Acute effects of repeated sprinting upon serum creatine kinase (CK), lactic dehydrogenase (LDH), and isozymal activities were studied in five collegiate runners (R_s) and six non-runners (NR_s ). After an intermittent running treadmill test, blood sampling showed three-fold mean increases in CK with no change in LDH in both groups; group differences were insignificant (p>.05). Results suggest (1) intense anaerobic exercise produces moderate enzyme elevations; (2) relatively equivalent exercise intensities are critical to enzyme responses in exercising individuals of varying fitness levels; and (3) exercise-induced enzyme release may be consequential to muscle cell membrane permeability changes from decreased intracellular high-energy phosphates.

A realização de uma sessão com ações excêntricas provoca dano na estrutura muscular. Durante o processo de recuperação, essa estrutura sofre adaptações que a protegem da ocorrência de dano nas sessões subseqüentes. Essas adaptações são chamadas de Efeito da Carga Repetida (ECR). Esse efeito foi estudado com a realização de apenas duas sessões de exercícios. A velocidade da ação excêntrica também pode contribuir para a variabilidade do dano induzido. O objetivo desse estudo foi investigar através da análise dos indicadores indiretos, creatina quinase (CK), força, dor, circunferência e amplitude de movimento (ADM), o dano induzido por diferentes velocidades da ação excêntrica e o efeito da carga repetida com a realização das diferentes velocidades (60ºs-1 (Exc60) e 180ºs-1 (Exc180)); e verificar se o efeito da carga repetida seria maior com a realização de três sessões de exercícios. Os resultados dos indicadores analisados tiveram alterações semelhantes nos grupos Exc60 e Exc180, sugerindo que as diferentes velocidades parecem não interferir na magnitude do dano induzido. O ECR não foi diferente entre as velocidades, pois o comportamento das variáveis analisadas foi semelhante entre os dois grupos nas duas sessões iniciais. A realização da terceira sessão de exercícios excêntricos não promove o aumento do efeito protetor, visto que não houve diferenças significantes entre a segunda e a terceira sessão. Indicando que o ECR advém principalmente da realização da primeira sessão / Performing a bout of eccentric exercise causes muscle damage. During recovery, some adaptations occur that can protect muscle structure. These adaptations are known as Repeated Bout Effect. However, this phenomenon has been studied with two bouts. Velocity of eccentric action has been referred as one possible factor which can affect the extension of muscle damage. The aim of this study was to investigate muscle damage induced by different velocities, the repeated bout effect with different velocities and to verify if the repeated bout effect could be larger if three bouts of eccentric exercise were performed. Results of indirect markers of muscle damage (CK, DOR, upper-arm circumference, maximal isometric force) showed similar alterations in groups Exc60 and Exc180, suggesting that different velocities do not affect the extension of muscle damage. Repeated bout effect is not different between velocities, because changes in markers were comparable in both groups after the first two bouts. After performing a third bout of eccentric exercise, there was not any significant differences between second and third bouts. It indicates that the first bout is responsible for the adaptations of the repeated bout effect

Hypertrophy of the heart is tightly bound to the metabolic adaptations and a cellular remodeling. An important and dynamic system contributing to the maintenance of energy homeostasis is the creatine kinase system (CK). The microcompartmentalization of CK isoforms maintains the flux of ATP between energy production and consumption sites and ensures the effectiveness of the CK system. Changes in expression and activity of CK isoforms during hypertrophy are already well described - to extend this knowledge, this thesis quantified changes in association of cytosolic CK isoforms and sarcomeres. Another essential system, maintaining homeostasis in overloaded heart is composed of the hexokinase (HK) isoforms, located also in cytosol and in mitochondrial compartment. HK1 is associated with mitochondria under physiological conditions, maintaining mitochondrial membrane potential, while HK2 is located mainly in the cytosol. Under stress conditions translocation of HK2 into mitochondrial membrane occurs, which increases the direct supply of ADP to complex V of the respiratory chain and decreases the probability of apoptosis activation. We analyzed association of individual HK isoforms with mitochondria within the second aim of this thesis. Third aim of the thesis was to characterize changes in the CK and M...

