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La thyroïde contrôle le niveau d’irisine

17/09/2014 | Etudes sur les hormones et Etudes Perte de poids et Etudes Anti-âge


Serum irisin levels and thyroid function—Newly discovered association
Marek Ruchala         Peptides Volume 60, October 2014, Pages 51–55


•We evaluate irisin level in patients with hypothyroidism and hyperthyroidism.
•The irisin level was lower in hypothyroid than hyperthyroid patients.
•The irisin level is positively correlated with free thyroxine level.
•The irisin concentration is negatively correlated with creatine kinase level.
•We report that irisin concentration vary according to the thyrometabolic state.

Irisin is a newly discovered adipo-myokin, which is reported to have a significant influence on the body metabolism and thermogenesis. Other influencing factors on metabolic state are thyroid hormones, which increase heat production and control the energy balance. Due to numerous similarities in action it seems imperative to explore these substances’ potential mutual influence on the body. The aim of the study is to provide the first ever, according to our knowledge, evaluation of serum irisin concentrations in patients with thyroid dysfunction and its correlation with creatine kinase (CK) levels – a serum marker of muscle damage. The studied group consisted of 20 patients with newly diagnosed thyroid disorder – hyperthyroidism or hypothyroidism. Venous blood samples were analyzed for irisin, thyrotropin (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and CK serum concentrations. Patients’ body mass index (BMI), body weight and muscle mass were evaluated using bioelectrical impedance analysis (BIA). Median serum irisin levels were lower in hypothyroid (117.30 ng/ml) than hyperthyroid (161.95 ng/ml) patients with a borderline statistical significance (p = 0.0726). The negative correlation between irisin and TSH levels was demonstrated (r = −0.4924, p = 0.0230), as well as the positive correlation between irisin and FT4 levels (r = 0.4833, p = 0.0360). The CK level was negatively correlated with irisin, FT4 and FT3 concentrations (r = −0.7272, p = 0.0140; r = −0.9636, p =

<0.0001; r = −0.8838, p = 0.0007, respectively). The study demonstrates that

irisin concentrations may vary according to the thyrometabolic state, which potentially could be related to the degree of muscle damage.

Effets bénéfiques de la graisse infra-articulaire

16/09/2014 | Echauffement et blessures et Etudes Perte de poids et Etudes Anti-âge


Infrapatellar fat pad in the knee: is local fat good or bad for knee osteoarthritis?
Weiyu Han   Arthritis Research & Therapy 2014, 16:R145


Recent studies regarding the infrapatellar fat pad (IPFP) mainly focus on the roles of the cells derived from the IPFP. There have been few clinical or epidemiological studies reporting on the association between the IPFP and knee osteoarthritis (OA). Our objective is to generate hypotheses regarding the associations between IPFP maximum area and knee OA measures in older adults.


A total of 977 subjects between 50 and 80 years of age (mean, 62.4 years) participated in the study. Radiographic knee osteophyte and joint space narrowing (JSN) were assessed using the Osteoarthritis Research Society International atlas. T1- or T2-weighted fat suppressed magnetic resonance imaging (MRI) was utilized to assess IPFP maximum area, cartilage volume, cartilage defects, and bone marrow lesions (BMLs). Knee pain was assessed by self-administered Western Ontario McMaster Osteoarthritis Index (WOMAC) questionnaire.


After adjustment for potential confounders, IPFP maximum area was significantly associated with joint space narrowing (odds ratio (OR): 0.75, 95% confidence interval (CI): 0.62 to 0.91 (medial), 0.77, 95% CI: 0.62 to 0.96 (lateral)) and medial osteophytes (OR: 0.52, 95% CI: 0.35 to 0.76), knee tibial and patellar cartilage volume (β: 56.9 to 164.9 mm3/cm2, all P

<0.001), tibial cartilage defects (OR: 0.58, 95% CI: 0.41 to 0.81 (medial), 0.53, 95% CI: 0.40-0.71 (lateral)), any BMLs (OR: 0.77, 95% CI: 0.63 to 0.94), and knee pain on a flat surface (OR: 0.79, 95% CI: 0.63 to 0.98). IPFP maximum area was negatively, but not significantly, associated with femoral cartilage defects, lateral tibiofemoral BMLs, and total knee pain or other knee pain subscales.


IPFP maximum area is beneficially associated with radiographic OA, MRI structural pathology and knee pain on a flat surface suggesting a

protective role for IPFP possibly through shock absorption. Consequently, we must pay special attention to IPFP in the clinical settings, avoiding resection of normal IPFP in knee surgery.

