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The present study compared the ipsilateral repeated bout effect (IL-RBE) and contralateral repeated bout effect (CL-RBE) of the elbow flexors (EF) and knee flexors (KF) for the same interval between bouts to shed light on their mechanisms. Fifty-two healthy sedentary young (20–28 years) men were randomly assigned to the IL-EF, IL-KF, CL-EF, and CL-KF groups (n = 13/group). Thirty maximal eccentric contractions of the EF were performed in IL-EF and CL-EF, and 60 maximal eccentric contractions of the KF were performed in IL-KF and CL-KF, with a 2-week interval between bouts. Changes in muscle damage markers such as maximal voluntary contraction (MVC) torque, muscle soreness, and plasma creatine kinase activity, and proprioception measures before to 5 days post-exercise were compared between groups. Changes in all variables were greater (p < 0.05) after the first than second bout for all groups, and the changes were greater (p < 0.05) for the EF than KF. The changes in all variables after the second bout were greater (p < 0.05) for the CL than IL condition for both EF and KF. The magnitude of the average protective effect was similar between CL-EF (33%) and CL-KF (32%), but slightly greater (p < 0.05) for IL-EF (67%) than IL-KF (61%). These demonstrate that the magnitude of CL-RBE relative to IL-RBE was similar between the EF and KF (approximately 50%), regardless of the greater muscle damage for the EF than KF. It appears that the CL-RBE is more associated with neural adaptations at cerebrum, cerebellum, interhemispheric inhibition, and coricospinal tract, but the IL-RBE is induced by additional adaptations at muscles.

Since the 1970s, researchers have studied a potential difference in muscle fatigue (acute strength loss) between maximal eccentric (ECCmax) and concentric (CONmax) resistance exercise. However, a clear answer to whether such a difference exists has not been established. Therefore, the aim of our paper was to overview methods and results of studies that compared acute changes in muscle strength after bouts of ECCmax and CONmax resistance exercise. We identified 30 relevant studies. Participants were typically healthy men aged 20–40 years. Exercise usually consisted of 40–100 isokinetic ECCmax and CONmax repetitions of the knee extensors or elbow flexors. Both ECCmax and CONmax exercise caused significant strength loss, which plateaued and rarely exceeded 60% of baseline, suggesting strength preservation. In upper-body muscles, strength loss at the end of ECCmax (31.4 ± 20.4%) and CONmax (33.6 ± 17.5%) exercise was similar, whereas in lower-body muscles, strength loss was less after ECCmax (13.3 ± 12.2%) than CONmax (39.7 ± 13.3%) exercise. Muscle architecture and daily use of lower-body muscles likely protects lower-body muscles from strength loss during ECCmax exercise. We also reviewed seven studies on muscle fatigue during coupled ECCmax-CONmax exercise and found similar strength loss in the ECC and CON phases. We also found evidence from three studies that more ECC than CON repetitions can be completed at equal relative loads. These results indicate that muscle fatigue may manifest differently between ECCmax and CONmax resistance exercise. An implication of the results is that prescriptions of ECC resistance exercise for lower-body muscles should account for greater fatigue resilience of these muscles compared to upper-body muscles.

Strengthening the femoral quadriceps (FQ) muscular group is very important due to its function in moving. The joint position may generate modifications in muscle recruitment. Consequently, the objective of this study was to verify if footposition variations during knee extension are efficient in the specific selection of the rectus femoris, vastus lateralis, and vastus medialis muscles comprising the FQ. Eleven female college students (ages 22.36 ± 3.56 years old) participated in the study. Muscle activation was evaluated through surface electromyography, with bipolar configuration, in 3 series of 10 maximum repetition (MR) of bilateral knee extension, in three foot positions: neutral position, internal rotation, and external rotation. Results do not indicate significant differences among the superficial FQ muscles in all foot positions. In conclusion, results suggest that variations in foot rotation degrees during knee extension are not efficient for the specific selection of the muscles comprising FQ., O fortalecimento do grupo muscular quadríceps femoral (QF) é muito importante devido sua função para o movimento. Mudanças na posição do pé, podem gerar alterações no recrutamento muscular, desta forma o presente estudo objetivou verificar se as variações nas posições dos pés, durante a extensão de joelhos, são eficazes para a seleção específica dos músculos reto femoral, vasto lateral e vasto medial, que compõem o QF. Onze mulheres universitárias (idade 22.36 ± 3.56 anos) participaram do estudo. Foi avaliada a ativação dos músculos através da eletromiografia de superfície, com configuração bipolar, em 3 séries de 10 repetições máximas (RM) de extensão de joelhos bilateral, em três posições dos pés: posição neutra, rotação interna e rotação externa. Os resultados não apontam diferenças significativas entre os músculos do QF superficial em todas as posições dos pés. Em conclusão, os resultados do presente estudo sugerem que as variações nos graus de rotação dos pés durante a extensão de joelhos, não são eficazes para a seleção específica dos músculos que compõem o QF., El fortalecimiento de los músculos del cuádriceps femoral (CF) es importante debido a su función en el movimiento. La posición de la articulación puede generar cambios en el reclutamiento muscular. De esa forma el presente estudio tiene como objetivo verificar si variaciones en las posiciones del pie durante la extensión de las rodillas son eficaces para la selección específica de los músculos recto femoral, vasto lateral y vasto medial, que componen el CF. Once mujeres universitarias (edad 22.36 ± 3.56 años) participaron del estudio. Fue evaluada la activación de los músculos a través de la electromiografía de superficie, con una configuración bipolar, en 3 series de 10 repeticiones máximas (RM) de extensión bilateral de rodilla, en tres posiciones de los pies: neutra, rotación interna y rotación externa. Los resultados no presentaron diferencias significativas entre los músculos del CF en todas las posiciones del pie. En conclusión, los resultados del presente estudio sugieren que las variaciones en los grados de rotación de los pies durante la extensión de las rodillas no son eficaces para la selección específica de los músculos que componen el CF.

