scholarly journals Training-Induced Acute Neuromuscular Responses to Military Specific Test during a Six-Month Military Operation

2020 ◽  
Vol 18 (1) ◽  
pp. 215
Author(s):  
Kai Pihlainen ◽  
Arto J Pesola ◽  
Joonas Helén ◽  
Keijo Häkkinen ◽  
Taija Finni ◽  
...  
Keyword(s):  
Endurance Training ◽  
High Intensity ◽  
Muscle Activation ◽  
Specific Test ◽  
Activation Level ◽  
Neural Input ◽  
Neuromuscular Responses ◽  
Performance Times ◽  
In The Beginning ◽  
Induced Changes

Limited data are available regarding strength and endurance training adaptations to occupational physical performance during deployment. This study assessed acute training-induced changes in neuromuscular (electromyography; EMG) and metabolic (blood lactate, BLa) responses during a high-intensity military simulation test (MST), performed in the beginning (PRE) and at the end (POST) of a six-month crisis-management operation. MST time shortened (145 ± 21 vs. 129 ± 16 s, −10 ± 7%, p < 0.001) during the operation. Normalized muscle activity increased from PRE to POST in the hamstring muscles by 87 ± 146% (116 ± 52 vs. 195 ± 139%EMGMVC, p < 0.001) and in the quadriceps by 54 ± 81% (26 ± 8 vs. 40 ± 20%EMGMVC, p < 0.001). In addition, higher acute BLa values were measured after MST during POST. Changes in BLa and EMG suggested an increased neural input and metabolic rate during POST MST, likely leading to faster performance times at the end of the operation. High EMG values throughout the different phases of MST suggested that despite the anaerobic nature of the test, the soldiers were able to maintain their voluntary muscle activation level until the end of the test. This indicates only limited neural fatigue during the two-minute high-intensity military specific performance. While learning effect may explain some part of the improvement in the MST performance times, combined strength and endurance training three times per week may improve neuromuscular performance in occupationally relevant tasks.

scholarly journals Electromyographic Evaluation of Specific Elastic Band Exercises Targeting Neck and Shoulder Muscle Activation

2020 ◽  
Vol 10 (3) ◽  
pp. 756 ◽  
Author(s):  
Ying Gao ◽  
Lars A. Kristensen ◽  
Thomas S. Grøndberg ◽  
Mike Murray ◽  
Gisela Sjøgaard ◽  
...  
Keyword(s):  
Shoulder Pain ◽  
High Intensity ◽  
Muscle Activation ◽  
Trapezius Muscle ◽  
Extensor Muscle ◽  
Voluntary Activation ◽  
Upper Trapezius ◽  
Activation Level ◽  
Elastic Bands ◽  
Upper Trapezius Muscle

Background: Specific strength training at a high intensity is effective in reducing work related neck/shoulder pain. However, it remains to be documented as to which exercises most specifically target neck and shoulder muscles at high activation level while using simple equipment as e.g., elastic bands. We hypothezised that selected exercises would specifically target the respective muscles, as follows: (1) shrugs and reverse flyes: the upper trapezius muscle, (2) cervical extension and lateral flexion: the upper neck extensor muscle, and (3) cervical flexion and rotation: the sternocleidomastoideus muscle. Methods: Eleven healthy males (25.9 ± 1.4 years, BMI 24.3 ± 1.4) with no neck/shoulder pain (VAS = 0) performed the six exercises with elastic bands at 12RM (repetition maximum) and 20RM in a randomized order. Electromyography was bilaterally recorded from the three muscles and it was normalized to maximal voluntary activation (%MVE). Exercises that evoke more than 60%MVE were considered as high intensity activation. Results: High muscle activation level was attained during 12RM in the upper trapezius muscle during shrugs (100.3 ± 29.8%MVE) and reverse flyes (91.6 ± 32.8%MVE) and in the upper neck extensor muscle during cervical extension (67.6 ± 29.8%MVE) and shrugs (61.9 ± 16.8%MVE). In the sternocleidomastoideus muscle, the highest activity was recorded during cervical flexion (51.7 ± 16.4%MVE) but it did not exceed 60%MVE. The overall activity was ~10% higher during 12RM when compared to 20RM. Conclusion: The simple exercises shrugs and reverse flyes resulted in high intensity activation of both the upper trapezius and neck extensors, while no exercises activated sternocleidomastoideus at high intensity.

