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Several studies have demonstrated that the obesity-related hyposomatropism is usually reversible after a consistent weight loss induced by diet and/or bariatric surgery. Recently, a single bout of respiratory muscle endurance training (RMET) by means of a specific commercially available device (Spiro Tiger ® ) has been reported to induce a marked GH response in obese adults, its GH-releasing effect being significantly lower in obese adolescents. The GH response disappeared in both obese adults and adolescents when RMET was repeated at 2-h intervals inbetween. The aim of the present study was to evaluate GH responses to repeated bouts of RMET administered before and after a 3-week in-hospital multidisciplinary body weight reduction program (entailing energy-restricted diet, 90 min/daily aerobic physical activity, psychological counseling, and nutritional education) combined with a progressively increasing RMET (15 daily sessions, 5 sessions per week) in 7 obese male adolescents [age: 12-17 years; body mass index (BMI): 38.5 ± 3.1 kg/m 2 ; percent fat mass (FM): 37.0 ± 2.0 %]. Blood samplings for GH determinations were collected during the 1 st and 15 th sessions, which were composed of 2 consecutive bouts of RMET (of identical intensity and duration) at 2-h interval in-between. At the beginning of the study, baseline GH levels significantly increased after the first bout of RMET in all subjects (p < 0.05). The administration of the second bout of RMET resulted in a significantly lower (p < 0.05) GH increase in comparison with the first one. Three weeks of the integrated intervention significantly reduced both body weight (from 115.3 ± 9.2 kg to 111.5 ± 8.7 kg, p < 0.05) and FM (from 43.1 ± 5.7 kg to 41.9 ± 5.3 kg, p < 0.05), these combined effects being, however, not sufficient to influence GH responsiveness to the 2 repeated bouts of RMET (GH peaks to the first bout: 4.8 ± 1.6 ng/ml vs. 4.8 ± 1.6 ng/ml; GH peaks to the second bout: 0.9 ± 0.2 ng/ml vs. 1.1 ± 0.1 ng/ ml, before and after 3 weeks of the treatment, respectively, p = NS). In conclusion, a 3-week incremental RMET combined with a body weight reduction intervention does not seem useful to positively influence the reduced GH responsiveness to 2 repeated RMET bouts in obese adolescents. More intensive and/or long-term RMET protocols, associated with energy-restricted diets, determining more consistent changes in body composition, are likely needed to restore the impaired GH-IGF-1 function of obese adolescents. [ABSTRACT FROM AUTHOR]

Repeated bouts of GH-releasing stimuli (both pharmacological and physiological, such as aerobic exercise) at 2-h intervals are associated with a blunting of somatotropic responsiveness in normal adults, while a persistent GH responsiveness to consecutive stimuli is reported to occur in children and adolescents. Recently, a single bout of respiratory muscle endurance training (RMET) by means of a specifi c commercially available device (Spiro Tiger ® ) has been shown to induce relevant GH responses in both normal-weighted and obese adult subjects. The aim of the present study was to evaluate GH responses to repeated bouts of RMET in obese adolescents and adults. Seven obese male adolescents (age: 15.7 ± 0.4 years; body mass index, BMI: 38.0 ± 3.3 kg/m ² ) and 10 obese adults (age: 22.2 ± 1.4 years; BMI: 39.9 ± 1.0 kg/m 2 ) underwent an incremental progressive RMET protocol of 11 daily sessions. Blood samplings for GH determinations were collected during the 12 th session, which was composed of 2 consecutive bouts of RMET (of identical intensity and 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) at a 2-h interval in-between. Baseline GH levels significantly increased after the first bout of RMET in all subjects, higher GH peaks being found in obese adults than in obese adolescents (peaks: 14.3 ± 2.1 ng/ml vs. 4.8 ± 1.6 ng/ml, respectively, p < 0.05). The administration of the second bout of RMET resulted in signifi cantly lower (p < 0.05) GH increases in both obese adolescents and obese adults (peaks: 0.9 ± 0.2 ng/ml and 1.6 ± 0.2 ng/ml, respectively) in comparison with the first one. In conclusion, exercise protocols based on repeated bouts of RMET do not seem a valid strategy to persistently stimulate GH-IGF-1 release in obese adolescents, since GH responses to a single bout are actually modest in comparison with those of obese adults and completely abolished after repeated bouts at 2 h interval in-between. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

It is well established that obese patients are hypo-responsive to classical GH-releasing stimuli, including aerobic exercise. Recently, we have demonstrated that whole body vibration was able to markedly stimulate GH secretion in obese patients, thus suggesting that this refractoriness is not absolute but dependent on the GH-releasing stimulus. Furthermore, we have shown the ability of a respiratory muscle endurance training (RMET) to stimulate GH and cortisol secretion in healthy subjects. The objective of this study was to evaluate the effects of RMET on GH and cortisol responses in severely obese patients. Eight severely obese patients (4 M/4 F, mean age ± SEM: 22.8 ± 1.6 years, body mass index, BMI: 39.9 ± 1.1 kg/m 2 ) 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, and lactate (LA) levels. An age- and sex-matched normal-weighted control group (n = 7, 4 M/3 F, age: 26.1 ± 3.1 years, BMI: 22.4 ± 0.6 kg/m 2 ) was also recruited. In both normal-weighted subjects and obese patients, GH secretion significantly increased after a 15-min RMET session. Although serum GH levels at 30 min were higher in normal-weighted subjects than in obese patients, there was no statistically significant difference in either GH peaks or net GH areas under the curve between the 2 groups. RMET significantly increased serum cortisol levels in normal-weighted subjects, but was associated to a progressive cortisol decline in obese patients. RMET stimulated LA production, with no significant differences in normalweighted subjects and in obese patients. A 15-min RMET session was capable to induce a GH response in severely obese patients, which was comparable to that recorded in normalweighted subjects. A progressive decline in serum cortisollevels occurred in obese patients after RMET, while an opposite pattern (i. e., a significant cortisol increase) was found in normalweighted subjects. Optimization of long-term RMET protocols could represent a valid strategy to (physiologically) stimulate GH/IGF-I system in those GH hyposecretory states such as obesity. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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/m2]. 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. [ABSTRACT FROM AUTHOR]