Echauffement et blessures

Effets du neural gliding sur la souplesse?

30/03/2019 | Echauffement et blessures

 

ACUTE EFFECTS OF NEURAL GLIDING ON HAMSTRING FLEXIBILITY AND ATHLETIC PERFORMANCE IN COLLEGE
BASKETBALL PLAYERS

K. SMITH AND A. WALDHELM     Journal of Strength and Conditioning Research   VOLUME 33 | NUMBER 2 | FEBRUARY 2019 | e73
University of South Alabama

Introduction: The pre-activity warm-up is a very important
aspect in preparation for competitive sports. Prior research
has demonstrated the ability of a warm-up to influence flexibility, strength and power. Neural gliding is a fairly new intervention used in rehabilitation to improve muscle flexibility and joint
mobility of individuals with musculoskeletal and neuromuscular
injuries but the use of neural gliding in sports performance is
limited.

Purpose: The objective of this study is to compare the
effects of neural gliding and dynamic stretching exercises on
hamstring flexibility and athletic performance in collegiate basketball players.

Methods: Eight-teen NCAA Division II basketball players (8 males, 10 females; age: 18.1 6 0.24; height:
1.78 6 0.09 m; weight: 60.0 6 17.2 kg) volunteered for the
study. Data was collect during a single session and block
assignment was used with 9 individuals (4 males, 5 females)
in each group: neural gliding and dynamic stretching. Before
testing each subject performed the same 5 minute warm-up
which included jogging, running and sprinting. Pre-and postintervention testing included bilateral hamstring flexibility using
the active straight leg test, 10 and 40-yard dash, countermovement vertical jump, and 20-yard shuttle run. Between testing
the participants performed a 5 minute exercise protocol which
included bilateral sciatic nerve gliding or a dynamic lower
extremity stretching program. Multiple 2 3 2 (time by group)
repeated measures ANOVAs with p # 0.05 was used to examine differences.

Results: The results did not show a significant
time by group interactions for all 6 measurements and all main
effects were insignificant except for the countermovement vertical jump (F = 15.0, p = 0.005). Post-hoc paired t tests with
Bonferroni correction (p # 0.025) did not show as significant
difference in countermovement vertical jump performance in
both the dynamic stretching (p = 0.250) or the neural gliding
group (p = 0.107).

Conclusions: The results demonstrate that
both neural gliding and dynamic stretching exercises did not
have a significant effect on hamstring flexibility or 4 athletic
performance tests.

Practical Applications: Neural gliding can
be used as part of the pre-participation warm-up without a negative effect on athletic performance, but more research is needed
to truly determine if neural gliding should be part of a warm-up.

Actions santé de la mélatonine

11/01/2019 | Etudes sur les hormones et Echauffement et blessures et Etudes Compléments alimentaires et Etudes Anti-âge

 

The multiple protective roles and molecular mechanisms of melatonin and its precursor N-acetylserotonin in targeting brain injury and liver damage and in maintaining bone health
ChengliangLuoa       Free Radical Biology and Medicine Volume 130, January 2019, Pages 215-233

Highlights
• Melatonin and NAS are protective agents for brain injury, liver damage and bone health.
• Melatonin and NAS are anti-oxidative stress and anti-inflammation.
• Melatonin and NAS are against autophagy dysfunction and anti-apoptosis.
• MT1/MT2 are needed for brain and liver injuries and MT2 is important for bone health.
• Melatonin and NAS will be likely to show utility in clinical trials.

Melatonin is a neurohormone associated with sleep and wakefulness and is mainly produced by the pineal gland. Numerous physiological functions of melatonin have been demonstrated including anti-inflammation, suppressing neoplastic growth, circadian and endocrine rhythm regulation, and its potent antioxidant activity as well as its role in regeneration of various tissues including the nervous system, liver, bone, kidney, bladder, skin, and muscle, among others.

In this review, we summarize the recent advances related to the multiple protective roles of melatonin receptor agonists, melatonin and N-acetylserotonin (NAS), in brain injury, liver damage, and bone health. Brain injury, including traumatic brain injury, ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, and newborn perinatal hypoxia-ischemia encephalopathy, is a major cause of mortality and disability. Liver disease causes serious public health problems and various factors including alcohol, chemical pollutants, and drugs induce hepatic damage. Osteoporosis is the most common bone disease in humans. Due in part to an aging population, both the cost of care of fracture patients and the annual fracture rate have increased steadily. Despite the discrepancy in the pathophysiological processes of these disorders, time frames and severity, they may share several common molecular mechanisms. Oxidative stress is considered to be a critical factor in these pathogeneses. We update the current state of knowledge related to the molecular processes, mainly including anti-oxidative stress, anti-apoptosis, autophagy dysfunction, and anti-inflammation as well as other properties of melatonin and NAS. Particularly, the abilities of melatonin and NAS to directly scavenge oxygen-centered radicals and toxic reactive oxygen species, and indirectly act through antioxidant enzymes are disscussed. In this review, we summarize the similarities and differences in the protection provided by melatonin and/or NAS in brain, liver and bone damage.

We analyze the involvement of melatonin receptor 1A (MT1), melatonin receptor 1B (MT2), and melatonin receptor 1C (MT3) in the protection of melatonin and/or NAS. Additionally, we evaluate their potential clinical applications. The multiple mechanisms of action and multiple organ-targeted properties of melatonin and NAS may contribute to development of promising therapies for clinical trials.

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.

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