Drug Induced Changes in Cell Organelles

1968 ◽  
Vol 26 ◽  
pp. 110-111
Author(s):  
Sarah A. Luse
Keyword(s):  
Clinical Medicine ◽  
Cell Organelles ◽  
Riboflavin Deficiency ◽  
Drug Induced ◽  
New Era ◽  
Health And Disease ◽  
In The Beginning ◽  
Cellular Pathology ◽  
Induced Changes ◽  
The Impact

In the mid-nineteenth century Virchow revolutionized pathology by introduction of the concept of “cellular pathology”. Today, a century later, this term has increasing significance in health and disease. We now are in the beginning of a new era in pathology, one which might well be termed “organelle pathology” or “subcellular pathology”. The impact of lysosomal diseases on clinical medicine exemplifies this role of pathology of organelles in elucidation of disease today.Another aspect of cell organelles of prime importance is their pathologic alteration by drugs, toxins, hormones and malnutrition. The sensitivity of cell organelles to minute alterations in their environment offers an accurate evaluation of the site of action of drugs in the study of both function and toxicity. Examples of mitochondrial lesions include the effect of DDD on the adrenal cortex, riboflavin deficiency on liver cells, elevated blood ammonia on the neuron and some 8-aminoquinolines on myocardium.

Sex differences in respiratory muscle activation patterns during high-intensity exercise in healthy humans

2018 ◽  
Vol 247 ◽  
pp. 57-60 ◽  
Author(s):  
Reid A. Mitchell ◽  
Michele R. Schaeffer ◽  
Andrew H. Ramsook ◽  
Sabrina S. Wilkie ◽  
Jordan A. Guenette
Keyword(s):  
Sex Differences ◽  
High Intensity ◽  
Respiratory Muscle ◽  
Muscle Activation ◽  
High Intensity Exercise ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Healthy Humans

Influence of endurance training on muscle [PCr] kinetics during high-intensity exercise

2007 ◽  
Vol 293 (1) ◽  
pp. R392-R401 ◽  
Author(s):  
Andrew M. Jones ◽  
Daryl P. Wilkerson ◽  
Nicolas J. Berger ◽  
Jonathan Fulford
Keyword(s):  
Endurance Training ◽  
High Intensity ◽  
Slow Component ◽  
Knee Extension ◽  
High Intensity Exercise ◽  
Whole Body ◽  
Time To Exhaustion ◽  
Exercise Tests ◽  
Before And After ◽  
Knee Extension Exercise

We hypothesized that a period of endurance training would result in a speeding of muscle phosphocreatine concentration ([PCr]) kinetics over the fundamental phase of the response and a reduction in the amplitude of the [PCr] slow component during high-intensity exercise. Six male subjects (age 26 ± 5 yr) completed 5 wk of single-legged knee-extension exercise training with the alternate leg serving as a control. Before and after the intervention period, the subjects completed incremental and high-intensity step exercise tests of 6-min duration with both legs separately inside the bore of a whole-body magnetic resonance spectrometer. The time-to-exhaustion during incremental exercise was not changed in the control leg [preintervention group (PRE): 19.4 ± 2.3 min vs. postintervention group (POST): 19.4 ± 1.9 min] but was significantly increased in the trained leg (PRE: 19.6 ± 1.6 min vs. POST: 22.0 ± 2.2 min; P < 0.05). During step exercise, there were no significant changes in the control leg, but end-exercise pH and [PCr] were higher after vs. before training. The time constant for the [PCr] kinetics over the fundamental exponential region of the response was not significantly altered in either the control leg (PRE: 40 ± 13 s vs. POST: 43 ± 10 s) or the trained leg (PRE: 38 ± 8 s vs. POST: 40 ± 12 s). However, the amplitude of the [PCr] slow component was significantly reduced in the trained leg (PRE: 15 ± 7 vs. POST: 7 ± 7% change in [PCr]; P < 0.05) with there being no change in the control leg (PRE: 13 ± 8 vs. POST: 12 ± 10% change in [PCr]). The attenuation of the [PCr] slow component might be mechanistically linked with enhanced exercise tolerance following endurance training.