Différence de dépenses caloriques entre groupes ethniques

15/09/2014 | Etudes Perte de poids


African American women exhibit similar adherence to intervention but lose less weight due to lower energy requirements
International Journal of Obesity (2014) 38, 1147–1152   J P DeLany

The observation that Black women lose less weight than White women during a weight loss program has been reported repeatedly. This paper describes a reduction in energy expenditure (EE) in Black women compared to White, despite apparently similar adherence to the elements of their weight loss program. The difference in energy expenditure was explained by a lower total daily EE and resting metabolic rate (RMR) adjusted for FFM in the Black women, although the decrease in RMR in response to weight loss was greater in Caucasian women. The conclusion that Black women may need more restrictive regimens for similar weight loss is very important for clinicians and makes the case stronger for highly individualized therapy in weight reduction programs. Further research is needed to confirm these findings, investigate whether similar differences are observed in other Ethnic groups, and identify the mechanisms of the lower EE.


African American (AA) women have been shown to lose less weight than Caucasian women in response to behavioral interventions. Our objective was to examine adherence to intervention and metabolic factors that may explain this difference.

Design and subjects:

We examined longitudinal changes in body weight and energy expenditure (EE), and objective assessment of physical activity (PA) and energy intake (EI) during 6 months of a weight-loss intervention program, including prescribed calorie restriction and increased PA in 66 Caucasian and 39 AA severely obese women. Comparisons were also made in 25 Caucasian and 25 AA women matched for initial body weight.


The AA women lost 3.6 kg less weight than Caucasian women. Total daily EE (TDEE) and resting metabolic rate (RMR) adjusted for fat free mass (FFM) were significantly lower in the AA women, whereas the decrease in RMR in response to weight loss was greater in Caucasian women. Adherence to the prescribed PA and change in PA in response to intervention were similar in AA and Caucasian women. Prescribed EI (1794±153 and 1806±153 kcal per day) and measured EI during intervention (2591±371 vs 2630±442 kcal per day) were nearly identical in matched AA and Caucasian women. However, the AA women lost significantly less body weight due to lower energy requirements (2924±279 vs 3116±340 kcal per day; P

<0.04), resulting in a lower energy deficit (333±210 vs 485±264 kcal per day).


Adherence to the behavioral intervention was similar in AA and Caucasian women. However, neglecting to account for the lower energy requirements in AA women when calculating the energy prescription resulted in a lower level of calorie restriction and, hence, less body weight loss. Therefore,

to achieve similar weight loss in AA women, the prescribed caloric restriction cannot be based on weight alone, but must be lower than in Caucasians, to account for lower energy requirements.

70% d’un poisson sont des déchets: pourquoi ne pas en faire des prot pour culturo?

15/09/2014 | Etudes Compléments alimentaires


Challenges and realistic opportunities in the use of by-products from processing of fish and shellfish
Pages 144-151   Ragnar L. Olsen, Jogeir Toppe, Iddya Karunasagar         70% d’un poisson sont des déchets: pourquoi ne pas en faire des prot pour culturo?

By-products may constitute as much as 70% of fish and shellfish after industrial processing and much focus has been on converting these into commercial products. The aim of this paper is therefore to evaluate important challenges and to consider the most realistic options in the use of by-products. Certain by-products like heads, frames and off-cuts from filleting of fish may be used directly as food while by-products in general can be transformed into feed ingredients e.g. for the expanding aquaculture industry. Although sometimes suggested, it is unlikely that by-products can be used to any large extent to produce high-priced products.

Acide et densité osseuse

13/09/2014 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge


The acid–ash hypothesis revisited: a reassessment of the impact of dietary acidity on bone
Journal of Bone and Mineral Metabolism September 2014, Volume 32, Issue 5, pp 469-475   Rachel Nicoll

The acid–ash hypothesis states that when there are excess blood protons, bone is eroded to provide alkali to buffer the net acidity and maintain physiologic pH. There is concern that with the typical Western diet, we are permanently in a state of net endogenous acid production, which is gradually reducing bone. While it is clear that a high acid-producing diet generates increased urinary acid and calcium excretion, the effect of diet does not always have the expected results on BMD, fracture risk and markers of bone formation and resorption, suggesting that other factors are influencing the effect of acid/alkali loading on bone. High dietary protein, sodium and phosphorus intake, all of which are necessary for bone formation, were thought to be net acid forming and contribute to low BMD and fracture risk, but appear under certain conditions to be beneficial, with the effect of protein being driven by calcium repletion. Dietary salt can increase short-term markers of bone resorption but may also trigger 1,25(OH)2D synthesis to increase calcium absorption; with low calcium intake, salt intake may be inversely correlated with BMD but with high calcium intake, salt intake was positively correlated with BMD. With respect to the effect of phosphorus, the data are conflicting. Inclusion of an analysis of calcium intake may help to reconcile the contradictory results seen in many of the studies of bone. The acid–ash hypothesis could, therefore, be amended to state that with an acid-producing diet and low calcium intake, bone is eroded to provide alkali to buffer excess protons but where calcium intake is high the acid-producing diet may be protective.

