Uvod: Problemi sedečega načina sodobnega življenja se kažejo v fizioloških odzivih, tako pri starejših kot tudi pri mlajših ljudeh. Cilj raziskave je bilugotoviti odziv morfoloških in skeletno-mišičnih značilnosti ter izgubo funkcionalnih sposobnosti ohranjanja ravnotežja po 35-dnevni popolni gibalni nedejavnosti in zagotovljeni uravnoteženi prehrani glede na njeno sestavo in preiskovančevo telesno težo. Metode: Deset moških preiskovancev (starih 24,32,6 let) je v bolnišničnem okolju preležalo 35 dni v vodoravnem položaju. Fiziološke odzive telesa smo vrednotili z merjenji telesne, maščobne in mišične mase, mineralne vsebnosti sprednje golenske kosti, togosti trebuha dveh funkcionalno različnih glav antigravitacijske mišice in sposobnost ohranjanja ravnotežja. Rezultati: Preiskovanci so v povprečju značilno izgubili 0,97 % (P=0,001) telesne teže, 4,1 % (P=0,009) mišične mase in 1,7 % (P=0,000) mineralne gostote tibialne kosti ter pridobili 1,4 % (P<0,000) maščobne mase. Mišična togost se je značilno zmanjšala od 8. dne ležanja (P=0,006) dalje pri distalni in že od 1. dneva (P=0,007) dalje pri proksimalniglavi notranje stegenske mišice ter se 14. dan po zaključku BR vrnila v izhodiščno stanje le pri distalni glavi. Po zaključku BR in dan kasneje smo ugotovili značilno izgubo ohranjanja ravnotežja za 9,5 % (P=0,006), in 17,4 % (P=0,000), medtem ko 14. dan po zaključku ležanja ni biloveč značilnih razlik. Zaključek: Povzamemo lahko, da z uravnoteženo prehrano lahko omejimo izgubo telesne teže in pridobivanje maščobne mase, vendar ne moremo zmanjšati izgube mišične mase ter mineralne vsebnosti tibialne kosti. Ugotovili smo, da se mišična togost zmanjšuje v dveh časovno zakasnjenih procesih. Sposobnost ohranjanja ravnotežja je zmanjšana v vsaj prvih 24 urah po zaključku ležanja.Introduction: Sedentary lifestyle causes morphological in physiological changes in both elderly and young people. Horizontal bed rest (BR) is one of the most widely used models for studying the effects of spaceflight, physical inactivity and sedentarism on human body. Our aim was to determine morphological and musculoskeletal changes, and changes in functional balance occurring as a result of total 35-day physical inactivity in persons eating nutritionally well balanced diet adjusted to individual body weight. Methods:Ten healthy young males (age 24.3 2.6 years) were submitted to a 35-day horizontal bed rest in strict hospital environment. Body mass, fat mass, muscle mass, tibial bone mineral content, muscle belly stiffness and postural stability were monitored prior to, during and after bed rest. Results: Body mass dropped by 1 % (P=0.001), muscle mass by 4.1 % (P=0.009) and tibial bone mineral content by 1.7 % (P=0.001), whereas fat mass increasedby 1.4 % (P=0.001). There was a significant decrease in belly muscle stiffness: in the distal head of the vastus medialis muscle it declined from the eighth day of bed rest (P=0.006), and in the proximal head from the very first day of inactivity (P=0.007). After the recovery phase, muscle stiffness returned to baseline levels in the distal head of the vastus medialis only. Postural stability deteriorated by 9.5 % (P=0.000) immediately after bed rest and by 17.4 % (P=0.000) at the first day of recovery. Fourteen days following the period of bed rest no significant postural stability loss was observed. Conclusions: Maintaining nearly neutral energy balance reduces body mass drop and fat mass gain, yet fails to preserve muscle mass or decrease tibial bone loss. The observed decrease in muscle belly stiffness varies among different muscles and occurs during two different phases of cessation and regaining of physical activity. Stance stability tests have proved an effective tool for evaluating postural stability in healthy young men submitted to bed rest
