The effects of acute hot-water immersion on force steadiness and motor unit discharge rate variability in young, healthy adults.

This study examined the effects of core and muscle temperature on force steadiness and motor unit discharge rate (MUDR) variability after a hot-water immersion session. Fifteen participants (6 women; 25±6 years) completed neuromuscular assessments before and after either 42ºC (hot) or 36ºC (control) water immersion. Force steadiness was measured during knee extension, while HD-sEMG signals were recorded from vastus lateralis and medialis for MUDR variability analysis.

Assessing the Effect of Riluzole on Motor Unit Discharge Properties.

This study aims to determine if Riluzole usage can change the function and excitability of motor neurons. The clinical data and indices of motor neuron excitability were assessed using high-density surface EMG parameters from 80 ALS participants. The persistent inward current was assessed using the discharge rate from paired motor units obtained from the tibialis anterior muscle.

Effects of multiple cold-water immersion during pre-season on recovery performance in under-20 male soccer players: A randomized controlled trial.

Introduction: This study was designed to evaluate the effects of multiple cold-water immersions performed daily during the preseason period on biochemical, clinical, and neuromuscular aspects of muscle damage of soccer players.

Methods: This two-arm, prospectively registered, randomized controlled trial, blinded to statistician and assessors, was conducted at professional football club facilities. Twenty-three under-20 semi-professionals male soccer players were randomly allocated into cold water immersion group (bathtub with water and ice at 10 °C ± 1 °C for 10 min) or control group (rest for 10 min), every day, after training sessions during a preseason.

One size does not fit all: Methodological considerations and recommended solutions for intramuscular temperature assessment.

Intramuscular temperature kinetics can provide insightful information for exercise and environmental physiology research. However, currently, there are no consistent method descriptions or guidelines for muscle temperature assessment in the literature. Studies have reported a great variation in muscle temperature assessment, from 1.

Persistent inward currents in human motoneurons: emerging evidence and future directions.

The manner in which motoneurons respond to excitatory and inhibitory inputs depends strongly on how their intrinsic properties are influenced by the neuromodulators serotonin and noradrenaline. These neuromodulators enhance the activation of voltage-gated channels that generate persistent (long-lasting) inward sodium and calcium currents (PICs) into the motoneurons. PICs are crucial for initiating, accelerating, and maintaining motoneuron firing.

Motoneuron persistent inward current contribution to increased torque responses to wide-pulse high-frequency neuromuscular electrical stimulation.

Purpose: To assess the effect of a remote handgrip contraction during wide-pulse high-frequency (WPHF) neuromuscular electrical stimulation (NMES) on the magnitude of extra torque, progressive increase in torque during stimulation, and estimates of the persistent inward current (PIC) contribution to motoneuron firing in the plantar flexors.

Methods: Ten participants performed triangular shaped contractions to 20% of maximal plantar flexion torque before and after WPHF NMES with and without a handgrip contraction, and control conditions. Extra torque, the relative difference between the initial and final torque during stimulation, and sustained electromyographic (EMG) activity were assessed.

The contribution of the tendon electrode to M-wave characteristics in the biceps brachii, vastus lateralis and tibialis anterior.

In some compound muscle action potentials (M waves) recorded using the belly-tendon configuration, the tendon electrode makes a noticeable contribution to the M wave. However, this finding has only been demonstrated in some hand and foot muscles. Here, we assessed the contribution of the tendon potential to the amplitude of the vastus lateralis, biceps brachii and tibialis anterior M waves, and we also examined the role of this tendon potential in the shoulder-like feature appearing in most M waves.

Caffeine does not influence persistent inward current contribution to motoneuron firing.

The purpose of this study was to investigate whether caffeine consumption would change persistent inward current (PIC) contribution to motoneuron firing at increased contraction intensities and after repetitive sustained maximal contractions. Before and after the consumption of 6 mg·kg of caffeine or placebo, 16 individuals performed isometric triangular-shaped ramp dorsiflexion contractions (to 20% and 40% of peak torque), followed by four maximal contractions sustained until torque production dropped to 60% of maximum, and consecutive 20% triangular-shaped contractions. Tibialis anterior motor unit firing frequencies were analyzed from high-density surface electromyograms.

Effects of jaw clenching and mental stress on persistent inward currents estimated by two different methods.

Spinal motoneuron firing depends greatly on persistent inward currents (PICs), which in turn are facilitated by the neuromodulators serotonin and noradrenaline. The aim of this study was to determine whether jaw clenching (JC) and mental stress (MS), which may increase neuromodulator release, facilitate PICs in human motoneurons. The paired motor unit (MU) technique was used to estimate PIC contribution to motoneuron firing.

Ageing reduces persistent inward current contribution to motor neurone firing: Potential mechanisms and the role of exercise.

Nervous system deterioration is a primary driver of age-related motor impairment. The motor neurones, which act as the interface between the central nervous system and the muscles, play a crucial role in amplifying excitatory synaptic input to produce the desired motor neuronal firing output. For this, they utilise their ability to generate persistent (long-lasting) depolarising currents that increase cell excitability, and both amplify and prolong the output activity of motor neurones for a given synaptic input.

Intrinsic motor neuron excitability is increased after resistance training in older adults.

