ECSS Paris 2023: OP-BM11
INTRODUCTION: The capacity of a muscle to produce force to move the human body is significantly affected by the aging process. Alongside the decline in neuromuscular function, structural changes in muscle architecture and in the morphology of the contractile and non-contractile tissues also occur with aging, which might in turn affect force capacity [1,2]. Namely, when contracted, pennate muscles change in fascicle length and angle [3], hence the absolute decrease in fascicle length and fascicle pennation angle with age [4] might also impact relative fascicle behave during contraction. In addition, aging muscles present greater muscle stiffness. As intramuscular connective tissue has a key role in maintaining the structural integrity of the muscle, these alterations might also impact how connective tissue and muscle stiffness will influence muscle shape changes during contraction [5]. In this study we analyzed age differences in fascicle behavior during ramped isometric knee extension. METHODS: In this preliminary analyses of an ongoing study, data of five (E) elderly (76 ±4 years) and five young (Y) adults (26±2 years) were analysed. Ultrasound imaging of the vastus lateralis (VL) was recorded during isometric ramp contractions up to 30% and 50% of the maximum voluntary contraction (MVC) with slow force increase (2% MVC/s). The probe was placed longitudinally and the recording was synchronized to the force trace. Changes in fascicle behaviour (fascicle length- Lf, fascicle angle- FA, and muscle thickness- MT) were compared from the beginning of the force contractions to 10, 20 and 30% of MVC. RESULTS: Paired sample t-tests did not reveal significant differences between E and Y were observed for Lf, FA and MT at any time point (p>0.05). In the E group, significant decrease in muscle thickness was observed between the beginning of the contraction to 10 (p=0.02), 20 (p=0.01) and 30% (p<0.01) of MVC, whereas no significant differences were detected in Lf and FA. In the Y group, no significant differences were detected in Lf, FA and MT from the beginning of the contraction to the different time points. CONCLUSION: Although preliminary, the change in muscle morphology, as described by the decrease in muscle thickness with increased contraction levels observed in the elderly, might indicate alterations of the contractile and non-contractile tissue interfering in muscle behaviour. References 1. Imrani L et al. (2022) J Gerontol A Biol Sci Med Sci 2. Fede C et al. (2022) Int J Mol Sci 3. Eng CM. et al. (2018) Integr Comp Biol. 4. Narici MV et al. (2021) J Cachexia. Sarcopenia Muscle 5. Holt NC et al. (2016) J Exp Biol
Read CV Clarissa M BruscoECSS Paris 2023: OP-BM11
INTRODUCTION: The Biceps Femoris Long Head (BFlh) has a high injury risk due to its complex architecture, with an intramuscular aponeurosis (IntApo) where fascicles from each region (e.g. proximal, middle and distal) attach. Previous studies using ultrasound (US) methodology have primarily assessed fascicle length (FL) differences among these regions, however, the interindividual variation between regions remains unclear. Additionally, fascicles are often assumed as straight-line (e.g. running in a single plane) (1). Novel techniques like Diffusion Tensor Imaging (DTI) enable tracking of fascicles and the observation of their orientation changes and curvature. While DTI has been applied effectively to muscles like the Medial Gastrocnemius (2), its application to the BFlh remains largely unexplored. This study aims to employ DTI analysis to observe fascicle characteristics between different regions of the BFlh. METHODS: Eight healthy subjects (four males and four females, 24.7 ± 2.3 years, 167.5 ± 7.2 cm, 62.8 ± 10.8 kg), without lower extremity injuries in the past year, participated in this study. Magnetic Resonance diffusion tensor imaging scans were taken with the subjects positioned prone and knee fully extended. Prior to imaging, subjects lay prone for 20 minutes to mitigate fluid content shifts, followed by pre-conditioning trials 50% MVC of knee flexion for five seconds. Segmentation of the BFlh muscle and IntApo was