Echauffement et blessures

De la carnosine pour la régénération nerveuse?

07/12/2018 | Etudes sur les hormones et Echauffement et blessures et Etudes Compléments alimentaires et Etudes Anti-âge

 

Carnosine improves functional recovery and structural regeneration after sciatic nerve crush injury in rats
Navideh Mirzakhani             Life Sciences volume 215, 15 December 2018, Pages 22-30


Aims
Peripheral nerve injury represents a substantial clinical problem with insufficient or unsatisfactory treatment options. Current researches have extensively focused on the new approaches for the treatment of peripheral nerve injuries. Carnosine is a naturally occurring pleotropic dipeptide and has many biological functions such as antioxidant property. In the present study, we examined the regenerative ability of carnosine after sciatic nerve crush injury using behavioral, biochemical, histological and ultrastructural evaluations.

Materials and methods
Seventy-two rats were divided into six groups including control, sham, crush and carnosine (10, 20 and 40 mg/kg) groups. Crush injury in left sciatic nerve was induced by a small haemostatic forceps. Carnosine was administered for 15 consecutive days after induction of crush injury. Sciatic functional index (SFI) was recorded weekly. Histopathological and ultrastructural evaluations were made using light and electron microscopes, respectively. Sciatic nerve tissue malondialdehyde (MDA), superoxide dismutase (SOD) and tumor necrosis factor-alpha (TNF-α) levels were measured. Gastrocnemius muscle weight was determined.

Key findings
Carnosine at the doses of 20 and 40 mg/kg accelerated SFI recovery. Wallerian degeneration severity and myelinated fibers density, myelin sheath thickness and diameter as well as ultrastructural changes of myelinated axons were improved. It also recovered nerve tissue biochemical (MDA, SOD and TNF-α) changes induced by crush injury. Muscle weight ratio was reached to near normal values.

Our results suggest a regenerative effect of carnosine. Inhibition of oxidative stress and inflammatory pathways, along with provocation of myelination and prevention of muscular atrophy might be involved in this effect of carnosine.

Significance
Carnosine treatment might be considered as a therapeutic agent for peripheral nerve regeneration and its functional recovery.

Utilisation de plaquettes contre les blessures

25/10/2018 | Etudes sur les hormones et Echauffement et blessures

 

Platelet releasate promotes skeletal myogenesis by increasing muscle stem cell commitment to differentiation and accelerates muscle regeneration following acute injury
David Scully Acta Physiol : 19 October 2018

Aim
The use of platelets as biomaterials has gained intense research interest. However, the mechanisms regarding platelet‐mediated skeletal myogenesis remain to be established. The aim of this study was to determine the role of platelet releasate in skeletal myogenesis and muscle stem cell fate in vitro and ex vivo respectively.

Methods
We analysed the effect of platelet releasate on proliferation and differentiation of C2C12 myoblasts by means of cell proliferation assays, immunohistochemistry, gene expression and cell bioenergetics. We expanded in vitro findings on single muscle fibres by determining the effect of platelet releasate on murine skeletal muscle stem cells using protein expression profiles for key myogenic regulatory factors.

Results
TRAP6 and collagen used for releasate preparation had a more pronounced effect on myoblast proliferation versus thrombin and sonicated platelets (P<0.05). In addition, platelet concentration positively correlated with myoblast proliferation. Platelet releasate increased myoblast and muscle stem cell proliferation in a dose‐dependent manner, which was mitigated by VEGFR and PDGFR inhibition. Inhibition of VEGFR and PDGFR ablated MyoD expression on proliferating muscle stem cells, compromising their commitment to differentiation in muscle fibres (P<0.001). Platelet releasate was detrimental for myoblast fusion and affected differentiation of myoblasts in a temporal manner. Most importantly we show that platelet releasate promotes skeletal myogenesis through the PDGF/VEGF‐Cyclin D1‐MyoD‐Scrib‐Myogenin axis and accelerates skeletal muscle regeneration after acute injury.

Conclusion
This study provides novel mechanistic insights on the role of platelet releasate in skeletal myogenesis and set the physiological basis for exploiting platelets as biomaterials in regenerative medicine.

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.

L’acide carnosique du romarin comme protecteur articulaire?

13/03/2018 | Echauffement et blessures et Etudes Compléments alimentaires et Etudes Anti-âge

 

Carnosic acid inhibits inflammation response and joint destruction on osteoclasts, fibroblast-like synoviocytes, and collagen-induced arthritis rats
Mei Liu       J. Cell. Physiol.      9 March 2018

The discovery of new therapeutic drugs with the ability of preventing inflammation and joint destruction with less adverse effects is urgently needed for rheumatoid arthritis (RA). Carnosic acid (CA), a major phenolic compound isolated from the leaves of Rosemary (Rosmarinus officinalis L.), has been reported to have antioxidative and antimicrobial properties. However, its effects on RA have not been elucidated. Here, we investigated the effects of CA on osteoclasts and fibroblast-like synoviocytes in vitro and on collagen-induced arthritis (CIA) in Wistar rats in vivo. Our in vitro and in vivo studies showed that CA suppressed the expression of pro-inflammatory cytokines including TNFɑ, IL-1β, IL-6, IL-8, IL-17 and MMP-3, and downregulated the production of RANKL. More importantly, we observed that CA inhibited osteoclastogenesis and bone resorption in vitro and exerted therapeutic protection against joint destruction in vivo. Further biochemical analysis demonstrated that CA suppressed RANKL-induced activations of NF-κB and MAPKs (JNK and p38) leading to the downregulation of NFATc1.

Taken together, our findings provide the convincing evidence that rosemary derived CA is a promising natural compound for the treatment of RA.

