Publications by authors named "Jean Francois Grosset"

To investigate the effect of moderate or heavy slow resistance training on structural and mechanical properties of patellar and Achilles tendons in older men, in vivo. Healthy older men (n = 27) undertook a 12-week resistance training program (3 times/week) of triceps surae and quadriceps muscle-tendon complexes. Participants were randomly assigned to either a moderate load of 55% 1RM (O55, n = 13, age: 70.

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The aim of this study was to investigate the effect of aging and resistance training with a moderate load on the size and mechanical properties of the patellar (PT) and Achilles tendon (AT) and their associated aponeuroses; medial gastrocnemius (MG) and vastus lateralis (VL). Young (Y55; 24.8 ± 3.

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The development of new, viable, and functional engineered tissue is a complex and challenging task. Skeletal muscle constructs have specific requirements as cells are sensitive to the stiffness, geometry of the materials, and biological micro-environment. The aim of this study was thus to design and characterize a multi-scale scaffold and to evaluate it regarding the differentiation process of C2C12 skeletal myoblasts.

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Background: To investigate how anatomical cross-sectional area and volume of quadriceps and triceps surae muscles were affected by ageing, and by resistance training in older and younger men, in vivo.

Methods: The old participants were randomly assigned to moderate (O55, n = 13) or high-load (O80, n = 14) resistance training intervention (12 weeks; 3 times/week) corresponding to 55% or 80% of one repetition maximum, respectively. Young men (Y55, n = 11) were assigned to the moderate-intensity strengthening exercise program.

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It remains unclear whether neuromuscular electrical stimulation can induce sufficient tendon stress to lead to tendon adaptations. Thus, we investigated the effect of such a training program on the triceps surae muscle following the morphological and mechanical properties of the Achilles tendon. Eight men participated in a 12-week high-frequency neuromuscular electrical stimulation training program of the triceps surae muscle under isometric conditions.

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Background: Sit-to-stand is used as a qualitative test to evaluate functional performance, especially to detect fall risks and frail individuals. The use of various quantitative criteria would enable a better understanding of musculoskeletal deficits and movement strategy modifications. This quantification was proven possible with a magneto-inertial unit which provides a compatible wearable device for clinical routine motion analysis.

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Tissue engineering is a promising approach to repair tendon and muscle when natural healing fails. Biohybrid constructs obtained after cells’ seeding and culture in dedicated scaffolds have indeed been considered as relevant tools for mimicking native tissue, leading to a better integration in vivo. They can also be employed to perform advanced in vitro studies to model the cell differentiation or regeneration processes.

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  • This study evaluates how the shape of the Probability Density Function (PDF) for High Density surface Electromyography (HD-sEMG) changes with different levels of muscle contraction.
  • It uses statistical measures like High Order Statistics (HOS) and Shape Distances (SD) to explore the non-Gaussian characteristics of sEMG signals as force varies, which can enhance muscle function assessment.
  • Both experimental tests on six subjects performing controlled muscle contractions and simulation studies with personalized modeling were conducted, revealing that PDF shape variations are influenced by motor unit recruitment strategies and electrode configurations.
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Substantial gains in muscle strength and hypertrophy are clearly associated with the routine performance of resistance training. What is less evident is the optimal timing of the resistance training stimulus to elicit these significant functional and structural skeletal muscle changes. Therefore, this investigation determined the impact of a single bout of resistance training performed either in the morning or evening upon acute anabolic signalling (insulin-like growth factor-binding protein-3 (IGFBP-3), myogenic index and differentiation) and catabolic processes (cortisol).

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  • The study compared Achilles tendon stiffness and plantar pressure in poorly and well-controlled diabetic patients with healthy controls, finding no differences between the two diabetes groups.
  • It was revealed that diabetic patients had significantly greater collagen cross-linking and tendon stiffness compared to controls, along with a higher forefoot/rearfoot peak-plantar-pressure ratio, potentially contributing to foot ulcer development.
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Life-long regular endurance exercise is known to counteract the deterioration of cardiovascular and metabolic function and overall mortality. Yet it remains unknown if life-long regular endurance exercise can influence the connective tissue accumulation of advanced glycation endproducts (AGEs) that is associated with aging and lifestyle-related diseases. We therefore examined two groups of healthy elderly men: 15 master athletes (64 ± 4 years) who had been engaged in life-long endurance running and 12 old untrained (66 ± 4 years) together with two groups of healthy young men; ten young athletes matched for running distance (26 ± 4 years), and 12 young untrained (24 ± 3 years).

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  • The study investigated the impact of low (40% 1RM) versus high (80% 1RM) intensity resistance training on tendon properties in older adults over 12 weeks.
  • Participants were pair-matched based on factors like gender and physical activity, with 9 in the low intensity group and 8 in the high intensity group.
  • Results showed significant improvements in tendon stiffness and Young's modulus in the high intensity group, indicating that lower intensities may not effectively enhance tendon properties in the elderly.
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Purpose: Neuromuscular electrical stimulation (NMES) training is known to induce improvement in force production capacities and fibre-type transition. The aim of this study was to determine whether NMES training also leads to changes in the mechanical properties of the human triceps surae (TS) muscle.

