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Although master athletes maintain high levels of physical activity, they also suffer from an age-related decline in skeletal muscle function. There are indications of disproportional age- and physical inactivity-induced muscle wasting between muscles. Tensiomyography is a noninvasive tool that has been used to study the effects of a variety of sports on the contraction time (Tc) in different skeletal muscles. The aim of this cross-sectional study was to assess age-related changes in the Tc of the vastus lateralis, gastrocnemius medialis, and biceps femoris muscles with Tensiomyography in older nonathletes (age = 62.1 ± 12.7 years; NMALES = 133; NFEMALES = 246), and power (age = 56.9 ± 13.5 years; NMALES = 100; NFEMALES = 78) and endurance master athletes (age = 56.5 ± 14.5 years; NMALES = 76; NFEMALES = 73). We found an age-related slowing in all muscles, irrespective of discipline, where endurance master athletes had the longest and power master athletes had the shortest Tc. The longer Tc in endurance master athletes than in nonathletes suggests that regular endurance sport activity aggravates slowing of skeletal muscles during aging. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine whether an improvement in jumping performance after 8 weeks of plyometric training (PT) runs in parallel with changes in lower-limb skeletal muscle contractile properties. Using noninvasive tensiomyography (TMG), we assessed contraction time (Tc) and the maximal amplitude of radial displacement (Dm) in 20 subjects (50% men; age 22.4 ± 4.7 years of age), randomly divided in PT group (N = 10; PLYO) and a control group (N = 10; CTRL). The PLYO performed 8 weeks of PT. Tensiomyography was measured in 5 leg skeletal muscles: vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius medialis (GM), and gastrocnemius lateralis (GL). Additionally, we evaluated countermovement jump (CMJ) height improvement on a ground force plate. Assessments were repeated before and after PT. After 8 weeks of PT, CMJ height increased by 12.2% in PLYO (p = 0.015), but not in CRTL. Contraction time, which is related to myosin heavy-chain type 1 (MHC-1) proportion, decreased in VL (-8.7%; p < 0.001), BF (-26.7%; p = 0.032), TA (-32.9%; p = 0.004), and GL (-25.8%; p = 0.044), but not in GM (-8.1%; p = 0.158). The estimated VL MHC-1 proportion decreased by -8.2% (p = 0.041). The maximal amplitude of radial displacement, inversely related to muscle tone, decreased in BF (-26.5%; p = 0.032), GM (-14.9%; p = 0.017), GL (-31.5%; p = 0.017), but not in TA (-16.8%; p = 0.113) and VL (-6.0%; p = 0.654). After PT, jumping performance increased, which was paralleled by decreased Tc and decreased muscle tone. Additionally, adaptations to contractile properties were muscle specific, which is important for future studies. It seems that adjustments were dose dependent, being higher in muscles with lower habitual load. [ABSTRACT FROM AUTHOR]

Motor activity in childhood is extremely important for the general development of a child, yet there is still not enough information about children's motor development. Contractile properties of skeletal muscles in children mainly reflect their inherited muscle characteristics. In early childhood the muscular structure is made mostly of slow-twitch muscular fibers. The finer motor abilities follow gradually from age three onwards when the muscular fiber is classified into slow-twitch, rapid and fast-twitch. The fastest development of this classification (muscle differentiation) takes place until the age of three and continues until the end of puberty. In this study muscles of 187 healthy 9-year-old children were assessed using a non-invasive and selective measuring method called tensiomyography (TMG) in order to estimate the stage of differentiation of their skeletal muscles. TMG enables selective measurements of radial muscle belly displacement as a response to a single electrical stimulus. The children measured were involved in this study after written consent had been obtained. TMG data were calculated on selected muscles: m. biceps brachii, m. vastus lateralis, m. biceps femoris and m. erector spinae. After TMG measurements had been carried out, each child performed a 14-metre sprint velocity test. TMG parameters were calculated and compared in three groups, namely, the ten fastest children, the ten slowest children and the average result of all the children measured. The ten fastest children had a smaller sum of delay time and contraction time, which correlates with a higher percentage of fast-twitch muscle fibers. They also had a significantly higher level of muscle activation. [ABSTRACT FROM AUTHOR]