Partial injuries could expect a higher functional outcome and muscle strength return. Acute repairs result in a quicker RTS with a reduced rate of re-rupture and sciatic nerve dysfunction. Cite this article: Bone Jt Open 2022;3(5):415-422.