Showing papers by "Marco Narici published in 2018"

Muscle thickness correlates to muscle cross‐sectional area in the assessment of strength training‐induced hypertrophy

Abstract: Muscle thickness (MT) measured by ultrasound has been used to estimate cross-sectional area (measured by CT and MRI) at a single time point. We tested whether MT could be used as a valid marker of MRI determined muscle anatomical cross-sectional area (ACSA) and volume changes following resistance training (RT). Nine healthy, young, male volunteers (24 ± 2 y.o., BMI 24.1 ± 2.8 kg/m(2) ) had vastus lateralis (VL) muscle volume (VOL) and ACSAmid (at 50% of femur length, FL) assessed by MRI, and VL MT measured by ultrasound at 50% FL. Measurements were taken at baseline and after 12 weeks of isokinetic RT. Differences between baseline and post-training were assessed by Student's paired t test. The relationships between MRI and ultrasound measurements were tested by Pearson's correlation. After RT, MT increased by 7.5 ± 6.1% (P .05). These data support evidence that MT is a reliable index of muscle ACSAmid and VOL at a single time point. MT changes following RT are associated with parallel changes in muscle ACSAmid but not with the changes in VOL, highlighting the impact of RT on regional hypertrophy.

Muscle Architecture Assessment: Strengths, Shortcomings and New Frontiers of in Vivo Imaging Techniques.

Abstract: Skeletal muscle structural assembly (and its remodeling in response to loading-unloading states) can be investigated macroscopically by assessing muscle architecture, described as fascicle geometric disposition within the muscle. Over recent decades, various medical imaging techniques have been developed to facilitate the in vivo assessment of muscle architecture. However, the main advantages and limitations of these methodologies have been fragmentally discussed. In the present article, the main techniques used for the evaluation of muscle architecture are presented: conventional B-mode ultrasonography, extended-field-of-view ultrasound, 3-D ultrasound and magnetic resonance imaging-based diffusion tensor imaging. By critically discussing potentials and shortcomings of each methodology, we aim to provide readers with an overview of both established and new techniques for the in vivo assessment of muscle architecture. This review may serve as decision guidance facilitating selection of the appropriate technique to be applied in biomedical research or clinical routine.

Regional regulation of focal adhesion kinase after concentric and eccentric loading is related to remodelling of human skeletal muscle.

Abstract: AIMS We assessed focal adhesion kinase (FAK) response to concentric (CON) versus eccentric (ECC) resistance training (RT) at two vastus lateralis (VL) sites, and the relationships between FAK, muscle protein synthesis (MPS), and morphological remodeling. METHODS Six young males trained both legs unilaterally 3 times/week for 8 weeks; one leg performed CON RT, the contralateral performed ECC RT. Muscle biopsies were collected after training from VL midbelly (MID) and distal (Distal) sites at 0, 4, 8 weeks. FAK content and activation were evaluated by immunoblotting. MPS was assessed by deuterium-oxide tracer; morphological adaptations were evaluated by ultrasound and DXA. RESULTS pY397-FAK 8 weeks levels were ~4-fold greater after ECC at the Distal site compared to CON (p<0.05); pY397FAK to total FAK ratio was greater in ECC versus CON at 4 (~2.2 fold, p<0.05) and 8 weeks (~9fold, p<0.001) at the Distal site. Meta-vinculin was found transiently increased at 4 weeks at the Distal site only after ECC RT. ECC presented greater fascicle length (Lf) increases (10.5% vs. 4%), whereas CON showed greater in pennation angle (PA) changes (12.3% vs. 2.1%). MPS did not differ between exercise types or muscle sites at all time points. Distal pY397-FAK and pY397-FAK/FAK values correlated to changes in Lf at 8weeks (r=0.76, p<0.01 and r=0.66, p<0.05, respectively). CONCLUSION FAK phosphorylation was greater at 8-wks after ECC RT and was muscle region-specific. FAK activity correlated to contraction-dependent architectural remodeling, suggesting a potential role of FAK in orienting muscle structural changes in response to distinct mechanical stimuli. This article is protected by copyright. All rights reserved.

Sarcolab pilot study into skeletal muscle's adaptation to long-term spaceflight.

