Thesis (MSc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The aim of the study was to investigate skeletal muscle changes induced by an acute bout of plyometric exercise before and after plyometric training. The study consisted of an acute study and training intervention study. The acute study, investigated whether direct evidence of ultrastructural damage and identification of indirect factors were more evident in subjects presenting with rhabdomyolysis. Moreover the training intervention study investigated whether plyometric training would protect the muscle from ultrastructural damage and rhabdomyolysis. During the acute intervention, twenty six healthy untrained individuals completed an acute bout of plyometric exercise (10 x 10 squat-jumps, 1 min rest). After, thirteen subjects continued with the training intervention. Eight of these subjects completed 8 weeks of plyometric jump training, while five subjects were instructed to rest from physical activity for 8 weeks. Seven days after the final training session the training and rest group repeated a second acute bout of plyometric exercise. Acute Study: Creatine kinase (CK) activity increased significantly following the single bout of plyometric exercise in all subjects (baseline: 129 to day 4: 5348 U/l). This was accompanied by an increase in perceived pain, C-reactive protein (CRP) a marker of inflammation as well as white blood cells (WBCs). Electron micrographs of muscle biopsies taken 3 days post exercise showed evidence of ultrasructural damage and membrane damage was apparent by immunofluorescence by the loss of dystrophin staining. A stretch of the c-terminus of titin was observed by immunogold, and western blot analysis indicated an increase in calpain-3 autolysis. Based on individual CK responses (CK range: 153-71,024 U/L at 4days after exercise) the twenty six subjects were divided into two groups, namely the high (n=10) and low responders (n=16). Training intervention: Following training the trained group did not experience: a rise of CK activity (110.0 U/l), perceived pain, CRP, WBCs, Z-line streaming, a stretch of titin or calpain-3 activation; while in the control group only two subjects presented with Z-line streaming. The results indicate that high responders have a more pronounced inflammatory response compared to low responders after eccentric exercise, therefore more WBCs and more specifically neutrophils are recruited to damaged areas resulting in greater membrane damage by respiratory burst in high responders. This damage can be limited with training by remodelling sarcomeric proteins via calpain activation resulting in the stable assembly of proteins in the sarcomere preventing the release of proteins. / AFRIKAANSE OPSOMMING: Die doel van die studie was om skeletspier veranderinge wat teweeggebring is deur voor en na afloop van akute pleometriese oefening, te ondersoek. Die studie bestaan uit ‘n akute intervensie en ‘n oefeningsintervensie gedeelte. Die akute intervensie het ondersoek ingestel na die direkte bewyse van ultrastrukturele skade en identifikasie van indirekte faktore meer sigbaar is in proefpersone wat met rhabdomiolose presenteer. Meerso het die oefningsintervensie die moontlikheid dat pleometriese oefening die spier van ultrastrukturele skade en rhabdomiolose beskerm, ondersoek. Tydens die akute intervensie is 26 gesonde ongeoefende individue die akute pleometriese oefeningsessie (10 x 10 hurkspronge, 1 min rus) voltooi. Hierna het 13 proefpersone voortgegaan met die oefeningsintervensie. Agt van hierdie proefpersone het agt weke pleometriese sprongsessie oefeninge voltooi, terwyl vyf proefpersone gevra is om vir 8 weke geen oefeninge te doen nie. Sewe dae na afloop van die finale oefeningssessie het die oefening en kontrole groep in ‘n tweede herhaalde akute pleometriese oefeningsessie deelgeneem. Akute intervensie: kreatienkinase (KK) aktiwiteit het betekenisvol verhoog na die enkel pleometriese oefeningsessie in all proefpersone (basislyn: 129 tot op dag vier: 5348 U/l). Hierdie is vergesel met ‘n toename in die persepsie van pyn, c-reaktiewe proteïen (CRP) ‘n merker van inflammasie sowel as witbloedselle (WBS). Elektronmikrograwe van spierbiopsies wat geneem is drie dae na afloop van die oefeninge, het tekens van ultrastrukturele skade en membraanskade getoon wat ook deur immunofluoresensie duidelik warneembaar was deur die verlies van distrofienverkleuring. ‘n Verrekking van die c-terminus van titin is ook waargeneem deur middel van immunogold. Westernblot analyse het ‘n toename in calpain-3 outolise getoon. Gegrond op individuele KK response (KK grense: 153-71,024 U/L na vier dae post oefening) is 26 proefpersone verdeel in twee groepe naamlik ‘n hoë (n=10) en lae responders (n=16). Oefeningintervensie:: Na oefening het die geoefende groep nie ‘n toename in KK aktiwiteit getoon nie (KK aktiwiteit (110.0 U/l)), pynervaring, CRP, WBS, Z-lynstroming, ‘n strekking van titin of calpain-3 aktivering; terwyl in die kontrole groep daar slegs twee proefpersone met Z-lynstroming geïdentifiseer is. Die resultate wyse daarop dat hoë responders ‘n meer uitgesproke inflammatoriese reaksie toon vergeleke met die lae responders na afloop van essentriese oefening. Daar word dus meer WBS en spesifiek meer neutrofiele na beskadigde areas gelokaliseer wat in grootter membraanskade deur respiratoriese inspanning in die hoë responders. Hierdie skade kan beperk word deur oefening waardeur hermodulering van sarkomeriese proteïene via calpain aktivering tot stabiele rangskiking van proteïene in die sarcomere lei en daardeur proteïen vrystelling verhinder. / The NRF for financial assistance