No description available.

An acute bout of resistance exercise (RE) and dietary protein consumption stimulate muscle protein synthesis (MPS). This anabolic effect is believed to be attenuated with resistance exercise training (RET), however, the mechanism for this plateau" is unknown. In addition, the ideal timing for protein consumption to optimize MPS is not well characterized. The central hypothesis of this research is that RE stimulates cumulative (measured over 24-36 h) MPS in rats and humans. Study one determined whether an acute bout of RE in rats enhances MPS when assessed with the traditional flooding dose (~ 25 min) and 2H2O (4 and 24 h measurements); thus a comparison of the two methodologies was made. An acute session of RE did not result in an elevation in MPS when quantified by either the flooding dose or 2H2O over 4 and 24 h (methods compared qualitatively). Therefore, an acute bout of RE in rats does not appear to be anabolic and adaptation resulting from multiple bouts is likely necessary. Study two determined if RET in rats results in attenuation in MPS (plateau effect) 16 h following the final RE session (peak anabolic window) and if it is due to an increase in 4E-BP1 (a key regulator of mRNA translation initiation) activity; or if the timing in anabolism changes, which could be detected with a cumulative assessment (2H2O). MPS at 16 h was unchanged following RE training. Consistent with this finding, there were no differences in 4E-BP1 activity. Conversely, cumulative MPS was significantly increased with RET, suggesting a temporal shift in anabolism. Study three determined if dietary protein consumed immediately following RE augments cumulative (24 h) MPS in young adult human males when energy and macronutrients are controlled. RE and post-RE protein had no effect on mixed MPS; however, myofibrillar MPS was significantly increased with RE suggesting specific changes within a heterogeneous protein pool. Collectively, these are the first studies to assess changes in cumulative MPS with RE in rats and humans. The long term goals of this research are to understand muscle protein anabolism in "free-living" mammals and the mechanisms that regulate this process.

An acute bout of resistance exercise (RE) and dietary protein consumption stimulate muscle protein synthesis (MPS). This anabolic effect is believed to be attenuated with resistance exercise training (RET), however, the mechanism for this plateau" is unknown. In addition, the ideal timing for protein consumption to optimize MPS is not well characterized. The central hypothesis of this research is that RE stimulates cumulative (measured over 24-36 h) MPS in rats and humans. Study one determined whether an acute bout of RE in rats enhances MPS when assessed with the traditional flooding dose (~ 25 min) and 2H2O (4 and 24 h measurements); thus a comparison of the two methodologies was made. An acute session of RE did not result in an elevation in MPS when quantified by either the flooding dose or 2H2O over 4 and 24 h (methods compared qualitatively). Therefore, an acute bout of RE in rats does not appear to be anabolic and adaptation resulting from multiple bouts is likely necessary. Study two determined if RET in rats results in attenuation in MPS (plateau effect) 16 h following the final RE session (peak anabolic window) and if it is due to an increase in 4E-BP1 (a key regulator of mRNA translation initiation) activity; or if the timing in anabolism changes, which could be detected with a cumulative assessment (2H2O). MPS at 16 h was unchanged following RE training. Consistent with this finding, there were no differences in 4E-BP1 activity. Conversely, cumulative MPS was significantly increased with RET, suggesting a temporal shift in anabolism. Study three determined if dietary protein consumed immediately following RE augments cumulative (24 h) MPS in young adult human males when energy and macronutrients are controlled. RE and post-RE protein had no effect on mixed MPS; however, myofibrillar MPS was significantly increased with RE suggesting specific changes within a heterogeneous protein pool. Collectively, these are the first studies to assess changes in cumulative MPS with RE in rats and humans. The long term goals of this research are to understand muscle protein anabolism in "free-living" mammals and the mechanisms that regulate this process.

