Search results for " Force"
showing 10 items of 2250 documents
Retrospective study of a series of 850 patients with temporomandibular dysfunction (TMD). Clinical and radiological findings
2009
Objective: To define the clinical and radiological characteristics of the four most common presentations of temporomandibular dysfunction-myofascial pain (MFP), disc displacement with reduction (DDWR), disc displacement without reduction (DDWoR), and osteoarthrosis (OR)-and to identify the differences among them. Material and methods: The study comprised a series of 850 patients (121 males and 729 females) seen between May 2003 and December 2006 in Valencia University General Hospital (Spain) for temporomandibular joint disease (TMJD). An analysis was made of the possible etiological factors (stress, traumatisms, sleep disturbances, parafunctional habits, reason for consultation), possible …
Effects of Sparring Load on Reaction Speed and Punch Force During the Precompetition and Competition Periods in Boxing.
2017
Seven, male, national-level boxers (age, 20.3 ± 2.7 years; height, 1.80 ± 0.06 m; mass, 73.8 ± 11.1 kg) participated in this study to investigate the effects of sparring on reaction time and punch force of straight punches measured during the precompetition and competition periods. Heart rate and blood lactate concentrations were also monitored. Sparring load was chosen in accordance with the current rules: 3 × 3-minute bouts with 1-minute break in between. Reaction time of rear straight lengthened (p < 0.01) during the sparring load of the precompetition period after the third round (to 390 milliseconds) in comparison to the competition period (to 310 milliseconds). Reaction time of lead s…
Influence of aging on the mechanical behavior of leg extensor muscles.
1980
Age dependence of the mechanical behavior of leg extensor muscle was investigated using vertical jumps with and without a stretch-shortening cycle on the force-platform. A total 226 subjects (113 females and 113 males) ranging in age from 4--73 years were examined. The results indicated in general that performance in males was better than that in females. This difference was reduced when body weight was taken into consideration. The peak performance of the various parameters, such as average force, height of rise of center of gravity, net impulse, and also the average power output, was reached in both sexes between the ages of 20 and 30 years. For example, the average vertical force in squa…
Bone Density, Structure and Strength, and Their Determinants in Aging Sprint Athletes
2012
This study was undertaken to examine bone properties in masters sprinters of different ages and younger reference subjects. In addition, the association of sport-specific ground reaction force, muscle, training, and hormone characteristics with the bone parameters was evaluated in the athletes.Bone densitometric, structural, and strength parameters were assessed by peripheral quantitative computed tomography at the distal and midtibia in 83 male sprinters (40-85 yr) and 19 physically active referents (31-45 yr). Between-group differences were analyzed by ANCOVA with body mass and height as covariates.Bone values were generally greater in athletes than referents, the greatest differences bei…
Maximal and explosive force production capacity and balance performance in men of different ages
1999
A group of 32 healthy men (M) divided into three different age groups, i.e. M20 years [mean 21 (SD 1); n = 12], M40 [mean 40 (SD 2); n = 10] and M70 [mean 71 (SD 5); n = 10] volunteered as subjects for examination of maximal and explosive force production of leg extensor muscles in both isometric and dynamic actions (squat jump, SJ and counter movement jump, CMJ, and standing long-jump, SLJ). The balance test was performed on a force platform in both isometric and dynamic actions. Maximal bilateral isometric force value in M70 was lower (P < 0.001) than in M40 and as much as 46% lower (P < 0.001) than that recorded in M20 (P < 0.001). The maximal rate of force development (RFD) on the force…
Maximal force, force/time and activation/coactivation characteristics of the neck muscles in extension and flexion in healthy men and women at differ…
2002
This study examined the force production characteristics, activation/coactivation and endurance capacity of the neck extension and flexion muscles in healthy men (n=29) and women (n=28) divided into three age groups (18–26 years, 30–37 years and 45–55 years). Force and electromyography (EMG) measurements were performed during the maximal voluntary isometric extension and flexion actions. This was followed by an endurance test (ET; 60% force level of maximal voluntary contraction sustained until exhaustion), after which the force and EMG recordings were repeated. Men were both stronger and had higher values (P<0.001) for explosive force (rate of force development, RFD) than women in both act…
The Temporal Structure of Vertical Arm Movements
2011
Import JabRef | WosArea Life Sciences and Biomedicine - Other Topics; International audience; The present study investigates how the CNS deals with the omnipresent force of gravity during arm motor planning. Previous studies have reported direction-dependent kinematic differences in the vertical plane; notably, acceleration duration was greater during a downward than an upward arm movement. Although the analysis of acceleration and deceleration phases has permitted to explore the integration of gravity force, further investigation is necessary to conclude whether feedforward or feedback control processes are at the origin of this incorporation. We considered that a more detailed analysis of…
Grip force regulates hand impedance to optimize object stability in high impact loads
2011
Anticipatory grip force adjustments are a prime example of the predictive nature of motor control. An object held in precision grip is stabilized by fine adjustments of the grip force against changes in tangential load force arising from inertia during acceleration and deceleration. When an object is subject to sudden impact loads, prediction becomes critical as the time available for sensory feedback is very short. Here, we investigated the control of grip force when participants performed a targeted tapping task with a hand-held object. During the initial transport phase of the movement, load force varied smoothly with acceleration. In contrast, in the collision, load forces sharply incre…
Effects of combined hand-arm vibration and cold on skin temperature
1989
Under laboratory conditions 14 healthy male subjects were exposed to hand-arm vibration (ahzw = 6.3 m/s2) at different air temperatures (5 degrees, 12 degrees, 18 degrees and 25 degrees C). Static load (grip force 15 N, push force 40 N) was kept constant. Finger tip temperature as an indirect criterion of the peripheral blood circulation was measured. As expected, low air temperatures (5 degrees, 12 degrees and 18 degrees C) cause a strong decrease of skin temperature. Under additional stress of vibration connected with static load, a further decrease of the mean skin temperature was noted. At this, static load proved to have a predominant influence on the acute diminution of skin temperatu…
Testing the flexibility of the modified receptive field (MRF) theory: evidence from an unspaced orthography (Thai).
2013
In the current study, we tested the generality of the modified receptive field (MRF) theory (Tydgat & Grainger, 2009) with English native speakers (Experiment 1) and Thai native speakers (Experiment 2). Thai has a distinctive alphabetic orthography with visually complex letters (ฝ ฟ or ผ พ) and nonlinear characteristics and lacks interword spaces. We used a two-alternative forced choice (2AFC) procedure to measure identification accuracy for all positions in a string of five characters, which consisted of Roman script letters, Thai letters, or symbols. For the English speakers, we found a similar pattern of results as in previous studies (i.e., a dissociation between letters and symbols). I…