Background:
Semitendinosus and gracilis muscles are frequently harvested for autologous tendon grafts for cruciate ligament reconstruction. This study investigated the joint-stabilizing effects of ...these hamstring muscles in cases of insufficiency of the medial collateral ligament (MCL).
Hypotheses:
First, both the semitendinosus and gracilis muscles can actively stabilize the joint against valgus moments in the MCL-deficient knee. Second, the stabilizing influence of these muscles decreases with an increasing knee flexion angle.
Study Design:
Controlled laboratory study.
Methods:
The kinematics was examined in 10 fresh-frozen human cadaveric knees using a robotic/universal force moment sensor system and an optical tracking system. The knee kinematics under 5- and 10-N·m valgus moments were determined in the different flexion angles of the (1) MCL-intact and (2) MCL-deficient knee using the following simulated muscle loads: (1) 0-N (idle) load, (2) 200-N semitendinosus (ST) load, and (3) 280-N (200/80-N) combined semitendinosus/gracilis (STGT) load.
Results:
Cutting the MCL increased the valgus angle under all tested conditions and angles compared with the MCL-intact knee by 4.3° to 8.1° for the 5-N·m valgus moment and 6.5° to 11.9° for the 10-N·m valgus moment (P < .01). The applied 200-N simulated ST load reduced the valgus angle significantly at 0°, 10°, 20°, and 30° of flexion under 5- and 10-N·m valgus moments (P < .05). At 0°, 10°, and 20° of flexion, these values were close to those for the MCL-intact joint under the respective moments (both P > .05). The combined 280-N simulated STGT load significantly reduced the valgus angle in 0°, 10°, and 20° of flexion under 5- and 10-N·m valgus moments (P < .05) to values near those for the intact joint (5 N·m: 0°, 10°; 10 N·m: 0°, 10°, 20°; P > .05). In 60° and 90° of flexion, ST and STGT loads did not decrease the resulting valgus angle of the MCL-deficient knee without hamstring loads (P > .05 vs deficient; P = .0001 vs intact).
Conclusion:
In this human cadaveric study, semitendinosus and gracilis muscles successfully stabilize valgus moments applied to the MCL-insufficient knee when the knee is near extension.
Clinical Relevance:
In the valgus-unstable knee, these data suggest that the hamstring muscles should be preserved in (multi-) ligament surgery when possible.
Background: Thigh muscle strength capacities are major modifiable risk factors for knee and thigh muscle injuries. Therefore, their valid assessment is essential. Most isokinetic knee tests are ...conducted in a seated position and rely on dynamometer-based data. However, their accuracy is doubtful because axis alignment is erroneous. Purpose: This study investigated if hip angle (flexed vs. extended) and assessment method (dynamometer-based vs. camera-based) affect isokinetic outcome parameters. Methods: Sixteen healthy male participants (27 years, 184 cm, 80 kg) performed discrete isokinetic tests of the knee flexors and extensors (60°/s) while their kinematics were captured (100 fps). Results: Both assessment methods revealed very strong linear relationships (94% ≤ R
2
≤ 98%) although peak moments (d ≤ 0.87), contractional work (d ≤ 1.26), and functional knee flexor:extensor ratios (d ≤ 0.81) significantly differed. Seated knee flexor tests demonstrated the largest knee trajectory center's misalignment (x = 4.0 cm, z = −2.5 cm; 1.37 ≤ d ≤ 4.74). Conclusion: Hip-angle induced kinematic changes did not affect the relation between the lever arms, thus causing highly proportional deviations of kinetic parameters. The assessment method altered the magnitude, but not the message of isokinetic knee tests, which should be preferentially performed with extended hip joint to improve axis alignment. Knowledge of these kinetic and kinematic interactions assists practitioners and scientists with isokinetic tests and/or rehabilitation training to ensure reasonable interpretations of gathered isokinetic outcomes.
Purpose This study was aimed to investigate the effects of Ergon® IASTM applications on the upper or lower part of the Superficial Back Line (SBL) on the hamstring’s flexibility. Participants and ...Methods Sixty University students (age=24.4 ± 4.39; height=176.78 ± 8.31 cm; weight=75.16 ± 11.21 kg) were randomly divided into three sub-groups and received a single 15-minute treatment with Ergon® Technique in a) the upper and b) the lower part of SBL or c) served as control. The participants received one treatment per week for four weeks with a simultaneous pre-and post-therapy assessment of their hamstrings flexibility using the passive Straight Leg Raising (SLR). Results Both experimental groups improved SLR performance from pre to post during the four weeks from 4.4% to 9.2% in the trunk group and from 4.9% to 8.0% in the lower body group. These differences were significantly greater from the CTRL group. No differences were observed between the two experimental groups. Conclusion In conclusion, application of Ergon Technique of either the upper or lower part of the SBL may lead to a significant increase in the hamstring flexibility irrespective of the site of application.
