Etudes cardio : page 3.8

Deux lignes plus loin, on te montre le contraire

29/06/2016 | Etudes cardio et Etudes Musculation

 

pour le coup, j’ai nettement moins de mal à croire cette étude

Concurrent exercise incorporating high-intensity interval or continuous training modulates mTORC1 signaling and microRNA expression in human skeletal muscle
Jackson J. Fyfe           American Journal of Physiology - Regulatory, Integrative and Comparative Physiology Published 1 June 2016 Vol. 310 no. 11, R1297-R1311

We compared the effects of concurrent exercise, incorporating either high-intensity interval training (HIT) or moderate-intensity continuous training (MICT), on mechanistic target of rapamycin complex 1 (mTORC1) signaling and microRNA expression in skeletal muscle, relative to resistance exercise (RE) alone. Eight males (mean ± SD: age, 27 ± 4 yr; V̇o2 peak, 45.7 ± 9 ml·kg−1·min−1) performed three experimental trials in a randomized order: 1) RE (8 × 5 leg press repetitions at 80% 1-repetition maximum) performed alone and RE preceded by either 2) HIT cycling [10 × 2 min at 120% lactate threshold (LT); HIT + RE] or 3) work-matched MICT cycling (30 min at 80% LT; MICT + RE). Vastus lateralis muscle biopsies were obtained immediately before RE, either without (REST) or with (POST) preceding endurance exercise and +1 h (RE + 1 h) and +3 h (RE + 3 h) after RE. Prior HIT and MICT similarly reduced muscle glycogen content and increased ACCSer79 and p70S6KThr389 phosphorylation before subsequent RE (i.e., at POST). Compared with MICT, HIT induced greater mTORSer2448 and rps6Ser235/236 phosphorylation at POST. RE-induced increases in p70S6K and rps6 phosphorylation were not influenced by prior HIT or MICT; however, mTOR phosphorylation was reduced at RE + 1 h for MICT + RE vs. both HIT + RE and RE. Expression of miR-133a, miR-378, and miR-486 was reduced at RE + 1 h for HIT + RE vs. both MICT + RE and RE.

Postexercise mTORC1 signaling following RE is therefore not compromised by prior HIT or MICT, and concurrent exercise incorporating HIT, but not MICT, reduces postexercise expression of miRNAs implicated in skeletal muscle adaptation to RE.

Ca serait bien si c’était vrai

29/06/2016 | Etudes cardio et Etudes Musculation

 

c’est le gros problème de la “science”

Aerobic exercise augments muscle transcriptome profile of resistance exercise

Tommy R. Lundberg           American Journal of Physiology - Regulatory, Integrative and Comparative Physiology Published 1 June 2016 Vol. 310 no. 11, R1279-R1287

Recent reports suggest that aerobic exercise may boost the hypertrophic response to short-term resistance training. This study explored the effects of an acute aerobic exercise bout on the transcriptional response to subsequent resistance exercise. Ten moderately trained men performed ∼45 min cycling on one leg followed by 4 × 7 maximal knee extensions for each leg, 15 min later. Thus, one limb performed aerobic and resistance exercise (AE + RE) while the opposing leg did resistance exercise only (RE). Biopsies were obtained from the vastus lateralis muscle of each leg 3 h after the resistance exercise bout. Using DNA microarray, we analyzed differences [≥1.5-fold, false discovery rate (FDR) ≤10%] in gene expression profiles for the two modes of exercise. There were 176 genes up (127)- or downregulated (49) by AE + RE compared with RE. Among the most significant differentially expressed genes were established markers for muscle growth and oxidative capacity, novel cytokines, transcription factors, and micro-RNAs (miRNAs). The most enriched functional categories were those linked to carbohydrate metabolism and transcriptional regulation. Upstream analysis revealed that vascular endothelial growth factor, cAMP-response element-binding protein, Tet methylcytosine dioxygenase, and mammalian target of rapamycin were regulators highly activated by AE + RE, whereas JnK, NF-κβ, MAPK, and several miRNAs were inhibited. Thus, aerobic exercise alters the skeletal muscle transcriptional signature of resistance exercise to initiate important gene programs promoting both myofiber growth and improved oxidative capacity.

These results provide novel insight into human muscle adaptations to diverse exercise modes and offer the very first genomic basis explaining how aerobic exercise may augment, rather than compromise, muscle growth induced by resistance exercise.