Regional changes in capillary supply in skeletal muscle of high-intensity endurance-trained rats

1996 ◽  
Vol 81 (2) ◽  
pp. 619-626 ◽  
Author(s):  
D. Gute ◽  
C. Fraga ◽  
M. H. Laughlin ◽  
J. F. Amann
Keyword(s):  
Training Program ◽  
Endurance Training ◽  
High Intensity ◽  
Gastrocnemius Muscle ◽  
Citrate Synthase ◽  
Muscle Fiber Types ◽  
Numerical Density ◽  
Image Analyzer ◽  
Fiber Types ◽  
Capillary Supply

The objective of this study was to test the hypothesis that an endurance training program designed to produce recruitment of all extensor muscle fiber types during each exercise bout would stimulate capillary angiogenesis throughout rat gastrocnemius and soleus muscles. Male Sprague-Dawley rats were exercise trained 5 days/wk for 12–14 wk with exercise bouts consisting of a combination of high intensity (32 m/min on a 15% incline) and long duration (90 min/day). On completion of high-intensity endurance training (HIET) or cage activity [sedentary (Sed)], rat hindquarters were vascularly isolated and perfusion fixed with a modified Karnovsky's fixative. Capillary supply was measured in soleus and gastrocnemius muscles by using Olympus Cue 2 image-analyzer software. Capillary supply was reflected in measurements of capillary-to-fiber ratio, capillary numerical density, capillary surface area density, and capillary volume density on transversely cut tissue sections. HIET increased citrate synthase activity by 20 and 42% in the medial and long heads of the triceps brachii, respectively. Sarcomere lengths were similar in gastrocnemius and soleus muscles of Sed and HIET rats after fixation. All four indexes of capillary supply were significantly greater throughout the gastrocnemius muscle of HIET rats compared with Sed values. The relative increase in capillarity was greater in white than in red gastrocnemius muscle of HIET rats. HIET also increased capillary supply of soleus muscle. However, only capillary numerical density was statistically greater (19%) in HIET soleus compared with Sed. These results support the hypothesis that this training program would produce an increase in capillary supply in all extensor muscles.

scholarly journals The relationship between the expression of PLIN3 and PLIN5 protein flowing endurance training in streptozotocin rats

2019 ◽  
Vol 21 (4) ◽  
pp. 194-199
Author(s):  
Mahdi Ghafari ◽  
Ebrahim Banitalebi ◽  
Mohamad Faramarzi
Keyword(s):  
Insulin Resistance ◽  
Endurance Training ◽  
High Intensity ◽  
Training Group ◽  
Control Group ◽  
High Intensity Training ◽  
Significant Difference ◽  
Post Hoc ◽  
The Relationship ◽  
Intensity Training

Background and aims: Intermuscular lipolysis disorder plays an important role in insulin resistance and diabetes mellitus and perilipin PLIN5 and PLIN3 are the key proteins in regulating muscle cellular lipolysis. Therefore, the purpose of this study was to examine the relationship between the expression of PLIN3 and PLIN5 protein following endurance training in streptozotocin (STZ) rats. Methods: A number of 24 male Wistar rats were randomly divided into low endurance training group (n = 8), high-intensity training group (n = 8), and control group (n = 8). Diabetes was induced in every rat by STZ injection. Three days after injection, the blood samples were taken from the cut tip of the tails of the mice and animals with blood glucose greater than 300 mg/dL were considered diabetic. The training program included eight weeks of aerobic training at different intensities. Training in high- and low-intensity groups included 22-25 and 5-8 m/min of training. Finally, one-way analysis of variance (ANOVA) and correlation was used to determine the significance of the differences between variables, followed by utilizing Tukey’s post-hoc test for significance. Results: The comparison between the groups by ANOVA showed significant differences in PLIN3 (P=0.0006) and PLIN5 (P=0.012). The results of Tukey post hoc test also demonstrated a statistical difference between the mean values of diabetic control group and high-intensity endurance group regarding PLIN3 (P=0.01) and PLIN5 (P=0.009), but no significant increase was observed in the lowintensity exercise group as compared to the control group (PLIN3, P=0.067 & PLIN5, P=0.44). As regards insulin resistance, there was a significant difference among the three groups (P=0.0001). Eventually, the result of the correlation between PLIN3 and PLIN5 showed similar enhancement by increasing the intensity (P=0.0026). Conclusion: According to research results, high-intensity endurance training increased the expression of PLIN3 and PLIN5 in diabetic specimens and PLIN3 and PLIN5 followed a similar increase pattern in high-intensity training

