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

Power-generating capacity should be a primary training outcome for football athletes. The ability to be explosive and use high levels of strength seems to differentiate between athletes and teams. Developing training interventions that can improve both strength- and power-generating capacity would therefore be considered a paramount endeavor when attempting to optimize the physiological and performance adaptations necessary for competitive success. Too often, strength and conditioning coaches forget that the foundation of powergenerating capacity is in fact high levels of muscular strength. When the development of strength is minimized or excluded from the training plan, the ability to express high-power outputs is compromised. In addition, a failure to use sequenced and integrated training programs decreases the possibility of successfully increasing strength- and power-generating capacity, thus decreasing the potential for competitive success. Therefore, this brief review attempts to explain how strength- and powergenerating capacity can be enhanced to increase the potential for developing the physiological and performance foundation necessary for competitive success with the football athlete.

O objetivo deste estudo foi investigar o efeito dos exercícios meio-agachamento, salto e complexo (agachamento + saltos), seguido por intervalos de 5 min, 10 min ou auto-selecionado sobre o desempenho no salto vertical com contramovimento (CMJ - countermovement jump) e frequency speed of kick test (FSKT). Para isso, 11 atletas de taekwondo, faixas-preta foram submetidos a nove protocolos experimentais e um controle realizados aleatoriamente. Cada sessão experimental foi composta pelo aquecimento, uma atividade condicionante (meio-agachamento: três séries de uma repetição a 95% de 1RM; pliometria: três séries de 10 saltos sobre barreira de 40 cm; ou exercicio complexo: meio-agachamento com três séries de duas repetições a 95% de 1RM seguido por quatro saltos sobre barreira de 40 cm), e um intervalo (5 min, 10 min ou intervalo auto-selecionado) antes da realização do CMJ e FSKT. Houve diferença estatisticamente significativa sobre o número de golpes aplicados (F9,90 = 2,90; P = 0,005, h2 = 0,225 [pequeno]). O exercício complexo com intervalo de 10 min (23 ± 5 repetições) foi superior a condição controle (19 ± 3 repetições), meio-agachamento com intervalo auto-selecionado (18 ± 2 repetições, P = 0,015) e saltos com intervalo de 5 min (18 ± 3 repetições, P < 0,001). Nossos resultados indicam que atletas de taekwondo podem aumentar o número de golpes aplicados em teste específico após a realização do exercício complexo. Outro objetivo deste estudo foi investigar o efeito do volume e intensidade sobre o desempenho no CMJ e FSKT. Para isso, nove atletas de taekwondo, faixaspreta foram submetidos a quatro sessões experimentais e uma sessão controle realizadas aleatoriamente. Cada sessão experimental foi composta pelo aquecimento, uma atividade condicionante no exercício meio-agachamento (sessões experimentais: uma série de três repetições a 50% ou 90% de 1RM ou três séries de três repetições a 50% ou 90% de 1RM), seguido por intervalo de 10 min antes da realização do CMJ e cinco séries do FSKT. O desempenho do FSKT caiu ao longo das séries (F3,21;128,36 = 25,344; P < 0,001, h2 = 0,388 [muito grande]). Não houve efeito do volume e intensidade sobre as variáveis investigadas. Nossos resultados indicam que os atletas de taekwondo não foram afetados pelo uso de diferentes volumes e intensidades em atividade de potência específica e não específica visando a manifestação da potencialização pós-ativação / The purpose of this study was to investigate the effect of half-squat, jump and complex exercise (half-squat + jump), followed by intervals of 5-min, 10-min or selfselected rest interval on performance of countermovement jump (CMJ) and the frequency speed of kick test (FSKT). Eleven black-belt taekwondo athletes were randomly submitted to nine experimental section and one control were randomly. Each experimental section was composed by warm-up, conditioning activity (halfsquat: three sets of one repetition at 95% of 1-RM; plyometric: three sets of 10 jumps above 40-cm barrier; or complex exercise: half-squat with three sets of two repetitions at 95% of 1-RM followed for four jumps above 40-cm barrier), and a rest interval (5-min, 10-min or self-selected rest interval) before performing CMJ and FSKT. There was statistically significant difference regarding the number of kicks applied (F9,90 = 2.90; P = 0.005, h2 = 0.225 [small]). The complex exercise with 10- min of rest interval (23 ± 5 repetitions) was higher that the control (19 ± 3 repetitions), as well as the half-squat with self-selected rest interval (18 ± 2 repetitions, P = 0.015) and the plyometric with 5-min rest interval (18 ± 3 repetitions, P < 0.001). Our results indicate that taekwondo athletes can increase the number of kicks applied in a specific test after perfoming the complex exercise. An other purpose of this study was to investigate the effect of volume and intensity of CMJ and FSKT. Nine blackbelt taekwondo athletes were randomly submitted to four experimental section and one control. Each experimental section was composed by warm-up, one conditioning activity on half-squat exercise (experimental section: one set of three repetitions at 50% or 90% 1-RM or three sets of three repetitions at 50% or 90% of 1-RM), followed by 10-min of interval before performance of CMJ and five sets of FSKT. The FSKT performance declined along of sets (F3,21;128,36 = 25.344; P < 0.001, h2 = 0.388 [very large]). It was not found difference regarding exercise volume and intensity on the investigated variables. Our results indicate that taekwondo athletes were not affected by different volume and intensities of specific and non-specific power activities on post-activation potentiation

