Interaction of breathing pattern and posture on abdominal muscle activation and intra-abdominal pressure in healthy individuals: a comparative cross-sectional study.

We aimed to assess the effects of interaction between several breathing patterns and postures on abdominal muscle activation and intra-abdominal pressure (IAP). This comparative cross-sectional study enrolled fourteen healthy university students majoring in sports science and/or physical education. They performed four active breathing tasks: quiet nasal breathing (Q-Bre), nasal deep breathing (Deep-Bre), completely forced expiration (Forced-Expi), and exertional nasal inhalation with abdominal muscles with isometric contraction (Exertion-Inspi) in the elbow-toe plank and supine postures.

Neuromuscular activation of the quadriceps femoris, including the vastus intermedius, during isokinetic knee extensions.

The purpose of this study was to compare the neuromuscular activation patterns of the individual muscles of the quadriceps femoris (QF), including the vastus intermedius (VI), during isokinetic concentric (CON) and eccentric (ECC) contractions. Thirteen healthy men performed maximum isokinetic CON and ECC knee extensions at angular velocities of 30, 90, and 120°/sec at knee joint angles from 80 to 180° (180° = full extension). The surface electromyographic (EMG) activities of the four individual muscles of the QF were recorded.

Effects of 8-Week Exhausting Deep Knee Flexion Flywheel Training on Persistent Quadriceps Weakness in Well-Trained Athletes Following Anterior Cruciate Ligament Reconstruction.

Persistent quadriceps weakness after anterior cruciate ligament (ACL) reconstruction is a common hurdle to efficient rehabilitation. Therefore, we evaluated a new treatment strategy for athletes with ACL reconstruction. Eleven athletes with unilateral ACL reconstruction performed one set of flywheel Bulgarian split squats to exhaustion with a maximum knee extension of 60°, over 16 sessions, on their reconstructed limb.

Quadriceps Function and Athletic Performance in Highly Trained Female Athletes.

Context: Quadriceps strength is considered a key contributor to performance in various athletic tasks. Yet, past research has reported conflicting results based on population, with little data available in highly trained female athletes.

Design: Cross-sectional.

Changes in biceps brachii muscle hardness assessed by a push-in meter and strain elastography after eccentric versus concentric contractions.

Changes in biceps brachii muscle hardness assessed by a push-in meter (PM) and strain elastography (SE) were compared between eccentric (ECC) and concentric contractions (CON) of the elbow flexors to test the hypothesis that muscle hardness would increase greater after ECC. Ten men performed 5 sets of 10 ECC with their non-dominant arms and 5 sets of 10 CON with their dominant arms using a dumbbell corresponding to 50% of maximum voluntary isometric contraction (MVIC) force at 90º elbow flexion. Before and 1-4 days after the exercise, MVIC force, elbow joint angles, upper-arm circumference, and muscle soreness as muscle damage makers, and biceps brachii muscle hardness at maximally extended elbow joint by PM and SE were measured.

Biceps brachii muscle hardness assessed by a push-in meter in comparison to ultrasound strain elastography.

This study investigated the relationship between push-in meter (PM) and ultrasound strain elastography (USE) for biceps brachii (BB) muscle hardness. BB hardness of 21 young men was assessed by PM and USE during rest and isometric contractions of six different intensities (15, 30, 45, 60, 75, 90% of maximal voluntary contraction: MVC) at 30°, 60° and 90° elbow flexion. Muscle hardness (E) was calculated from the force-displacement relationship in PM, and strain ratio (SR) between an acoustic coupler (elastic modulus: 22.

Characteristics of Upper-Limb Pull Power and Power Endurance in Japanese Female Wrestlers.

Naka, T, Kanno, M, Shidochi, S, Sakae, K, and Shima, N. Characteristics of upper-limb pull power and power endurance in Japanese female wrestlers. J Strength Cond Res 36(5): e82-e87, 2022-This study aimed at elucidating the characteristics of upper-limb physical strength required by female wrestlers by comparing the pull power, power endurance, and number of repetitions between female wrestlers at world and national levels.

Effects of Wearing a Compression Garment During Night Sleep on Recovery From High-Intensity Eccentric-Concentric Quadriceps Muscle Fatigue.

This study aimed to investigate the effects of wearing a compression garment (CG) during night sleep on muscle fatigue recovery after high-intensity eccentric and concentric knee extensor exercises. Seventeen male college students participated in 2 experimental sessions under CG and non-CG (NCG) wearing conditions. Before night sleep under CG or NCG wearing conditions, the subjects performed a fatiguing protocol consisting of 10 sets of 10 repetitions of maximal isokinetic eccentric and concentric knee extensor contractions, with 30-second rest intervals between the sets.