Strengthening the femoral quadriceps (FQ) muscular group is very important due to its function in moving. The joint position may generate modifications in muscle recruitment. Consequently, the objective of this study was to verify if foot position variations during knee extension are efficient in the specific selection of the rectus femoris, vastus lateralis, and vastus medialis muscles comprising the FQ. Eleven female college students (ages 22.36 ± 3.56 years old) participated in the study. Muscle activation was evaluated through surface electromyography, with bipolar configuration, in 3 series of 10 maximum repetition (MR) of bilateral knee extension, in three foot positions: neutral position, internal rotation, and external rotation. Results do not indicate significant differences among the superficial FQ muscles in all foot positions. In conclusion, results suggest that variations in foot rotation degrees during knee extension are not efficient for the specific selection of the muscles comprising FQ., O fortalecimento do grupo muscular quadríceps femoral (QF) é muito importante devido sua função para o movimento. Mudanças na posição do pé, podem gerar alterações no recrutamento muscular, desta forma o presente estudo objetivou verificar se as variações nas posições dos pés, durante a extensão de joelhos, são eficazes para a seleção específica dos músculos reto femoral, vasto lateral e vasto medial, que compõem o QF. Onze mulheres universitárias (idade 22.36 ± 3.56 anos) participaram do estudo. Foi avaliada a ativação dos músculos através da eletromiografia de superfície, com configuração bipolar, em 3 séries de 10 repetições máximas (RM) de extensão de joelhos bilateral, em três posições dos pés: posição neutra, rotação interna e rotação externa. Os resultados não apontam diferenças significativas entre os músculos do QF superficial em todas as posições dos pés. Em conclusão, os resultados do presente estudo sugerem que as variações nos graus de rotação dos pés durante a extensão de joelhos, não são eficazes para a seleção específica dos músculos que compõem o QF., El fortalecimiento de los músculos del cuádriceps femoral (CF) es importante debido a su función en el movimiento. La posición de la articulación puede generar cambios en el reclutamiento muscular. De esa forma el presente estudio tiene como objetivo verificar si variaciones en las posiciones del pie durante la extensión de las rodillas son eficaces para la selección específica de los músculos recto femoral, vasto lateral y vasto medial, que componen el CF. Once mujeres universitarias (edad 22.36 ± 3.56 años) participaron del estudio. Fue evaluada la activación de los músculos a través de la electromiografía de superficie, con una configuración bipolar, en 3 series de 10 repeticiones máximas (RM) de extensión bilateral de rodilla, en tres posiciones de los pies: neutra, rotación interna y rotación externa. Los resultados no presentaron diferencias significativas entre los músculos del CF en todas las posiciones del pie. En conclusión, los resultados del presente estudio sugieren que las variaciones en los grados de rotación de los pies durante la extensión de las rodillas no son eficaces para la selección específica de los músculos que componen el CF.

Astronauts suffer degradation of postural muscles and weight-bearing bones during long-duration spaceflight. Resistance exercise is used as a primary countermeasure against these degradations. However, it has proven difficult to predict appropriate exercise loads, and the countermeasure regimens in current use are not fully preventing bone and muscle loss. It is likely that gravity-independent exercise devices, based on flywheel inertial resistance, will be implemented in future musculoskeletal countermeasure regimens. In this thesis, biomechanical analyses of external and internal exercise loads during flywheel leg resistance exercises, were performed through experimental data collection and musculoskeletal modelling. The thesis is based on four separate studies with the collective aim to provide knowledge that can be implemented when designing flywheel-based strength-training regimens to be used both in terrestrial settings and as countermeasures against musculoskeletal deconditioning in weightlessness. The first study analyzed computed joint kinematics and kinetics, and relative muscle forces in the lower limb during maximal effort flywheel leg press (FWLP) and flywheel squat (FWS) exercises. Results showed that total exercise load was slightly higher during FWS than FWLP, whereas relative muscle force did not differ between the two exercises, suggesting that they may have similar strength training effects. The second study investigated the effect of gravity on internal joint load distribution during leg resistance exercise. This was done in two steps: 1) by comparing joint kinetics during FWLP and FWS at a given submaximal exercise load (80% of the isometric maximum load in FWLP), and 2) by simulating both FWLP and FWS in zero gravity and studying changes in joint loads. The first step revealed greater hip extension moment and lumbar joint-contact forces in FWLP than in FWS, indicating a notable effect of the direction of motion relative to the gravity vector, o, Vid långvariga rymdresor drabbas astronauter av att kropssviktsbärande muskler och skelett förtvinas respektive urkalkas. Den huvudsakliga åtgärden för att motverka denna nedbrytning är styrketräning, men det har visat sig vara svårt att förutsäga hur belastningen från en specifik träningsövning kommer att bli i tyngdlöshet. Den typen av träning som utförs vid rymdresor idag är inte tillräckligt bra för att helt motverka nedbrytningen av det muskuloskelettala systemet. Därför behövs ytterligare forskning för att förbättra förutsättningarna för astronauterna att bibehålla styrka och funktion under långvariga rymdfärder. I denna avhandling undersöktes externa och interna belastningar vid styrketräningsövningar för benen som utfördes med svänghjulsapparat, en gravitationsoberoende träningsutrustning som genererar motstånd via trögheten hos ett svänghjul. Fyra studier, baserade på experimentell datainsamling och muskuloskelettal modellering, ligger till grund för avhandlingen. Det övergripande syftet med studierna var att generera kunskap som kan utnyttjas vid utveckling av nya svänghjulsbaserade styrketräningsrutiner som kan användas inte enbart på jorden utan även i rymden, för att förhindra nedbrytning av astronauternas muskel- och benvävnad. I den första studien undersöktes ledvinklar och moment samt relativa muskelkrafter i benen vid två maximala styrketräningsövningar utförda med svänghjulsutrustning: benpress (FWLP) och knäböj (FWS). Försökspersonerna uppnådde högre krafter i FWS än i FWLP men de relativa muskelkrafterna var lika i de båda övningarna, vilket indikerar att de torde framkalla jämförbara träningseffekter. Den andra studien undersökte gravitationens effekt på belastningsfördelningen i kroppen vid styrketräning av benen. Detta gjordes i två steg: 1) genom att jämföra belastningen i leder vid de två övningarna FWLP och FWS som utfördes med samma totala belastning (motsvarande 80% av isometriskt maximum i FWLP) och 2) genom att simulera FWLP och FWS i t, QC 2020-10-20

Introduction This study aimed to assess the efficacy of a 6‐week cycling‐specific, isometric resistance training program on peak power output (PPO) in elite cyclists. Methods Twenty‐four elite track sprint cyclists were allocated to EXP (n = 13, PPO, 1537 ± 307 W) and CON (n = 11, PPO, 1541 ± 389 W) groups. All participants completed a 6‐week training program; training content was identical except participants in the EXP group replaced their usual compound lower body resistance training exercise with a cycling‐specific, isometric resistance training stimulus. Cycling PPO, knee extensor and cycling‐specific isometric strength, and measures of muscle architecture were assessed pre‐ and post‐training. Results In EXP, absolute and relative PPO increased (46 ± 62 W and 0.8 ± 0.7 W/kg, P < .05), and the change in relative PPO was different to CON (−0.1 ± 1.0 W/kg, group × time interaction P = .02). The increase in PPO was concurrent with an increase in extrapolated maximal torque in EXP (7.1 ± 6.5 Nm, P = .007), but the effect was not different from the change in CON (2.4 ± 9.7 Nm, group × time P = .14). Cycling‐specific isometric strength also increased more in EXP (group × time P = .002). There were no other between‐group differences in response to training. Conclusion A 6‐week novel, cycling‐specific isometric resistance training period improved PPO in a group of elite sprint cyclists by 3%‐4%. These data support the use of a cycling‐specific isometric resistance training stimulus in the preparation programs of world‐class cyclists