Abstract: Spaceflight causes muscle wasting. The Sarcolab pilot study investigated two astronauts with regards to plantar flexor muscle size, architecture, and function, and to the underlying molecular adaptations in order to further the understanding of muscular responses to spaceflight and exercise countermeasures. Two crew members (A and B) spent 6 months in space. Crew member A trained less vigorously than B. Postflight, A showed substantial decrements in plantar flexor volume, muscle architecture, in strength and in fiber contractility, which was strongly mitigated in B. The difference between these crew members closely reflected FAK-Y397 abundance, a molecular marker of muscle's loading history. Moreover, crew member A showed downregulation of contractile proteins and enzymes of anaerobic metabolism, as well as of systemic markers of energy and protein metabolism. However, both crew members exhibited decrements in muscular aerobic metabolism and phosphate high energy transfer. We conclude that countermeasures can be effective, particularly when resistive forces are of sufficient magnitude. However, to fully prevent space-related muscular deterioration, intersubject variability must be understood, and intensive exercise countermeasures programs seem mandatory. Finally, proteomic and metabolomic analyses suggest that exercise benefits in space may go beyond mere maintenance of muscle mass, but rather extend to the level of organismic metabolism.

Assessing sarcopenia with vastus lateralis muscle ultrasound: an operative protocol.

Abstract: Muscle ultrasound (MUS) has so far not been implemented for sarcopenia assessment in clinical geriatric practice due to allegedly low reproducibility of results in the absence of standardization of procedures. However, rigorous and standardized application of this technique yields highly reproducible results. Its application, especially if integrated with clinical evaluation and comprehensive geriatric assessment, proofs very useful for rapidly obtaining information on muscle mass and architecture. Here, we present a standardized protocol for performing right vastus lateralis (RVL) MUS and measuring parameters of muscle size and architecture. RVL muscle thickness (MT), fascicle length (FL), pennation angle (PA), echo-intensity (EI) and cross-sectional area (CSA) can be assessed with this protocol. A portable instrument equipped with a 5-cm long 3–11 mHz linear probe should be used with both B-mode real-time and extended-field-of-view (EFOV) techniques. Longitudinal B-mode and transverse EFOV images should be acquired during each exam, and analyzed with NIH-ImageJ software. This operative protocol represents a good compromise between the feasibility of MUS in clinical settings and the need of obtaining precise measurements of muscle parameters. Future studies should verify the reproducibility of the proposed technique, and its correlation with appendicular lean mass and parameters of muscle function.

Muscle and Tendon Contributions to Reduced Rate of Torque Development in Healthy Older Males

Abstract: Background The ability to rapidly generate and transfer muscle force is essential for effective corrective movements in order to prevent a fall. The aim of this study was to establish the muscle and tendon contributions to differences in rate of torque development (RTD) between younger (YM) and older males (OM). Method Twenty-eight young males (23.9 years ± 1.1) and 22 old males (68.5 years ± 0.5) were recruited for assessment of Quadriceps Anatomical CSA (ACSA), maximal voluntary contraction (MVC), rate of torque development (RTD), and tendon biomechanical properties. Activation capacity (AC), maximal muscle twitch df/dt) and time to peak EMG amplitude (TTPE) were also assessed. Results Absolute RTD (aRTD) was lower in OM (577.5 ± 34.6 Nm/s vs 881.7 ± 45.6 Nm/s, p < .0001). RTD remained lower in OM following normalization (nRTD) for muscle ACSA (9.93 ± 0.7 Nm/s/cm2 vs 11.9 ± 0.6 Nm/s/cm2, p < .05). Maximal muscle twitch df/dt (1,086 Nm∙s-1 vs 2,209 Nm∙s-1, p < .0001), TTPE (109.2 ± 8.6ms vs 154.6 ± 16.6 ms, p < .05), and AC (75.8 ± 1.5% vs 80.1 ± 0.9%, p < .01) were all affected in OM. Tendon stiffness was found to be lower in OM (1,222 ± 78.4 N/mm vs 1,771 ± 154.1 N/mm, p < .004). nRTD was significantly correlated with tendon stiffness (R2 = .15). Conclusion These observations provide evidence that in absolute terms, a lower RTD in the elderly adults is caused by slower muscle contraction speeds, slower TTPE, reduced ACSA, reduced MVC, and a decrease in tendon stiffness. Once the RTD is normalized to quadriceps ACSA, only MVC and tendon stiffness remain influential. This strongly reinforces the importance of both muscle and tendon characteristics when considering RTD.

Developing a toolkit for the assessment and monitoring of musculoskeletal ageing.