Comment le sport endommage t’il le coeur sur le long terme?

19/05/2016 | Etudes cardio et Echauffement et blessures et Etudes Anti-âge

 

Long-term leucine supplementation aggravates prolonged strenuous exercise-induced cardiovascular changes in trained rats
Gustavo Barbosa dos Santos             Experimental Physiology 2016

Observational studies have raised concerns that prolonged strenuous exercise training may be associated with increased risk of cardiac arrhythmia and even primary cardiac arrest or sudden death. It has been demonstrated that leucine can reduce prolonged exercise-induced muscle damage and accelerate the recovery process. The aim of this study was to investigate the effects of prolonged strenuous endurance exercise on cardiovascular parameters and biomarkers of cardiac injury in trained adult male rats and assess the use of leucine as an auxiliary substance to prevent the likely cardiac adverse effects caused by strenuous exercise. Twenty-four male Wistar rats were randomly allocated to receive a balanced control diet (18% protein) or a leucine-rich diet (15% protein plus 3% leucine) for 6 weeks. The rats were submitted to 1 hour of exercise, 5 d.wk−1 for 6 wk. Three days after the training period rats were submitted to swimming exercises until exhaustion and cardiac parameters were assessed.

Exercising until exhaustion significantly increased cardiac biomarker levels and cytokines, glycogen content and inhibited protein synthesis signaling also led to cardiac electrical disturbances. When combined with exercise, leucine supplementation led to further increases in the aforementioned parameters and also significant increase in blood pressure and protein degradation signaling. We report, for the first time, that leucine supplementation not only does not prevent cardiac fatigue symptoms, but may also aggravate prolonged strenuous exercise-induced cardiovascular disturbances in trained rats. Furthermore, we find that exercising until exhaustion can cause cardiac electrical disturbances and cardiac myocyte damage.

Le rameur brûle plus de gras que le vélo

07/05/2016 | Etudes cardio et Etudes Perte de poids

 

Higher rate of fat oxidation during rowing compared with cycling ergometer exercise across a range of exercise intensities
B. Egan           Scandinavian Journal of Medicine & Science in Sports Volume 26, Issue 6, pages 630–637, June 2016

The relative contribution of carbohydrate and fat oxidation to energy expenditure during exercise is dependent on variables including exercise intensity, mode, and recruited muscle mass. This study investigated patterns of substrate utilization during two non-weightbearing exercise modalities, namely cycling and rowing. Thirteen young, moderately trained males performed a continuous incremental (3-min stages) exercise test to exhaustion on separate occasions on an electronically braked cycle (CYC) ergometer and an air-braked rowing (ROW) ergometer, respectively. On two further occasions, participants performed a 20-min steady-state exercise bout at ∼50%VO2peak on the respective modalities.

Despite similar oxygen consumption, rates of fat oxidation (FATox) were ∼45% higher during ROW compared with CYC (P 

< 0.05) across a range of power output increments.

The crossover point for substrate utilization occurred at a higher relative exercise intensity for ROW than CYC (57.8 ± 2.1 vs 42.1 ± 3.6%VO2peak, P < 0.05). During steady-state submaximal exercise, the higher FATox during ROW compared with CYC was maintained (P < 0.05), but absolute FATox were 42% (CYC) and 28% (ROW) lower than during incremental exercise.

FATox is higher during ROW compared with CYC exercise across a range of exercise intensities matched for energy expenditure, and is likely as a consequence of larger muscle mass recruited during ROW.

La natation: pas super efficace dans la chasse au gras

01/04/2016 | Etudes cardio et Etudes Perte de poids et Etudes Anti-âge

 

HIGH INTENSITY CROSSFIT TRAINING COMPARED TO HIGH
INTENSITY SWIMMING: A PRE-POST TRIAL TO ASSESS THE
IMPACT ON BODY COMPOSITION, MUSCLE STRENGTH AND
RESTING ENERGY EXPENDITURE

S. Perna   Nutrition 32 (2016) 399–408


Introduction: The aim of this study was to evaluate the impact of
two high intensity training as different high intensity training, i.e.
power CrossFit and intermittent Swimming, on body composition
markers, max strength and resting energy expenditure.
Material and Methods: This pre-post trial was conducted in
Twenty-three subjects (14 female, 9 male; mean age ¼ 31.74 
7.46 years; BMI ¼ 23.665  2.994 kg/m2
). They were assigned to
intervention of CrossFit training or Swimming training (CrossFit/
Swimming: 10/13) for 8-weeks (60 min, 3 times per week). Using
Dual X ray Energy Absorptiometry, we measured body mass
composition markers. Muscle strength and resting energy
expenditure were measured at baseline and immediate after 8
weeks of training intervention. This variables were measured at
baseline and after 8 weeks.