Reflexive Response of Neck Muscle to Sudden Perturbation after Prolonged Smartphone Use

2021 ◽  
Vol 65 (1) ◽  
pp. 1250-1253
Author(s):  
Eunjee Kim ◽  
Donghyun Song ◽  
Dasom Park ◽  
Hyorim Kim ◽  
Gwanseob Shin
Keyword(s):  
Cervical Spine ◽  
Muscle Activation ◽  
Neck Muscle ◽  
Spinal Stability ◽  
Delayed Onset ◽  
Activation Level ◽  
Before And After ◽  
Smartphone Use ◽  
Head Stability ◽  
Passive Stretch

Prolonged smartphone use induces passive stretch of neck tissues and muscle fatigue, affecting spinal stability and pain. It is necessary to evaluate the effect of smartphone use on the reflexive response to detect the changes in neck tissues and head stability. A laboratory experiment (n=10) was conducted to investigate the reflexive response of neck muscle to perturbation after 30 minutes of smartphone use. Neck extensor muscle activation and its activation timing to perturbation were investigated before and after smartphone use. Head angle and muscle activation level were collected during smartphone use. During smartphone use, muscle activation gradually increased. After smartphone use, neck muscles showed a higher activation level and significantly delayed onset to perturbation. Smartphone use changed the reflexive response of the neck muscle. Further study is needed to investigate the association between smartphone use and neuromuscular changes to the tissues of the cervical spine.

Polarized Versus High-Intensity Multimodal Training in Recreational Runners

2019 ◽  
Vol 14 (1) ◽  
pp. 105-112 ◽  
Author(s):  
Andrew J. Carnes ◽  
Sara E. Mahoney
Keyword(s):  
Body Composition ◽  
Oxygen Uptake ◽  
Endurance Training ◽  
Maximal Oxygen Uptake ◽  
High Intensity ◽  
Time Trial ◽  
Lower Volume ◽  
High Zone ◽  
Multimodal Training ◽  
Recreational Runners

Purpose: This study longitudinally compared changes in running performance (5-km time trial) and fitness (maximal oxygen uptake [VO2max] and body composition [BC]) between polarized training and CrossFit Endurance (CFE) in recreational runners. Methods: Participants (N = 21) completed 12 wk of CFE or polarized endurance training (POL). Both groups trained 5 d·wk−1. POL ran 5 d·wk−1, whereas CFE ran 3 d·wk−1 and performed CrossFit 3 d·wk−1 (run + CrossFit 1 d·wk−1). Intensity was classified as low, moderate, or high (zone 1, 2, or 3) according to ventilatory thresholds. POL was prescribed greater volume (295 [67] min·wk−1), distributed as 85%/5%/10% in Z1/Z2/Z3. CFE emphasized a lower volume (110 [18] min·wk−1) distribution of 48%/8%/44%. Results: POL ran 283 (75.9) min·wk−1 and 47.3 (11.6) km·wk−1, both exceeding the 117 (32.2) min·wk−1 and 19.3 (7.17) km·wk−1 in CFE (P < .001). The POL distribution (74%/11%/15%) had greater total and percentage Z1 (P < .001) than CFE (46%/15%/39%), which featured higher percentage Z3 (P < .001). Time trial improved −93.8 (40.4) s (−6.21% [2.16%]) in POL (P < .001) and −84.2 (65.7) s (−5.49% [3.56%]) in CFE (P = .001). BC improved by −2.45% (2.59%) fat in POL (P = .02) and −2.62% (2.53%) in CFE (P = .04). The magnitude of improvement was not different between groups for time trial (P = .79) or BC (P = .88). Both groups increased VO2max (P ≤ .01), but with larger magnitude (P = .04, d = 0.85) in POL (4.3 [3.6] mL·kg·min−1) than CFE (1.78 [1.9] mL·kg·min−1). Conclusions: Recreational runners achieved similar improvement in 5-km performance and BC through polarized training or CFE, but POL yielded a greater increase in VO2max. Extrapolation to longer distances requires additional research.