conducted utilizing 3DSlicer software, and tractography was performed by dsi_studio software. Fascicles attaching to the IntApo and intersecting at 30%, 50% and 70% of aponeurosis lengths (e.g. proximal, middle and distal regions) were selected. FL was defined as the length between muscle surface to the IntApo and calculated by multiplying the number of coordinates within the fascicle by the distance between these coordinates. Fascicle curvature (FC) was expressed as the ratio of its length to the straight-line distance between its endpoints. RESULTS: No significant changes in FL (proximal: 113.03 ±17.455 (95% CI [95.575 – 130.485]) , middle: 117.80 ±15.938 (95% CI [101.862 – 133.738]) , distal: 112.11 ±13.845 (95% CI [98.265 – 125.955])) or FC (proximal: 2.76 ±0.194 (CI 95% [2.566 – 2.954]), middle: 2.78 ±0.249 (CI 95% [2.531 – 3.029]) , distal: 2.92 ±0.284 (CI 95% [2.636 – 3.204])) were observed within regions. However, fascicles were shown to change its orientation along its length, elucidating that the fascicles run in the sagittal and coronal planes. CONCLUSION: DTI tractography allows to observe differences in FL and FC between regions of the BFlh. Additionally, it demonstrated that BFlh runs along the sagittal and coronal planes rather than just a single plane, which can lead to measurement errors when measuring FL using two-dimensional US methods. References Franchi MV et al. Med Sci Sports Exerc. 2020 Jan;52(1):233-243 Takahashi, K et al. J Anat, 2022 Aug; 241, 1324–1335.
Read CV Carmela Julia Mantecon TagarroECSS Paris 2023: OP-BM11
INTRODUCTION: The hamstring muscles play an important role in many sports, and hamstring muscle strengthening is needed to improve performance and prevent injuries (1). Hamstring strengthening programs are commonly composed of hip extension-oriented (e.g., stiff-leg deadlift) and/or knee flexion-oriented (e.g., leg curl) exercises. It is well known that a similar magnitude of muscle hypertrophy can be achieved across a wide spectrum of loading ranges from 30% to 80% of 1-RM. In recent years, low load training has been combined with blood flow restriction (BFR) to promote muscle hypertrophy (2) and enhance strength (3). However, the effect of such loading combined with blood flow restriction on the distribution of hypertrophy within the hamstring muscle group has not been investigated. METHODS: A parallel randomized controlled trial design was implemented to compare the effect of a nine-week of High Load (HL) or Low Load-Blood flow restriction (LL-BFR) resistance training on the distribution of hamstring muscle hypertrophy. Participants were randomly allocated to one of three groups: HL, LL-BFR and control (CON). Two training sessions were composed of (a) stiff-leg deadlift and front squat and (b) a bi-set of bilateral seated leg curl and seated leg extension. They were alternated over the duration of the training program. Muscle volumes were assessed the week before and after the training program with freehand 3D ultrasound (3DUS) measurements (4). RESULTS: Notable hypertrophy was observed for the ST (+26.5%) and SM (+17.1%) (all P values <0.01) during HL, while no changes were found for BF (+4.0%; P=1.0). LL-BFR group exhibited significant hypertrophy for SM (+21.6%), BF (+14.6%) and ST (+12.2%) (all P values <0.01). CONCLUSION: Although LL-BFR and HL improved hamstring muscle volume to a similar extent, its distribution differed between SM, ST and BF. The hypertrophy was most in ST and SM for the HL group while it was balanced across all muscles for the BFR-LL group, the magnitude of which varied greatly among participants. These results provide new findings for optimizing training, prevention, and rehabilitation programs that aim to induce a selective hypertrophy among the hamstring muscles. 1. Maniar N, Carmichael DS, Hickey JT, et al. Br J Sports Med. 2023;57(2):109–16. 2. Biazon TMPC, Ugrinowitsch C, Soligon SD, et al. Front Physiol. 2019;10:446. 3. Lixandrão ME, Ugrinowitsch C, Berton R, et al. Sports Med. 2018;48(2):361–78. 4. Frouin A, Guenanten H, Le Sant G, et al. Ultrasound in medecine and Biology. 2023;49(6):1457–64.
Read CV antoine frouinECSS Paris 2023: OP-BM11