This study investigated the effects of high-intensity resistance training on estimates of the motor neuron persistent inward current (PIC) in older adults. Seventeen participants (68.5 ± 2.

Telehealth multicomponent exercise and health education in breast cancer patients undergoing primary treatment: rationale and methodological protocol for a randomized clinical trial (ABRACE: Telehealth).

Background: Current guidelines emphasize cancer patients should increase their physical activity levels, encouraging physical exercise practice as a complementary therapy to mitigate adverse effects during treatment. Telehealth can be a feasible method to improve adherence and interventional support for breast cancer patients, of which most do not meet sufficient physical activity levels after diagnosis. The Adaptations to Breast Cancer and Exercise Using Telehealth (ABRACE: Telehealth) study aims to investigate the effects of a 12-week telehealth multicomponent training program plus a health education program (MTHE), compared to a health education program alone (HE), on physical and psychological outcomes in breast cancer patients undergoing treatment.

Effects of Plyometric Training on Physical Performance: An Umbrella Review.

Background: Plyometric training can be performed through many types of exercises involving the stretch-shortening cycle in lower limbs. In the last decades, a high number of studies have investigated the effects of plyometric training on several outcomes in different populations.

Objectives: To systematically review, summarize the findings, and access the quality of published meta-analyses investigating the effects of plyometric training on physical performance.

Increases in muscle temperature by hot water improve muscle contractile function and reduce motor unit discharge rates.

Purpose: Examine the effects of 42°C hot-water immersion on muscle contraction function and motor unit discharge rates. Voluntary and evoked contraction assessments were examined first with a concomitant increase in the core and muscle temperature, and thereafter with increased muscle temperature but cooled core temperature.

Methods: Fifteen participants (24.

The effects of α-lactalbumin supplementation and handgrip contraction on soleus motoneuron excitability.

Introduction: We tested two strategies that hypothetically increase serotonin availability (α-lactalbumin consumption and a remote submaximal handgrip contraction) on estimates of persistent inward currents (PICs) amplitude of soleus muscle in healthy participants.

Methods: With a randomised, double-blind, and cross-over design, 13 healthy participants performed triangular-shaped ramp contractions with their plantar flexors (20% of maximal torque), followed by a 30-s handgrip sustained contraction (40% of maximal force) and consecutive repeated triangular-shaped contractions. This was performed before and after the consumption of either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (Corn-starch).

Effects of α-lactalbumin on strength, fatigue and psychological parameters: a randomised double-blind cross-over study.

Purpose: The neurotransmitter serotonin has a strong effect on behaviour and motor control. Regarding motor control, serotonin contributes to the development of fatigue and is also involved in the ability of motor neurones to operate across a large range of forces (gain control). The consumption of tryptophan-rich supplements (such as α-lactalbumin) is of interest because this amino acid is the only precursor for brain serotonin synthesis.

Lower motor unit discharge rates in gastrocnemius lateralis, but not in gastrocnemius medialis or soleus, in runners with Achilles tendinopathy: a pilot study.

Objectives: Deficits in muscle performance could be a consequence of a reduced ability of a motor neuron to increase the rate in which it discharges. This study aimed to investigate motor unit (MU) discharge properties of each triceps surae muscle (TS) and TS torque steadiness during submaximal intensities in runners with Achilles tendinopathy (AT).

Methods: We recruited runners with (n = 12) and without (n = 13) mid-portion AT.

Facilitation-inhibition control of motor neuronal persistent inward currents in young and older adults.

A well-coordinated facilitation-inhibition control of motor neuronal persistent inward currents (PICs) via diffuse neuromodulation and local inhibition is essential to ensure motor units discharge at required times and frequencies. Present best estimates indicate that PICs are reduced in older adults; however, it is not yet known whether PIC facilitation-inhibition control is also altered with ageing. We investigated the responses of PICs to (i) a remote handgrip contraction, which is believed to diffusely increase serotonergic input onto motor neurones, and (ii) tendon vibration of the antagonist muscle, which elicits reciprocal inhibition, in young and older adults.

Variability of Biceps Muscle Stiffness Measured Using Shear Wave Elastography at Different Anatomical Locations With Different Ultrasound Machines.

Shear wave elastography is an emerging diagnostic tool used to assess for changes in the stiffness of muscle. Each region of the muscle may have a different stiffness; therefore, the anatomical region should be carefully selected. Machine vendors each have unique methods for calculating the returned stiffness values and, consequently, a high level of agreement in measurement between machines (quantified using the intraclass correlation coefficient [ICC] and Bland-Altman analysis) will allow research findings to be translated to the clinic.

Power Training Prescription in Older Individuals: Is It Safe and Effective to Promote Neuromuscular Functional Improvements?

Muscle power has been reported to be critical in counteracting age-related declines in functional performance. Muscle power output in functional performance exercises can be greatly improved in a short period of time (i.e.

Effects of three neuromuscular electrical stimulation methods on muscle force production and neuromuscular fatigue.

This study compared the acute responses of three neuromuscular electrical stimulation (NMES) methods on muscle torque-time integral (TTI) and neuromuscular fatigue. Narrow-pulse (0.2 ms; NP), wide-pulse (1 ms; WP), and tendon vibration superimposed onto wide-pulse (WP + VIB)-NMES conditions were applied to sixteen healthy individuals (n = 16) in three separate sessions in a randomized order.