Introduction This study aimed to assess the efficacy of a 6‐week cycling‐specific, isometric resistance training program on peak power output (PPO) in elite cyclists. Methods Twenty‐four elite track sprint cyclists were allocated to EXP (n = 13, PPO, 1537 ± 307 W) and CON (n = 11, PPO, 1541 ± 389 W) groups. All participants completed a 6‐week training program; training content was identical except participants in the EXP group replaced their usual compound lower body resistance training exercise with a cycling‐specific, isometric resistance training stimulus. Cycling PPO, knee extensor and cycling‐specific isometric strength, and measures of muscle architecture were assessed pre‐ and post‐training. Results In EXP, absolute and relative PPO increased (46 ± 62 W and 0.8 ± 0.7 W/kg, P < .05), and the change in relative PPO was different to CON (−0.1 ± 1.0 W/kg, group × time interaction P = .02). The increase in PPO was concurrent with an increase in extrapolated maximal torque in EXP (7.1 ± 6.5 Nm, P = .007), but the effect was not different from the change in CON (2.4 ± 9.7 Nm, group × time P = .14). Cycling‐specific isometric strength also increased more in EXP (group × time P = .002). There were no other between‐group differences in response to training. Conclusion A 6‐week novel, cycling‐specific isometric resistance training period improved PPO in a group of elite sprint cyclists by 3%‐4%. These data support the use of a cycling‐specific isometric resistance training stimulus in the preparation programs of world‐class cyclists

Astronauts suffer degradation of postural muscles and weight-bearing bones during long-duration spaceflight. Resistance exercise is used as a primary countermeasure against these degradations. However, it has proven difficult to predict appropriate exercise loads, and the countermeasure regimens in current use are not fully preventing bone and muscle loss. It is likely that gravity-independent exercise devices, based on flywheel inertial resistance, will be implemented in future musculoskeletal countermeasure regimens. In this thesis, biomechanical analyses of external and internal exercise loads during flywheel leg resistance exercises, were performed through experimental data collection and musculoskeletal modelling. The thesis is based on four separate studies with the collective aim to provide knowledge that can be implemented when designing flywheel-based strength-training regimens to be used both in terrestrial settings and as countermeasures against musculoskeletal deconditioning in weightlessness. The first study analyzed computed joint kinematics and kinetics, and relative muscle forces in the lower limb during maximal effort flywheel leg press (FWLP) and flywheel squat (FWS) exercises. Results showed that total exercise load was slightly higher during FWS than FWLP, whereas relative muscle force did not differ between the two exercises, suggesting that they may have similar strength training effects. The second study investigated the effect of gravity on internal joint load distribution during leg resistance exercise. This was done in two steps: 1) by comparing joint kinetics during FWLP and FWS at a given submaximal exercise load (80% of the isometric maximum load in FWLP), and 2) by simulating both FWLP and FWS in zero gravity and studying changes in joint loads. The first step revealed greater hip extension moment and lumbar joint-contact forces in FWLP than in FWS, indicating a notable effect of the direction of motion relative to the gravity vector, o, Vid långvariga rymdresor drabbas astronauter av att kropssviktsbärande muskler och skelett förtvinas respektive urkalkas. Den huvudsakliga åtgärden för att motverka denna nedbrytning är styrketräning, men det har visat sig vara svårt att förutsäga hur belastningen från en specifik träningsövning kommer att bli i tyngdlöshet. Den typen av träning som utförs vid rymdresor idag är inte tillräckligt bra för att helt motverka nedbrytningen av det muskuloskelettala systemet. Därför behövs ytterligare forskning för att förbättra förutsättningarna för astronauterna att bibehålla styrka och funktion under långvariga rymdfärder. I denna avhandling undersöktes externa och interna belastningar vid styrketräningsövningar för benen som utfördes med svänghjulsapparat, en gravitationsoberoende träningsutrustning som genererar motstånd via trögheten hos ett svänghjul. Fyra studier, baserade på experimentell datainsamling och muskuloskelettal modellering, ligger till grund för avhandlingen. Det övergripande syftet med studierna var att generera kunskap som kan utnyttjas vid utveckling av nya svänghjulsbaserade styrketräningsrutiner som kan användas inte enbart på jorden utan även i rymden, för att förhindra nedbrytning av astronauternas muskel- och benvävnad. I den första studien undersöktes ledvinklar och moment samt relativa muskelkrafter i benen vid två maximala styrketräningsövningar utförda med svänghjulsutrustning: benpress (FWLP) och knäböj (FWS). Försökspersonerna uppnådde högre krafter i FWS än i FWLP men de relativa muskelkrafterna var lika i de båda övningarna, vilket indikerar att de torde framkalla jämförbara träningseffekter. Den andra studien undersökte gravitationens effekt på belastningsfördelningen i kroppen vid styrketräning av benen. Detta gjordes i två steg: 1) genom att jämföra belastningen i leder vid de två övningarna FWLP och FWS som utfördes med samma totala belastning (motsvarande 80% av isometriskt maximum i FWLP) och 2) genom att simulera FWLP och FWS i t, QC 2020-10-20