Abstract: The complexities and heterogeneity of the ageing process have slowed the development of consensus on appropriate biomarkers of healthy ageing. The Medical Research Council–Arthritis Research UK Centre for Integrated research into Musculoskeletal Ageing (CIMA) is a collaboration between researchers and clinicians at the Universities of Liverpool, Sheffield and Newcastle. One of CIMA’s objectives is to ‘Identify and share optimal techniques and approaches to monitor age-related changes in all musculoskeletal tissues, and to provide an integrated assessment of musculoskeletal function’—in other words to develop a toolkit for assessing musculoskeletal ageing. This toolkit is envisaged as an instrument that can be used to characterise and quantify musculoskeletal function during ‘normal’ ageing, lend itself to use in large-scale, internationally important cohorts, and provide a set of biomarker outcome measures for epidemiological and intervention studies designed to enhance healthy musculoskeletal ageing. Such potential biomarkers include: biochemical measurements in biofluids or tissue samples, in vivo measurements of body composition, imaging of structural and physical properties, and functional tests. This review assesses candidate biomarkers of musculoskeletal ageing under these four headings, details their biological bases, strengths and limitations, and makes practical recommendations for their use. In addition, we identify gaps in the evidence base and priorities for further research on biomarkers of musculoskeletal ageing.

Relationship of changes in strain rate indices estimated from velocity‐encoded MR imaging to loss of muscle force following disuse atrophy

Abstract: Purpose This study explores changes in strain rate (SR) (rate of regional deformation) parameters extracted from velocity-encoded MRI and their relationship to muscle force loss following 4-week unilateral lower limb suspension in healthy humans Methods Two-dimensional SR maps were derived from three directional velocity-encoded MR phase-contrast images of the medial gastrocnemius in seven subjects Atrophy-related and regional differences in the SR eigenvalues, angle between the SR and muscle fiber (SR-fiber angle), and strain rates in the fiber basis were statistically analyzed using analysis of variance and linear regression Results During isometric contraction, SR in the fiber cross section (SRin-plane) was significantly lower, and the SR-fiber angle was significantly higher postsuspension (P < 005) On multiple variable regression analysis, the volume of medial gastrocnemius, SRin-plane, and SR-fiber angle were significantly associated with force and changes in the, and the SR eigenvalues and shear SR were significantly associated with change in force with disuse Conclusions Changes in SR-fiber angle, SRin-plane, and shear SR as well as their ability to predict force and force changes may reflect the role of remodeling of the extracellular matrix in disuse atrophy and its functional consequence in reducing lateral transmission of force Magn Reson Med 79:912–922, 2018 © 2017 International Society for Magnetic Resonance in Medicine

Effects of 14 days of bed rest and following physical training on metabolic cost, mechanical work, and efficiency during walking in older and young healthy males

Abstract: In this study, we investigated: i) the effects of bed rest and a subsequent physical training program on metabolic cost (Cw), mechanical work and efficiency during walking in older and young men; ii) the mechanisms underlying the higher Cw observed in older than young men.Twenty-three healthy male subjects (N = 16 older adults, age 59.6±3.4 years; N = 7 young, age: 23.1±2.9 years) participated in this study. The subjects underwent 14 days of bed rest followed by two weeks of physical training (6 sessions). Cw, mechanical work, efficiency, and co-contraction time of proximal muscles (vastus lateralis and biceps femoris) and distal muscles (gastrocnemius medialis and tibialis anterior) were measured during walking at 0.83, 1.11, 1.39, 1.67 m·s-1 before bed rest (pre-BR), after bed rest (post-BR) and after physical training (post-PT).No effects of bed rest and physical training were observed on the analysed parameters in either group. Older men showed higher Cw and lower efficiency at each speed (average +25.1 and -20.5%, P<0.001, respectively) compared to young. Co-contraction time of proximal and distal muscles were higher in older than in young men across the different walking speeds (average +30.0 and +110.3%, P<0.05, respectively).The lack of bed rest and physical training effects on the parameters analyzed in this study may be explained by the healthy status of both young and older men, which could have mitigated the effects of these interventions on walking motor function. On the other hand, the fact that older adults showed greater Cw, overall higher co-contraction time of antagonist lower limb muscles, and lower efficiency compared to the young cohort throughout a wide range of walking speed may suggest that older adults sacrificed economy of walking to improve stability.

