scholarly journals Changes in Spinal-Reflex Excitability during Static Stretch and/or Explosive Contraction

2021 ◽  
Vol 11 (6) ◽  
pp. 2830
Author(s):  
Kyeong Eun Min ◽  
YongSuk Lee ◽  
Jihong Park
Keyword(s):  
Motor Response ◽  
Vertical Jump ◽  
Spinal Reflex ◽  
Static Stretch ◽  
Young Males ◽  
Reflex Excitability ◽  
Contraction Condition ◽  
Exercise Activity ◽  
Point Condition ◽  
The Right

To examine individual or combined effects of static stretch and explosive contraction on quadriceps spinal-reflex excitability (the peak Hoffmann’s reflex normalized by the peak motor-response) and the latency times of the Hoffmann’s reflex and motor-response. Fourteen healthy young males randomly experienced four conditions (stretch, contraction, stretch + contraction, and control—no intervention). For the stretch condition, three sets of a 30 s hold using the modified Thomas test on each leg were performed. For the contraction condition, three trials of maximal countermovement vertical jump were performed. Quadriceps spinal-reflex excitability and the latent period of each value on the right leg were compared at pre- and post-condition. All measurement values across conditions were not changed at any time point (condition × time) in spinal-reflex excitability (F6,143 = 1.10, p = 0.36), Hoffmann’s reflex latency (F6,143 = 0.45, p = 0.84), motor-response latency (F6,143 = 0.37, p = 0.90), and vertical jump heights (F2,65 = 1.82, p = 0.17). A statistical trend was observed in the contraction condition that spinal-reflex excitability was increased by 42% (effect size: 0.63). Neither static stretch nor explosive contraction changed the quadriceps spinal-reflex excitability, latency of Hoffmann’s reflex, and motor-response. Since our stretch protocol did not affect jumping performance and our contraction protocol induced the post-activation potentiation effect, either protocol could be used as pre-exercise activity.

scholarly journals Compartment Syndrome: an Acute Femoral Stress Fracture in a Young Male Athlete

2021 ◽  
Author(s):  
Amelie Kanovsky ◽  
Ernst J. Mueller
Keyword(s):  
Compartment Syndrome ◽  
Muscle Mass ◽  
Stress Fracture ◽  
Acute Stress ◽  
Young Male ◽  
Young Males ◽  
Fatigued Muscle ◽  
Fracture Osteosynthesis ◽  
Initial Fracture ◽  
The Right

AbstractThe incidence of an acute compartment syndrome (ACS) of the thigh is less than 1%. It is most common in the setting of muscle overuse or muscle injury, as well as secondary to trauma, such as a femoral fracture. We present a case of an ACS in a young, healthy, and semiprofessional athlete with normal coagulation who sustained an acute stress fracture of the distal femur. After the initial fracture osteosynthesis, the patient suffered from a compartment syndrome in the right anterior aspect of the distal thigh. Following rapid surgical fasciotomy, the case was uneventful, and he returned to his preinjury sport level without any neurological consequences. This case confirms that ACS in the thigh is rare, but mainly occurs in young males with a large muscle mass due to participation in various athletic programs. We hypothesize that constant muscle over-usage primes for a larger amount of contused and protruding muscle mass in the small femoral compartment. Hence, the fatigued muscle subjects the bone to an increased mechanical force resulting in an overloading process. This ensues the accumulation of femoral microfractures and primes for the occurrence of an increased rate of stress fractures and an ACS in the thigh.

Changes in H-reflex amplitude to muscle stretch and lengthening in humans

2016 ◽  
Vol 27 (5) ◽  
pp. 511-522 ◽  
Author(s):  
Francesco Budini ◽  
Markus Tilp
Keyword(s):  
Human Movement ◽  
Careful Consideration ◽  
H Reflex ◽  
Spinal Reflex ◽  
Neural Pathways ◽  
Static Stretching ◽  
Plantar Flexors ◽  
Reflex Excitability ◽  
Apparent Disagreement ◽  
Shed Light

AbstractSpinal reflex excitability is traditionally assessed to investigate neural adjustments that occur during human movement. Different experimental procedures are known to condition spinal reflex excitability. Among these, lengthening movements and static stretching the human triceps have been investigated over the last 50 years. The purpose of this review is to shed light on several apparent incongruities in terms of magnitude and duration of the reported results. In the present review dissimilarities in neuro-spinal changes are examined in relation to the methodologies applied to condition and measure them. Literature that investigated three different conditioning procedures was reviewed: passive dorsiflexion, active dorsiflexion through antagonists shortening and eccentric plantar-flexors contractions. Measurements were obtained before, during and after lengthening or stretching. Stimulation intensities and time delays between conditioning procedures and stimuli varied considerably. H-reflex decreases immediately as static stretching is applied and in proportion to the stretch degree. During dorsiflexions the inhibition is stronger with greater dorsiflexion angular velocity and at lower nerve stimulation intensities, while it is weaker if any concomitant muscle contraction is performed. Within 2 s after a single passive dorsiflexion movement, H-reflex is strongly inhibited, and this effect disappears within 15 s. Dorsiflexions repeated over 1 h and prolonged static stretching training induce long-lasting inhibition. This review highlights that the apparent disagreement between studies is ascribable to small methodological differences. Lengthening movements and stretching can strongly influence spinal neural pathways. Results interpretation, however, needs careful consideration of the methodology applied.

