RESUMEN
This study describes the motor-learning process of older individuals during the course of a training intervention on a motor-driven eccentric bicycle ergometer. Seventeen women and 16 men (64 ± 6 yr) took part in a 10-wk training program. Uniformity of force production and consistency of timing were used to describe their motor performance. The results suggested that participants improved the coefficient of variation of peak force during the intervention (measured at the 2nd, 4th, 6th, 8th, 10th, 12th, and the 18th training sessions). They reached a fairly constant level of motor performance around the 12th training session (5 wk). Age and sex affected improvements in the early phases of the learning process to an extent, but the differences diminished by the end of the intervention. These results suggest that the force control of continuous eccentric muscle contractions improves as a result of training in older adults.
Asunto(s)
Envejecimiento/fisiología , Ciclismo/fisiología , Ergometría/instrumentación , Aprendizaje/fisiología , Destreza Motora/fisiología , Factores de Edad , Anciano , Envejecimiento/psicología , Análisis de Varianza , Ciclismo/psicología , Ergometría/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Actividad Motora , Análisis de Regresión , AutoinformeRESUMEN
BACKGROUND: Diabetes has negative, and exercise training positive, effects on the skeletal muscle vasculature, but the mechanisms are not yet fully understood. In the present experiment the effects of running exercise on the mRNA expression of pro- and antiangiogenic factors were studied in healthy and diabetic skeletal muscle. The responses in capillaries and muscle fibers, collected from the muscle with laser capture microdissection, were also studied separately. METHODS: Healthy and streptozotocin-induced diabetic mice were divided into sedentary and exercise groups. Exercise was a single bout of 1 h running on a treadmill. Gastrocnemius muscles were harvested 3 h and 6 h post exercise, and angiogenesis-related gene expressions were analyzed with real-time PCR. In addition to muscle homogenates, capillaries and muscle fibers were collected from the muscle with laser capture microdissection method and analyzed for vascular endothelial growth factor-A (VEGF-A) and thrombospondin-1 (TSP-1) mRNA expression. RESULTS: Of the proangiogenic factors, VEGF-A and VEGF receptor-2 (VEGFR-2) mRNA expression increased significantly (P < 0.05) in healthy skeletal muscle 6 h post exercise. VEGF-B also showed a similar trend (P = 0.08). No significant change was observed post exercise in diabetic muscles in the expression of VEGF-A, VEGFR-2 or VEGF-B. The expression of angiogenesis inhibitor TSP-1 and angiogenic extracellular matrix protein Cyr61 were significantly increased in diabetic muscles (P < 0.05-0.01). Capillary mRNA expression resembled that in the muscle homogenates, however, the responses were greater in capillaries compared to muscle homogenates and pure muscle fibers. CONCLUSION: The present study is the first to report the effects of a single bout of exercise on the expression of pro- and antiangiogenic factors in diabetic skeletal muscle, and it provides novel data about the separate responses in capillaries and muscle fibers to exercise and diabetes. Diabetic mice seem to have lower angiogenic responses to exercise compared to healthy mice, and they show markedly increased expression of angiogenesis inhibitor TSP-1. Furthermore, exercise-induced VEGF-A expression was shown to be greater in capillaries than in muscle fibers.
Asunto(s)
Diabetes Mellitus Experimental/fisiopatología , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/fisiología , Condicionamiento Físico Animal/fisiología , Trombospondina 1/genética , Factor A de Crecimiento Endotelial Vascular/genética , Animales , Glucemia , Peso Corporal , Capilares/fisiología , Masculino , Ratones , Ratones Endogámicos , Fibras Musculares Esqueléticas/fisiología , Neovascularización Fisiológica/fisiología , ARN Mensajero/metabolismoRESUMEN
Blood and lymphatic vessels together form the circulatory system, allowing the passage of fluids and molecules within the body. Recently we showed that lymphatic capillaries are also found in the capillary bed of skeletal muscle. Exercise is known to induce angiogenesis in skeletal muscle, but it is not known whether exercise has effects on lymphangiogenesis or lymphangiogenic growth factors. We studied lymphatic vessel density and expression of the main lymphangiogenic growth factors VEGF-C and VEGF-D and their receptor VEGFR-3 in response to acute running exercise and endurance exercise training in the skeletal muscle of healthy and diabetic mice. VEGF-C mRNA expression increased after the acute exercise bout (P < 0.05) in healthy muscles, but there was no change in diabetic muscles. VEGF-C levels were not changed either in healthy or in diabetic muscle after the exercise training. Neither acute exercise nor exercise training had an effect on the mRNA expression of VEGF-D or VEGFR-3 in healthy or diabetic muscles. Lymphatic vessel density was similar in sedentary and trained mice and was >10-fold smaller than blood capillary density. Diabetes increased the mRNA expression of VEGF-D (P < 0.01). Increased immunohistochemical staining of VEGF-D was found in degenerative muscle fibers in the diabetic mice. In conclusion, the results suggest that acute exercise or exercise training does not significantly affect lymphangiogenesis in skeletal muscle. Diabetes increased the expression of VEGF-D in skeletal muscle, and this increase may be related to muscle fiber damage.