scholarly journals Mechanisms of Hamstring Strain Injury: Interactions between Fatigue, Muscle Activation and Function

Sports ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 65 ◽  
Author(s):  
Shaun Huygaerts ◽  
Francesc Cos ◽  
Daniel D. Cohen ◽  
Julio Calleja-González ◽  
Marc Guitart ◽  
...  
Keyword(s):  
High Intensity ◽  
Injury Risk ◽  
Muscle Activation ◽  
Injury Mechanism ◽  
Hamstring Injury ◽  
Current Evidence ◽  
Hamstring Muscle ◽  
Hamstring Strain ◽  
And Function

Isolated injury to the long head of biceps femoris is the most common type of acute hamstring strain injury (HSI). However, the precise hamstring injury mechanism (i.e., sprint-type) is still not well understood, and research is inconclusive as to which phase in the running cycle HSI risk is the greatest. Since detailed information relating to hamstring muscle function during sprint running cannot be obtained in vivo in humans, the findings of studies investigating HSI mechanisms are based on modeling that requires assumptions to be made based on extrapolations from anatomical and biomechanical investigations. As it is extremely difficult to account for all aspects of muscle-tendon tissues that influence function during high-intensity running actions, much of this complexity is not included in these models. Furthermore, the majority of analyses do not consider the influence of prior activity or muscular fatigue on kinematics, kinetics and muscle activation during sprinting. Yet, it has been shown that fatigue can lead to alterations in neuromuscular coordination patterns that could potentially increase injury risk. The present critical review will evaluate the current evidence on hamstring injury mechanism(s) during high-intensity running and discuss the interactions between fatigue and hamstring muscle activation and function.

Effect of endurance training on muscle activation and force sensation

1995 ◽  
Vol 73 (12) ◽  
pp. 1765-1773 ◽  
Author(s):  
E. Cafarelli ◽  
F. Liebesman ◽  
J. Kroon
Keyword(s):  
Endurance Training ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Endurance Performance ◽  
Motor Units ◽  
Control Group ◽  
Reduction In Force ◽  
Leg Cycling ◽  
Before And After ◽  
And Control

One of the consequences of endurance training is a reduction in force sensation in trained muscles at any exercise intensity. To study the central and peripheral contributions to this adaptation, we trained six male subjects with single-leg cycling at 60% [Formula: see text] peak (30 min/day × 3 days/week × 8 weeks); six others were matched controls. Measurements were made during separate 20-min, single-leg rides at 70% pre-training [Formula: see text] peak, with trained (TR), untrained (UT), and control (CT) legs, before and after training. No pre–post differences were observed in the control group. [Formula: see text] peak increased 18% (p < 0.05) in the TR leg and 6% (p < 0.05) in the UT leg of the trained subjects. Force sensation was significantly less in both the TR (70%; p < 0.05) and UT (50%; p < 0.05) legs during 20 min of single-leg cycling after training. Vastus lateralis EMG, plasma lactate, and heart rate were all significantly (p < 0.05) lower when cycling with either the TR or UT leg, which were both lower than when cycling with the CT leg, at the end of each 20-min ride. These data reflect an intramuscular environment that is better adapted to endurance performance by virtue of both central and peripheral mechanisms. Thus, there is less need to recruit additional motor units to maintain the same power output, and this reduced motor outflow leads to a decline in force sensation.Key words: kinesthesia, proprioception, electromyography, single-leg training, endurance training.

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