Blow/trauma to the chest and sudden cardiac death: Commotio cordis and contusio cordis are leading causes

2018 ◽  
Vol 58 (2) ◽  
pp. 93-96 ◽  
Author(s):  
Lydia Krexi ◽  
Mary N Sheppard
Keyword(s):  
Sudden Cardiac Death ◽  
Cardiac Death ◽  
Traffic Accidents ◽  
Left Ventricular ◽  
Young Males ◽  
Contusio Cordis ◽  
Commotio Cordis ◽  
Forensic Practice ◽  
Acute Changes ◽  
The Right

Background In forensic practice, a blow to the chest can lead to sudden cardiac death (SCD). Commotio cordis and contusio cordis are leading causes. Methods From a database of 4678 patients who suffered from SCD, we found three patients with commotio cordis and two patients with contusio cordis. All the patients were examined macroscopically and microscopically and had negative toxicology screen. Results The three patients who died due to commotio cordis were young males (16, 23 and 38 years old). The circumstances of death were: a blow to the chest by a football, by a friend during a party and during an assault. The hearts were completely normal at autopsy. The two patients who had contusio cordis were older males (42 and 63 years old). Both patients died during traffic accidents. At autopsy, one had significant contusion over the left ventricle, and the second had contusion over the right ventricle. Conclusion This study indicates that a blow to the chest is very important to document in the circumstances of death, and a detailed history is vital. It raises the left ventricular intra-cavitary pressure, leading to commotio cordis with immediate death with a normal heart. Blunt chest trauma can cause direct myocardial lesions, with acute changes leading to contusio cordis.

scholarly journals Neuromuscular Function of the Knee Joint Following Knee Injuries: Does It Ever Get Back to Normal? A Systematic Review with Meta-Analyses

2020 ◽  
Author(s):  
Beyza Tayfur ◽  
Chedsada Charuphongsa ◽  
Dylan Morrissey ◽  
Stuart Charles Miller
Keyword(s):  
Systematic Review ◽  
Knee Joint ◽  
Strong Evidence ◽  
Knee Injuries ◽  
Neuromuscular Function ◽  
Spinal Reflex ◽  
Voluntary Activation ◽  
Moderate Evidence ◽  
Reflex Excitability ◽  
Meta Analyses

Abstract Background Neuromuscular deficits are common following knee injuries and may contribute to early-onset post-traumatic osteoarthritis, likely mediated through quadriceps dysfunction. Objective To identify how peri-articular neuromuscular function changes over time after knee injury and surgery. Design Systematic review with meta-analyses. Data Sources PubMed, Web of Science, Embase, Scopus, CENTRAL (Trials). Eligibility Criteria for Selecting Studies Moderate and high-quality studies comparing neuromuscular function of muscles crossing the knee joint between a knee-injured population (ligamentous, meniscal, osteochondral lesions) and healthy controls. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and other torque related outcomes. Results A total of 46 studies of anterior cruciate ligament (ACL) and five of meniscal injury were included. For ACL injury, strength and voluntary activation deficits were evident (moderate to strong evidence). Cortical excitability was not affected at < 6 months (moderate evidence) but decreased at 24+ months (moderate evidence). Spinal-reflex excitability did not change at < 6 months (moderate evidence) but increased at 24+ months (strong evidence). We also found deficits in torque variability, rate of torque development, and electromechanical delay (very limited to moderate evidence). For meniscus injury, strength deficits were evident only in the short-term. No studies reported gastrocnemius, soleus or popliteus muscle outcomes for either injury. No studies were found for other ligamentous or chondral injuries. Conclusions Neuromuscular deficits persist for years post-injury/surgery, though the majority of evidence is from ACL injured populations. Muscle strength deficits are accompanied by neural alterations and changes in control and timing of muscle force, but more studies are needed to fill the evidence gaps we have identified. Better characterisation and therapeutic strategies addressing these deficits could improve rehabilitation outcomes, and potentially prevent PTOA. Trial Registration Number PROSPERO CRD42019141850.