Le soldats français semble loin des réalités

12/09/2014 | Etudes Compléments alimentaires et Etudes Perte de poids


Utilisation des compléments alimentaires à visée ergogénique chez les militaires français : prévalence et modes de consommation lors d’une opération extérieure
Science & Sports Volume 29, Issue 4, September 2014, Pages 188–195   C. Dubecq



L’usage de compléments alimentaires à visée ergogénique se développe parmi les sportifs. Cette consommation n’est pas sans risque. Le but de ce travail est de connaître la prévalence de la consommation de ces produits parmi les militaires français en opération, leurs motivations, et l’influence du départ en mission sur leur consommation.

Matériels et méthodes

Nous avons procédé à une étude chez les militaires français en opération en Afghanistan entre avril et septembre 2012. Ceux-ci ont participé volontairement à un sondage par questionnaire anonyme. Les données ont été saisies puis analysées grâce aux logiciels Epi data™ v3.1 et Epi info™ v3.5.1, en utilisant le test du Chi2 (χ2), et l’analyse de la variance (Anova).


Mille trois cent quatre-vingt-onze réponses ont été obtenues. La prévalence de la consommation est de 20,6 % (IC95 % = 18,5 %–22,8 %). Parmi les utilisateurs, 75,9 % ont débuté leur consommation en mission, 71,1 % n’en consomment pas en métropole. Les principales motivations sont la recherche du gain de volume musculaire (62,5 % des cas), d’une meilleure récupération (57,7 %), de l’amélioration des performances sportives (56,5 %) et de l’image corporelle (56 %). Seuls 22,9 % rapportent une amélioration de leurs capacités opérationnelles.


La consommation d’aides ergogéniques concerne 20,6 % des militaires interrogés. Cette consommation est sensiblement liée à leurs départs en mission. Ces résultats conduisent à mettre en œuvre une véritable politique de prévention et d’information objective sur ces produits au sein des armées.

Stimulation magnétique transcrânienne: application à l’exercice

12/09/2014 | Etudes Musculation


Stimulation magnétique transcrânienne: application à la physiologie de l’exercice
Science & Sports Volume 29, Issue 4, September 2014, Pages 173–187   M. Gruet


L’objectif de cette revue est d’illustrer le potentiel de la stimulation magnétique transcrânienne (TMS) dans le domaine de la physiologie de l’exercice. Elle propose tout d’abord un descriptif des différents paramètres mesurés par TMS et considère différents aspects méthodologiques. Ensuite, par l’analyse des réponses mécaniques et électromyographiques induites par TMS, cette revue synthétise les adaptations corticospinales à l’exercice aigu fatigant et à l’exercice chronique (i.e. entraînement physique) chez le sujet sain.


Au cours d’un exercice musculaire fatigant, la TMS permet classiquement de mettre en évidence le développement d’une fatigue d’origine supraspinale (i.e. au niveau ou en amont du cortex moteur) ainsi que des modifications de l’excitabilité corticospinale et de l’inhibition intracorticale. Il existe cependant une variabilité des réponses corticospinales à la fatigue en fonction du muscle considéré (e.g. membre inférieur vs supérieur) et de la nature de la tâche (i.e. locale vs globale). Les études récentes ayant étudié les adaptations des paramètres TMS à l’exercice chronique ont principalement montré une réduction de l’inhibition corticospinale après un entraînement en force.

Perspectives et projets

Des études complémentaires combinant la TMS avec d’autres techniques d’investigations neuromusculaires sont nécessaires afin de dissocier plus précisément les manifestations corticales et spinales de la fatigue musculaire. Il serait également intéressant de déterminer si la composante supraspinale de la fatigue qui se développe au cours d’un exercice prolongé peut être réduite par un entraînement physique. (c’est en français, mais je suis sûr que personne ne l’a lu, contredisez moi dans les messages FB)

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