Methods: Fifteen young male subjects performed a training protocol (4 weeks, 18 sessions, 4-5 sessions per week) based on a high-frequency isometric NMES programme of TS muscle.

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It has previously been shown that low-frequency neuromuscular electrical stimulation (NMES) techniques can induce increases in energy expenditure similar to those associated with exercise. This study investigated the metabolic and cardiovascular effects of a 1 h session of lower limb NMES and compared cardiovascular response with that observed during walking in nine obese subjects (three males) (age = 43.8 ± 3.

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Recent studies have suggested that subtetanic neuromuscular electrical stimulation (NMES) protocols applied to the quadriceps and hamstrings may have potential as an alternative aerobic exercise modality. However, its tolerability and effectiveness in the physically active population has been questioned. The primary purpose of this study was to measure physiological and subjective responses to a modified subtetanic NMES protocol in a physically active adult population.

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  • The study examines the relationship between the H-reflex (a spinal reflex) parameters and aerobic capacity in a group of 56 young, untrained men.
  • It measures various reflex excitability parameters, including the normalized H-reflex and the M-wave, alongside oxygen consumption and aerobic power through specific running and cycling tests.
  • The findings reveal that maximal oxygen consumption is only correlated with the slope of the M-wave recruitment curve, indicating that, in untrained individuals, the H-reflex may not be linked to aerobic capacity as previously thought.
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  • The study explores how the timing of intense exercise (morning vs. evening) affects inflammatory responses, specifically the release of the cytokine Interleukin-6 (IL-6) in healthy males.
  • Although they found significant time-of-day differences in IL-6 levels in control participants (not exercising), those who exercised showed no changes in IL-6 post-workout.
  • Cortisol levels were influenced by the timing of exercise, but the overall findings suggest that the time of day does not significantly impact IL-6 release in trained individuals.
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Clinical manual tests refer to increased ankle stiffness in children immobilized due to hip osteochondritis. The aim of the present study was to investigate musculo-articular stiffness via different techniques in immobilized children to confirm or not and quantify these observations. Ankle stiffness was quantified monthly during the long immobilization period in three diseased children and compared to healthy age-matched children.

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Our aim was to determine the time course of any changes in muscle volume and shape in the lower limbs following immobilization. A healthy young woman (29 years) had suffered a fracture of the fifth metatarsal of the right foot. MRI scanning of her right thigh and calf muscles had been performed 1 month before the injury (Pre) during a scan initially planned as a teaching tool, 2 days following a 4-week immobilization period (Post), and after a 2-month recovery period (Post+2).

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When measured in vivo electromechanical delay (EMD) depends mainly on the elastic properties of the muscle-tendon unit. Recent studies have shown changes in stiffness of the triceps surae (TS) following a period of training. To confirm the influence of musculo-tendinous stiffness on EMD, this study investigates paired changes in these two parameters after a training period.

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  • Musculo-articular stiffness in the triceps surae muscle increases with age in prepubescent children, affecting both passive and active conditions.
  • A study measured muscle stiffness and reflex responses (H and T reflexes) in 46 children (ages 7-11) and 9 adults, finding that children's reflexes are smaller and their stiffness lower compared to adults.
  • Although children's T reflexes grew with age, they still remained significantly less than adults', and there was a correlation between increased stiffness and reflex response as children aged.
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The activation capacities and neuromuscular efficiency (NME) of the triceps surae (TS) of prepubescent children (7-11 years) and adults were evaluated during submaximal and maximal (MVC) isometric plantarflexion to determine whether they varied with age. TS-EMG were obtained by summing-up the rectified electromyograms of the soleus and gastrocnemii muscles; these data were quantified using a sliding average method and normalized with reference to the TS maximal compound action potential (TS-M-wave). The maximal EMG increased significantly with age in the children, but less than MVC, what led to a significant increase in NME(Max) (MVC/TS-EMG(max) ratio).

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The twitch of the triceps surae muscle (TS), which characterizes the contractile properties independently of volition, differs in amplitude, but not in time course, when evoked in pre or postpubertal children. The aim of the present study was to compare the TS twitch contractile properties in prepubertal children (7 to 11 y). M-wave and twitch were recorded at rest by supramaximal electrical stimulations of the posterior tibial nerve.

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Musculotendinous (MT) stiffness of the triceps surae (TS) muscle group was quantified in 28 prepubertal children (7-10 yr) by using quick-release movements at different levels of submaximal contractions. Surface electromyograms (EMG) of each part of the TS and of the tibialis anterior were also recorded. A stiffness index, defined as the slope of the angular stiffness-torque relationship (SIMT-Torque), was used to quantify changes in MT stiffness with age.

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