Astronauts suffer degradation of postural muscles and weight-bearing bones during long-duration spaceflight. Resistance exercise is used as a primary countermeasure against these degradations. However, it has proven difficult to predict appropriate exercise loads, and the countermeasure regimens in current use are not fully preventing bone and muscle loss. It is likely that gravity-independent exercise devices, based on flywheel inertial resistance, will be implemented in future musculoskeletal countermeasure regimens. In this thesis, biomechanical analyses of external and internal exercise loads during flywheel leg resistance exercises, were performed through experimental data collection and musculoskeletal modelling. The thesis is based on four separate studies with the collective aim to provide knowledge that can be implemented when designing flywheel-based strength-training regimens to be used both in terrestrial settings and as countermeasures against musculoskeletal deconditioning in weightlessness. The first study analyzed computed joint kinematics and kinetics, and relative muscle forces in the lower limb during maximal effort flywheel leg press (FWLP) and flywheel squat (FWS) exercises. Results showed that total exercise load was slightly higher during FWS than FWLP, whereas relative muscle force did not differ between the two exercises, suggesting that they may have similar strength training effects. The second study investigated the effect of gravity on internal joint load distribution during leg resistance exercise. This was done in two steps: 1) by comparing joint kinetics during FWLP and FWS at a given submaximal exercise load (80% of the isometric maximum load in FWLP), and 2) by simulating both FWLP and FWS in zero gravity and studying changes in joint loads. The first step revealed greater hip extension moment and lumbar joint-contact forces in FWLP than in FWS, indicating a notable effect of the direction of motion relative to the gravity vector, o, Vid långvariga rymdresor drabbas astronauter av att kropssviktsbärande muskler och skelett förtvinas respektive urkalkas. Den huvudsakliga åtgärden för att motverka denna nedbrytning är styrketräning, men det har visat sig vara svårt att förutsäga hur belastningen från en specifik träningsövning kommer att bli i tyngdlöshet. Den typen av träning som utförs vid rymdresor idag är inte tillräckligt bra för att helt motverka nedbrytningen av det muskuloskelettala systemet. Därför behövs ytterligare forskning för att förbättra förutsättningarna för astronauterna att bibehålla styrka och funktion under långvariga rymdfärder. I denna avhandling undersöktes externa och interna belastningar vid styrketräningsövningar för benen som utfördes med svänghjulsapparat, en gravitationsoberoende träningsutrustning som genererar motstånd via trögheten hos ett svänghjul. Fyra studier, baserade på experimentell datainsamling och muskuloskelettal modellering, ligger till grund för avhandlingen. Det övergripande syftet med studierna var att generera kunskap som kan utnyttjas vid utveckling av nya svänghjulsbaserade styrketräningsrutiner som kan användas inte enbart på jorden utan även i rymden, för att förhindra nedbrytning av astronauternas muskel- och benvävnad. I den första studien undersöktes ledvinklar och moment samt relativa muskelkrafter i benen vid två maximala styrketräningsövningar utförda med svänghjulsutrustning: benpress (FWLP) och knäböj (FWS). Försökspersonerna uppnådde högre krafter i FWS än i FWLP men de relativa muskelkrafterna var lika i de båda övningarna, vilket indikerar att de torde framkalla jämförbara träningseffekter. Den andra studien undersökte gravitationens effekt på belastningsfördelningen i kroppen vid styrketräning av benen. Detta gjordes i två steg: 1) genom att jämföra belastningen i leder vid de två övningarna FWLP och FWS som utfördes med samma totala belastning (motsvarande 80% av isometriskt maximum i FWLP) och 2) genom att simulera FWLP och FWS i t, QC 2020-10-20

Astronauts suffer degradation of postural muscles and weight-bearing bones during long-duration spaceflight. Resistance exercise is used as a primary countermeasure against these degradations. However, it has proven difficult to predict appropriate exercise loads, and the countermeasure regimens in current use are not fully preventing bone and muscle loss. It is likely that gravity-independent exercise devices, based on flywheel inertial resistance, will be implemented in future musculoskeletal countermeasure regimens. In this thesis, biomechanical analyses of external and internal exercise loads during flywheel leg resistance exercises, were performed through experimental data collection and musculoskeletal modelling. The thesis is based on four separate studies with the collective aim to provide knowledge that can be implemented when designing flywheel-based strength-training regimens to be used both in terrestrial settings and as countermeasures against musculoskeletal deconditioning in weightlessness. The first study analyzed computed joint kinematics and kinetics, and relative muscle forces in the lower limb during maximal effort flywheel leg press (FWLP) and flywheel squat (FWS) exercises. Results showed that total exercise load was slightly higher during FWS than FWLP, whereas relative muscle force did not differ between the two exercises, suggesting that they may have similar strength training effects. The second study investigated the effect of gravity on internal joint load distribution during leg resistance exercise. This was done in two steps: 1) by comparing joint kinetics during FWLP and FWS at a given submaximal exercise load (80% of the isometric maximum load in FWLP), and 2) by simulating both FWLP and FWS in zero gravity and studying changes in joint loads. The first step revealed greater hip extension moment and lumbar joint-contact forces in FWLP than in FWS, indicating a notable effect of the direction of motion relative to the gravity vector, o, Vid långvariga rymdresor drabbas astronauter av att kropssviktsbärande muskler och skelett förtvinas respektive urkalkas. Den huvudsakliga åtgärden för att motverka denna nedbrytning är styrketräning, men det har visat sig vara svårt att förutsäga hur belastningen från en specifik träningsövning kommer att bli i tyngdlöshet. Den typen av träning som utförs vid rymdresor idag är inte tillräckligt bra för att helt motverka nedbrytningen av det muskuloskelettala systemet. Därför behövs ytterligare forskning för att förbättra förutsättningarna för astronauterna att bibehålla styrka och funktion under långvariga rymdfärder. I denna avhandling undersöktes externa och interna belastningar vid styrketräningsövningar för benen som utfördes med svänghjulsapparat, en gravitationsoberoende träningsutrustning som genererar motstånd via trögheten hos ett svänghjul. Fyra studier, baserade på experimentell datainsamling och muskuloskelettal modellering, ligger till grund för avhandlingen. Det övergripande syftet med studierna var att generera kunskap som kan utnyttjas vid utveckling av nya svänghjulsbaserade styrketräningsrutiner som kan användas inte enbart på jorden utan även i rymden, för att förhindra nedbrytning av astronauternas muskel- och benvävnad. I den första studien undersöktes ledvinklar och moment samt relativa muskelkrafter i benen vid två maximala styrketräningsövningar utförda med svänghjulsutrustning: benpress (FWLP) och knäböj (FWS). Försökspersonerna uppnådde högre krafter i FWS än i FWLP men de relativa muskelkrafterna var lika i de båda övningarna, vilket indikerar att de torde framkalla jämförbara träningseffekter. Den andra studien undersökte gravitationens effekt på belastningsfördelningen i kroppen vid styrketräning av benen. Detta gjordes i två steg: 1) genom att jämföra belastningen i leder vid de två övningarna FWLP och FWS som utfördes med samma totala belastning (motsvarande 80% av isometriskt maximum i FWLP) och 2) genom att simulera FWLP och FWS i t, QC 2020-10-20