Asunto(s)
Diabetes Mellitus Experimental/metabolismo , Linfangiogénesis , Vasos Linfáticos/metabolismo , Músculo Esquelético/metabolismo , Esfuerzo Físico , Factor C de Crecimiento Endotelial Vascular/metabolismo , Factor D de Crecimiento Endotelial Vascular/metabolismo , Receptor 3 de Factores de Crecimiento Endotelial Vascular/metabolismo , Animales , Glucemia , Peso Corporal , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/fisiopatología , Regulación de la Expresión Génica , Inmunohistoquímica , Linfangiogénesis/genética , Vasos Linfáticos/fisiopatología , Masculino , Ratones , Músculo Esquelético/fisiopatología , Reacción en Cadena de la Polimerasa , ARN Mensajero/metabolismo , Factores de Tiempo , Factor C de Crecimiento Endotelial Vascular/genética , Factor D de Crecimiento Endotelial Vascular/genética , Receptor 3 de Factores de Crecimiento Endotelial Vascular/genéticaRESUMEN
High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1alpha. The mRNA expression of Cyr61 and CTGF increased 30 min after the exercise (14- and 2.5-fold, respectively; P < 0.001). Cyr61 remained elevated 48 h postexercise (threefold; P < 0.05). The mRNA levels of VEGF-A, VEGF-B, VEGF-C, VEGF-D, or hypoxia-inducible factor-1alpha did not change significantly at either 30 min or 48 h postexercise; however, the variation between subjects increased markedly in VEGF-A and VEGF-B mRNA. Cyr61 protein levels were higher at both 30 min and 48 h after the exercise compared with the control (P < 0.05). Cyr61 and CTGF proteins were localized to muscle fibers and the surrounding ECM by immunohistochemistry. Fast fibers stained more intensively than slow fibers. In conclusion, mechanical loading induces rapid expression of CCN proteins in human skeletal muscle. This may be one of the early mechanisms involved in skeletal muscle remodeling after exercise, since Cyr61 and CTGF regulate the expression of genes involved in angiogenesis and ECM remodeling.
Asunto(s)
Precursor de Proteína beta-Amiloide/metabolismo , Ejercicio Físico/fisiología , Proteínas Inmediatas-Precoces/metabolismo , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Músculo Esquelético/metabolismo , Fragmentos de Péptidos/metabolismo , Adulto , Precursor de Proteína beta-Amiloide/genética , Biopsia , Factor de Crecimiento del Tejido Conjuntivo , Proteína 61 Rica en Cisteína , Expresión Génica , Regulación de la Expresión Génica , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Proteínas Inmediatas-Precoces/genética , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/genética , Péptidos y Proteínas de Señalización Intercelular/genética , Masculino , Fragmentos de Péptidos/genética , Estrés Mecánico , Factor A de Crecimiento Endotelial Vascular/genética , Factor A de Crecimiento Endotelial Vascular/metabolismo , Factor B de Crecimiento Endotelial Vascular/genética , Factor B de Crecimiento Endotelial Vascular/metabolismoRESUMEN
The present study was aimed to localise lymphatic vessels and their growth factors in human and mouse skeletal muscle with immunohistochemistry and specific antibodies (VEGFR-3, LYVE-1, VEGF-C and VEGF-D). The largest lymphatic vessels were found in perimysial connective tissue next to the arteries and veins, as has been shown earlier with electron microscopy. As a new finding, we also found small LYVE-1 positive vessels in the capillary bed between muscle fibres. These vessels were located next to CD31 positive blood capillaries and were of the same size, but fewer in number. In addition, we described the localisation of the two main lymphangiogenic growth factor proteins, vascular endothelial growth factor-C and -D. Both proteins were expressed in skeletal muscle at mRNA and protein levels. VEGF-D was located under the sarcolemma in some of the muscle fibres, in the endothelia of larger blood vessels and in fibroblasts. VEGF-C protein was localised to the nerves and muscle spindles, to fibroblasts and surrounding connective tissue, but was not found in muscle fibres or endothelial cells. Our results are the first to suggest the presence of lymphatic capillaries throughout the skeletal muscle, and to present the localisation of VEGF-C and -D in the muscles.