Muscle activation characteristics of the front leg during baseball swings with timing correction for sudden velocity decrease.

This study aimed to clarify the activation characteristics of the vastus lateralis muscle in the front leg during timing correction for a sudden decrease in the velocity of a target during baseball swings. Eleven male collegiate baseball players performed coincident timing tasks that comprised constant velocity of 8 m/s (unchanged) and a sudden decrease in velocity from 8 to 4 m/s (decreased velocity). Electromyography (EMG) revealed that the muscle activation was typically monophasic when responding unchanged conditions.

Regular change in spontaneous preparative behaviour on intra-abdominal pressure and breathing during dynamic lifting.

Purpose: Intra-abdominal pressure (IAP) and breathing behaviour are important preparative pre-lifting actions for functional stability during lifting. This study aimed to examine spontaneous changes in the peak rate of IAP development (Rate-IAP), peak IAP (Peak-IAP), the time of Rate- and Peak-IAP occurrence and respiratory volume in response to dynamic load lifting.

Methods: Eleven healthy men performed quick dynamic deadlifting using 30, 45, 60 and 75% of the isometric maximal lifting effort (iMLE).

Utility of noninvasive brachial-ankle pulse wave velocity measurement in people with spinal cord injury.

The purpose of the present study was to examine the utility of non-invasive brachial-ankle pulse wave velocity measurement in people with spinal cord injury based on the comparison of the data of the compliance of common femoral artery measured by ultrasonography. Five physically active persons with spinal cord injury volunteered for this study. Subjects were in a supine position on the bed, and estimate brachial-ankle pulse wave velocity and the compliance coefficient of common femoral artery.

The effect of summation of contraction on acceleration signals in human skeletal muscle.

The purpose of this study was to determine the effects of summation of contraction on acceleration signals in human skeletal muscle. The torque parameters of dorsiflexion and acceleration signals in the tibialis anterior muscle were measured during evoked isometric contractions. In an examination of two-pulse trains with different inter-pulse intervals, the torque and accelerometer responses to inter-pulse intervals of 10-100 ms were recorded.

Changes in intra-abdominal pressure and spontaneous breath volume by magnitude of lifting effort: highly trained athletes versus healthy men.

Intra-abdominal pressure (IAP) is closely related to breathing behavior during lifting. Abdominal muscles contribute to both IAP development and respiratory function. The purpose of this study was to examine whether spontaneous breath volume and IAP altered with increased isometric lifting effort, and to compare the effect of different abdominal muscle strengths on these parameters.

Changes in force and tendinous tissue elongation during the early phase of tetanic summation in in vivo human tibialis anterior muscle.

The purpose of this study was to determine the changes that occur in tendinous tissue properties during the early phase of tetanic summation in the in vivo human tibialis anterior muscle (TA). The torque response and tendinous tissue elongation following single stimuli, two-pulse trains, and three-pulse trains were recorded in the TA during isometric contractions. The elongation, compliance, and lengthening velocity of tendinous tissue were determined by real-time ultrasonography.

Orthostatic influence on heart rate and blood pressure variability in trained persons with tetraplegia.

To examine the orthostatic influence on heart rate and blood pressure variability in persons with tetraplegia playing wheelchair basketball, ten trained persons with tetraplegia, ten untrained persons with tetraplegia, and ten able-bodied participated in this study. Spectrum analysis of the ECG R-R interval and blood-pressure on a beat-by-beat basis during head-up tilt 60 degrees sitting were performed. The ratio of the high frequency to total frequency (HF/TF) in the R-R interval decreased from supine (0.

In vivo behaviour of human muscle architecture and mechanomyographic response using the interpolated twitch technique.

This study investigated the origin of curvilinear change in the superimposed mechanomyogram (MMG) amplitude of the human medial gastrocnemius muscle (MG) with increasing contraction intensity. The superimposed twitch amplitude, the superimposed MMG amplitude and the extent of fascicle shortening were measured using ultrasonic images of electrical stimulation during isometric plantar flexions at levels 20%, 40%, 60%, 80%, and 100% of the maximal voluntary contraction (MVC). The superimposed twitch amplitude, the superimposed MMG amplitude and the extent of fascicle shortening decreased with increasing contraction intensity.