Astronauts suffer degradation of postural muscles and weight-bearing bones during long-duration spaceflight. Resistance exercise is used as a primary countermeasure against these degradations. However, it has proven difficult to predict appropriate exercise loads, and the countermeasure regimens in current use are not fully preventing bone and muscle loss. It is likely that gravity-independent exercise devices, based on flywheel inertial resistance, will be implemented in future musculoskeletal countermeasure regimens. In this thesis, biomechanical analyses of external and internal exercise loads during flywheel leg resistance exercises, were performed through experimental data collection and musculoskeletal modelling. The thesis is based on four separate studies with the collective aim to provide knowledge that can be implemented when designing flywheel-based strength-training regimens to be used both in terrestrial settings and as countermeasures against musculoskeletal deconditioning in weightlessness. The first study analyzed computed joint kinematics and kinetics, and relative muscle forces in the lower limb during maximal effort flywheel leg press (FWLP) and flywheel squat (FWS) exercises. Results showed that total exercise load was slightly higher during FWS than FWLP, whereas relative muscle force did not differ between the two exercises, suggesting that they may have similar strength training effects. The second study investigated the effect of gravity on internal joint load distribution during leg resistance exercise. This was done in two steps: 1) by comparing joint kinetics during FWLP and FWS at a given submaximal exercise load (80% of the isometric maximum load in FWLP), and 2) by simulating both FWLP and FWS in zero gravity and studying changes in joint loads. The first step revealed greater hip extension moment and lumbar joint-contact forces in FWLP than in FWS, indicating a notable effect of the direction of motion relative to the gravity vector, o, Vid långvariga rymdresor drabbas astronauter av att kropssviktsbärande muskler och skelett förtvinas respektive urkalkas. Den huvudsakliga åtgärden för att motverka denna nedbrytning är styrketräning, men det har visat sig vara svårt att förutsäga hur belastningen från en specifik träningsövning kommer att bli i tyngdlöshet. Den typen av träning som utförs vid rymdresor idag är inte tillräckligt bra för att helt motverka nedbrytningen av det muskuloskelettala systemet. Därför behövs ytterligare forskning för att förbättra förutsättningarna för astronauterna att bibehålla styrka och funktion under långvariga rymdfärder. I denna avhandling undersöktes externa och interna belastningar vid styrketräningsövningar för benen som utfördes med svänghjulsapparat, en gravitationsoberoende träningsutrustning som genererar motstånd via trögheten hos ett svänghjul. Fyra studier, baserade på experimentell datainsamling och muskuloskelettal modellering, ligger till grund för avhandlingen. Det övergripande syftet med studierna var att generera kunskap som kan utnyttjas vid utveckling av nya svänghjulsbaserade styrketräningsrutiner som kan användas inte enbart på jorden utan även i rymden, för att förhindra nedbrytning av astronauternas muskel- och benvävnad. I den första studien undersöktes ledvinklar och moment samt relativa muskelkrafter i benen vid två maximala styrketräningsövningar utförda med svänghjulsutrustning: benpress (FWLP) och knäböj (FWS). Försökspersonerna uppnådde högre krafter i FWS än i FWLP men de relativa muskelkrafterna var lika i de båda övningarna, vilket indikerar att de torde framkalla jämförbara träningseffekter. Den andra studien undersökte gravitationens effekt på belastningsfördelningen i kroppen vid styrketräning av benen. Detta gjordes i två steg: 1) genom att jämföra belastningen i leder vid de två övningarna FWLP och FWS som utfördes med samma totala belastning (motsvarande 80% av isometriskt maximum i FWLP) och 2) genom att simulera FWLP och FWS i t, QC 2020-10-20

Neural control of eccentric contractions differs from that of concentric and isometric contractions, but no previous study has compared responses to motor cortex stimulations at long muscle lengths during such contraction types. In this study, we compared the effect of muscle length on corticospinal excitability between maximal concentric, isometric and eccentric contractions of the knee extensors. Twelve men performed 12 maximal concentric, isometric and eccentric voluntary contractions (36 contractions in total), separated by a 5 min rest between contraction types. The 12 contractions for the same contraction type were performed every 10 s, and transcranial magnetic stimulations (first eight contractions) and electrical femoral nerve stimulations (last four contractions) were superimposed alternately at 75 and 100 deg of knee flexion. Average motor evoked potential amplitude, normalized to the maximal M wave amplitude (MEP/M) and cortical silent period duration were calculated for each angle and compared among the contraction types. The MEP/M was lower (−23 and −28%, respectively) during eccentric than both concentric and isometric contractions at 75 deg, but similar between contraction types at 100 deg (P < 0.05). The cortical silent period duration was shorter (−12 and −10%, respectively) during eccentric than both concentric and isometric contractions at 75 deg, but longer (+11 and +9%, respectively) during eccentric contractions at 100 deg (P < 0.05). These results show that corticospinal excitability during eccentric contractions is angle dependent such that cortical inhibitory processes are greater with no alteration of corticospinal excitability at 100 deg, whereas this control is reversed at 75 deg.

Introduction Maximal strength ratios such as the limb symmetry index (LSI) and hamstring-to-quadriceps ratio (HQ) may be considered the main outcome measures in the monitoring of recovery after anterior cruciate ligament (ACL) reconstruction. Although explosive strength is much more important than maximal strength, it is generally disregarded in the follow-up of muscle function recovery. Objective The purpose of this study was to compare ratios between maximal (Fmax) and explosive strength (rate of force development - RFD) in individuals with ACL reconstruction. Methods Fifteen male athletes were enrolled and had maximum voluntary isometric quadriceps and hamstring contractions tested (4.0 ± 0.1 months post reconstruction). In addition to Fmax, RFD was estimated (RFDmax as well as RFD at 50, 100, and 200 ms from onset of contraction) and LS gt I and HQ ratios were calculated. Results The involved leg demonstrated significant hamstring and quadriceps deficits compared to uninvolved leg (p lt 0.01). Deficits were particularly significant in the involved quadriceps, causing higher HQ ratios (average 0.63), compared to the uninvolved leg (0.44). LSI was significantly lower for RFD variables (average 55%) than for Fmax (66%). Conclusion The assessment of RFD may be considered an objective recovery parameter for one's readiness to return to sports and should be an integral part of standard follow-up protocol for athletes after ACL reconstruction. Moreover, the combination of indices derived from maximal and explosive strength may provide better insight in muscle strength balance, as well as a clear picture of functional implications., Uvod Maksimalne jačine ekstenzora i fleksora kolena, njihov međusobni odnos (eng. hamstrings-to-quadriceps ratio; HQ), kao i indeks simetrije operisane i neoperisane noge (eng. limb symmetry index; LSI) važni su pokazatelji pomoću kojih se prati oporavak nakon rekonstrukcije LCA. Iako je za izvođenje brojnih funkcionalnih zadataka eksplozivna jačina važnija od maksimalne, ova sposobnost generalno je zanemarena u praćenju oporavka mišićne funkcije. Cilj rada bio je da se uporede odnosi (maksimalne jačine (Fmax) i odnosi eksplozivne jačine (eng. Rate of Force Development - RFD) kod sportista sa rekonstrukcijom LCA. Metode rada U studiju je uključeno 15 sportista, kojima je testirana maksimalna voljna izometrijska kontrakcija (MBK) ekstenzora i fleksora kolena (4,0 ± 0,1 meseca postoperativno). Pored Fmax, procenjivan je i RFD (RFDmax, kao i RFD na 50, 100 i 200 ms od početka kontrakcije) i računati odnosi jačine (LSI i HQ odnos). Rezultati Maksimalna jačina i ekstenzora i fleksora operisane noge bila je značajno niža nego kod neoperisane noge (p lt 0,01). Deficiti su bili posebno izraženi kod ekstenzora operisane noge, usled čega su i HQ odnosi na toj strani (prosečno 0,63) bili veći nego kod neoperisane noge (0,44). Indeks simetrije je bio značajno niži za varijable RFD (prosečno 55%) nego za Fmax (66%). Zaključak Procena eksplozivne jačine može biti još jedan objektivni pokazatelj oporavka i spremnosti za izlaganje specifičnim opterećenjima i kretnjama, zbor čega bi trebalo da bude deo standardnog protokola za praćenje sportista nakon rekonstpukcije LCA. Štaviše, kombinacija indeksa izvedenih iz maksimalne i eksplozivne jačine morala bi dati kompletniji uvid u balans jačine mišića za kretnje koje zahtevaju maksimalne i eksplozivne akcije, kao i jasnu sliku o funkcionalnim implikacijama.

