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In recent years, whole body vibration (WBV) has become an efficient complement or alternative to resistance training. Very limited data on the effects of different WBV protocols on anabolic hormones are available. In this study, we compared the growth hormone (GH), blood lactate (LA), and cortisol responses to different protocols involving WBV. Six healthy women recreationally active performed 10 sets of 12 dynamic squats in the following conditions: squatting alone (S), squatting+vibration (SV), squatting+external load (SE), and squatting+external load+vibration (SEV). All responses at the different stimuli determined acute increases in GH, cortisol, and LA. In particular, GH secretion significantly increased in all 4 conditions immediately after the exercise session compared to other time points. Furthermore, a significantly larger increase was identified following SEV as compared to the other conditions. Cortisol concentrations significantly decreased after S, SV and SE whereas they increased significantly following SEV. LA peaks occurred immediately at the end of each condition. However it reached statistical significance only following SEV. The results of our study demonstrate that the combination of squatting+external load+vibration (SEV) could represent the most suitable modality to potentiate the somatotropic function and, indirectly, to obtain an increase in muscle strength and positive changes in the body composition. Further studies are necessary in order to determine the chronic effects of this exercise modality on the hormonal profile.

ObjectiveEating slowly increases the postprandial responses of some anorexigenic gut hormones in healthy lean subjects. As the rate of food intake is positively associated with obesity, the aim of the study was to determine whether eating the same meal at different rates evokes different postprandial anorexigenic responses in obese adolescent and adult subjects.Design and methodsEighteen obese adolescents and adults were enrolled. A test meal was consumed on two different sessions by each subject, meal duration taking either 5 min (fast feeding) or 30 min (slow feeding). Circulating levels of glucagon-like peptide 1 (GLP1), peptide YY (PYY), glucose, insulin, and triglycerides were measured over 210 min. Visual analog scales were used to evaluate the subjective feelings of hunger and satiety.ResultsFast feeding did not stimulate GLP1 release in obese adolescent and adults, whereas slow feeding increased circulating levels of GLP1 only in obese adolescents. Plasma PYY concentrations increased both in obese adolescents and in adults, irrespective of the eating rate, but slow feeding was more effective in stimulating PYY release in obese adolescents than in adults. Simultaneously, slow feeding evoked a higher satiety only in obese adolescents compared with fast feeding but not in obese adults. In obese adolescents, slow feeding decreased hunger (only at 210 min). Irrespective of the eating rate, postprandial responses of insulin and triglycerides were higher in obese adults than in obese adolescents. Conclusion: Slow feeding leads to higher concentrations of anorexigenic gut peptides and favors satiety in obese adolescents, but this physiological control of food intake is lost in obese adults.

Background: Whole body vibration (WBV) has been reported to exert growth hormone(GH)-releasing effects in healthy subjects. Despite the potential of WBV to positively affect body composition changes via lipolytic effects, few studies have been performed in obese subjects to date. Methods: This study evaluated the acute effects of WBV alone or in combination with squatting plus external load (WBV+S) on serum GH levels and blood lactate concentrations in 7 severely obese women (age 22 ± 5 years; BMI 39.9 ± 2.9 kg/m2). Results: WBV and WBV+S determined a significant GH increase (mean GH peaks 5.1 ± 1.9 ng/ml, p < 0.001 vs. basal, and 6.5 ± 3.7 ng/ml, p < 0.001 vs. basal, respectively), GH peaks occurring immediately after both exercise sessions. No significant differences were observed between GH peaks and GH net incremental area under the curve (nAUC) after both conditions (p = 0.39 and p = 0.53, respectively), the whole pattern of GH responsiveness being comparable among all the subjects. Lactate concentrations increased after both conditions (mean lactate peaks 2.0 ± 0.5 mmol/l, p < 0.05 vs. basal, and 4.5 ± 2.0 mmol/l, p < 0.001 vs. basal, respectively). The lactate response was significantly higher after WBV+S than after WBV (p < 0.05). Baseline GH and GH peak values positively correlated to baseline lactate and lactate peak concentrations in both conditions (R2 = 0.64, p < 0.001, and R2 = 0.52, p < 0.05, respectively). Conclusions: WBV alone stimulates GH release and lactate production in severely obese female subjects, with no additive effect when combined with squatting plus external load. Further additional studies are required to verify the chronic effects of WBV exercise on the GH/IGF-1 system, which could represent a potentially effective approach for weight management in obese subjects.

To date, the large majority of studies evaluating growth hormone (GH) response to acute physical exercise has been performed involving gross muscle groups. To the best of our knowledge, none has evaluated the effects of a respiratory muscle endurance training (RMET) on hormonal secretions, particularly on GH release, though some respiratory devices have been widely used in athletes to train respiratory muscles and to improve cardiopulmonary function and physical performance. 8 healthy men underwent an incremental progressive RMET protocol of 11 daily sessions, obtained through the use of a specifically designed respiratory device (Spiro Tiger®). The 12th session of RMET (15 min duration: 1 min at a respiration rate of 28 acts/min, 5 min at 32 acts/min, 5 min at 34 acts/min, 4 min at 36 acts/min) was associated with blood samplings for determination of GH, cortisol, ghrelin, glucose, and lactate (LA) levels. GH and cortisol responses significantly increased after a 15-minute RMET session, which, in contrast, inhibited ghrelin secretion. There was a minimal, though significant, increase in LA levels with a significant elevation in glycemia. A 15-minute RMET session, administered after a 11-days incremental progressive RMET protocol, was capable of stimulating GH and cortisol release and suppressing ghrelin secretion. Optimization of incremental progressive RMET protocols would be important to maximize the positive chronic effects of this intervention on somatotropic function and muscle performance.

Obese patients have decreased fasting and postprandial levels of peptide YY (PYY), an anorexigenic peptide produced by the L cells of the gastrointestinal mucosa. Fatty nutrients are the most powerful stimulus for PYY release. Cholestyramine, an anion exchanger which adsorbs bile salts, reduces digestion of lipids. The aim of the present study was to investigate the effects of cholestyramine or placebo on PYY secretion in obese women administered a high-fat meal [n=8; age: 30.9±2.7 years; BMI: 47.3 ± 3.3 kg/m 2 ]. Postprandial PYY levels in obese women given placebo significantly increased in plasma at 30, 60, 90, and 120 min after meal ingestion. Cholestyramine administration significantly reduced postprandial PYY response at 15, 30, and 60 min. Percent fat mass (FM%) was negatively correlated with the percent increment of plasma PYY concentrations induced by meal administration at 30 min; conversely, there was a positive correlation between FM% and the percent decrement of plasma PYY concentrations induced by cholestyramine at the same time interval. These correlations failed to reach statistical significance when related to BMI. This study implies that in the obese state the altered PYY response to food consumption is a consequence of a dysfunction of L cells, which become less sensitive to the positive feedback effect of lipids.