The effect of a 12-week combined exercise intervention program on physical performance and gait kinematics in community-dwelling elderly women.

This study aimed to determine if combined exercise intervention improves physical performance and gait joint-kinematics including the joint angle and dynamic range of motion (ROM) related to the risk of falling in community-dwelling elderly women. A 12-week combined exercise intervention program with extra emphasis on balance, muscle strength, and walking ability was designed to improve physical performance and gait. Twenty participants attended approximately two-hour exercise sessions twice weekly for 12 weeks.

Mechanomyographic and electromyographic responses to stimulated and voluntary contractions in the dorsiflexors of young and old men.

The effect of age on mechanomyography (MMG) has not been examined for electrically evoked contractions. Similar to torque, we expected that postactivation potentiation of the MMG would differ between young and old subjects. Additionally, under voluntary conditions, we compared normalized MMG and electromyographic (EMG) signals in relation to torque, and expected that MMG, unlike EMG, would be affected by age.

The effect of postactivation potentiation on the mechanomyogram.

To examine whether postactivation potentiation (PAP) was related to changes in the electromyogram (EMG) and in the mechanomyogram (MMG), evoked twitch torque properties were compared before and after a 10 s plantar flexion MVC in ten male subjects. Peak twitch torque (Pt), and the peak acceleration of the twitch torque development (d2T/dt2) were measured from electrical tibial nerve stimulation. In addition, from the medial gastrocnemius muscle, peak to peak MMG (p-p MMG) by means of accelerometer, and peak to peak EMG (M-wave) amplitudes were recorded.

Ventilatory and heart rate responses at the onset of chair rotation in man.

In the present study, we attempted to confirm whether pulmonary ventilation and heart rate increased immediately after passive chair rotation in man. Inspiratory minute volume (V(I)), tidal volume (V(T)), respiratory frequency (f), and heart rate (HR) were determined by breath-by-breath and beat-by-beat techniques before, during, and after rotation for a total of 45 s. It was found that V(I) significantly increased immediately after chair rotation, but HR remained almost constant.

Lower extremity function in terms of shock absorption when landing with unsynchronized feet.

The purpose of this study was to clarify the lower extremity function in terms of the shock absorption during unsynchronized-foot landings. The characteristics of the supination and pronation in the ankle joint at landing were investigated, assuming that the measurements of the impact force on the body could be demonstrated by the changes that occurred during 3 different landing motions: -unsynchronized-foot landings, synchronized-foot landings, and one-foot landings. Subjects jumped to the floor from 10-cm footstools 3 times for each type of landing.

Age comparison of H-reflex modulation with the Jendrássik maneuver and postural complexity.

Objective: The purpose of this study was to examine modulation of the soleus Hoffmann (H)-reflex in response to the Jendrássik maneuver (JM) in standing positions in young and elderly subjects.

Methods: Seventeen elderly (mean age=72.0 years) and 23 young (mean age=23.

Cardiorespiratory responses to hypoxia and hypercapnia at rest in vocalists.

In order to clarify whether or not ventilatory and circulatory responses to hypoxia and hypercapnia at rest in male vocalists (n = 11) are identical to those of untrained subjects (n = 11), ventilatory responses to hypoxia (HVR) and hypercapnia (HCVR) were estimated as the slope of regression relating .VI to SaO(2) (Delta.VI/DeltaSaO(2)) or the slope factor (A) for the .

Enhanced chemosensitivity after intermittent hypoxic exposure does not affect exercise ventilation at sea level.

The purpose of the present study was to test the hypothesis that the ventilatory response to exercise at sea level may increase after intermittent hypoxic exposure for 1 week, accompanied by an increase in hypoxic or hypercapnic ventilatory chemosensitivity. One group of eight subjects (hypoxic group) were decompressed in a chamber to 432 torr (where 1 torr=1.0 mmHg, simulating an altitude of 4,500 m) over a period of 30 min and maintained at that pressure for 1 h daily for 7 days.

Cross education of muscular strength during unilateral resistance training and detraining.

The purpose of the present study was to examine the changes in maximum voluntary isometric contraction (MVC) in the contralateral untrained limb during unilateral resistance training and detraining, and to examine the factors inducing these changes by means of electrophysiological techniques. Nine healthy males trained their plantar flexor muscles unilaterally 4 day-s x week(-1) for 6 weeks using 3 sets of 10-12 repetitions at 70-75% of one-repetition maximum a day, and detrained for 6 weeks. Progressive unilateral resistance training significantly (P < 0.