Introduction Maximal strength ratios such as the limb symmetry index (LSI) and hamstring-to-quadriceps ratio (HQ) may be considered the main outcome measures in the monitoring of recovery after anterior cruciate ligament (ACL) reconstruction. Although explosive strength is much more important than maximal strength, it is generally disregarded in the follow-up of muscle function recovery. Objective The purpose of this study was to compare ratios between maximal (Fmax) and explosive strength (rate of force development - RFD) in individuals with ACL reconstruction. Methods Fifteen male athletes were enrolled and had maximum voluntary isometric quadriceps and hamstring contractions tested (4.0 ± 0.1 months post reconstruction). In addition to Fmax, RFD was estimated (RFDmax as well as RFD at 50, 100, and 200 ms from onset of contraction) and LS gt I and HQ ratios were calculated. Results The involved leg demonstrated significant hamstring and quadriceps deficits compared to uninvolved leg (p lt 0.01). Deficits were particularly significant in the involved quadriceps, causing higher HQ ratios (average 0.63), compared to the uninvolved leg (0.44). LSI was significantly lower for RFD variables (average 55%) than for Fmax (66%). Conclusion The assessment of RFD may be considered an objective recovery parameter for one's readiness to return to sports and should be an integral part of standard follow-up protocol for athletes after ACL reconstruction. Moreover, the combination of indices derived from maximal and explosive strength may provide better insight in muscle strength balance, as well as a clear picture of functional implications., Uvod Maksimalne jačine ekstenzora i fleksora kolena, njihov međusobni odnos (eng. hamstrings-to-quadriceps ratio; HQ), kao i indeks simetrije operisane i neoperisane noge (eng. limb symmetry index; LSI) važni su pokazatelji pomoću kojih se prati oporavak nakon rekonstrukcije LCA. Iako je za izvođenje brojnih funkcionalnih zadataka eksplozivna jačina važnija od maksimalne, ova sposobnost generalno je zanemarena u praćenju oporavka mišićne funkcije. Cilj rada bio je da se uporede odnosi (maksimalne jačine (Fmax) i odnosi eksplozivne jačine (eng. Rate of Force Development - RFD) kod sportista sa rekonstrukcijom LCA. Metode rada U studiju je uključeno 15 sportista, kojima je testirana maksimalna voljna izometrijska kontrakcija (MBK) ekstenzora i fleksora kolena (4,0 ± 0,1 meseca postoperativno). Pored Fmax, procenjivan je i RFD (RFDmax, kao i RFD na 50, 100 i 200 ms od početka kontrakcije) i računati odnosi jačine (LSI i HQ odnos). Rezultati Maksimalna jačina i ekstenzora i fleksora operisane noge bila je značajno niža nego kod neoperisane noge (p lt 0,01). Deficiti su bili posebno izraženi kod ekstenzora operisane noge, usled čega su i HQ odnosi na toj strani (prosečno 0,63) bili veći nego kod neoperisane noge (0,44). Indeks simetrije je bio značajno niži za varijable RFD (prosečno 55%) nego za Fmax (66%). Zaključak Procena eksplozivne jačine može biti još jedan objektivni pokazatelj oporavka i spremnosti za izlaganje specifičnim opterećenjima i kretnjama, zbor čega bi trebalo da bude deo standardnog protokola za praćenje sportista nakon rekonstpukcije LCA. Štaviše, kombinacija indeksa izvedenih iz maksimalne i eksplozivne jačine morala bi dati kompletniji uvid u balans jačine mišića za kretnje koje zahtevaju maksimalne i eksplozivne akcije, kao i jasnu sliku o funkcionalnim implikacijama.

Finswimming is a sport where athlete uses one big monofin to produce propulsion. The purpose of this study was to describe relationship between isokinetic strength of different muscle groups and 100 meters finswimming time. Study questions was: what muscle groups have relationship with finswimming time. Methods: 17 international level monfin swimmers, 9 male (age 16,9 ±1,8 yrs., height 180,0 ± 10.0 cm., weight 76.0±6.9 kg) and 8 female finswimmers ( age 17,6 ±4,7 yrs., height 170,0 ± 10.0 cm., weight 68,6 ± 13,5 kg) performed 100 meters monofin surface swim and where also tested within a two days on isokinetic dynamometer (knee, hip and trunk extensors and flexors at angular speeds of 60°/sec ). Force data at angles from 0-90 degrees with 10 degree step were used for correlation. Results: There was a strong correlation (p<0.05) between swimming time and knee extensors (r=-0.82 at angle 50°), hip flexors (r=-0.70 at angle 10°) and trunk flexors (r =-0.77 at angle 20°) in male swimmers. Surprisingly, we did not find corresponding correlations among female finswimmers. Conclusion: Current study found relationship between strength of main muscle groups and swimming speed only in male swimmers. It is expected that strength plays a role in swimming time, but the lack of relationship in female swimmers suggests at the need to introduce a measure of swimming effectiveness instead of pure resultant time. The proposed hypothesis is further supported by the high level of competence among study participants (incl. multiple European champion, and several finalists).