Persistent deficits in strength and voluntary activation have been observed in athletes with a history of hamstring strain injury. The mechanisms contributing to these deficits are poorly understood ...and consequently may not be appropriately addressed during rehabilitation. This study aimed to investigate the impact of intended knee flexor contraction mode (concentric, eccentric or isometric) on the rate of torque development and surface electromyography (sEMG) rise in athletes with and without a history of unilateral hamstring strain injury. The impact of the previous injury on hip extensor rate of torque development was also investigated. Previously injured limbs exhibited a slower rate of torque development (mean difference = −31%, p = 0.02, Cohen's d = 0.62) and biceps femoris rate of sEMG rise (mean difference = −181% · s
−1
, p = 0.003, Cohen's d = 1.10) during intended eccentric knee flexor contractions compared with control limbs. Previously injured (mean difference = −29%, p = 0.01, Cohen's d = 0.85) and contralateral uninjured limbs (mean difference = −31%, p = 0.007, Cohen's d = 0.73) exhibited a slower rate of torque development during isometric hip extensor contractions compared with control limbs. These findings may highlight lower levels of descending input to hamstring motoneurons in previously injured athletes.
Hamstring injuries constitute the single largest cause of lost playing time in professional football. While restoring high‐speed running ability is paramount for rehabilitation from these injuries, ...little evidence exists regarding the extent of return to sport running performance after hamstring injury in football. We examined medical and match performance data available from a sample of 38 professional soccer players competing in the Qatar Stars League (N = 1426 observations) to describe high‐speed running performance during match‐play prior and subsequent to a hamstring strain injury. Multivariable‐adjusted random‐effects generalized additive models estimated post‐ versus pre‐hamstring injury differences in maximal speed (km/h), high‐speed running (>20 km/h), and sprinting (>25 km/h) distance. Mean effects and uncertainty (95% confidence interval, CI) were interpreted against the estimated random match‐to‐match variability in maximal sprinting speed, high‐speed running distance, and sprinting running distance of ±1.67 km/h (95% CI, 1.62–1.72 km/h), ±102 m (95% CI, 99–105 m), and ±60 m (95% CI, 58–61 m), respectively. The estimated post‐ versus pre‐hamstring injury mean differences in maximal sprinting speed, high‐speed running distance, and sprinting running distance primary outcomes were −0.25 km/h (95% CI, −0.38 to −0.12 km/h), −43 m (95% CI, −56 to −30 m), and −22 m (95% CI, −29 to −16 m). Players returning to football match‐play after hamstring strain injury experienced reductions in high‐speed match physical performance that were well within normal match‐to‐match variation in performance.
Abstract. Purpose This study was aimed to investigate the effects of Ergon(R) IASTM applications on the upper or lower part of the Superficial Back Line (SBL) on the hamstring's flexibility. ...Participants and Methods Sixty University students (age=24.4+-4.39; height=176.78+-8.31cm; weight=75.16+-11.21kg) were randomly divided into three sub-groups and received a single 15-minute treatment with Ergon(R) Technique in a) the upper and b) the lower part of SBL or c) served as control. The participants received one treatment per week for four weeks with a simultaneous pre-and post-therapy assessment of their hamstrings flexibility using the passive Straight Leg Raising (SLR). Results Both experimental groups improved SLR performance from pre to post during the four weeks from 4.4% to 9.2% in the trunk group and from 4.9% to 8.0% in the lower body group. These differences were significantly greater from the CTRL group. No differences were observed between the two experimental groups. Conclusion In conclusion, application of Ergon Technique of either the upper or lower part of the SBL may lead to a significant increase in the hamstring flexibility irrespective of the site of application.
Purpose
Hamstring strain injuries may occur due to differential fatigue and compromised mechanical properties among the hamstring muscles. We examined (1) the effect of fatigue on hamstrings active ...muscle stiffness, and (2) whether contraction type affects active muscle stiffness changes during a submaximal fatiguing task.