Asunto(s)
Vasos Linfáticos/química , Músculo Esquelético/química , Factor C de Crecimiento Endotelial Vascular/análisis , Factor D de Crecimiento Endotelial Vascular/análisis , Animales , Humanos , Inmunohistoquímica , Ratones , ARN Mensajero/análisis , Distribución TisularRESUMEN
Diabetes alters microvascular structure and function and is a major risk factor for cardiovascular diseases. In diabetic skeletal muscle, impaired angiogenesis and reduced VEGF-A expression have been observed, whereas in healthy muscle exercise is known to have opposite effects. We studied the effects of type 1 diabetes and combined exercise training on angiogenic mRNA expression and capillarization in mouse skeletal muscle. Microarray and real-time PCR analyses showed that diabetes altered the expression of several genes involved in angiogenesis. For example, levels of proangiogenic VEGF-A, VEGF-B, neuropilin-1, VEGFR-1, and VEGFR-2 were reduced and the levels of antiangiogenic thrombospondin-1 and retinoblastoma like-2 were increased. Exercise training alleviated some of these changes, but could not completely restore them. VEGF-A protein content was also reduced in diabetic muscles. In line with the reduced levels of VEGF-A and other angiogenic factors, and increased levels of angiogenesis inhibitors, capillary-to-muscle fiber ratio was lower in diabetic mice compared to healthy controls. Exercise training could not restore capillarization in diabetic mice. In conclusion, these data illustrate that type 1 diabetes is associated with reduced skeletal muscle capillarization and the dysregulation of complex angiogenesis pathways.
Asunto(s)
Capilares/fisiología , Diabetes Mellitus Experimental/fisiopatología , Diabetes Mellitus Tipo 1/fisiopatología , Regulación de la Expresión Génica , Músculo Esquelético/fisiopatología , Neovascularización Patológica/genética , Neovascularización Fisiológica/genética , Condicionamiento Físico Animal , Ribonucleasa Pancreática/fisiología , Inductores de la Angiogénesis , Animales , Modelos Animales de Enfermedad , Masculino , Ratones , Ratones Endogámicos , Músculo Esquelético/irrigación sanguínea , Neovascularización Patológica/prevención & controlRESUMEN
The effects of daily repeated prolonged exercise on gonadotrophin levels and mood states were studied in six physically active army officers participating in a 4-day march totaling 185 km. We hypothesized that submaximal daily repeated prolonged exercise may disturb the balance of the hypothalamic-pituitary-testicular axis, which could be determined from the concentrations of serum luteinizing hormone and follicle-stimulating hormone with time-resolved immunofluorometric assay. In addition, the mood states of the men were followed during the exercise period. The results indicate that soldiers who are in good physical condition and are accustomed to marching are capable of marathon walking on 4 successive days while carrying a 10-kg backpack, without any major adverse effects on the function of the hypothalamic-pituitary-testicular axis or mood states. This study indicates that psychological monitoring and physiological measurements could be of value in following responses to daily repeated prolonged psychophysiological stress in field conditions with soldiers.
Asunto(s)
Afecto/fisiología , Gonadotropinas/fisiología , Medicina Militar , Personal Militar , Caminata/fisiología , Caminata/psicología , Adulto , Humanos , Masculino , Persona de Mediana Edad , Estrés Psicológico , Factores de TiempoRESUMEN
The cohort consisted of 1,489 Finnish female physical education and 8,560 language teachers born after 1920 and alive in 1967. The 2 study populations were similar in social class and way of living and clearly discordant in physical activity both during their university studies and later in life. The incidence of breast cancer among these teachers up to the year 2000 was assessed through a record linkage with the Finnish Cancer Registry. The number of breast cancer cases among physical education teachers was 61 in 32,862 person-years and among language teachers was 404 in 177,188 person-years. In Poisson-regression analysis, the incidence rate ratio--adjusted for age, calendar time, number of children and age at first birth--for physical education vs. language teachers was overall 0.83 (95% confidence interval 0.63-1.09). This relative rate was 0.79 (0.46-1.36) in ages <50 years and 0.86 (0.62-1.18) in ages > or =50 years. Our study is concordant with the hypothesis that life-long physical activity may reduce the risk of breast cancer.
