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Toutes les techniques d’entraînement se valent t-elles chez le débutant?

18/10/2018 | Etudes Musculation

 

Load and time under tension do not determine motor unit
activation during resistance exercise performed to volitional
failure in young, healthy men

R.W. Morton   Appl. Physiol. Nutr. Metab. Vol. 43, 2018       S83

We aimed to determine if performing resistance exercise (RE) to volitional
failure with heavier or lighter loads and shorter or longer times
under tension would result in similar motor unit activation.

Ten recreationally
active young men performed three sets of unilateral knee
extension exercise that varied in speed of contraction and load:
80%RM Regular (80R; 1 eccentric: 1 pause: 1 concentric), 80%RM Slow
(80S; 3:1:3), 30%RM Regular (30R; 1:1:1) and 30%RM Slow (30S; 3:1:3).
Peak EMG amplitude increased in every condition but was higher in
the heavy-load conditions during the first and last repetitions of each
set. The integrated EMG signal was higher in the light-load conditions.
Maximum voluntary force decreased between each set in every condition
with no difference between conditions. At rest, type II muscle
fibres had more glycogen than type I fibres with no difference between
type IIA and type IIX fibres. There were no differences in glycogen
depletion between conditions; however, glycogen depletion was
greater in type II than type I fibres and type IIA fibres depleted more
than type IIX fibres.

We conclude that performing RE to volitional
failure results in significant fatigue and motor unit activation that is
similar regardless of load or speed of contraction.

Efficacité des repos extrêmes entre les séries?

18/10/2018 | Etudes cardio et Echauffement et blessures et Etudes Musculation

 

Sprint exercise snacks: A novel approach to increase aerobic
fitness

G. Jackson         Appl. Physiol. Nutr. Metab. Vol. 43, 2018

Sprint interval training (SIT) is a time-efficient way to improve aerobic
fitness. The purpose of this study was to determine if performing
isolated sprints throughout the day with longer (>1 hour) rest periods
(i.e., “sprint snacks”) could comparably improve aerobic capacity. In a
randomized pilot trial, healthy, young, inactive participants performed
six weeks of training (3 d/wk) as either sprint snacks (SS; 3x20
sec with 1-4-hour rest, n=12) or SIT (3x20 sec with 3-minute rest within
a 10-minute session, n=16).

The primary outcome was peak oxygen
uptake (V˙ O2peak) assessed before and after training. Absolute
V˙ O2peak increased by 4% after SS and 6% after SIT (main effect of
time P = 0.004) with no difference between groups (group X time
interaction, P = 0.559). In SIT, exercise enjoyment increased from the
first training session (3.8 ± 1.4) to final training session (5.2 ± 1.2)
whereas enjoyment of SS did not change (4.8 ± 1.9 to 4.5 ± 1.4) (group X
time interaction, P = 0.01). Performing three all-out intensity “sprint
snacks” spread throughout the day can lead to similar aerobic adaptations
when compared to a time-efficient SIT protocol involving the
same number and length of sprints.
Future research should examine
whether sprint snacks can be translated into an effective real-world
intervention.

Le jus de cassis comme inhibiteur MAO?

10/10/2018 | Etudes Compléments alimentaires et Etudes Perte de poids et Etudes Anti-âge et Etudes sur les boosters sexuels et la sexualité

 

The pharmacodynamic profile of “Blackadder” blackcurrant juice effects upon the monoamine axis in humans: A randomised controlled trial
Anthony W. Watson       Nutritional Neuroscience         05 Oct 2018

Emerging evidence from human intervention trials indicates health benefits of consuming blackcurrant fruit, including improvements to cognitive performance, modulation of blood flow, regulation of blood glucose and inhibition of enzymes underpinning normal cognitive function. Of particular relevance is our previous demonstration of monoamine oxidase (MAO)-A and B inhibition after the consumption of a New Zealand “Blackadder” blackcurrant juice in humans.

The current study uses a double-blind, placebo-controlled, randomised cross- over design to assess the pharmacodynamics of the effects on platelet MAO-B inhibition and associated substrates, plasma prolactin levels and blood glucose levels after consumption of a single serve of “Blackadder” blackcurrant juice standardised to 500 mg polyphenols. Eight healthy male (20-–35 years) participants completed the trial. Measurements were obtained at baseline 15, 30, 45, 60, 100, 120, 150, 180, 240 mins and 24 h post dose.

