Hamstrings load bearing in different contraction types and intensities: A shear-wave and B-mode ultrasonographic study

Abstract

The main aim was to examine the load bearing of individual hamstring muscles in different contraction types and intensities, through local stiffness measurement by shear wave elastography (SWE). A secondary aim was to examine the relationship between the SWE stiffness measure and hamstrings morphology. Ten healthy males (age 22.1±4.1 years; height 173.7±5.9 cm; body mass 68.6±12.4 kg; mean ± SD) performed knee flexions on an isokinetic dynamometer at different intensities (20–70%MVC, random order) in three separate, randomized conditions: isometric (ISO), concentric (CON) and eccentric (ECC). SWE was used to measure muscle shear wave velocity (SWV) in biceps femoris long head (BFlh), semitendinosus (ST) and semimembranosus (SM) during contraction. Muscle anatomical cross-sectional area (ACSA) was measured with magnetic resonance imaging and muscle architecture with B-mode ultrasonography. Muscle SWV increased linearly with contraction intensity, but at a varying rate among muscles and contraction types. ST exhibited greater SWV than BFlh and SM in all contraction types, however, there was an upward shift in the SM SWV–torque relationship in ECC compared to ISO and CON. Strong negative correlations were found between peak ISO SWV and ST ACSA (r = -0.81, p = 0.005) and BFlh pennation angle (r = -0.75, p = 0.012). These results suggest that ST has a primary role in hamstrings load bearing in all contraction types, likely due to its morphology; however, there is evidence of increased contribution from SM in eccentric muscle actions.

In vivo assessment of the passive stretching response of the bicompartmental human semitendinosus muscle using shear-wave elastography

“…Due to technical limitations (e.g., elastography map saturation; see Refs. 23 and 24 ), shear modulus cannot currently be assessed in the hamstrings in vivo at maximal levels of muscle activation. Conversely, passive ST shear modulus has been assessed in several studies, during both static resting ( 25 – 27 ) and passive stretching ( 28 , 29 ); however, no 2D-SWE studies have thoroughly examined both ST compartments in humans.…”

Fatigue-induced changes in hamstrings' active muscle stiffness: Effect of contraction type and implications for strain injuries

“…Ten young, healthy males were originally recruited (also examined in 15 ), however, one participant dropped out for personal reasons (age 21.8 ± 4.2 years, height 172.8 ± 5.4 cm; body mass 67.1 ± 12.1 kg and iPAQ score 1768 ± 1453 MET-minutes/week [mean ± SD]). Participants provided written informed consent and completed health screen and physical activity questionnaires (iPAQ short version) 27 prior to any measurements.…”

“…As described previously 15 , participants lay prone on the isokinetic dynamometer (Con-Trex MJ, CMV AG, Dübendorf, Switzerland) at a 30° hip exion (0° full extension). Inelastic straps across the pelvis, torso and above the knee of the right leg were used to minimise any extraneous movements.…”

“…Muscle SWV was measured with an Aixplorer ultrasound scanner (SuperSonic Imagine, Aix-en-Provence, France) using a linear transducer (SL15-4, 4-15 Hz) and constant settings (musculoskeletal preset, smoothing 9, persistence high) as previously described 15 . Brie y, measurements were taken at 50% of the thigh length (greater trochanter to knee joint space).…”

“…A fatigued muscle has a compromised capacity to actively exert force and resist mechanical strains, becoming susceptible at loads and strain magnitudes that could previously bear successfully 11 . Although the distribution of actual forces within a muscle group cannot be determined in vivo, inferences can be drawn from the measurement of muscle activation (electromyography, EMG) 12 , metabolic activity (functional MRI) 13 , and active stiffness (shear wave elastography, SWE) 14,15 . Variable hamstrings load distribution patterns have been reported depending on whether the examined task is hip-or knee-dominant, the type of contraction and range of motion.…”