Contraction forces generated by non-muscle cells, such as fibroblasts, play important roles in determining cell morphology, vasoconstriction, and/or wound healing. We have searched among various plant extracts for ingredients that generate cell contraction forces using fibroblast-populated collagen gels. Using that model, we found that an extract of horse chestnuts (Aesculus hippocastanum) is able to generate such contraction forces in fibroblasts. The involvement of stress fiber formation in that response is suggested by the inhibition of such force generation by cytochalasin D and rhodamine phalloidin stain. Clinical testing of the extract was carried out using 40 healthy female volunteers. A gel formulation that included 3% of the extract was applied topically to the skin around the eye three times daily for nine weeks. The efficacy of the extract to diminish wrinkles was evaluated by visual scoring based on photo scales. After six weeks, significant decreases in the wrinkle scores at the corners of the eye or in the lower eyelid skin were observed compared with controls. After nine weeks, similar results were obtained. Taken together, our results suggest that an extract of horse chestnuts can generate contraction forces in fibroblasts and is a potent anti-aging ingredient.
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Int J Sports Physiol Perform
January 2025
Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
Purpose: Maximal muscle strength is often assessed with single-joint or repetition-maximum testing. The purpose of this study was to evaluate the reliability of countermovement-jump (CMJ) velocity-load testing and assess the relationship between CMJ velocity-load kinetics and concentric-isometric-eccentric multijoint leg-extension strength tested on a robotic servomotor leg press in trained athletes.
Methods: University athletes (N = 203; 52% female) completed 3 concentric, isometric, and eccentric maximum voluntary leg-extension contractions on the robotic leg press, followed by CMJ velocity-load testing with an additional external load of 0% (CMJBW), 30% (CMJ30), and 60% (CMJ60) of body mass.
J Biomech
January 2025
Walker Department of Mechanical Engineering, The University of Texas at Austin Austin TX USA.
Skipping represents a training alternative to running due to its lower knee contact forces and higher whole-body metabolic cost. The increased metabolic cost of skipping is associated with a higher vertical center-of-mass (COM) displacement during the support and flight phases of the skipping hop compared to running. However, skipping has lower muscle force impulses than running.
View Article and Find Full Text PDFActa Bioeng Biomech
September 2024
Institute of Advanced Research for Sport and Health Science, Ritsumeikan University, Japan.
: Toe flexor strength (TFS) has been determined to evaluate the toe flexor muscle function. However, it is unclear how strength and size relationships of toe flexor muscles vary depending on the toes intended for force production. We aimed to clarify this by examining the relationship between TFS and toe flexor muscle size, and hypothesized TFS produced by all toes (TFS-All), the great toe (TFS-Great) and lesser toes (TFS-Lesser) would be specifically associated with the size of the muscles specialized in each corresponding toe flexion.
View Article and Find Full Text PDFJ Gen Physiol
March 2025
Department of Animal, Veterinary, and Food Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, USA.
The mechanisms underlying cooperative activation and inactivation of myocardial force extend from local, near-neighbor interactions involving troponin-tropomyosin regulatory units (RU) and crossbridges (XB) to more global interactions across the sarcomere. To better understand these mechanisms in the hearts of small and large mammals, we undertook a simplified mathematical approach to assess the contribution of three types of near-neighbor cooperative interactions, i.e.
View Article and Find Full Text PDFJ Appl Physiol (1985)
January 2025
Experimental Biomechanics Group, Institute of Structural Mechanics and Dynamics in Aerospace Engineering, Faculty of Aerospace Engineering and Geodesy, University of Stuttgart, Germany.
Characterizing individual muscle behavior is crucial for understanding joint function and adaptations to exercise, diseases, or aging. Shear wave elastography (SWE) is a promising tool for measuring the intrinsic material properties of muscle. This study assessed the passive and active shear modulus of the triceps surae muscle group in 14 volunteers (7 females, 25.
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