A fast, absolute and reversible inhibition of blood platelet MAO-B (P 

< 0.001) and a significant but delayed reduction in plasma prolactin (P 

< 0.001) were observed following the consumption of “Blackadder” blackcurrant juice when compared to a placebo control. No interpretable changes in substrates of MAO or associated metabolites were seen.

These data provide a clear time course of the reversible inhibition of MAO-B after the single consumption of a of New Zealand “Blackadder” blackcurrant juice standardised at

500 mg of polyphenols and, therefore, provide a therapeutic window on which to base future nutritional interventions.

Liens Cordyceps sinensis et cancer?

02/10/2018 | Etudes Compléments alimentaires et Etudes Anti-âge et Etudes sur les boosters sexuels et la sexualité

 

Cordyceps sinensis Promotes the Growth of Prostate Cancer Cells
Ming-wei Ma           Nutrition and Cancer   01 Oct 2018

Abstract
Background: This study aims to test whether Cordyceps sinensis (CS), the most expensive Asian nutrient supplement might stimulate growth of prostate cancer cells.

Methods: Impact of CS on growth of prostate cancer was determined in vivo and in vitro.

Results: Firstly, the serum testosterone level was significantly elevated in mice fed CS. Prostate glands were significantly enlarged (weight index 0.53 ± 0.04 mg/g vs. 0.31 ± 0.04 mg/g, P = 0.006). Furthermore, cell viability was increased twofold in the androgen-responsive prostate cancer cell line (VCaP) after CS treatment. This promoting effect disappeared after bicalutamide was added. In addition, serum prostate-specific antigen (PSA) in mice bearing VCaP xenografts was significantly elevated (0.66 ± 0.04 ng/ml vs. 0.26 ± 0.06 ng/ml, P 

< 0.001) after treatment with CS. Finally, VCaP tumors in mice treated with CS grew much faster (479.2 ± 78.74 mm3 vs. 283 ± 58.97 mm3, P = 0.074). However, the above promoting effects of CS were not observed in parallel studies using the PC-3 cell line which lacks AR expression.

Conclusions:

These results suggest that CS promotes growth of prostate cancer cells by increasing production of testosterone and stimulating the AR-dependent pathway. Additional studies are required to see whether CS is safely consumed by patients with prostate cancer.

Faut-il conserver sa whey au frigo?

26/09/2018 | Etudes Compléments alimentaires

 

Génération de rougeur via les réactions de Maillard d’isolat de protéine de lactosérum (WPI) et d’acide ascorbique (vitamine C) dans des poudres séchées par pulvérisation
Chao Zhong Songwen Tan Timothy LangrishJournal of Food Engineering

Points forts
• Les réactions de Maillard de WPI et d’acide ascorbique dans les poudres séchées par pulvérisation sont étudiées.
• Le changement de couleur et la génération de fluorescence sont observés après la réaction de Maillard.
• La température de stockage affecte de manière significative les réactions de Maillard.
• Les basses températures ou le faible stockage de l’oxygène peuvent réduire les effets des réactions de Maillard.

Des rougeurs évidentes ont été observées lors du stockage et du traitement des poudres d’acide WPI-ascorbique séchées par pulvérisation. La limite inférieure de détection par observation humaine est de 0,001 g / mL pour la concentration d’ acide ascorbique (rapport AA: WPI de 1: 100). La rougeur est liée à l’ adsorption de la lumière violette (380 nm) et de la lumière bleue / verte (500 nm). L’analyse par fluorescence suggère la formation de formylthéosylpyrroles et de poly (acides aminés) réticulés. L’analyse DSC montre que les pics d’acide ascorbique disparaissent sous forme de réaction de Maillard. La température de stockage s’est avérée affecter de manière significative les réactions de Maillard entre le WPI et l’acide ascorbique.

Les résultats montrent que les taux de réaction de Maillard entre WPI et acide ascorbique sont rapides dans les poudres séchées par pulvérisation, même à 20 ° C. Il est suggéré que les laits en poudre pour nourrissons / bébés formulés sur le marché nécessitent un stockage à basse température (4 ° C) ou à faible teneur en oxygène ( atmosphère N 2) afin de réduire les effets des réactions de Maillard (génération de rougeurs).

Effets du Cissus Quadrangularis sur la force et la prise de muscle?