Eccentric overload in training settings utilizes loads higher than concentric one repetition maximum (1RM). There is no clear definition of eccentric “failure” or 1RM using conventional weights, so eccentric 1RM is estimated to be between 145-190% concentric 1RM. Historically, the highest intensity used for eccentric overload is typically 120% of concentric 1RM despite little research using conventional weights with higher eccentric intensities. The purpose of this study was to conduct an exploratory neuro-mechanical analysis of different intensities of elbow flexors eccentric overload using free weights by examining angular kinematics during contraction. Twenty male participants with weight training experience had unilateral concentration curl isometric peak torque assessed on a Humac Norm Dynamometer and concentric 1RM assessed with dumbbells while biceps brachii electromyography (EMG) and elbow joint angle were recorded. Angles were recorded using a custom made electrogoniometer and elbow joint torque was estimated using inverse dynamics. Participants were randomly assigned in counter balanced order to perform eccentric actions at 120%, 140%, 150%, 160% and 170% concentric 1RM with 4 minutes rest between. Variables included peak torque, angular velocity at peak torque, impulse, power, mean EMG, and EMG normalized to peak. Data were analyzed using repeated measures ANOVA or a Friedman test. Angular velocity at peak torque was significantly lower for 120% (65.3 ± 40.8°/s) compared to all other conditions (range: 65.3 ± 40.8 to 162.1 ± 75.2°/s; p<0.01). Peak torque for all conditions (range: 98.2 ± 16.2 to 108.2 ± 21.6 Nm) was significantly higher than isometric peak torque (77.4 ± 16.8Nm; p<0.05). Peak torque at 160% (108.2 ± 21.6Nm) was significantly higher than at 120% (98.2 ± 16.2Nm; p<0.05). Power for 140-170% (range: 166.2 ± 85.7W to 265.8 ± 111.3W) was significantly higher than power at 120% (79.9 ± 66.8W; p<0.05). Impulse was highest at 120% (56.1 ± 54.6Nms) compared to all other conditions (range: 56.2 ± 54.6 to 9.6 ± 3.8Nms; p≤0.05). Impulse at 140% (20.6 ± 11.8Nms) was significantly higher than 170% (9.6 ± 3.8Nms; p<0.05). Isometric mean EMG (0.792 ± 0.285 mV) was significantly higher than all eccentric conditions (range: 0.654 ± 0.313 to 0.533 ± 0.259mV; p<0.05) with no difference between eccentric conditions for mean EMG or EMG normalized to peak. It was concluded that compared to 120%, eccentric overload with intensity ranging from 140-170% concentric 1RM involves minimal increases in peak torque and no change in EMG activation. Intensities above 120% enhance power and decrease impulse. This research has implications on future training prescription of eccentric exercise.

