Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 5 de 5
Filter
Add more filters










Database
Language
Publication year range
1.
Article in English | MEDLINE | ID: mdl-34300141

ABSTRACT

Bio-electromagnetic-energy-regulation (BEMER) therapy is a technology using a low-frequency pulsed electromagnetic field (PEMF) in a biorhythmic format. BEMER has been shown to optimize recovery and decrease fatigue by increasing blood flow in microvessels. Our aim was to determine its effects during preseason training in endurance athletes. A total of 14 male cross-country runners (19.07 ± 0.92 y.o.) were placed in either the intervention (PEMF; n = 8) or control (CON; n = 6) group using a covariate-based, constrained randomization. Participants completed six running sessions at altitudes ranging from 881.83 (±135.98 m) to 1027.0 (±223.44 m) above sea level. PEMF group used BEMER therapy before and after each training session, totaling 12 times. There were no significant changes in absolute or relative VO2Peak, ventilation or maximum respiration rate for either the PEMF or CON group (p > 0.05). There was a significant effect of time for absolute and relative ventilatory threshold (VT), and maximum heart rate, heart rate at VT and respiration rate at VT. This study was the first of its kind to study PEMF technology in combination with elevated preseason training. Results indicate some evidence for the use of PEMF therapy during short-term training camps to improve VT.


Subject(s)
Electric Stimulation Therapy , Magnetic Field Therapy , Electromagnetic Fields , Heart Rate , Humans , Male , Pilot Projects
2.
Antioxidants (Basel) ; 9(3)2020 Mar 23.
Article in English | MEDLINE | ID: mdl-32210013

ABSTRACT

Clinical use of the chemotherapeutic doxorubicin (DOX) promotes skeletal muscle atrophy and weakness, adversely affecting patient mobility and strength. Although the mechanisms responsible for DOX-induced skeletal muscle dysfunction remain unclear, studies implicate the significant production of reactive oxygen species (ROS) in this pathology. Supraphysiological ROS levels can enhance protein degradation via autophagy, and it is established that DOX upregulates autophagic signaling in skeletal muscle. To determine the precise contribution of accelerated autophagy to DOX-induced skeletal muscle dysfunction, we inhibited autophagy in the soleus via transduction of a dominant negative mutation of the autophagy related 5 (ATG5) protein. Targeted inhibition of autophagy prevented soleus muscle atrophy and contractile dysfunction acutely following DOX administration, which was associated with a reduction in mitochondrial ROS and maintenance of mitochondrial respiratory capacity. These beneficial modifications were potentially the result of enhanced transcription of antioxidant response element-related genes and increased antioxidant capacity. Specifically, our results showed significant upregulation of peroxisome proliferator-activated receptor gamma co-activator 1-alpha, nuclear respiratory factor-1, nuclear factor erythroid-2-related factor-2, nicotinamide-adenine dinucleotide phosphate quinone dehydrogenase-1, and catalase in the soleus with DOX treatment when autophagy was inhibited. These findings establish a significant role of autophagy in the development of oxidative stress and skeletal muscle weakness following DOX administration.

3.
Toxicon ; 144: 48-54, 2018 Mar 15.
Article in English | MEDLINE | ID: mdl-29407164

ABSTRACT

Botulinum neurotoxin type A (BoNT/A) is used as a therapeutic tool to induce chemical denervation of spastically contracted muscles, yet the neurotoxin can also cause skeletal muscle atrophy. The underlying proteolytic mechanisms that induce this atrophy remain unclear. Our previous work has highlighted increased ubiquitin proteasome system (UPS) activity in soleus muscle of male Sprague Dawley rats following hind limb injection of BoNT/A, with the chymotrypsin-like activity of the 20s proteasome the most active. Thus, we chose to inhibit 20s proteasome activity in BoNT/A injected hind limb to determine the effect on soleus muscle atrophy. Epoxomicin is commonly used to inhibit the proteasome in vivo, binding specifically and irreversibly to the 20s proteasome catalytic subunits. Daily subcutaneous injections of epoxomicin abolished BoNT/A-induced elevations in 20s chymotrypsin-like activity both 3 days and 10 days post BoNT/A injection. Furthermore, BoNT/A-induced elevations in polyubiquitination remained elevated in BoNT/A + epoxomicin treated muscle, presumably due to epoxomicin's inhibition of the proteasome causing a back-up of polyubiquitinated proteins. Despite inhibition of the proteasome, epoxomicin was insufficient to significantly attenuate soleus muscle fiber atrophy 3 days following BoNT/A injection however, 10 days of daily epoxomicin injection was sufficient to spare ∼20% of muscle wasting. The mechanism of the remaining 80% of BoNT/A-induced atrophy presumably occurs via mechanisms outside of the 20s proteasome.