Results: Between groups, data demonstrated a significant
changes on gynoid fat (-1.670 %; P¼0.024) in favour of CrossFit
training. Suggestive but not significant differences (0.05 <0.10) between groups in decreasing of Fat Mass (-1439 g;
P¼0.073) and Android Fat (-2.614%; P¼0.075), were found. The
pre-post differences within training interventions were signifi-
cant (P<0.05) for Fat mass, gynoid fat, free fat mass and Resting
Energy Expenditure (REE) in CrossFit group.

Conclusions: This study showed the potential benefits of High
Intensity Training in improvement on body composition markers.
In particular, CrossFit is more performing than swimming in
losses of total fat mass, specifically of gynoid and android fat mass.

Nouvelles découvertes sur le perte de graisse: mal au crâne garanti

10/03/2016 | Etudes cardio et Etudes Perte de poids et Etudes Anti-âge

 

Abdominal fat-reducing outcome of exercise training: Fat burning versus hydrocarbon source redistribution?
Chia-Hua Kuo             Revue canadienne de physiologie et pharmacologie 05 March 2016.

Fat burning, defined by fatty acid oxidation into carbon dioxide, is the most described hypothesis to explain the actual abdominal fat-reducing outcome of exercise training. This hypothesis is strengthened by evidence of increased whole-body lipolysis during exercise. As a result, aerobic training is widely recommended for obesity management.

This intuition raises several paradoxes:
First, both aerobic and resistance exercise training do not actually elevate 24-h fat oxidation, according to data from chamber-based indirect calorimetry.
Second, anaerobic high-intensity intermittent training produces greater abdominal fat reduction than continuous aerobic training at similar amounts of energy expenditure.
Third, significant body fat reduction in athletes occurs when oxygen supply decreases to inhibit fat burning during altitude-induced hypoxia exposure at the same training volume. Lack of oxygen increases post-meal blood distribution to human skeletal muscle, suggesting that shifting the postprandial hydrocarbons towards skeletal muscle away from adipose tissue might be more important than fat burning in decreasing abdominal fat.

Conclusion: Creating a negative energy balance in fat cells due to competition of skeletal muscle for circulating hydrocarbon sources may be a better model to explain the abdominal fat-reducing outcome of exercise than the fat burning model.

Les secrets de la perte de graisses expliqués à mon cheval

08/03/2016 | Etudes cardio et Etudes Perte de poids

 

Abdominal fat-reducing outcome of exercise training: Fat burning versus hydrocarbon source redistribution?
Chia-Hua Kuo Revue canadienne de physiologie et pharmacologie 05 March 2016.

Fat burning, defined by fatty acid oxidation into carbon dioxide, is the most described hypothesis to explain the actual abdominal fat-reducing outcome of exercise training. This hypothesis is strengthened by evidence of increased whole-body lipolysis during exercise. As a result, aerobic training is widely recommended for obesity management.

This intuition raises several paradoxes:
First, both aerobic and resistance exercise training do not actually elevate 24-h fat oxidation, according to data from chamber-based indirect calorimetry.
Second, anaerobic high-intensity intermittent training produces greater abdominal fat reduction than continuous aerobic training at similar amounts of energy expenditure.
Third, significant body fat reduction in athletes occurs when oxygen supply decreases to inhibit fat burning during altitude-induced hypoxia exposure at the same training volume. Lack of oxygen increases post-meal blood distribution to human skeletal muscle, suggesting that shifting the postprandial hydrocarbons towards skeletal muscle away from adipose tissue might be more important than fat burning in decreasing abdominal fat.

Conclusion: Creating a negative energy balance in fat cells due to competition of skeletal muscle for circulating hydrocarbon sources may be a better model to explain the abdominal fat-reducing outcome of exercise than the fat burning model.

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