Do athletes with hamstring strain injury have shorter muscle fascicles in the injured limb?

INTRODUCTION: Previous studies have suggested that a reduced length of the biceps femoris long head (BFlh) fascicles may increase the risk of hamstring strain injury (HSI). However, it remains unclear whether the BFlh fascicles of the injured limb are shorter than those of the contralateral limb in athletes with an acute HSI. OBJECTIVE: To investigate the between-limb asymmetry of BFlh fascicle length in amateur athletes with an acute HSI. METHODS: Male amateur athletes were evaluated using ultrasound scans within five days following an HSI. The BFlh fascicle length was estimated using a validated equation. RESULTS: Eighteen injured athletes participated in this study. There was no significant difference (p = 0.27) in the length of BFlh fascicles between the injured limb (9.53 ± 2.55 cm; 95%CI 8.26 to 10.80 cm) and the uninjured limb (10.54 ± 2.87 cm; 95%CI 9.11 to 11.97 cm). Individual analysis revealed high heterogeneity, with between-limb asymmetries (percentage difference of the injured limb compared to the uninjured limb) ranging from -42% to 25%. Nine out of the 18 athletes had a fascicle length that was more than 10% shorter in the injured limb compared to the uninjured limb, five athletes had a difference of less than 10%, and four athletes had a fascicle length that was more than 10% longer in the injured limb compared to the uninjured limb. CONCLUSION: The architecture characteristics of injured and uninjured muscles is not consistent among athletes with HSI. Therefore, rehabilitation programs focused on fascicle lengthening should be evaluated on a case-by-case basis.

The Single Leg Bridge Test does not replace handheld dynamometer hamstring tests in a clinical setting.

OBJECTIVE: To examine the correlation of Single Leg Bridge Test (SLBT) scores with maximum isometric strength values obtained in handheld dynamometer (HHD) hamstring tests performed in a clinical setting. DESIGN: Cross-sectional study. SETTING: Physical therapy clinic. PARTICIPANTS: Fifty healthy and physically active men. MAIN OUTCOME MEASURES: Correlation between SLBT scores and force values found in three HHD hamstring tests: test 'A', volunteer in prone with hip in neutral position and the knee flexed at ∼90°; test 'B', volunteer in supine with hip and knee flexed at ∼90°; and test 'C', volunteer in the same position used to perform the SLBT. RESULTS: The volunteers' SLBT score was 27.55 ± 7.81 repetitions. The SLBT scores were poorly associated with mean (r = 0.246) and peak (r = 0.321) results provided by HHD test 'A'. There were no significant correlations between the SLBT scores and mean or peak values obtained in tests 'B' and 'C' (p > 0.05). Similarly, the SLBT between-limb asymmetry was not associated with asymmetries found in HHD hamstring tests (p > 0.05). CONCLUSIONS: HHD hamstring tests should not be replaced by the SLBT. We recommend for clinicians to applying such tests in a complementary way to assess the hamstring's functional status.

Conservative treatment of Achilles tendon partial tear in a futsal player: A case report.

Background and purpose: Achilles tendon is the most commonly injured part in the lower limb, especially in athletes. Treatment options for Achilles tendinopathy and total rupture are well described; however, there is a lack of information regarding treatment protocols for partial tears. Thus, the purpose of this case report was to describe the examination, intervention and outcomes of patient who suffered an acute Achilles tendon partial tear. Case description: A case is described here, in which the diagnosis of Achilles tendon partial tear was based on both magnetic resonance imaging and physical evaluation. Both the patient and the physical therapy team opted for non-surgical treatment. A 12-week course of conservative treatment including exercise, tendon loading, electrical stimulation, and photobiomodulation is described. Outcomes: Ankle dorsiflexion range of motion and hop tests. Discussion: This case report demonstrated that non-surgical treatment for Achilles tendon partial tear was effective for this patient and enabled the athlete to return to pre-injury levels of activity 6 months following the injury.

Effect of Nordic Hamstring Exercise Training on Knee Flexors Eccentric Strength and Fascicle Length: A Systematic Review and Meta-Analysis.

CONTEXT: Nordic hamstring exercise (NHE) has been widely employed to prevent hamstring strain injuries. However, it is still not clear which adaptations are responsible for the NHE preventive effects. OBJECTIVES: The aim of this study was to investigate the effects of NHE on knee flexors eccentric strength and fascicle length. EVIDENCE ACQUISITION: The search strategy included MEDLINE, PEDro, and Cochrane CENTRAL from inception to April 2020. Randomized clinical trials that have analyzed the effects of NHE training on hamstring eccentric strength and/or fascicle length were included. EVIDENCE SYNTHESIS: From the 1932 studies identified, 12 were included in the systematic review, and 9 studies presented suitable data for the meta-analysis. All studies demonstrated strength increments in response to NHE training (10%-15% and 16%-26% in tests performed on the isokinetic dynamometer and on the NHE device, respectively), as well as significant enhancement of biceps femoris long head fascicle length (12%-22%). Meta-analysis showed NHE training was effective to increase knee flexors eccentric strength assessed with both isokinetic tests (0.68; 95% confidence interval, 0.29 to 1.06) and NHE tests (1.11; 95% confidence interval, 0.62 to 1.61). NHE training was also effective to increase fascicle length (0.97; 95% confidence interval, 0.46 to 1.48). CONCLUSIONS: NHE training has the potential of increasing both knee flexors eccentric strength and biceps femoris long head fascicle length.

