Dynamic versus isometric electromechanical delay in non-fatigued and fatigued muscle: A combined electromyographic, mechanomyographic, and force approach

Comparison of single and multiple joint muscle functions and neural drive of trained athletes and untrained individuals

Isokinetics and Exercise Science ◽

10.3233/ies-203225 ◽

2021 ◽

pp. 1-11

Author(s):

Kale Mehmet

Keyword(s):

Muscle Activation ◽

Time Windows ◽

Knee Extension ◽

Electromechanical Delay ◽

Neural Drive ◽

Lower Limb Muscles ◽

Explosive Force ◽

Biarticular Muscle ◽

Voluntary Contractions ◽

Maximum Voluntary Force

BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC’s). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC’s (p< 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p< 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities.

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

Indian Journal of Surgery ◽

10.1007/s12262-021-02842-x ◽

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.

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The effects of 12 weeks of static stretch training on the functional, mechanical, and architectural characteristics of the triceps surae muscle–tendon complex

European Journal of Applied Physiology ◽

10.1007/s00421-021-04654-z ◽

2021 ◽

Author(s):

Stefano Longo ◽

Emiliano Cè ◽

Angela Valentina Bisconti ◽

Susanna Rampichini ◽

Christian Doria ◽

...

Keyword(s):

Muscle Activation ◽

Maximum Voluntary Contraction ◽

Muscle Stiffness ◽

Triceps Surae ◽

Maximum Force ◽

Passive Stiffness ◽

Electromechanical Delay ◽

Fascicle Length ◽

Generating Capacity ◽

Plantarflexor Muscles

Abstract Purpose We investigated the effects of 12 weeks of passive static stretching training (PST) on force-generating capacity, passive stiffness, muscle architecture of plantarflexor muscles. Methods Thirty healthy adults participated in the study. Fifteen participants (STR, 6 women, 9 men) underwent 12-week plantarflexor muscles PST [(5 × 45 s-on/15 s-off) × 2exercises] × 5times/week (duration: 2250 s/week), while 15 participants (CTRL, 6 women, 9 men) served as control (no PST). Range of motion (ROM), maximum passive resistive torque (PRTmax), triceps surae architecture [fascicle length, fascicle angle, and thickness], passive stiffness [muscle–tendon complex (MTC) and muscle stiffness], and plantarflexors maximun force-generating capacity variables (maximum voluntary contraction, maximum muscle activation, rate of torque development, electromechanical delay) were calculated Pre, at the 6th (Wk6), and the 12th week (Wk12) of the protocol in both groups. Results Compared to Pre, STR ROM increased (P < 0.05) at Wk6 (8%) and Wk12 (23%). PRTmax increased at Wk12 (30%, P < 0.05), while MTC stiffness decreased (16%, P < 0.05). Muscle stiffness decreased (P < 0.05) at Wk6 (11%) and Wk12 (16%). No changes in triceps surae architecture and plantarflexors maximum force-generating capacity variables were found in STR (P > 0.05). Percentage changes in ROM correlated with percentage changes in PRTmax (ρ = 0.62, P = 0.01) and MTC stiffness (ρ = − 0.78, P = 0.001). In CTRL, no changes (P > 0.05) occurred in any variables at any time point. Conclusion The expected long-term PST-induced changes in ROM were associated with modifications in the whole passive mechanical properties of the ankle joint, while maximum force-generating capacity characteristics were preserved. 12 weeks of PST do not seem a sufficient stimulus to induce triceps surae architectural changes.

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Evaluation of left atrial mechanics and p-wave dispersion as markers of left atrial cardiopathy in patients of embolic stroke of undetermined source (ESUS)

European Heart Journal ◽

10.1093/ehjci/ehaa946.2437 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

S Masood ◽

M.M Azharuddin ◽

S.M.K Ashraf ◽

S Wahab

Keyword(s):

Left Atrial ◽

Wave Dispersion ◽

Embolic Stroke ◽

P Wave ◽

Electromechanical Delay ◽

P Wave Dispersion ◽

Atrial Electromechanical Delay ◽

Wave Duration ◽

P Wave Duration ◽

Increased Risk

Abstract Introduction Around 25% of all ischaemic strokes have no known cause despite standard investigations. Most of these cases are suspected to have an embolic source for ischaemia, leading to the moniker of Embolic Stroke of Undetermined Source (ESUS). Recent studies suggest that abnormalities of the left atrium, in the form of atrial cardiopathy, can lead to increased risk of stroke even in the absence of atrial fibrillation (AF), which may be either as precursors to AF or as independent risk factors for the development of left atrial thrombus and subsequent stroke. Purpose The aim of this study was to measure LA electromechanical dissociation, LA volumes and P-wave dispersion as markers of atrial cardiopathy in patients with ESUS to determine whether atrial cardiopathy may be in the causal pathway of ESUS. Methods 28 patients presenting with ischaemic stroke and fulfilling the criteria for ESUS were enrolled into this cross-sectional, observational study. All patients had 24-hour Holter monitoring done to rule out the presence of AF. The control group consisted of 28 age- and gender-matched apparently healthy individuals. On ECG, P-wave Dispersion (PWD) was calculated by subtracting minimum P-wave duration from maximum P-wave duration. On echocardiography, time intervals from the beginning of P-wave to beginning of A' wave from the lateral mitral annulus in tissue doppler imaging was measured as the atrial electromechanical delay. LA volumes were recorded using the Modified Biplane Simpson's method. Statistical analysis was performed using student's t-test, chi-square test, and Pearson's test. Results Baseline demographic and laboratory characteristics were similar between the two groups. Increased PWD (34.14±9.89 ms vs. 27.32±8.95 ms; p=0.01), atrial electromechanical delay (73.32±16.31 ms vs. 63.63±13.59 ms; p=0.02) and LA volumes were observed in patients with ESUS as compared to controls. A significant correlation was also found between these parameters (p<0.01). Discussion According to the results of our study, PWD, atrial electromechanical delay and LA volumes may be novel predictors for ESUS. Atrial cardiopathy is a unique mechanism of thrombo-embolism in ESUS patients and our data establishes its association with ESUS. Further studies will be needed to shed more light on its role in the causality of stroke in the ESUS population. Measurement of electromechanical delay Funding Acknowledgement Type of funding source: None

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