Finswimming is a sport where athlete uses one big monofin to produce propulsion. The purpose of this study was to describe relationship between isokinetic strength of different muscle groups and 100 meters finswimming time. Study questions was: what muscle groups have relationship with finswimming time. Methods: 17 international level monfin swimmers, 9 male (age 16,9 ±1,8 yrs., height 180,0 ± 10.0 cm., weight 76.0±6.9 kg) and 8 female finswimmers ( age 17,6 ±4,7 yrs., height 170,0 ± 10.0 cm., weight 68,6 ± 13,5 kg) performed 100 meters monofin surface swim and where also tested within a two days on isokinetic dynamometer (knee, hip and trunk extensors and flexors at angular speeds of 60°/sec ). Force data at angles from 0-90 degrees with 10 degree step were used for correlation. Results: There was a strong correlation (p<0.05) between swimming time and knee extensors (r=-0.82 at angle 50°), hip flexors (r=-0.70 at angle 10°) and trunk flexors (r =-0.77 at angle 20°) in male swimmers. Surprisingly, we did not find corresponding correlations among female finswimmers. Conclusion: Current study found relationship between strength of main muscle groups and swimming speed only in male swimmers. It is expected that strength plays a role in swimming time, but the lack of relationship in female swimmers suggests at the need to introduce a measure of swimming effectiveness instead of pure resultant time. The proposed hypothesis is further supported by the high level of competence among study participants (incl. multiple European champion, and several finalists).

The purpose of this study was to examine the differences in knee extensor maximal and endurance strength in elderly. Sixteen healthy elderly served as subjects, eight of them trained , age 61.0±8.9 yrs; height, 170.6±6.8 cm; weight, 71.8±11.7 kg [mean ± standard deviation] and eight untrained 61.4±8.1 yrs, height 174.6±7.4 cm; weight 83.9 ±14.2 kg. Maximal strength in single leg extension exercise was measured unilaterally with the dominant leg until the subjects reached their 1 Repetition Maximum (RM) covering the full Range of Motion (ROM). Muscular endurance was obtained with a load of 75% of 1-RM for 3 consecutive sets, with 2 min rest periods till failure. Load at 1 RM was lower in absolute terms in untrained, but not significant, while the relative 1-RM test was significantly lower in untrained subjects (0.20 vs. 0.25 kg load/kg body weight) (p<0.05). The number of repetitions and amount of weight lifted performed of all 3 sets was higher in trained subjects, but not significant. In the trained group both repetitions and the load managed in the third set was significant lower compared with the first two sets. The result that maximal force output is more affected compared to muscular endurance in these subjects might be due to the habitual use of quadriceps femoris muscles during activity of daily living in both trained and untrained elderly.

The purpose of this study was to examine the differences in knee extensor maximal and endurance strength in elderly. Sixteen healthy elderly served as subjects, eight of them trained , age 61.0±8.9 yrs; height, 170.6±6.8 cm; weight, 71.8±11.7 kg [mean ± standard deviation] and eight untrained 61.4±8.1 yrs, height 174.6±7.4 cm; weight 83.9 ±14.2 kg. Maximal strength in single leg extension exercise was measured unilaterally with the dominant leg until the subjects reached their 1 Repetition Maximum (RM) covering the full Range of Motion (ROM). Muscular endurance was obtained with a load of 75% of 1-RM for 3 consecutive sets, with 2 min rest periods till failure. Load at 1 RM was lower in absolute terms in untrained, but not significant, while the relative 1-RM test was significantly lower in untrained subjects (0.20 vs. 0.25 kg load/kg body weight) (p<0.05). The number of repetitions and amount of weight lifted performed of all 3 sets was higher in trained subjects, but not significant. In the trained group both repetitions and the load managed in the third set was significant lower compared with the first two sets. The result that maximal force output is more affected compared to muscular endurance in these subjects might be due to the habitual use of quadriceps femoris muscles during activity of daily living in both trained and untrained elderly.

The aim of the research was to define the relationship between success in teaching basic skiing skills to students of Police Academy and the dimensions of isometric knee extensor muscle force. The sample consisted of 183 students of Police Academy (Age = 20.100.50 years, VH = 1.8140.005 cm, BM = 78.427.29 kg) who had no previous experience in skiing. The mark that the students got at the final skiing test was used as the criterion variable, where the system of 29 predictor variables was represented by the characteristics of isometric knee extensor muscle force, which were used to assess the level of maximal isometric force at 10% from 10 to 100% of Fmax (NogeF10% - NogeF100%), absolute rate of force development (explosibility index) at 10% from 10 to 100% of Fmax (NogeRFD10% -NogeRFD100%), and muscle unit involvement velocity assessment index at every 10% of the force realised (NogeC10%-NogeC90%). The predictors gave a statistically significant description of the criterion with 10.30% describing common variance (R2=0.103, Fratio=3.114, pvalue=0.0037). As for the individual variables, the criterion was significantly described by two variables that were used to assess the level of maximal force at 20 and 30% of Fmax (NogeF20% and NogeF20%), muscle unit involvement velocity at 50 and 60% of Fmax (NogeC50% and NogeC60%), and rate of force development at 60 and 70% of Fmax (NogeRFD60% and NogeRFD70%). The results were used to define the equation of criterion prediction (success in skiing instruction) with the assessment error of  0.82 of the mark. The formula we obtained for the equation of model prediction has the following form: Mark = 8.03238 - 0.301976*NogeF20% + 0.198425*NogeF30% + 0.161689*NogeC50% - 0.564403*NogeC60% + 0.00319422*NogeRFD60% - 0.00232235*NogeRFD70%., Predmet istraživanja je definisanje povezanosti između uspešnosti savladavanja osnovne obuke u skijanju kod studenata Policijske akademije i dimenzija izometrijske mišićne sile mišića opružača nogu. Uzorak ispitanika se sastojao od 183 studenta Policijske akademije (Uzrast = 20.100.50 godina, TV = 1.8140.005 cm, TM = 78.427.29 kg) bez prethodnog znanja skijanja. Kriterijsku varijablu je predstavljala ocena studenta dobijena na završnom ispitu iz skijanja, dok su sistem od 29 prediktorskih varijabli predstavljale karakteristike izometrijske sile mišića opružača nogu kojima je procenjivan nivo maksimalne sile na 10% od 10 do 100% od Fmax (NogeF10% - NogeF100%), intenzitet ispoljavanja sile na 10% od 10 do 100% od Fmax (NogeRFD10% - NogeRFD100%) i indeks procene brzine uključenja motornih jedinica na svakih 10% realizovane sile (NogeC10% - NogeC90%). Prediktori su statistički značajno opisali kriterijum sa 10.30% objašnjenja zajedničke varijanse (R2=0.103, Fratio=3.114, pvalue=0.0037). Od pojedinačnih varijabli kriterijum su statistički značajno opisale po dve varijable kojima je procenjivan nivo maksimalne sile na 20 i 30% od Fmax (NogeF20% i NogeF20%), brzina uključenja motornih jedinica na 50 i 60% od Fmax (NogeC50% i NogeC60%) i intenzitet ispoljavanja sile na 60 i 70% od Fmax (NogeRFD60% i NogeRFD70%). Na osnovu dobijenih rezultata definisana je jednačina predikcije kriterija (uspešnost obuke skijanja) sa greškom procene od  0.82 ocene. Dobijena formula jednačine predikcije modela ima sledeći oblik: Ocena = 8.03238 - 0.301976*NogeF20% + 0.198425*NogeF30% + 0.161689*NogeC50% - 0.564403*NogeC60% + 0.00319422*NogeRFD60% - 0.00232235*NogeRFD70%.