Subject(s)
Botulinum Toxins, Type A/toxicity , Muscle, Skeletal/drug effects , Muscular Atrophy/chemically induced , Proteasome Endopeptidase Complex/drug effects , Animals , Male , Muscle, Skeletal/pathology , Muscular Atrophy/metabolism , Muscular Atrophy/pathology , Oligopeptides/pharmacology , Proteolysis , Rats, Sprague-Dawley , Ubiquitination/drug effects
4.
Eur J Sport Sci ; 16(8): 1087-94, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27686403

ABSTRACT

Attenuated performance during intense exercise with limited endogenous carbohydrate (CHO) is well documented. Therefore, this study examined whether caffeine (CAF) mouth rinsing would augment performance during repeated sprint cycling in participants with reduced endogenous CHO. Eight recreationally active males (aged 23 ± 2 yr, body mass 84 ± 4 kg, stature 178 ± 7 cm) participated in this randomized, single-blind, repeated-measures crossover investigation. Following familiarization, participants attended two separate evening glycogen depletion sessions. The following morning, participants completed five, 6 s sprints on a cycle ergometer (separated by 24 s active recovery), with mouth rinsing either (1) a placebo solution or (2) a 2% CAF solution. During a fifth visit, participants completed the sprints without prior glycogen depletion. Repeated-measures ANOVA identified significant main effect of condition (CAF, placebo, and control [P < .05; effect size (ES) = 0.850-0.897]), sprint (1-5 [P < .005; ES = 0.871-0.986]), and interaction (condition × sprint [P < .05; ES = 0.831-0.846]), for peak and mean power. The control condition exhibited the highest peak power (overall mean 760 ± 77 W) and mean power (overall mean 699 ± 83W) over the five sprints (P < .001 in both instances). CAF peak power (overall mean 643 ± 79 W) was significantly greater than placebo (mean 573 ± 79 W [P < .05; ES = 0.850]). Additionally, CAF mean power (overall mean 589 ± 80 W) was significantly greater than placebo (519 ± 82 W [P < .05; ES = 0.397]). These data indicate that mouth rinsing a caffeinated solution reduces decrements caused by CHO reduction, which may benefit athletes wishing to train in a low-CHO state.


Subject(s)
Athletic Performance/physiology , Bicycling/physiology , Caffeine/pharmacology , Mouthwashes/pharmacology , Adult , Cross-Over Studies , Dietary Carbohydrates , Exercise Test , Humans , Male , Myalgia , Pain Perception/drug effects , Young Adult
5.
J Appl Physiol (1985) ; 119(1): 83-92, 2015 Jul 01.
Article in English | MEDLINE | ID: mdl-25953835

ABSTRACT

Botulinum neurotoxin type A (BoNT/A) is used clinically to induce therapeutic chemical denervation of spastically contracted skeletal muscles. However, BoNT/A administration can also cause atrophy. We sought to determine whether a major proteolytic pathway contributing to atrophy in multiple models of muscle wasting, the ubiquitin proteasome system (UPS), is involved in BoNT/A-induced atrophy. Three and ten days following BoNT/A injection of rat hindlimb, soleus muscle fiber cross-sectional area was reduced 25 and 65%, respectively. The transcriptional activity of NF-κB and Foxo was significantly elevated at 3 days (2- to 4-fold) and 10 days (5- to 6-fold). Muscle RING-finger protein-1 (MuRF1) activity was elevated (2-fold) after 3 days but not 10 days, while atrogin-1 activity was not elevated at any time point. BoNT/A-induced polyubiquitination occurred after 3 days (3-fold increase) but was totally absent after 10 days. Proteasome activity was elevated (1.5- to 2-fold) after 3 and 10 days. We employed the use of heat shock protein 70 (Hsp70) to inhibit NF-κB and Foxo transcriptional activity. Electrotransfer of Hsp70 into rat soleus, before BoNT/A administration, was insufficient to attenuate atrophy. It was also insufficient to decrease BoNT/A-induced Foxo activity at 3 days, although NF-κB activity was abolished. By 10 days both NF-κB and Foxo activation were abolished by Hsp70. Hsp70-overexpression was unable to alter the levels of BoNT/A-induced effects on MuRF1/atrogin-1, polyubiquitination, or proteasome activity. In conclusion, Hsp70 overexpression is insufficient to attenuate BoNT/A-induced atrophy. It remains unclear what proteolytic mechanism/s are contributing to BoNT/A-induced atrophy, although a Foxo-MuRF1-ubiquitin-proteasome contribution may exist, at least in early BoNT/A-induced atrophy. Further clarification of UPS involvement in BoNT/A-induced atrophy is warranted.


Subject(s)
Botulinum Toxins, Type A/toxicity , Gene Expression/drug effects , HSP70 Heat-Shock Proteins/biosynthesis , Muscle, Skeletal/pathology , Animals , Electroporation , Forkhead Transcription Factors/biosynthesis , Forkhead Transcription Factors/genetics , Hindlimb/pathology , Male , Muscle Contraction/drug effects , Muscle, Skeletal/drug effects , Muscular Atrophy/metabolism , NF-kappa B/metabolism , Nerve Tissue Proteins/biosynthesis , Nerve Tissue Proteins/genetics , Peptide Hydrolases/drug effects , Peptide Hydrolases/genetics , Peptide Hydrolases/metabolism , Plasmids/drug effects , Plasmids/genetics , Proteasome Endopeptidase Complex/metabolism , Rats , Rats, Sprague-Dawley
SELECTION OF CITATIONS
SEARCH DETAIL
...