Asunto(s)
Neoplasias de la Mama/epidemiología , Ejercicio Físico , Lenguaje , Educación y Entrenamiento Físico , Enseñanza , Adulto , Neoplasias de la Mama/etiología , Estudios de Cohortes , Femenino , Finlandia/epidemiología , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Factores de RiesgoRESUMEN
The hormonal response to 4 days' walking exercise (totaling 164 km) was examined among 15 healthy males. We hypothesised that submaximal daily, repeated, prolonged exercise may disturb the balance of the adrenal cortex and pituitary-testicular axis, which could be analysed from the concentrations of serum cortisol and testosterone, and with time-resolved immunofluorometric assay (IFMA) of luteinising hormone (LH) and follicle stimulating hormone (FSH). In the adrenal cortex the increased response to acute exercise could be seen after the 1st day. The concentration of testosterone was reduced after the first two exercise sessions and a plateau was reached after the 3rd day of walking. LH decreased during the 2nd and 3rd day by 31% (P = 0.04 and 0.001, respectively) and remained steady on the 4th day. In FSH the suppression was seen all the time after the second exercise session and before the final walk it was reduced by 19% (P = 0.02) compared with the baseline. The acute response of the adrenal cortex and pituitary-gonadal axis (excluding secretion of FSH) disappeared within 4 days of repeated prolonged walking and no dramatic lasting changes occurred despite this major 4-day effort. However, when using the sensitive IFMA, which can detect low concentrations of gonadotropins, secretion of FSH was seen to remain reduced and no stability was seen.
Asunto(s)
Hormona Folículo Estimulante/sangre , Hidrocortisona/sangre , Hormona Luteinizante/sangre , Testosterona/sangre , Caminata/fisiología , Adulto , Proteínas Sanguíneas/análisis , Peso Corporal , Fluoroinmunoensayo , Humanos , Masculino , Factores de TiempoRESUMEN
The anatomy of the human cervical region has a special complexity. Ultrasonography is a scanning technique, which has been successfully used to identify and measure the cervical muscle dimensions. The purpose of this study was to detect with the use of real-time ultrasonography the dimensional changes of the human semispinalis capitis muscle (SECM) during isometric cervical extension. Six junior ice hockey players took part in the study. We simultaneously measured the values of estimates, such as breadth or anteroposterior dimension (APD) and width or lateral dimension (LD), of the SECM cross-sectional area during isometric cervical extension at different maximum voluntary contraction (MVC) percent levels (0%, 20%, 40%, 60%, 80%, and 100%). The result of multiplication of the linear dimensions (APD x LD), considered as the size of the SECM, increased (p < 0.05) with increasing the level of the cervical extension force. The correlation between muscle size and extension force of 100% MVC was r = 0.79 (p = 0.05). The ultrasonography method may be useful in evaluating the function of an individual cervical muscle.
Asunto(s)
Antropometría , Contracción Isométrica/fisiología , Músculos del Cuello , Rango del Movimiento Articular , Adolescente , Adulto , Análisis de Varianza , Antropometría/instrumentación , Antropometría/métodos , Estatura , Índice de Masa Corporal , Peso Corporal , Humanos , Modelos Lineales , Masculino , Músculos del Cuello/anatomía & histología , Músculos del Cuello/diagnóstico por imagen , Músculos del Cuello/fisiología , UltrasonografíaRESUMEN
OBJECTIVES: The association between the risk of breast cancer and the physical load of work was studied because physical activity may reduce breast cancer risk via hormonal mechanisms. METHODS: Occupational physical activity was estimated from a self-determined rating [scale 1 (low)-5 (high)] of occupational physical load for 1800 randomly selected women born in 1930-1969. The medians of the ratings were used as occupation-specific indices of occupational physical activity. All 65 occupations with at least 5 ratings, covering 75% of the economically active female population in Finland, were included in further analyses. The occupation-specific numbers of observed and expected cases of breast cancer during 1971-1995 among women born in 1906-1945 (17,986 cases) were grouped according to the index for occupational physical activity. Expected rates were calculated with the social-class-specific population and the entire Finnish female population as reference populations. The relative risks (RR) of breast cancer for categories 3-5, in comparison with categories 1-2 were calculated using Poisson regression models. The occupation-specific mean number of children and mean age at first childbirth were adjusted for. RESULTS: The RR was lower for occupations in category 5 than for those in categories 1-4, especially in the youngest (25-39 years) age group (RR 0.51, 95% confidence interval 0.44-0.58). Adjustment for social class and reproductive factors raised the RR (95% confidence interval 0.56-0.74) for category 5 in different age strata, all the RR values still being statistically significant. CONCLUSIONS: The results support the hypothesis that occupational physical activity, if high enough, markedly reduces breast cancer risk.