Search results for "muscles"
showing 10 items of 616 documents
Neuromuscular fatigue and recovery in male and female athletes during heavy resistance exercise.
1993
To examine neuromuscular fatigue and recovery ten male and nine female athletes performed a strenuous heavy resistance exercise protocol. The subjects strained their leg extensor muscles with the same maximal relative intensity by performing one maximal squat-lift with a load of 100% of 1 RM (one repetition maximum) 20 times (20 x 1 x 100%). Maximal voluntary neural activation (integrated EMG), maximal bilateral isometric force, force-time and relaxation-time curves of the leg extensor muscles were measured before and immediately after the exercise session as well as after resting for 1 hour, 2 hours, 1 day and 2 days. The session resulted in considerable gradual decreases in maximal force …
Daily hormonal and neuromuscular responses to intensive strength training in 1 week.
1988
Daily adaptive responses in the neuromuscular and endocrine systems to a 1-week very intensive strength training period with two training sessions per day were investigated in eight elite weight lifters. The morning and the afternoon sessions resulted in acute decreases (P less than 0.05-0.01) in maximal isometric strength and in the maximal neural activation (iEMG) of the leg extensor muscles, but the basic levels remained unaltered during the entire training period. Significant (P less than 0.05-0.01) acute increases in serum total and free testosterone levels were found during the afternoon sessions. During the 1-week training period, serum total and free testosterone concentrations decr…
Individual Region- and Muscle-specific Hamstring Activity at Different Running Speeds
2019
Introduction \ud Hamstring strain injuries typically occur in the proximal biceps femoris long head (BFlh) at high running speeds. Strain magnitude seems to be the primary determinant of strain injury, and may be regulated by muscle activation. In running, BFlh strain is largest in the proximal region, especially at high speeds. However, region-specific activity has not been examined. This study examined the proximal–distal and intermuscular activity of BFlh and semitendinosus (ST) as a function of increasing running speed.\ud \ud Methods \ud Thirteen participants ran at steady speeds of 4.1 (slow), 5.4 (moderate), and 6.8 m·s−1 (fast) on a treadmill. Region- and muscle-specific EMG activit…
Attentional Focus and Grip Width Influences on Bench Press Resistance Training.
2018
This study evaluated the influence of different attentional foci for varied grip widths in the bench press. Eighteen resistance-trained men were familiarized with the procedure and performed a one-repetition maximum (1RM) test during Session 1. In Session 2, they used three different standardized grip widths (100%, 150%, and 200% of biacromial width distance) in random order at 50% of 1RM while also engaged in three different attention focus conditions (external focus on the bench press, internal focus on pectoralis major muscles, and internal focus on triceps brachii muscles). Surface electromyography (EMG) signals were recorded from the triceps brachii and pectoralis major, and peak EMG …
High-density electromyography activity in various hamstring exercises
2019
Proximal-distal differences in muscle activity are rarely considered when defining the activity level of hamstring muscles. The aim of this study was to determine the inter-muscular and proximal-distal electromyography (EMG) activity patterns of hamstring muscles during common hamstring exercises. Nineteen amateur athletes without a history of hamstring injury performed 9 exercises, while EMG activity was recorded along the biceps femoris long head (BFlh) and semitendinosus (ST) muscles using 15-channel high-density electromyography (HD-EMG) electrodes. EMG activity levels normalized to those of a maximal voluntary isometric contraction (%MVIC) were determined for the eccentric and concentr…
Effects of a nonsurgical exercise program on the decreased mouth opening in patients with systemic scleroderma.
2004
The decreased mouth opening (microstomia) represents a frequent finding in patients with systemic scleroderma (SSD), but little information is available about the efficacy of nonsurgical management of this condition. The aim of this study is to assess the effects of a nonsurgical exercise program on the decreased mouth opening in a group of 10 SSD patients with severe microstomia (maximal mouth opening 0.1). At the end of the 18-week period, all patients commented that eating, speaking and oral hygiene measures were easier. The edentulous subjects also experienced less difficulty inserting their own dentures. These findings suggest that regular application of the proposed exercise program m…
Muscle activity levels in upper-body push exercises with different loads and stability conditions.
2014
Exercises that aim to stimulate muscular hypertrophy and increase neural drive to the muscle fibers should be used during rehabilitation. Thus, it is of interest to identify optimal exercises that efficiently achieve high muscle activation levels.The purpose of this study was to compare the muscle activation levels during push-up variations (ie, suspended push-ups with/without visual input on different suspension systems, and push-ups on the floor with/without additional elastic resistance) with the bench press exercise and the standing cable press exercise both performed at 50%, 70%, and 85% of the 1-repetition maximum.Young fit male university students (N = 29) performed 3 repetitions in …
Neutral Spine Control Exercises in Rehabilitation After Lumbar Spine Fusion
2014
Lumbar spine fusion (LSF) has been reported to change the biomechanics of the spine and therefore the rehabilitation after LSF is important. In this study, the effect of selected neutral spine control exercises on activation of trunk muscles after LSF was evaluated. Muscle activity was measured by surface electromyography of the rectus abdominis, external oblique, longissimus, and multifidus muscles during 6 exercises in 22 LSF patients (mean age = 59 years; age range = 25-84 years; 50% women). Muscle activity concurrent with trunk flexion and extension during maximal voluntary isometric contraction (MVIC) was used as a reference value. Pain during the effort was assessed with a visual anal…
Persistent unilateral tibialis anterior muscle hypertrophy with complex repetitive discharges and myalgia
1992
Unilateral enlargement of the tibialis anterior muscle associated with complex repetitive discharges occurred over several months in two patients and was preceded by pain and numbness in the lower leg. Neuroradiologic investigations excluded a compressive radiculopathy, but pharmacologic and neurophysiologic studies suggested a neurogenic basis for the muscle hypertrophy. Botulinum toxin A injection into the hypertrophied muscles led to a decreased muscle volume and cessation of muscle pain.
Relationship between electrical and mechanical properties of motor units.
1990
In six healthy volunteers, the size of the motor unit action potential (MUAP) was related to its contractile behaviour. Electrical activity was determined by measuring amplitude and area of the potential, using the macro electromyography (EMG) technique. The mechanical response was characterised by contraction time, twitch force and relaxation time, recorded with the spike triggered averaging technique. With increasing tension of the whole muscle corresponding to an increasing threshold, the force of single units enlarged exponentially compared to their EMG. There was only a weak relationship between contraction time and electrical activity and none between EMG and relaxation time.