Estudos têm mostrado que o treinamento de força de baixa intensidade com oclusão vascular (TFOV) tem apresentado resultados similares nos ganhos de força e hipertrofia comparado ao treinamento de força (TF) de alta intensidade. O objetivo deste estudo foi comparar os efeitos de três diferentes programas de TF nos ganhos de força e hipertrofia musculares e na expressão da miostatina (MSTN) e seus antagonistas. Para isso, vinte e nove jovens do sexo masculino, sem experiência em TF, foram recrutados e divididos randomicamente nos grupos: treinamento de força de baixa intensidade sem oclusão (BI), treinamento de força de baixa intensidade com oclusão (BIO) e treinamento de força de alta intensidade sem oclusão (AI). Os grupos BIO e BI treinaram com intensidade de 20% 1RM, enquanto o grupo AI treinou com intensidade de 80% 1RM. A ANOVA one way foi utilizada para testar as diferenças percentuais nos ganhos de força (1RM) e na área de secção transversa (AST) do músculo quadríceps femoral. O modelo misto para análise das medidas repetidas foi utilizado para testar as diferenças nas variáveis miostatina (MSTN), folistatina-3 (FLST-3), SMAD-7 e GASP-1 nos grupos BI, BIO e AI nas condições pré e pós-treinamento. Os resultados mostraram que os aumentos de força e hipertrofia musculares nos grupos BIO e AI foram similares, entretanto superiores ao grupo BI. Esses resultados podem ser atribuídos a maior diminuição na expressão da MSTN nos grupos BIO (45%) e AI (41%) comparados com o grupo BI (16%) e o aumento na expressão dos genes que antagonizam sua atividade (SMAD-7, FLST-3 e GASP-1). Podemos concluir que a inibição na atividade da MSTN dos grupos BIO e AI podem responder em parte a similaridade nos ganhos de força e hipertrofia entre os grupos e a diferença para o grupo BI / It has been demonstrated that low intensity training associated to vascular occlusion (LIO) promotes similar gains in strength and muscle mass when compared to high intensity strength training (HI). The aim of the present study was to evaluate the effect of three different training programs on skeletal muscle hypertrophy and atrophy related gene expression. Twenty nine young male, with no previous experience in strength training were randomly allocated in three groups: low intensity strength training (i.e. 20% - 1-RM) (LI); low intensity strength training associated to vascular occlusion (i.e. 20% - 1-RM) (LIO); high intensity strength training (HI) (i.e. 80% - 1-RM). One-way ANOVA was used to assess differences in % delta change values of 1-RM and cross sectional area (CSA) of the quadriceps femoris. Mixed model analysis was used to compare myostatin (MSTN), folistatyn-3 (FLST-3), SMAD-7 e GASP-1 changes between groups pre and post training. Results demonstrated similar increases in strength and muscle hypertrophy for LIO and HI groups. Moreover, such increases were significantly greater when compared to LI. These results may be, at least in part, explained by a significant decrease in MSTN mRNA expression in LIO (45%) and HI (41%) when compared to LI (16%); additionally, SMAD-7; FLST-3 and GASP-1 mRNA expression were significantly increased. In conclusion, LIO training promotes similar gains than HI training. The results may be explained by changes in MSTN and related genes mRNA expression

No description available.

Early strength increase with training is normally attributed to neural adaptations but recent evidence suggests that muscle hypertrophy occurs earlier than previously thought. The purpose of this study was to examine the time course of adaptation through 20 days of training and 5 days of detraining. Twenty-two untrained subjects trained one arm every 2nd day for 20 days. Subjects performed isokinetic eccentric biceps training at 90°/s (6 sets of 8 reps). Muscle thickness (reported in cm) via ultrasound, strength (reported in Nm) and muscle activation (electromyography) were measured before, during and after training (9 time points). Muscle thickness increased after 8 days of training (3.66±0.11 to 3.90±0.12; p<0.05) and remained above baseline until the end of training (3.97±0.12). After 5 days of detraining muscle thickness decreased (3.97±0.12 vs. 3.85±0.11; p<0.05), but remained higher than baseline (p<0.05). Muscle thickness did not change significantly in the untrained arm at any time point. Strength in the trained arm decreased after 8 days of training (65.6±4.1 to 57.5±3.5; p<0.05) and remained suppressed throughout the study. Muscle activation amplitude increased after 14 days of training (p<0.05) and remained elevated throughout the study. In conclusion, biceps muscle thickness increases very rapidly with frequent intense eccentric training although this type of training appears to impair strength. These findings provide additional evidence that muscle hypertrophy may occur much faster than has been generally accepted.

Early strength increase with training is normally attributed to neural adaptations but recent evidence suggests that muscle hypertrophy occurs earlier than previously thought. The purpose of this study was to examine the time course of adaptation through 20 days of training and 5 days of detraining. Twenty-two untrained subjects trained one arm every 2nd day for 20 days. Subjects performed isokinetic eccentric biceps training at 90°/s (6 sets of 8 reps). Muscle thickness (reported in cm) via ultrasound, strength (reported in Nm) and muscle activation (electromyography) were measured before, during and after training (9 time points). Muscle thickness increased after 8 days of training (3.66±0.11 to 3.90±0.12; p<0.05) and remained above baseline until the end of training (3.97±0.12). After 5 days of detraining muscle thickness decreased (3.97±0.12 vs. 3.85±0.11; p<0.05), but remained higher than baseline (p<0.05). Muscle thickness did not change significantly in the untrained arm at any time point. Strength in the trained arm decreased after 8 days of training (65.6±4.1 to 57.5±3.5; p<0.05) and remained suppressed throughout the study. Muscle activation amplitude increased after 14 days of training (p<0.05) and remained elevated throughout the study. In conclusion, biceps muscle thickness increases very rapidly with frequent intense eccentric training although this type of training appears to impair strength. These findings provide additional evidence that muscle hypertrophy may occur much faster than has been generally accepted.

