Project in brief
This particular project will determine if changes in enzyme protein content, and expression of selected enzymes or enzyme isoforms, take place regardless of altered total skeletal muscle protein content resulting from unilateral lower limb unloading (UL) or resistance exercise (RE). Thus, this investigation examines in detail, skeletal muscle metabolic adaptations following 5 wk UL, UL+RE or RE alone. Thirty-one healthy men and women, age 35-55 yr, are assigned to either protocol. Grps UL+RE and RE perform 4 sets of 7 maximal unilateral, concentric and eccentric open-chain knee extensions using YoYo™ technology, 2 or 3 x wk-1. Enzyme activity and content, mRNA and expression of citrate synthase, hexokinase, phosphofructokinase, glycogen synthase, and glycogen phosphorylase are analyzed in percutaneous biopsy samples obtained from m. vastus lateralis before and after either intervention. While this research program will explore the effects of concurrent UL and RE, it will determine if exercise induced changes in enzyme activity or content follow the same paths, regardless of state of ambulatory loading history. Thus, it may be that unloaded muscle is more or less prone to certain favorable exercise stimuli compared with weight bearing muscle.
The results of this study will be important in describing global skeletal muscle adaptations, which take place in response to UL with or without RE. Collectively, and with results from other partners, the knowledge gained will be fundamental in providing exercise guidelines for astronauts on extended missions in Orbit, but also for terrestrial applications.
The goal of our research group is to bring more insights into control mechanisms of energy metabolism of injured, healthy and trained skeletal muscle, using both human and animal experimental models.
Research in the field
- Irimia JM, Rovira J, Nielsen JN, Guerrero M, Wojtaszewski JF, Cussó R. Hexokinase 2, glycogen synthase and phosphorylase play a key role in muscle glycogen supercompensation. PLoS One 7: e42453, 2012.
- Rovira J, Irimia JM, Guerrero M, Cadefau JA, Cussó R. Upregulation of heart PFK-2/FBPase-2 isozyme in skeletal muscle after persistent contraction. Pflügers Arch 463: 603-613, 2012.
- Guerrero M, Guiu-Comadevall M, Cadefau JA, Parra J, Balius R, Estruch A, Rodas G, Bedini JL, Cussó R. Fast and slow myosin's as markers of muscle injury. British J Sports Med 42: 581-584, 2008
- Frias JA, Cadefau JA, Prats C, Morán M, Megías A, Cussó R. Disturbances of the sarcoplasmic reticulum and transverse tubular system in 24-hour electrostimulated fast-twitch skeletal muscle. Biochim Biophys Acta- Membranes 1668: 64-74, 2005.