Effects of low-level laser therapy on hamstring strain injury rehabilitation: A randomized controlled trial.

OBJECTIVES: To evaluate the effects of low-level laser therapy (LLLT) on functional rehabilitation following hamstring strain injury (HSI) in amateur athletes treated with an exercise-based rehabilitation program. DESIGN: Randomized controlled trial. METHODS: Male athletes (18-40 years old) who sustained HSI were randomized in LLLT or placebo groups. All patients were engaged in the same exercise-based rehabilitation program until they met specific criteria to return to sport. Hamstring muscles were treated with LLLT or placebo immediately after each rehabilitation session. The primary outcome was time-to-return to sport. Secondary outcomes were the number of rehabilitation sessions, hamstring flexibility, hamstring strength, and re-injury rate. RESULTS: Twenty-four athletes began rehabilitation, and 22 (11 per group) completed the study schedule. Participants of LLLT and placebo groups had similar age, body size, injury characteristics, and baseline levels of hamstring flexibility and strength. The two groups increased flexibility and strength similarly throughout the rehabilitation program. Time-to-return to sport was the same for athletes treated with LLLT (23 ± 9 days) and placebo (24 ± 13 days). There were no re-injuries within 6 months after return to sport. CONCLUSION: LLLT, as used in this study, did not optimize functional rehabilitation following HSI in amateur athletes treated with an exercise-based rehabilitation program.

ACCURACY OF THE FUNCTIONAL MOVEMENT SCREEN (FMSTM) ACTIVE STRAIGHT LEG RAISE TEST TO EVALUATE HAMSTRING FLEXIBILITY IN SOCCER PLAYERS.

BACKGROUND: Poor flexibility is considered a risk factor for the hamstring strain injury, and the active straight leg raise (ASLR) test proposed as a part of the Functional Movement Screen™ (FMS™) has been used to assess athletes hamstring flexibility. However, the accuracy of this screening test remains undescribed. PURPOSE: To examine the accuracy of the FMS™ ASLR test for assessment of hamstring flexibility in soccer players. STUDY DESIGN: Cross-sectional study. METHODS: One-hundred and one male soccer players (age, 21 ± 3 years; height, 179 ± 7 cm; weight, 75 ± 9 kg) were bilaterally evaluated. All players performed a gold standard test for hamstring flexibility evaluation: the passive straight leg raise (PSLR) test measured using a gravitational inclinometer. All players also performed the ASLR test and were scored using the criteria proposed by the FMS™. RESULTS: Of the 202 lower limbs evaluated, 17.82% scored a 1 on the ASLR [mean passive flexibility: 80.44 ± 14.69 ° (55 °-110 °)], 50.99% scored a 2 on the ASLR [mean passive flexibility = 84.60 ± 10.59 ° (56 °-115 °)], and 31.18% scored a 3 on the ASLR [mean passive flexibility = 92.32 ± 11.53 ° (70 °-120 °)]. Limbs with FMS™ score of 3 presented significantly higher values for passive flexibility than limbs with scores of 1 and 2 (p < 0.05), but there was no significant difference between limbs with scores of 1 and 2 (p > 0.05). CONCLUSION: The score obtained in the FMS™ ASLR test does not satisfactorily stratify the level of hamstring flexibility in soccer players. LEVEL OF EVIDENCE: 3a.

Chronic effect of different types of stretching on ankle dorsiflexion range of motion: Systematic review and meta-analysis.

The calf muscles are one of the muscle groups that have the most need for adequate flexibility since they are deeply related to normal lower limb function. When the goal is to increase flexibility, the most commonly used technique is stretching. However, it remains unknown which stretching technique and parameters are the most effective to increase flexibility. Hence, the aim of the current review was to investigate the influence of chronic stretching on ankle dorsiflexion range of motion (DFROM) of healthy individuals. The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, LILACS, and manual search from inception to February 2017. Randomized and controlled clinical trials that have analyzed the influence of chronic stretching on DFROM were included. On the other hand, studies with special populations (children, and people with any dysfunction/disease), and articles with no control group were excluded. Twenty studies were included out of 493 identified. The meta-analysis was performed according to the stretching technique used in the study. The results show that static stretching (5.17°; 95% CI: 4.39-5.95; I2: 0%) and proprioceptive neuromuscular facilitation (4.32°; 95% CI: 1.59-7.04; I2: 46%) are effective in increasing DFROM. Ballistic stretching did not show positive results to increase DFROM (3.77°; 95% CI: -0.03 to 7.56; I2: 46%). In conclusion, chronic stretching is an effective way of improving ankle mobility in healthy individuals, especially when it contains a static component.