名古屋大学博士学位論文 学位の種類:博士(リハビリテーション療法学) (課程) 学位授与年月日　平成22年3月25日

Estudos têm mostrado que o treinamento de força de baixa intensidade com oclusão vascular (TFOV) tem apresentado resultados similares nos ganhos de força e hipertrofia comparado ao treinamento de força (TF) de alta intensidade. O objetivo deste estudo foi comparar os efeitos de três diferentes programas de TF nos ganhos de força e hipertrofia musculares e na expressão da miostatina (MSTN) e seus antagonistas. Para isso, vinte e nove jovens do sexo masculino, sem experiência em TF, foram recrutados e divididos randomicamente nos grupos: treinamento de força de baixa intensidade sem oclusão (BI), treinamento de força de baixa intensidade com oclusão (BIO) e treinamento de força de alta intensidade sem oclusão (AI). Os grupos BIO e BI treinaram com intensidade de 20% 1RM, enquanto o grupo AI treinou com intensidade de 80% 1RM. A ANOVA one way foi utilizada para testar as diferenças percentuais nos ganhos de força (1RM) e na área de secção transversa (AST) do músculo quadríceps femoral. O modelo misto para análise das medidas repetidas foi utilizado para testar as diferenças nas variáveis miostatina (MSTN), folistatina-3 (FLST-3), SMAD-7 e GASP-1 nos grupos BI, BIO e AI nas condições pré e pós-treinamento. Os resultados mostraram que os aumentos de força e hipertrofia musculares nos grupos BIO e AI foram similares, entretanto superiores ao grupo BI. Esses resultados podem ser atribuídos a maior diminuição na expressão da MSTN nos grupos BIO (45%) e AI (41%) comparados com o grupo BI (16%) e o aumento na expressão dos genes que antagonizam sua atividade (SMAD-7, FLST-3 e GASP-1). Podemos concluir que a inibição na atividade da MSTN dos grupos BIO e AI podem responder em parte a similaridade nos ganhos de força e hipertrofia entre os grupos e a diferença para o grupo BI / It has been demonstrated that low intensity training associated to vascular occlusion (LIO) promotes similar gains in strength and muscle mass when compared to high intensity strength training (HI). The aim of the present study was to evaluate the effect of three different training programs on skeletal muscle hypertrophy and atrophy related gene expression. Twenty nine young male, with no previous experience in strength training were randomly allocated in three groups: low intensity strength training (i.e. 20% - 1-RM) (LI); low intensity strength training associated to vascular occlusion (i.e. 20% - 1-RM) (LIO); high intensity strength training (HI) (i.e. 80% - 1-RM). One-way ANOVA was used to assess differences in % delta change values of 1-RM and cross sectional area (CSA) of the quadriceps femoris. Mixed model analysis was used to compare myostatin (MSTN), folistatyn-3 (FLST-3), SMAD-7 e GASP-1 changes between groups pre and post training. Results demonstrated similar increases in strength and muscle hypertrophy for LIO and HI groups. Moreover, such increases were significantly greater when compared to LI. These results may be, at least in part, explained by a significant decrease in MSTN mRNA expression in LIO (45%) and HI (41%) when compared to LI (16%); additionally, SMAD-7; FLST-3 and GASP-1 mRNA expression were significantly increased. In conclusion, LIO training promotes similar gains than HI training. The results may be explained by changes in MSTN and related genes mRNA expression