Methods
Nine healthy males completed 99 submaximal knee flexions in isometric (ISO), concentric (CON), and eccentric (ECC) conditions. We measured the knee flexor maximal voluntary torque (MVT) (pre/post), shear wave velocity (SWV) during contraction and transverse relaxation times (T2) (pre/post) in biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) muscles.
Results
MVT decreased substantially after all conditions (− 18.4 to − 33.6%). The average relative torque sustained during the task was lower in CON than ISO and ECC, but absolute torque was similar. SWV interindividual responses were highly variable across muscles and contraction types. On average, BFlh SWV tended to increase in ISO (0.4 m/s, 4.5%,
p
= 0.064) but decreased in ECC condition (− 0.8 m/s, − 7.7%,
p
< 0.01). ST SWV decreased in CON (− 1.1 m/s, − 9.0%,
p
< 0.01), while it remained unchanged in ISO and ECC. SM SWV decreased in CON (− 0.8 m/s, − 8.1%,
p
< 0.01), but it was unaffected in ISO and variable in ECC.
Conclusion
Fatigue has a differential effect on the mechanical properties of the constituent hamstring muscles, as measured with shear wave elastography, depending upon contraction type. We found preliminary evidence that BFlh is more fatigued than ST or SM during eccentric contractions, which may explain its susceptibility to strain injuries.
Context:
Soccer players often have a dominant (D) leg, which could influence the relative strength between the quadriceps and hamstrings. The hamstring-to-quadriceps (H:Q) ratio can be assessed on a ...dynamometer at various velocities to provide information on injury risk.
Objective:
To assess the concentric hamstrings and concentric quadriceps strength ratio (conventional H:Q ratio) assessed in D and nondominant (ND) legs at various speeds in male soccer players.
Data Sources:
A systematic literature search was completed from inception to 2020 in PubMed, Academic Search Ultimate, CINAHL, and SPORTDiscus.
Study Selection:
Keywords associated with the H:Q ratio were connected with terms for soccer players. Titles and abstracts were screened by 2 reviewers based on inclusion and exclusion criteria related to sex, playing level, language, and measurement. A total of 81 studies were reviewed and 17 studies (21%) were used.
Study Design:
A meta-analysis with random effects modeling generated standardized mean differences with 95% CIs between legs and speeds.
Level of Evidence:
Level 3.
Data Extraction:
A total of 38 cohorts were identified, with 14, 13, and 11 cohorts assessed at low, intermediate, and high velocities, respectively. The Quality Assessment Tool for Observational Cohort and Cross-sectional Studies from the National Institutes of Health was used.
Results:
The mean H:Q ratio at low velocities was 59.8 ± 9.5% in D leg and 58.6 ± 9.9% in ND leg, 64.2 ± 10.7% (D) and 63.6 ± 11.3% (ND) at the intermediate velocity, and 71.9 ± 12.7% (D) and 72.8 ± 12.7% (ND) at the high velocity. Low, intermediate, and high velocities had small effects of 0.13, 0.10, and -0.06, respectively.
Conclusion:
Conventional H:Q ratios vary across velocities but did not differ between D and ND limbs in male soccer players. This study may provide the foundation to establish norms and clinically meaningful differences.
Involuntary hamstring muscle activity is present in some people during the straight leg raise test, but it is not known to what extent involuntary muscle activity limits passive joint range of ...motion. This study aimed to determine whether small amounts of involuntary hamstring activity limit passive hip range of motion during the straight leg raise test in healthy people.
Thirty healthy subjects were recruited from The University of Sydney. As the hamstring muscles were continuously stimulated to generate 0, 2.5, 5, 7.5 and 10% of knee flexion maximal voluntary contraction force, an investigator blinded to the amount of stimulation performed a straight leg raise test by passively raising the tested leg while keeping the knee extended. The test was stopped when the knee started to flex, at which point hip range of motion was recorded.
On average, passive hip range of motion decreased by 0.6° for every 1% increase in knee flexion force caused by muscle activation (95% CI 0.3 to 0.9°, p = 0.0012). Subjects were instructed to fully relax when the straight leg raise test was performed, but a small amount of involuntary muscle activity (median 2.4% of maximal activation) was present during the trial without stimulation.
Small amounts of involuntary hamstring muscles activity reduce passive hip range of motion during the straight leg raise test in healthy people.
The protocol for this study was registered with the Open Science Framework, reference: https://osf.io/fejpf/ . Registered 9 March 2017.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