21/09/2018 | Etudes Compléments alimentaires

 

The Effects of 6 weeks of Cissus Quadrangularis Supplementation and High Intensity Exercise Training
Eric E. Noreen,      MEDICINE & SCIENCE IN SPORTS & EXERCISE   2018 S598 Vol. 49 No. 5 Supplement

Previous studies have shown that supplementation with Cissus Quadrangularis
(CQ) can positively alter body composition in sedentary adults. However, it is
unknown if this same effect is observed in active adults.

PURPOSE: The purpose
of this study was to determine the effects of 6 wks of supplementation with CQ on
body composition and exercise performance in healthy adults enrolled in a crossfit
class.

METHODS: A total of 18 adults (9 males, 9 females, 40.2+8.3 y; mean+SD)
completed this study. All subjects had been enrolled in crossfit classes prior to the
study. Baseline body composition was assessed by whole body densitometry using air
displacement plethysmogrophy, and exercise performance was assessed using a time
to completion 1000 m rowing test and a 3 repetition max for the standing press and
back squat. Following baseline testing, subjects were randomly assigned in a doubleblind
manner into one of two groups: 3.2 g/d of CQ; or 3.2 g/d of a maltodextrin
placebo (PL). Subjects consumed half of the daily dose in the morning and half in the
evening on an empty stomach. All testing was repeated following 6 wks of treatment.
Pre to post differences were analyzed using a treatment by time repeated measures
ANOVA.

RESULTS: After 6 wks of treatment, there were no significant differences
observed between the CQ or PL group for change in body weight (CQ= -0.2+0.8 kg,
PL= -0.07+1.5 kg, p=0.77), fat mass (CQ= -1.1+0.7 kg, PL= -1.0+1.9 kg, p=0.96),
fat free mass (CQ= +0.8+0.7 kg, PL= +0.7+1.5 kg, p=0.89), body fat % (CQ=
-1.2+0.7 % body fat, PL= -1.1+1.9 % body fat, p=0.94), 3 rep max back squats (CQ=
+16.7+11.5 lbs, PL= +16.7+13.2 lbs, p=1.0), 3 rep standing press (CQ= +8.3+6.1 lbs,
PL= +3.30+5.6 lbs, p=0.08), or 1000 m rowing test (CQ= -3.0+6.0s, PL= -3.9+9.3s,
p=0.81).

CONCLUSION: Compared to the placebo, 6wk of supplementation with
CQ did not alter the body composition or exercise performance adaptations to crossfit
training in experienced crossfitters.

Existe-t’il une fatigue digestive?

23/08/2018 | Etudes Compléments alimentaires

 

Excess of nutrient-induced morpho-functional adaptation and inflammation degree in a Caco2/HT-29 in vitro intestinal co-culture
M. Bottani,        j.nut.2018.07.018

Highlights
•A nutrient excess increases in vitro mucus production and reduces tight junctions.
•A nutrient excess increases the specific activity of intestinal enzymes.
•A nutrient excess increases the intestinal permeability.
•A higher ROS, NO and PYY hormone production is associated to a nutrient excess.
•A low grade inflammation status is induced by a nutrient excess.

Abstract
The intestinal cell function can be modulated by the type and quantity of nutrients. The aim of this study was to evaluate the effects due to an excess of nutrients on intestinal morpho-functional features and a possible associated inflammation in a 70/30 Caco2/HT-29 intestinal in vitro co-culture. An excess of nutrients (EX) has been obtained by increasing progressively the medium change frequency respect to standard cell growth conditions (ST) from confluence (T0) to 15 days after confluence (T15). In comparison with ST group, the EX group revealed a maintenance of the number of microvilli, an increase of follicle like-structures and mucus production, a decrease in the number of tight junction. The specific activity of markers of intestinal differentiation, Alkaline Phosphatase and Aminopeptidase N, and of the enterocyte differentiation specific marker, Dipeptidyl Peptidase-IV, progressively raised. The Transepithelial Electrical Resistance, indicative of the co-culture barrier properties, decreased, while Lucifer Yellow Papp evaluation, an index of the paracellular permeability to large molecules, showed an increase. ROS and NO production, indicative of an oxidative status, together with IL-6, IL-8, indicative of a low inflammation grade, and PYY secretion were higher in EX than in ST condition. The differences between ST and EX were particularly evident at T15.

These data support the suitability of our in vitro gut model for obesity studies at the molecular level and the necessity to standardize the medium frequency change in intestinal culture.

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