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Sur-alimentation de prise de masse : c’est pas bon pour le pancréas
Effects of a hypercaloric diet on β-cell responsivity in lean healthy men
Myrte Brands Clinical Endocrinology
Objective
Insulin resistance and hyperinsulinemia precede the onset of obesity-induced DM2. The early adaptation of the β-cell during the initial phase of overfeeding and weight gain has only been partly elucidated. We studied the early changes in insulin clearance and β-cell responsivity during a positive and negative energy balance in lean healthy subjects.
Design
We studied in 9 healthy lean men (age 37 [27-43] years and BMI 23.6 [20.6-25.6] kg/m2), insulin sensitivity, insulin clearance, insulin secretion and static and dynamic β-cell responsivity at baseline and after the hypercaloric and subsequent hypocaloric diet.
Results
Participants gained 7 [5.1-7.6]% of their initial body weight on the hypercaloric diet. Compared to baseline, insulin sensitivity and insulin clearance decreased, while glucose-stimulated insulin secretion was higher. The GLP-1 response to oral glucose did not change. The dynamic β-cell responsivity index increased but the basal and static responsivity indices did not change. Total and static disposition indexes in the hypercaloric state showed a trend towards a decrease.
During the hypocaloric diet, insulin sensitivity, glucose-stimulated insulin secretion and insulin clearance returned to baseline. The responsivity and the disposition indexes were not different in the hypocaloric phase compared to baseline.
Conclusion
A positive energy balance resulting in weight gain in lean men induces hyperinsulinemia, which is explained by a combined effect on insulin clearance and insulin secretion. Increased insulin secretion was related to insulin resistance-induced higher glucose concentrations but also to increased dynamic β cell responsivity. Glucose sensitivity of the β-cell did not change. These early adaptations are completely reversible during a negative energy balance after loss of the gained weight.
Les effets de la caféine sur le force sont très variables
Pour tous les crétins qui pensent que je ne réponds pas aux questions, cette étude illustre bien le fait qu’un ou un non est une mauvaise réponse
After caffeine ingestion, 11 subjects performed more repetitions, 14 performed fewer repetitions, and 4 performed the same number of repetitions.
No Effects of Caffeine on Muscle Hypertrophy-Style Resistance Exercise
Marius Steiro Fimland and Atle Hole Saeterbakken
Journal of Caffeine Research. June 2011, 1(2): 117-121.
Objective: The purpose of this study was to investigate effects of prior caffeine ingestion on repetitions performed during muscle hypertrophy-style bench press in men and women.
Methods: In a counterbalanced, placebo-controlled, cross-over design, 29 resistance trained men (n=19) and women (n=10) ingested either caffeine (6 mg/kg) or identical placebo pills 1 hour before two experimental sessions. A separate familiarization and one repetition maximum (1-RM) testing session was performed. The experimental sessions consisted of warm-up and six sets of bench press with 70% of 1-RM. Each set was performed until volitional failure and separated by 2-minute rest periods. Repetitions were performed at a constant pace (2 seconds eccentric and 2 seconds concentric).
Results: No effects of caffeine were observed. The total number of repetitions during 6 consecutive sets for men in the caffeine trial was 44±6, and in the placebo trial 44±7. Women performed 51±15 repetitions in the caffeine trial, and 52±19 repetitions in the placebo trial. Men and women combined performed on average 46±10 repetitions in the caffeine trial, and 47±13 repetitions in the placebo trial. After caffeine ingestion, 11 subjects performed more repetitions, 14 performed fewer repetitions, and 4 performed the same number of repetitions.
Conclusions: This study suggests that resistance trained men and women do not benefit from caffeine supplementation before muscle hypertrophy-style bench press.
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