The effects of long-term space flight on human triceps surae (TS) muscle function and electromechanical delay (EMD) have been investigated. Voluntary and electrically evoked contractions of the TS were obtained from 7 male cosmonauts 30 days before and 3 days after landing. For all cosmonauts the isometric maximal voluntary contraction was reduced by 41.7 % (p < 0.01), whereas the electrically evoked maximal tetanic contraction force (Po) was found to decrease by 25.6 % (p < 0.05). Force deficit increased by 50 % (p < 0.001). This suggests that most of the force loss is due to a reduction in motor drive (motor control). The decrease in Po was associated with a significant increase of the corresponding maximal rates of tension development (43.7 %). The twitch tension (Pt) was not significantly changed and the Pt/Po ratio was increased by 46.7 % (p < 0.05) after space mission. The twitch time-to-peak tension of the TS increased by 7.7 %, but half-relaxation time decreased by 20.6 %. Force-velocity properties of the TS calculated according to a relative scale of voluntary contraction development significantly decreased. The calculations of the same properties of electrically evoked contraction development did not differ substantially from the initial physiological state. Total reaction time (TRT), pre-motor time (PMR) and motor time or EMD were determined. In response to a supramaximal single electrical pulses applied to the tibial nerve, the latent period between the M-wave and Рt beginning was determined. The voluntary contraction EMD increased by 34.1 %; but PMR and TRT decreased by 19.0 and 14.1 %, respectively. The EMD of electrically evoked contraction did not significantly change. Thus, the comparison of the mechanical alterations recorded during voluntary contractions and in contractions evoked by electrical stimulation of the motor nerve, suggests that weightlessness not only modifies the peripheral processes associated with contractions, but also changes central and/or neural command of the contraction. Show less

Aging mammalian skeletal muscle satellite cells (MuSCs) undergo a decline of stem cell/progenitor cell proliferative and regenerative capacity, and the development of a physiological milieu characteristic of a state of chronic sterile inflammation. p38αMAPK and ERK1/2 are two major signaling pathways that regulate the age-associated decline of MuSC proliferative capacity. In this review we propose the following mechanism that links the p38αMAPK pathway to the decline of self-renewal and regenerative capacity of aged MuSCs: a) the HS-FGF-2-FGFR1-p38αMAPK-Axis, a tightly linked homeostatic signaling complex, is in synchrony with the autoinhibition of FGFR1; b) autoinhibition contributes to the Axis’ regulation of the homeostasis of P-p38αMAPK activity in juvenile MuSC; c) this combination of protein-protein interactions is characteristic of a juvenile cytoplasmic milieu of beneficial P-p38αMAPK activity and d) includes Sprouty1 inhibition that supports the stimulation of FGF-2 --> miR-29a; e) the miR29a dismantles the basement membrane in preparation for the initiation of replication; f) an age-associated impaired, dysregulated, over-sulfated heparan sulfate ligand (HS)-FGF-2 fails to activate FGFR1 in aged MuSCs; g) this uncouples its regulation of p38αMAPK and ERK1/2 pathways and results in desensitization of FGFR1; h) desensitization of FGFR1 and Sprouty1 interaction in aged MuSC uncouples their regulation of P-p38αMAPK in the aged MuSCs; i) this enables a state of chronic sterile inflammation to promote and sustain an increased level of P-p38αMAPK activity; and, j) the increased activity of P-p38αMAPK in aged MuSC stimulates the production of cell cycle inhibitors, miR-1 and miR-133, thereby attenuating the expression of the cell cycle regulators, SP1 and cyclin D1, resulting in a G1/S arrest; j) the increased level of p38αMAPK activity promotes the apoptosis of the aged activated MuSCs. This mechanism involves the synergistic interactions of HS-FGF2-FGFR-1, Sprouty (spry1), miR-1, miR-133 and miR-29a that unify the extracellular niche and intracellular milieu for the juvenile vs age-associated regulation of proliferative capacity of the MuSC. Our hypothesis unifies these interactions with the role of the extracellular niche and intracellular milieu in the stimulation of juvenile proliferation vs age-associated decline of skeletal muscle satellite cell self-renewal and regenerative proliferation. Word Count = 344 Show less

Some certain foods or drinks have specific effects on musculoskeletal frameworks in time of pain. For instance, the extra intake of salt declines muscular spams (or cramps) in different limbs. The regular consumptions of milk products reduce the upper or lower musculature weakness and pain. The hot drinks and foods as other examples can help to mitigate the abdominal pains. Indeed, warm drinks boost memory through lowering the pressures in different brain ‘sections (or lobs) in fatigue time. Some plant - based diets assist to the better digestion through faster and more smooth facilitation of food transformation in stomach areas. The plant – based dietary also can decline the heart muscle shocking impulse. However, some people for different reasons (i.e. cultural) do not consume some specific foods and drinks that can be kind of disadvantages for musculature system. Nonetheless, increasing the knowledge of daily food intakes can significantly help to improve musculoskeletal health in different individual in an uncertain condition. Show less