Mechanisms underlying the neuroendocrine response to physical exercise.

Exercise initiates a coordinated series of physiological responses, including hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system activation, that, in combination, lead to the appropriate selection and utilization of metabolic substrates. Physical activity acts as a powerful stimulus for the hypothalamic-pituitary axis, leading to the liberation of several neuroendocrine hormones. The nature of this stimulation varies according to the kind of exercise (intensity, duration, aerobic, strength) and subject characteristics (gender, previous training), as well as depending on the time of the day and meal ingestion. As a whole, the neuroendocrine responses to exercise represent an accurate regulator of fuels (glucose, free fatty acids) homeostasis in a special situation characterized by a drastic increase of the energy requirements at muscle level. In this article the current knowledge about this topic is reviewed.

Effect of long-term strength training on glucose metabolism. Implications for individual impact of high lean mass and high fat mass on relationship between BMI and insulin sensitivity.

The aim of this study was to examine the independent effect of high lean mass on glucose metabolism, as well as its consequences on the classic relationship between BMI and insulin sensitivity (SI) in 3 groups: 1) 8 strength-trained males with BMI >27 kg/m2 (athletes); 2) 10 sedentary males with BMI >27 kg/m2 (obese); and 3) 12 sedentary males with BMI 22-25 kg/m2 (control). Body composition was measured with impedance analysis. Iv glucose tolerance test was performed at 09:00 h after overnight fast. Estimation of insulin sensitivity and glucose effectiveness by Minimal Model Approach. Plasma glucose and insulin determination by glucose-oxidase and RIA respectively. BMI and lean mass (LM) were greater in athletes than in controls, but there were no differences in fat mass (FM), basal glucose (Gb), basal insulin (Ib), glucose tolerance (Kg), SI, glucose effectiveness (Sg), acute insulin response to glucose (AIRG) and leptin. Obese showed greater FM, leptin, lb and AIRG than athletes, while SI was lower; BMI, LM, Gb, Kg and Sg were similar. BMI, FM, LM, Ib, AIRG and leptin were lower in controls than in obese, while SI index was greater; Gb, Sg and Kg were similar. We found that: 1) Resistance exercise does not modify glucose effectiveness, but can improve insulin sensitivity through FM reduction (LM augmentation alone has no effect on glucose metabolism); and 2) High BMI causes insulin resistance only if it depends on adipose tissue hypertrophy.

Effect of resistance exercise (body building) training on serum leptin levels in young men. Implications for relationship between body mass index and serum leptin.

UNLABELLED: Available data about the influence of exercise on leptin level are controversial, and there are no studies concerning leptin levels in trained men with low fat mass plus large increase of muscle. 65 healthy young male matched for age were separated in three groups. 1) 25 non-professional body builders; 2) 21 mild overweight sedentary subjects; 3) 19 normal weight sedentary controls. Body composition was determined by bioelectrical impedance. Serum leptin was measured in duplicate by RIA. STATISTICS: Student's t and Pearson's test. Athletes showed similar BMI than overweight subjects: 26.98+/-0.49 vs 27.12+/-0.41 but lower fat mass: 12.53+/-0.96 vs 16.16+/-1.01 % (p=0.0064) and lower leptin: 4.66+/-0.51 vs 7.31+/-0.76 microg/l (p=0.014). Athletes showed higher BMI than controls: 26.98+/-0.49 vs 23.08+/-0.30 (p<0.0001) but similar fat mass: 12.53+/-0.96 vs 12.48+/-0.73% and leptin: 4.66+/-0.51 vs 4.79+0.58 microg/l. Overweight subjects showed higher BMI than controls: 27.12+/-0.41 vs 23.08+/-0.30 (p<0.0001), higher fat mass: 16.16+/-1.01 vs 12.48+/-0.73% (p=0.0064) and higher leptin: 7.31+/-0.76 vs 4.79+/-0.589 microg/l (p=0.014). When leptin was calculated by fat mass no differences were observed between the three groups. There was a significant correlation between leptin and fat mass in all groups. Leptin correlated with BMI in overweight subjects (r=0.438, p=0.0463), but this correlation was not observed either in athletes or in controls. In conclusion 1) regardless of the high BMI characteristic of body builders, no correlation was observed with leptin; 2) trained state induced by resistance exercise does not influence leptin production independently of variations in body composition.

[Differentiated carcinoma of the thyroid gland in an area of endemic goiter. Clinical study and prognostic correlation]. / Carcinoma diferenciado de tiroides en un área de bocio endémico. Estudio clínico y correlación pronóstica.

OBJECTIVE: Differentiated thyroid Carcinoma is a relatively frequent malignant neoplasia with three histologic types: papillary, follicular, and Hürtle cell carcinoma. Although papillary is the most common type, in endemic goitre areas the frequency of follicular type increases. Up to now, the only European studies about clinical aspects of differentiated thyroid carcinoma in endemic goitre areas are those performed in the Bavarian region until 1983. As the province of Orense (assistance zone concerning to the Hospital Virgen del Cristal) is a zone of endemic goitre, we have analyzed clinical presentation features and prognostic correlation factors in patients with differentiated thyroid carcinoma living in this area. DESIGN: Retrospective study. Variables analyzed: 1) Age. 2) Sex. 3) Histologic type. 4) Tumor size. 5) Stage. 6) Presence of multinodular goitre. 7) Posttherapeutic disease persistence. 8) Recurrence. 9) Distant metastases. 10) Death attributed to thyroid carcinoma. PATIENTS: 61 cases of differentiated thyroid carcinoma, detected from 1983 to 1993. Mean follow-up period: 5 years (minimum 1, maximum 21). All patients were treated with total thyroidectomy followed by radioiodine ablation. RESULTS: 67.2% of papillary, 31.2% of follicular and 1.6% of Hürtle cell carcinoma. Male/female ratio: 1/4. Mean age: 48.8 +/- 2.9 (M +/- ESM) in papillary and 55 +/- 3.2 in follicular. Tumor size was smaller in papillary: 2.2 +/- 0.2 vs 6.2 +/- 0.5 cm (p < 0.001). Papillary type was detected more frequently than follicular in stages I, II and III, whereas follicular prevailed in stage IV (p < 0.03). Positive correlation between age and size in papillary: r = 0.393 (p < 0.01) and similar tendency in follicular: r = 0.423 (p = 0.057). Multinodular goitre was more frequent in follicular: 47% vs 25% (p = 0.02). Free of disease cases after treatment: 81% of papillary (p < 0.05) and 42% of follicular. Stage correlated independently with disease persistence after treatment (p = 0.0006). Age was minor in free of disease group: 50.0 +/- 3.8 vs 65.3 +/- 3.8 (p = 0.01). CONCLUSIONS: In our area, papillary is the most common type, but follicular proportion is higher than reported from non endemic goitre areas. PC is a small tumor detected in stage I, whereas FC is large and detected in stage IV. Tumor stage is an independent prognostic factor. Frequent presence of multinodular goitre in patients with differentiated thyroid carcinoma suggests that in zones of endemic goitre, clinical attitude in multinodular goitre and solitary nodule must be similar.