The aim of the research was to define the relationship between success in teaching basic skiing skills to students of Police Academy and the dimensions of isometric knee extensor muscle force. The sample consisted of 183 students of Police Academy (Age = 20.100.50 years, VH = 1.8140.005 cm, BM = 78.427.29 kg) who had no previous experience in skiing. The mark that the students got at the final skiing test was used as the criterion variable, where the system of 29 predictor variables was represented by the characteristics of isometric knee extensor muscle force, which were used to assess the level of maximal isometric force at 10% from 10 to 100% of Fmax (NogeF10% - NogeF100%), absolute rate of force development (explosibility index) at 10% from 10 to 100% of Fmax (NogeRFD10% -NogeRFD100%), and muscle unit involvement velocity assessment index at every 10% of the force realised (NogeC10%-NogeC90%). The predictors gave a statistically significant description of the criterion with 10.30% describing common variance (R2=0.103, Fratio=3.114, pvalue=0.0037). As for the individual variables, the criterion was significantly described by two variables that were used to assess the level of maximal force at 20 and 30% of Fmax (NogeF20% and NogeF20%), muscle unit involvement velocity at 50 and 60% of Fmax (NogeC50% and NogeC60%), and rate of force development at 60 and 70% of Fmax (NogeRFD60% and NogeRFD70%). The results were used to define the equation of criterion prediction (success in skiing instruction) with the assessment error of  0.82 of the mark. The formula we obtained for the equation of model prediction has the following form: Mark = 8.03238 - 0.301976*NogeF20% + 0.198425*NogeF30% + 0.161689*NogeC50% - 0.564403*NogeC60% + 0.00319422*NogeRFD60% - 0.00232235*NogeRFD70%., Predmet istraživanja je definisanje povezanosti između uspešnosti savladavanja osnovne obuke u skijanju kod studenata Policijske akademije i dimenzija izometrijske mišićne sile mišića opružača nogu. Uzorak ispitanika se sastojao od 183 studenta Policijske akademije (Uzrast = 20.100.50 godina, TV = 1.8140.005 cm, TM = 78.427.29 kg) bez prethodnog znanja skijanja. Kriterijsku varijablu je predstavljala ocena studenta dobijena na završnom ispitu iz skijanja, dok su sistem od 29 prediktorskih varijabli predstavljale karakteristike izometrijske sile mišića opružača nogu kojima je procenjivan nivo maksimalne sile na 10% od 10 do 100% od Fmax (NogeF10% - NogeF100%), intenzitet ispoljavanja sile na 10% od 10 do 100% od Fmax (NogeRFD10% - NogeRFD100%) i indeks procene brzine uključenja motornih jedinica na svakih 10% realizovane sile (NogeC10% - NogeC90%). Prediktori su statistički značajno opisali kriterijum sa 10.30% objašnjenja zajedničke varijanse (R2=0.103, Fratio=3.114, pvalue=0.0037). Od pojedinačnih varijabli kriterijum su statistički značajno opisale po dve varijable kojima je procenjivan nivo maksimalne sile na 20 i 30% od Fmax (NogeF20% i NogeF20%), brzina uključenja motornih jedinica na 50 i 60% od Fmax (NogeC50% i NogeC60%) i intenzitet ispoljavanja sile na 60 i 70% od Fmax (NogeRFD60% i NogeRFD70%). Na osnovu dobijenih rezultata definisana je jednačina predikcije kriterija (uspešnost obuke skijanja) sa greškom procene od  0.82 ocene. Dobijena formula jednačine predikcije modela ima sledeći oblik: Ocena = 8.03238 - 0.301976*NogeF20% + 0.198425*NogeF30% + 0.161689*NogeC50% - 0.564403*NogeC60% + 0.00319422*NogeRFD60% - 0.00232235*NogeRFD70%.

In rehabilitation medicine one is concerned with the consequences of diseases, congenital deformations and trauma. On the level of functions and structures the consequences consist of impairments of muscle strength, sensibility, co-ordination, etc. These impairments may cause disabilities like restricted ambulation, problems with self-care, etc. In rehabilitation one feels a need to measure the impairments in a reliable way, in order to assess the effects of certain training programmes or to registrate the course of a chronic disease objectively. The tests used to measure the impairment have to be reliable. The variability of a test is a usefull indication of the reliability. Furthermore, a test has to be valid, i.e. the test measures what it is supposed to measure. The validity of a test becomes acceptable if there is a relationship between the impairment itself and the consequences on the functional level. The object of this thesis is the testing of muscle strength of the knee extensors in healthy subjects and in patients

Chen, T. C., Chen, H. L., Cheng, L. F., Chou, T. Y., & Nosaka, K. (2021). Effect of leg eccentric exercise on muscle damage of the elbow flexors after maximal eccentric exercise. Medicine & Science in Sports & Exercise, 53(7), 1473-1481. https://doi.org/10.1249/MSS.0000000000002616

Maeo, S., Ochi, Y., Yamamoto, M., Kanehisa, H., Nosaka, K. (2015). Effect of a prior bout of preconditioning exercise on muscle damage from downhill walking in Applied Physiology, Nutrition and Metabolism, 40(3), 274-279. Available here.

Doguet, V., Nosaka, K., Guevel, A., Thickbroom, G., Ishimura, K., & Jubeau, M. (2017). Muscle length effect on corticospinal excitability during maximal concentric, isometric and eccentric contractions of the knee extensors. Experimental Physiology, 102(11), 1513-1523. Available here.