Hamstring Muscle Architecture and Viscoelastic Properties: Reliability and Retrospective Comparison Between Previously Injured and Uninjured Athletes

Abstract

The architecture of the biceps femoris (BF) and stiffness of the hamstrings have been found to be associated with injury risk. However, less is known about the architecture of the equally voluminous semitendinosus (ST) and viscoelastic properties of both muscles in individuals with a prior injury. Methods: BF and ST of 15 athletes (previously injured, [Formula: see text]; control, [Formula: see text]) were assessed using ultrasonography and myotonometry. Mean architecture (muscle thickness (MT), pennation angle (PA) and fascicle length (FL)) and viscoelastic measures (stiffness, oscillation frequency and decrement) were compared between the previously injured and contralateral uninjured limb, and between the previously injured and control limbs (mean of both limbs of the control group). Control group participants returned for a duplicate measurement. Findings: Both muscles exhibited high reliability between sessions (intraclass correlation coefficient [Formula: see text]) for architecture. BF PA was larger in the previously injured than both uninjured [Formula: see text] and control [Formula: see text]. BF fascicles were shorter in the previously injured limb compared to the uninjured [Formula: see text] and control [Formula: see text]. BF was stiffer in the previously injured compared to uninjured [Formula: see text]. ST architecture and viscoelasticity were similar across limbs. Conclusion: A prior hamstring strain injury is associated with a stiffer BF characterized by larger PAs and shorter fascicles.

Is Muscle Architecture Different in Athletes with a Previous Hamstring Strain? A Systematic Review and Meta-Analysis

“…Eleven studies on muscle architecture compared the injured with the uninjured limb [ 6 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 33 , 34 , 35 ] while five studies compared the injured individuals with controls [ 18 , 19 , 20 , 21 , 24 ].…”

“…Of the included studies, five examined the FL [ 18 , 19 , 20 , 21 , 22 ], four studies examined muscle PA [ 18 , 20 , 21 , 22 ], MT [ 18 , 20 , 21 , 35 ] and muscle volume [ 6 , 22 , 24 , 34 ] while the CSA was examined by three studies [ 22 , 24 , 36 ]. Nine studies examined the BFlh, four studies the ST, two studies the BFsh and one investigated the SM.…”

“…As evidenced in Table 1, studies received a high-risk bias score for items 11 and 12, which address whether participants are representative of the population, item 27, which indicates a lack of power calculations, and item 25, which examines the absence or presence of adequate adjustment for confounding factors in the analyses. 1 1 1 1 1 1 0 0 0 1 0 1 1 0 0 0 0 9 45 Low Nin et al [20] 1 1 1 1 1 1 0 0 0 1 1 1 1 0 0 0 0 10 50 Low Sanfilippo et al [6] 1 1 1 2 1 1 1 0 0 1 1 1 1 1 0 2 2 17 85 High Silder et al [23] 1 1 1 0 1 1 1 0 0 1 1 1 0 1 0 2 1 13 65 Low Timmins et al [18] 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 2 1 16 80 High Timmins et al [21] 1 1 1 2 1 1 0 0 0 1 1 1 1 0 1 1 0 13 65 Low…”

“…The sample size ranged from 6 [35] to 80 participants [19] with an age range from 19.25 ± 2.40 to 28.6 ± 5.2 years. Eleven studies on muscle architecture compared the injured with the uninjured limb [6,[18][19][20][21][22][23][24][33][34][35] while five studies compared the injured individuals with controls [18][19][20][21]24].…”

“…Such events may influence the size and morphology of the muscle–tendon unit. However, the evidence is inconsistent as some studies have found that hamstring injury influences muscle architecture such as the fascicle length (FL) and angle of pennation (PA) [ 18 , 19 , 20 ] but others have reported opposite results [ 21 , 22 ]. One might also expect that injury influences muscle size parameters, such as muscle volume, thickness (MT) or cross-sectional area (CSA) but the results are conflicting [ 6 , 22 , 23 , 24 ].…”