Shear strain rate from phase contrast velocity encoded MRI: Application to study effects of aging in the medial gastrocnemius muscle

Abstract: BACKGROUND Strain rate (SR) is a measure of the rate of regional deformation that can be computed by analyzing velocity-encoded phase-contrast 2D images. Recent studies have explored the changes in normal components of the strain tensor in aging muscle, while shear strain may also provide valuable information. PURPOSE To compute the shear SR from velocity-encoded MRI of the lower leg and to study the correlation of SR parameters measured in the medial gastrocnemius (MG) to muscle force in a cohort of young and senior subjects. STUDY TYPE Prospective cohort study. SUBJECTS Six young (26.1 ± 2.3 years) and six senior (76.7 ± 8.3 years) healthy females; two other subjects were scanned on three separate occasions for repeatability studies. FIELD STRENGTH/SEQUENCE 1.5T using a single oblique sagittal slice with velocity-encoding in three directions (velocity-encoded phase contrast gradient echo sequence). ASSESSMENT Age-related and regional differences in the SR eigenvalues (SRfiber , SRin-plane ), normal SRs (SRff , SRcc ), and shear SRs (SRfc , SRfc_max ) were statistically analyzed. STATISTICAL TESTS Difference between young and senior cohorts were assessed using two-way analysis of variance (ANOVAs). The coefficient of variation and repeatability coefficient were calculated from repeat studies. Univariate and stepwise multivariable linear regression was performed to identify predictors of force. RESULTS During isometric plantarflexion contraction, SRs in the principal basis (SRfiber , SRin-plane ) and maximum shear SR (SRfc_max ) was significantly lower in the senior cohort (P < 0.05). On multiple variable regression, maximum shear SR (SRfc_max ) and normal SR in the fiber cross-section (SRcc ) were significantly associated with force (R = 0.681, F = 14.034, P < 0.001). DATA CONCLUSION This study establishes that computation of shear strain is feasible and is a significant predictor of force variability with age. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1351-1357.

Erratum: Author Correction: Sarcolab pilot study into skeletal muscle's adaptation to longterm spaceflight.

Abstract: The original version of this Article contained an error in the spelling of the author Claudio Franceschi, which was incorrectly given as Claudio Francheschi. This has now been corrected in both the PDF and HTML versions of the Article.

Response to the letter to editor by Dankel et al. 2017 "Changes in muscle size via MRI and ultrasound: Are they equivalent?"

Abstract: We thank Dr. Dankel and colleagues for their letter (Dankel et al. 2017) concerning our manuscript Franchi et al. 2017.1 In summary, while acknowledging the new insight the work provides regarding the association between ultrasoundbased imaging and MRI when quantifying increases in muscle mass with resistance exercise training, Dankel and colleagues propose that an equivalency test could have been adopted involving the use of half of the minimal difference for muscle thickness (MT) as a confidence interval. This suggestion was made on the basis that the reported correlation between changes in MT and anatomical crosssectional area (ACSA) (Figure 4 of the manuscript) appeared to be “primarly driven by 4 limbs (likely from two individuals).” Using a graph digitizer, Dankel and colleagues estimated the values plotted in Figure 4A of the manuscript and concluded that the reported association was less robust (r = .34, P = .236) when the aforementioned 4 limbs were removed from the data set. While we understand these methodological considerations raised by Dankel and colleagues, we can see no valid reason to remove these data (ie, 22.2% of the whole data pool) when both ultrasound and MRI identified large hypertrophic changes with training. Biological variance between volunteers should be expected when considering temporal responses to chronic exercise intervention in human volunteer research, rather than crosssectional comparisons. Moreover, these data were obtained from 3 volunteers (not 2), which is 33% of the volunteers recruited in to the study. Finally, we would like to highlight that we do not claim that MT and ACSA are “deemed equivalent,” as it is clear from Table 1 and the Results section of Franchi et al. 2017.1 Indeed, we make it transparent that our results are bound by a matter of scaling and dimension. A linear, single, dimension (muscle thickness) correlates better with a twodimensional measure (CSA) than a threedimensional measure (muscle volume). As stated in the manuscript, “From a simple mathematical point of view, the three parameters (MT, ACSA, and VOL) would be expected to change proportionally only if the muscle had a perfectly regular geometrical shape (eg, ellipsoid); in fact, if assuming that the length and the width of a muscle are constant, the increases in muscle VOL should be reflected in a proportional increases in ACSA and MT.” Thus, we agree with Dankel and colleagues that MT shows a tendency in detecting greater changes in muscle growth compared to ACSA. This however does not detract in any way from the stated aims of the study “to examine relationships between ultrasound and MRI assessed changes in muscle size in response to a resistance training protocol” and “that resistance traininginduced change in VL MT would be positively correlated to changes in VL ACSA and VOL.”