Cryothérapie Corps Entier Vs eau froide pour la récupération?

10/01/2018 | Etudes cardio et Echauffement et blessures

 

Recovery following a marathon: a comparison of cold water immersion, whole body cryotherapy and a placebo control
Laura J. Wilson     European Journal of Applied Physiology January 2018, Volume 118, Issue 1, pp 153–163 | Cite as

Purpose
Cryotherapy is an increasingly popular recovery strategy used in an attempt to attenuate the negative impact of strenuous physical activity on subsequent exercise. Therefore, this study aimed to assess the effects of whole body cryotherapy (WBC) and cold water immersion (CWI) on markers of recovery following a marathon.

Methods
Thirty-one endurance trained males completed a marathon. Participants were randomly assigned to a CWI, WBC or placebo group. Perceptions of muscle soreness, training stress and markers of muscle function were recorded before the marathon and at 24 and 48 h post exercise. Blood samples were taken at baseline, post intervention and 24 and 48 h post intervention to assess inflammation and muscle damage.

Results
WBC had a harmful effect on muscle function compared to CWI post marathon. WBC positively influenced perceptions of training stress compared to CWI. With the exception of C-reactive protein (CRP) at 24 and 48 h, neither cryotherapy intervention positively influenced blood borne markers of inflammation or structural damage compared to placebo.

Conclusion
The findings show WBC has a negative impact on muscle function, perceptions of soreness and a number of blood parameters compared to CWI, contradicting the suggestion that WBC may be a superior recovery strategy. Further, cryotherapy is no more effective than a placebo intervention at improving functional recovery or perceptions of training stress following a marathon. These findings lend further evidence to suggest that treatment belief and the placebo effect may be largely responsible for the beneficial effects of cryotherapy on recovery following a marathon.

Effet contra-latéral du foam roller

23/12/2017 | Echauffement et blessures

 

Does Foam Rolling Increase Pressure Pain Threshold Of Ipsilateral Lower Extremity Antagonist And Contralateral Muscles?
Scott W. Cheatham   Medicine & Science in Sports & Exercise. 49(5S):1066, May 2017.

Sports medicine professionals often prescribe foam rolling as an intervention to treat myofascial restrictions. Of particular interest, is the effect foam rolling has on the ipsilateral antagonist muscle and contralateral muscles. Recent research has observed ROM changes in these muscles after a foam rolling intervention. To date, no studies have examined how foam rolling effects the pressure pain threshold (PPT) levels of the ipsilateral antagonist and contralateral muscles. PURPOSE: To examine the acute effects of a foam rolling intervention on ipsilateral antagonist and contralateral muscle group PPT levels. METHODS: Twenty-one healthy participants (mean age 27.52± 8.9 years) (M=13, F=8) were recruited for this study and signed an IRB consent. Participants underwent pretest and immediate posttest PPT measures after a 2-minute video-guided foam roll intervention to the left quadriceps. PPTs were measured using a digital algometer to the ipsilateral left hamstrings and right quadriceps. Pretest and posttest measures were calculated using the paired t-test. Statistical significance was considered p< 0.05 using a two-tailed test. RESULTS: A significant difference was found between pretest to posttest measures for the ipsilateral hamstrings (t (20) = -6.2, p<0.001) and contralateral quadriceps (t (20) = -9.1, p<0.001) suggesting an increase in PPT.

CONCLUSIONS: These finding suggest that foam rolling of the quadriceps musculature may have an acute effect on the PPT of the ipsilateral hamstrings and contralateral quadriceps muscles. Individual may feel less discomfort due to a higher PPT. The ipsilateral decrease in hamstring PPT may have occurred through reciprocal inhibition and agonist pain perception from rolling on the left quadriceps. The cross-over effect of decreased right quadriceps PPT may have been from a more global neurophysiological response. Clinicians must consider these results to be exploratory and future investigations examining this intervention on PPT is warranted.

Chaleur ou froid pour optimiser l’anabolisme?

22/11/2017 | Echauffement et blessures et Etudes Musculation

 

Plus d’anabolisme, moins de catabolisme avec…

Impact of local heating and cooling on skeletal muscle transcriptional response related to myogenesis and proteolysis
Roksana B. Zak European Journal of Applied Physiology October 2017

Purpose

To determine the impact of local muscle heating and cooling on myogenic and proteolytic gene responses following resistance exercise.

Methods

Recreationally trained males (n = 12), age 25.3 ± 1.5, % body fat 13.6 ± 1.92, completed four sets of 8–12 repetitions of unilateral leg press and leg extension while heating one leg, and cooling the other. Muscle biopsies were taken from the vastus lateralis of each leg pre and 4 h post exercise.

Results

MyoD, FOXO1, and MuRF1 mRNA increased with exercise regardless of temperature (p < 0.05). Myostatin, MYF5, and atrogin-1 mRNA decreased with exercise regardless of temperature (p < 0.05). Myogenin, MRF4, and CASP3 mRNA were higher in the hot condition, compared to the cold (p < 0.05). PAX7 mRNA was lower in the hot compared to cold condition (p = 0.041). FOXO3 mRNA was higher in the cold compared to hot condition (p = 0.037). AKT1 and AKT2 were unaffected by either exercise or temperature. Femoral artery blood flow volume was higher in the hot (375.2 ± 41.2 ml min− 1), compared to the cold condition (263.5 ± 23.9 ml min− 1), p = 0.01. Tissue oxygen saturation was higher in the hot (71.7 ± 4.8%) than cold condition (55.3 ± 5.0%).

Conclusion

These results suggest an impaired muscle growth response with local cold application compared to local heat application.

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