Purpose: To examine the effects of deer antler velvet on muscular strength, performance, and markers of delayed onset muscle soreness following a 10-week resistance training period. Participants: 16 resistance-trained males (18-35) volunteered. Measures: DEXA, 1-RM, a power test, and a 70% performance trial were measured. Creatine kinase and self-reported soreness levels were measured following an eccentric trial. Results: No pre-experimental significant differences existed between the groups for any of the variables measured. There were no significant differences between the groups regarding body composition, strength, muscular performance, or improvements in creatine kinase and soreness levels from pre to post-intervention. Both groups demonstrated significant (p<0.05) increases in creatine kinase and soreness levels immediately post-exercise and 48 hours following the eccentric trial at the 0 and 10-week measurement periods. Conclusions: Deer antler velvet does not improve muscle size, strength, or performance. Nor does it reduce markers of DOMS following a 10-week supplementation period.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 34-36). / viii, 36 leaves, bound col. ill. 29 cm

Thesis (M.S.)--Florida State University, 2005. / Advisor: Dr. Ross Ellington, Florida State University, College of Arts and Sciences, Dept. of Biological Science. Title and description from dissertation home page (viewed June 8, 2005). Document formatted into pages; contains xiii, 55 pages. Includes bibliographical references.

A realização de uma sessão com ações excêntricas provoca dano na estrutura muscular. Durante o processo de recuperação, essa estrutura sofre adaptações que a protegem da ocorrência de dano nas sessões subseqüentes. Essas adaptações são chamadas de Efeito da Carga Repetida (ECR). Esse efeito foi estudado com a realização de apenas duas sessões de exercícios. A velocidade da ação excêntrica também pode contribuir para a variabilidade do dano induzido. O objetivo desse estudo foi investigar através da análise dos indicadores indiretos, creatina quinase (CK), força, dor, circunferência e amplitude de movimento (ADM), o dano induzido por diferentes velocidades da ação excêntrica e o efeito da carga repetida com a realização das diferentes velocidades (60ºs-1 (Exc60) e 180ºs-1 (Exc180)); e verificar se o efeito da carga repetida seria maior com a realização de três sessões de exercícios. Os resultados dos indicadores analisados tiveram alterações semelhantes nos grupos Exc60 e Exc180, sugerindo que as diferentes velocidades parecem não interferir na magnitude do dano induzido. O ECR não foi diferente entre as velocidades, pois o comportamento das variáveis analisadas foi semelhante entre os dois grupos nas duas sessões iniciais. A realização da terceira sessão de exercícios excêntricos não promove o aumento do efeito protetor, visto que não houve diferenças significantes entre a segunda e a terceira sessão. Indicando que o ECR advém principalmente da realização da primeira sessão / Performing a bout of eccentric exercise causes muscle damage. During recovery, some adaptations occur that can protect muscle structure. These adaptations are known as Repeated Bout Effect. However, this phenomenon has been studied with two bouts. Velocity of eccentric action has been referred as one possible factor which can affect the extension of muscle damage. The aim of this study was to investigate muscle damage induced by different velocities, the repeated bout effect with different velocities and to verify if the repeated bout effect could be larger if three bouts of eccentric exercise were performed. Results of indirect markers of muscle damage (CK, DOR, upper-arm circumference, maximal isometric force) showed similar alterations in groups Exc60 and Exc180, suggesting that different velocities do not affect the extension of muscle damage. Repeated bout effect is not different between velocities, because changes in markers were comparable in both groups after the first two bouts. After performing a third bout of eccentric exercise, there was not any significant differences between second and third bouts. It indicates that the first bout is responsible for the adaptations of the repeated bout effect

