[Effects and mechanisms of 6-week intensive training on renal function in rats].

OBJECTIVE: To study the effect of 6-week intensive training on renal function in rats and the mechanism of exercise-induced proteinuria. METHODS: Thirty-six male SD rats, aged 6 weeks, were divided into two groups, including a control group(C,n=12)and an overtraining group(M,n=24). After the rats adapted to feeding for 4 d, group C did not carry out any exercise, and the M group did 6-week of increasing load swimming, 6 days a week, once a day. Started with the load of 1%weight at the beginning of the 4th week,and gradually increased (to 6% weight). Took a single urine from both groups 30 min after the end of the training. Blood was taken from the main ventral vein, and the bilateral kidneys were to be tested. The levels of tested urine protein, microalbumin and neutrophil gelatinase associated lipocalin(NGAL) was determined by using enzyme linked immunosorbent assaytest. The content of urine creatinine was tested with alkaline picric acid method,. The serum levels of colorimetric method to determine serum creatinine and urea nitrogen were determined by colorimetric method. The expression of Nephrin in renal tissue was detected by Western blot and the radioimmunoassay was used to test serum testosterone, corticosterone and renin-angiotensin system related index. RESULTS: Compared with group C, the serum testosterone/cortisone(T/C) of group M was decreased significantly (P<0.01). The urine total protein(TP), microalbumin (mAlb), microalbumin/creatinine (mAlb/CRE), NGAL, blood urea nitrogen (BUN) and serum creatinine(SCr) were increased significantly (P<0.01). The abnormality of glomerular structure was obvious, and the paller scores were higher. The protein expression of Nephrin was obviously down decreased (P<0.01). The renin activity (Ra) and angiotension Ⅱ (Ang Ⅱ) in renal and circulating blood were decreased significantly (P<0.01). CONCLUSIONS: The effects of 6-week intensive training on renal function in rats and the mechanism of exercise-induced proteinuria may be that overtraining can induce the continuous excitation of Reninrenin activity in renal and circulating blood, down-regulated the expression of Nephrin, lead to abnormality of renal structure and function, and proteinuria.

Effects and mechanisms of 6-week intensive training on renal function in rats / 中国应用生理学杂志

OBJECTIVE@#To study the effect of 6-week intensive training on renal function in rats and the mechanism of exercise-induced proteinuria.@*METHODS@#Thirty-six male SD rats, aged 6 weeks, were divided into two groups, including a control group(C,=12)and an overtraining group(M,=24). After the rats adapted to feeding for 4 d, group C did not carry out any exercise, and the M group did 6-week of increasing load swimming, 6 days a week, once a day. Started with the load of 1%weight at the beginning of the 4 week,and gradually increased (to 6% weight). Took a single urine from both groups 30 min after the end of the training. Blood was taken from the main ventral vein, and the bilateral kidneys were to be tested. The levels of tested urine protein, microalbumin and neutrophil gelatinase associated lipocalin(NGAL) was determined by using enzyme linked immunosorbent assaytest. The content of urine creatinine was tested with alkaline picric acid method,. The serum levels of colorimetric method to determine serum creatinine and urea nitrogen were determined by colorimetric method. The expression of Nephrin in renal tissue was detected by Western blot and the radioimmunoassay was used to test serum testosterone, corticosterone and renin-angiotensin system related index.@*RESULTS@#Compared with group C, the serum testosterone/cortisone(T/C) of group M was decreased significantly (<0.01). The urine total protein(TP), microalbumin (mAlb), microalbumin/creatinine (mAlb/CRE), NGAL, blood urea nitrogen (BUN) and serum creatinine(SCr) were increased significantly (<0.01). The abnormality of glomerular structure was obvious, and the paller scores were higher. The protein expression of Nephrin was obviously down decreased (<0.01). The renin activity (Ra) and angiotension Ⅱ (Ang Ⅱ) in renal and circulating blood were decreased significantly (<0.01).@*CONCLUSIONS@#The effects of 6-week intensive training on renal function in rats and the mechanism of exercise-induced proteinuria may be that overtraining can induce the continuous excitation of Reninrenin activity in renal and circulating blood, down-regulated the expression of Nephrin, lead to abnormality of renal structure and function, and proteinuria.

Training-related changes in the EMG-moment relationship during isometric contractions: Further evidence of improved control of muscle activation in strength-trained men?

The possibility of using electromyography (EMG) to track muscle activity has raised the question of its relationship with the effort exerted by the muscles around the joints. However, the EMG-moment relationship is yet to be fully defined, and increasing knowledge of this topic could contribute to research in motor control and to the development of EMG-based algorithms and devices. With regards the training-related adaptations at the peripheral and central level, the present study investigated the effect of strength training on EMG-moment relationship. Our aim was to clarify its nature and gain further understanding of how morphological and neural factors may affect its form. The EMG-moment relationship was determined during knee flexion and extension isometric contractions performed by strength-trained male athletes and untrained male participants. The results showed that strength training induced linearity of the EMG-moment relationship concomitantly with enhanced maximum force production capacity and decreased co-activation of knee agonist-antagonist muscle pair. These results clarified discordant results regarding the linear or curved nature of the EMG-moment in isometric conditions and suggested that the remarkable linearity of the EMG-moment found in trained participants could indicate improved control of muscle activation.