GROUND REACTION FORCES OF COMMONLY USED VOLLEYBALL BLOCKING APPROACHES

2020 ◽  
Vol 30 (89) ◽  
pp. 13-20
Author(s):  
Dimitrije Cabarkapa ◽  
Andrew Fry ◽  
Damjana Cabarkapa ◽  
Arden Rogers ◽  
Eric Mosier
Keyword(s):  
Vertical Jump ◽  
Force Plate ◽  
Ground Reaction Forces ◽  
Strength And Conditioning ◽  
Advanced Level ◽  
Warm Up ◽  
Concentric Force ◽  
Vertical Jump Height ◽  
Reaction Forces ◽  
The Right

Aim: The purpose of this study was to quantify ground reaction forces for some of the most commonly utilised volleyball blocking approaches and to examine their kinetic and kinematic characteristics. Basic procedures: The study was comprised of 18 healthy recreationally active women who volunteered to participate. Immediately after completion of the warm-up protocol, subjects performed 5 blocking approaches: stationary blocking approach (SBA), shuffle block to the right (SHBR), shuffle block to the left (SHBL), swing block to the right (SWBR) and swing block to the left (SWBL). In order to allow adequate recovery, each trial was randomly assigned and separated by a 1-2 minute rest interval. A uni-axial force plate with data acquisition system sampling at 1000 Hz was used to measure ground reaction forces. Main findings: SWBR and SWBL unveiled the greatest peak concentric force and rate of force development when compared to SBA, while no difference was observed when compared to SHBR and SHBL. Results: No significant differences were observed in peak landing force, impulse, and vertical jump height between any of the blocking approaches examined in this study. Conclusions: Knowing biomechanical characteristics of some of the most commonly utilised volleyball blocking approaches may help athletes to appropriately respond and quickly adjust to the opponent’s attacking position. Kinetic and kinematic variables are likely to be augmented with an advanced level of competition and can be trained and improved by properly designed and implemented strength and conditioning programmes.

scholarly journals Maturational trajectories of white matter microstructure underlying the right presupplementary motor area reflect individual improvements in motor response cancellation in children and adolescents

2020 ◽  
Author(s):  
Kathrine Skak Madsen ◽  
Louise Baruël Johansen ◽  
Wesley K. Thompson ◽  
Hartwig R. Siebner ◽  
Terry L. Jernigan ◽  
...  
Keyword(s):  
White Matter ◽  
Children And Adolescents ◽  
Fractional Anisotropy ◽  
Motor Response ◽  
Stop Signal ◽  
Motor Area ◽  
Stop Signal Task ◽  
List Type ◽  
White Matter Microstructure ◽  
The Right

AbstractThe ability to effectively suppress motor response tendencies is essential for focused and goal-directed behavior. Here, we tested the hypothesis that developmental improvement in the ability to cancel a motor response is reflected by maturational changes in the white matter underlying the right presupplementary motor area (preSMA) and posterior inferior frontal gyrus (IFG), two cortical key areas of the fronto-basal ganglia “stopping” network. Eighty-eight typically-developing children and adolescents, aged 7-19 years, were longitudinally assessed with the stop-signal task (SST) and diffusion tensor imaging (DTI) of the brain over a period of six years. Participants were examined from two to nine times with an average of 6.6 times, resulting in 576 SST-DTI datasets. We applied tract-based spatial statistics to extract mean fractional anisotropy (FA) from regions-of-interest in the white matter underlying the right IFG (IFGFA) and right preSMA (preSMAFA) at each time point. Motor response cancelation performance, estimated with the stop-signal reaction time (SSRT), improved with age. Initially well performing children plateaued around the age of 11 years, while initially poor performers caught up at the age of 13-14 years. White matter microstructure continued to mature across the investigated age range. Males generally displayed linear maturational trajectories, while females displayed more curvilinear trajectories that leveled off around 12-14 years of age. Maturational increases in right preSMAFA but not right IFGFA were associated with developmental improvements in SSRT. This association differed depending on the mean right preSMAFA across the individual maturational trajectory. Children with lower mean right preSMAFA exhibited poorer SSRT performance at younger ages but steeper developmental trajectories of SSRT improvement. Children with higher mean right preSMAFA exhibited flatter trajectories of SSRT improvement along with faster SSRT already at the first assessments. The results suggest that no further improvement in motor response cancellation is achieved once a certain level of maturity in the white matter underlying the right preSMA is reached. Similar dynamics may apply to other behavioral read-outs and brain structures and, thus, need to be considered in longitudinal MRI studies designed to map brain structural correlates of behavioral changes during development.HighlightsMotor response cancellation, i.e. SSRT, improvement plateaued at 13-14 years of ageFractional anisotropy (FA) captured maturation of white matter (WM) microstructureFA in the WM underlying right preSMA (preSMAFA) reflected SSRT improvement with ageIndividual SSRT improvement depended on mean right preSMAFA across all DTI sessionsChildren with lower mean right preSMAFA had the steepest improvements in SSRT

Sign in / Sign up

Export Citation Format

Share Document