O objetivo deste estudo foi investigar o efeito dos exercícios meio-agachamento, salto e complexo (agachamento + saltos), seguido por intervalos de 5 min, 10 min ou auto-selecionado sobre o desempenho no salto vertical com contramovimento (CMJ - countermovement jump) e frequency speed of kick test (FSKT). Para isso, 11 atletas de taekwondo, faixas-preta foram submetidos a nove protocolos experimentais e um controle realizados aleatoriamente. Cada sessão experimental foi composta pelo aquecimento, uma atividade condicionante (meio-agachamento: três séries de uma repetição a 95% de 1RM; pliometria: três séries de 10 saltos sobre barreira de 40 cm; ou exercicio complexo: meio-agachamento com três séries de duas repetições a 95% de 1RM seguido por quatro saltos sobre barreira de 40 cm), e um intervalo (5 min, 10 min ou intervalo auto-selecionado) antes da realização do CMJ e FSKT. Houve diferença estatisticamente significativa sobre o número de golpes aplicados (F9,90 = 2,90; P = 0,005, h2 = 0,225 [pequeno]). O exercício complexo com intervalo de 10 min (23 ± 5 repetições) foi superior a condição controle (19 ± 3 repetições), meio-agachamento com intervalo auto-selecionado (18 ± 2 repetições, P = 0,015) e saltos com intervalo de 5 min (18 ± 3 repetições, P < 0,001). Nossos resultados indicam que atletas de taekwondo podem aumentar o número de golpes aplicados em teste específico após a realização do exercício complexo. Outro objetivo deste estudo foi investigar o efeito do volume e intensidade sobre o desempenho no CMJ e FSKT. Para isso, nove atletas de taekwondo, faixaspreta foram submetidos a quatro sessões experimentais e uma sessão controle realizadas aleatoriamente. Cada sessão experimental foi composta pelo aquecimento, uma atividade condicionante no exercício meio-agachamento (sessões experimentais: uma série de três repetições a 50% ou 90% de 1RM ou três séries de três repetições a 50% ou 90% de 1RM), seguido por intervalo de 10 min antes da realização do CMJ e cinco séries do FSKT. O desempenho do FSKT caiu ao longo das séries (F3,21;128,36 = 25,344; P < 0,001, h2 = 0,388 [muito grande]). Não houve efeito do volume e intensidade sobre as variáveis investigadas. Nossos resultados indicam que os atletas de taekwondo não foram afetados pelo uso de diferentes volumes e intensidades em atividade de potência específica e não específica visando a manifestação da potencialização pós-ativação / The purpose of this study was to investigate the effect of half-squat, jump and complex exercise (half-squat + jump), followed by intervals of 5-min, 10-min or selfselected rest interval on performance of countermovement jump (CMJ) and the frequency speed of kick test (FSKT). Eleven black-belt taekwondo athletes were randomly submitted to nine experimental section and one control were randomly. Each experimental section was composed by warm-up, conditioning activity (halfsquat: three sets of one repetition at 95% of 1-RM; plyometric: three sets of 10 jumps above 40-cm barrier; or complex exercise: half-squat with three sets of two repetitions at 95% of 1-RM followed for four jumps above 40-cm barrier), and a rest interval (5-min, 10-min or self-selected rest interval) before performing CMJ and FSKT. There was statistically significant difference regarding the number of kicks applied (F9,90 = 2.90; P = 0.005, h2 = 0.225 [small]). The complex exercise with 10- min of rest interval (23 ± 5 repetitions) was higher that the control (19 ± 3 repetitions), as well as the half-squat with self-selected rest interval (18 ± 2 repetitions, P = 0.015) and the plyometric with 5-min rest interval (18 ± 3 repetitions, P < 0.001). Our results indicate that taekwondo athletes can increase the number of kicks applied in a specific test after perfoming the complex exercise. An other purpose of this study was to investigate the effect of volume and intensity of CMJ and FSKT. Nine blackbelt taekwondo athletes were randomly submitted to four experimental section and one control. Each experimental section was composed by warm-up, one conditioning activity on half-squat exercise (experimental section: one set of three repetitions at 50% or 90% 1-RM or three sets of three repetitions at 50% or 90% of 1-RM), followed by 10-min of interval before performance of CMJ and five sets of FSKT. The FSKT performance declined along of sets (F3,21;128,36 = 25.344; P < 0.001, h2 = 0.388 [very large]). It was not found difference regarding exercise volume and intensity on the investigated variables. Our results indicate that taekwondo athletes were not affected by different volume and intensities of specific and non-specific power activities on post-activation potentiation