This study examined the effects of carbohydrate supplementation on resistance exercise performance, cortisol levels, and creatine kinase levels in trained males undergoing energy restriction. Sixteen experimental subjects were randomly assigned to a carbohydrate (C, n=8) or placebo group (P, n=8). The remaining six subjects served as controls (N). Performance tests were done before (Trials 1 and 2) and after (Trial 3) energy restriction. Experimental subjects consumed a low calorie formula diet for three days (18 kcal-1 kg-1 d-1). They had blood drawn before and after T2 and T3. For T3, they consumed either a carbohydrate (1g kg-1) or a placebo beverage 30 minutes before exercise. There was a significant increase in resting cortisol levels following energy restriction. CK levels were significantly elevated after exercise, suggestion muscle damage. Carbohydrate supplementation had no effect on blood glucose, cortisol, creatine kinase, or RPE. The number of repetitions performed during the final set of bench press showed significant interaction between groups and time. P and N increased the number of repetitions performed from T2 to T3 (15.0 + 1.4 to 17.3 + 0.8 for P, 15.0 + 2.7 to 16.7 + 2.3 for N). C decreased the number of repetitions performed 17.6 + 0.7 to 17.3 + 1.0). The number of repetitions performed during the final set of leg extensions showed no interaction between groups and time (p=0.801). This study did not support a benefit of consuming carbohydrate prior to resistance exercise for dieting athletes but illustrates that energy restriction increases a catabolic hormone. / Master of Science

No description available.

Thesis (MSc)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The aim of this study was to investigate the powerful muscle regulator, myostatin, and its regulators in response to an acute bout of plyometric training. The participants were recruited and screened by characterization by means of isometric force production tests, baseline blood creatine kinase levels and VO2 max results. The selected individuals (n=15) were subjected to a baseline muscle biopsy for comparative purposes. The study made use of plyometric jumping, as source of eccentric exercise, to serve as an exercise intervention after which muscle biopsies (4 hours post and 24 hours post) and blood draw (4 hours post, 24 hours post and 48 hours post) samples were taken. Maximal voluntary isometric contractions of the knee extensors were also measured immediately after the exercise protocol and after 1 week recovery. Creatine kinase (CK) analysis on the serum samples was used to conclude muscle damage. The muscle biopsy samples were used for protein quantification (Western blot) and gene expression assessment (semi-quantitative and real-time PCR). The results showed decreased force production immediately after eccentric exercise (p < 0.05), while returning back to baseline values at 1 week post exercise and CK results showed a significant increases at 4 hours (p<0.05), 24 hours (p<0.001) and 48 hours (p<0.01) after exercise. There were no significant differences in myostatin precursor protein (43 kDa), phosphorylated Smad2,3, Smad7 or activin receptor IIb in response to eccentric exercise. However, the follistatin protein was increased at both 4 hours and 24 hours after exercise (p<0.01). RNA analysis of the extracellular matrix (ECM) protein, decorin, revealed the existence of the splice variants A1 and A2 in human skeletal muscle. The RT-PCR analysis (n=4) of these variants showed no significant difference when comparing pre- to post-exercise. The decorin core protein was also investigated by means of antibody probing and results revealed the need for ABC chondroitinase enzyme treatment before immunoblotting of human skeletal muscle samples. The results concerning knee extensor force reduction and circulating creatine kinase showed the effectiveness of plyometric jumping in producing skeletal muscle damage in the lower limbs of unfit individuals, unaccustomed to eccentric exercise. In conclusion, myostatin, and its associated signalling cascade, are not activated in early muscle regeneration, but follistatin is increased during this phase possibly aiding and initiating the muscle repair process. Future studies: Variants of decorin are expressed in human skeletal muscle, increasing the complexity that should be taken into account in studies concerning the regulation of decorin in a human model. Investigation into myostatin protein at different post-translational levels needs more clarification. Published methods and materials used in different laboratories are not consistent and investigators should attempt to standardise protocols in order to compare results between studies more effectively. Of importance, these results show that the myostatin at protein level report different results compared to mRNA analysis and that more investigation into myostatin regulatory factors, with special reference to follistatin and decorin, is needed in future human models. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die kragtige spiere reguleerder, miostatin, en sy reguleerders in reaksie op 'n akute aanval van pliometriese spronge te ondersoek. Die deelnemers is gewerf en gekeur deur karakterisering deur middel van isometriese krag produksie toetse, basislyn bloed kreatien kinase vlakke en VO2maks resultate. Die geselekteerde individue (N = 15) is onderhewig aan 'n basislyn spierbiopsie vir vergelykende doeleindes. Die studie het gebruik gemaak van pliometriese spronge (essentriese spier aksie) as die oefening intervensie waarna spierbiopsie (4 uur na en 24 uur na) en bloed (4 uur na, 24 uur na en 48 uur na) monsters geneem is. Isometriese kontraksies van die knieverlengers is ook gemeet onmiddellik na die oefening protokol en na 1 week se herstel. Kreatine kinase (KK) ontleding van die serum monsters is gebruik om spierskade aftelei. Die spierbiopsie monsters was gebruik vir proteïen kwantifisering (Western klad) en die assessering van geen uitdrukking (semi-kwantitatiewe en real-time PCR). Die resultate het gewys dat krag produksie afgeneem het onmiddellik na essentriese oefening (p <0.05), terwyl dit terugkeer na die oorspronklike waardes 1 week na oefening en KK resultate toon 'n beduidende toename by 4 uur (p <0,05), 24 uur (p <0,001) en 48 uur (p <0,01) na oefening. Daar was geen betekenisvolle verskille in Miostatien voorloper proteïen (43 kDa), gefosforileerde Smad2,3, Smad7 of Activin reseptoor IIb in reaksie op essentriese oefening. Dit is egter die follistatien proteïen wat verhoog by beide 4 uur en 24 uur na oefening (p <0,01). RNS ontleding van die ekstrasellulêre matriks (ESM) proteïen, decorin, het die bestaan van die splitsing variante A1 en A2 in menslike skeletspier, aan die lig gebring. Die RT-PCR analise (n = 4) van hierdie variante het geen betekenisvolle verskille getoon wanneer voor met na-oefening vergelyk is. Die decorin kern proteïen is ook ondersoek deur middel van teenliggaam afhanklike metodes en resultate het die behoefte aan ABC chondroitinase ensiem behandeling voor immunokladding van menslike skeletspier monsters gesteun. Die resultate aangaande knieverlenger krag vermindering en sirkuleerende kreatien kinase het die doeltreffendheid van pliometriese spronge in die vervaardiging van skeletspier skade in die onderste ledemate van individue ongewoond aan essentriese oefening verseker. Ten slotte, Miostatien, en sy verwante sein kaskade, is nie geaktiveer vroeg in spier herstelling, maar follistatien is tydens hierdie fase verhoog en help moontlik met die aanvang van die spier herstel. Toekomstige studies: variante van decorin word uitgedruk in menslike skeletspier, wat die kompleksiteit aangaande decorin verhoog en dit is iets wat in ag geneem moet word in studies wat handel oor die regulering van decorin in mens modelle. Ondersoek na miostatien proteïen op verskillende na-translasie vlakke moet meer duidelikheid verkry. Gepubliseer metodes en materiaal wat gebruik word in verskillende laboratoriums is nie konsekwent en ondersoekbeamptes moet probeer om protokolle te standaardiseer sodat resultate van studies meer effektief kan vergelyk word. Van belang is, die resultate wys dat miostatien op proteïen vlak verskillende resultate vertoon in vergelyking met boodskapper-RNS ontleding en dat meer ondersoek na miostatien regulerende faktore, met spesiale verwysing na follistatien en decorin, nodig is in toekomstige menslike modelle.