Search results for "Torque"
showing 10 items of 373 documents
Self-drilling and self-tapping miniscrews for osteosynthesis fixture after LeFort I osteotomy: An ex vivo trial for primary stability and a randomize…
2017
Abstract Background Self-drilling osteosynthesis screws (SDS) have a potential higher primary stability together with clinical advantages such as less time effort compared to self-tapping screws (STS). The aims of the study were to compare the primary stability of SDS and STS ex vivo and to analyze of the time-saving effect in vivo . Materials and methods Ex vivo , both screws were placed in porcine bone. Torque was measured for insertion and removal. Four specimens were kept in bone for histologic bone-to-implant-contact examination. In vivo , 49 patients who received orthognathic surgery in the maxilla were included in 2 centers. In a split-mouth design, the time for osteosynthesis fixati…
Plantar flexor activation capacity and H reflex in older adults: adaptations to strength training.
2002
The purpose of this study was to investigate whether the voluntary neural drive and the excitability of the reflex arc could be modulated by training, even in old age. To this aim, the effects of a 16-wk strengthening program on plantar flexor voluntary activation (VA) and on the maximum Hoffman reflex (Hmax)-to-maximum M wave (Mmax) ratio were investigated in 14 elderly men (65–80 yr). After training, isometric maximum voluntary contraction (MVC) increased by 18% ( P < 0.05) and weight-lifting ability by 24% ( P < 0.001). Twitch contraction time decreased by 8% ( P < 0.01), but no changes in half relaxation time and in peak twitch torque were observed. The VA, assessed by twitch …
Effects of Constant and Doublet Frequency Electrical Stimulation Patterns on Force Production of Knee Extensor Muscles
2016
International audience; This study compared knee extensors' neuromuscular fatigue in response to two 30-minute stimulation patterns: constant frequency train (CFT) and doublet frequency train (DFT). Fifteen men underwent two separate sessions corresponding to each pattern. Measurements included torque evoked by each contraction and maximal voluntary contractions (MVC) measured before and immediately after the stimulation sessions. In addition, activation level and torque evoked during doublets (Pd) and tetanic contractions at 80-Hz (P80) and 20-Hz (P20) were determined in six subjects. Results indicated greater mean torque during the DFT stimulation session as compared with CFT. But, no dif…
Achilles tendon length changes during walking in long-term diabetes patients
2010
Diabetes leads to numerous side effects, including an increased density of collagen fibrils and thickening of the Achilles tendon. This may increase tissue stiffness and could affect stretch distribution between muscle and tendinous tissues during walking. The primary aim of this study was to examine stretch distribution between muscle and tendinous tissues in the medial gastrocnemius muscle-tendon unit in long-term diabetes patients and control subjects during walking.Achilles tendon length changes were investigated in 13 non-neuropathic diabetes patients and 12 controls, whilst walking at a self selected speed across a 10 m force platform. Electromyographic activity was recorded in the me…
Effect of time-of-day-specific strength training on serum hormone concentrations and isometric strength in men.
2007
A time-of-day influence on the neuromuscular response to strength training has been previously reported. However, no scientific study has examined the influence of the time of day when strength training is performed on hormonal adaptations. Therefore, the primary purpose of this study was to examine the effects of time-of-day-specific strength training on resting serum concentrations and diurnal patterns of testosterone (T) and cortisol (CORT) as well as maximum isometric strength of knee extensors. Thirty eight diurnally active healthy, previously untrained men (age 20-45 yrs) underwent a ten-week preparatory strength training period when sessions were conducted between 17:00-19:00 h. Ther…
Strength athletes are capable to produce greater muscle activation and neural fatigue during high-intensity resistance exercise than nonathletes.
2009
Acute neuromuscular responses to maximum versus forced repetition (FR) knee extension resistance exercises (4 sets of 12 repetitions [reps] with a 2-minute recovery between the sets) were examined in 4 male strength athletes (SAs) and 4 nonathletes. Maximum repetition (MR) sets were performed to voluntary exhaustion (12 repetition maximum [RM]), whereas in the FR sets, the load was greater (8RM) and the set was continued after voluntary fatigue with 4 additional assisted reps. Maximal isometric force and electromyogram (EMG) activity of the knee extensors were measured before and after the exercise, as well as 2 recovery days after the exercise. Electromyogram activity was also measured dur…
Training Effects of Alternated and Pulsed Currents on the Quadriceps Muscles of Athletes
2018
AbstractThe aim of the study was to evaluate the effects of 6 weeks training with different neuromuscular electrical stimulation (NMES) currents (medium alternated and low-frequency pulsed current) on muscle architecture and neuromuscular performance of competitive athletes. A double-blind controlled and randomized experimental study was carried out with 33 athletes (22.2±2.6 yrs, 74.7±9.8 kg, 176.8±6.0 cm), divided into 3 groups: mid-frequency current (MF, n=12), pulsed current (PC, n=11) and the control group (CG, n=10). Quadriceps maximal voluntary peak torque (PT) and corresponding vastus lateralis electromyographic activity, evoked torque (PT-NMES), vastus lateralis muscle thickness, f…
Central Contribution to Electrically Induced Fatigue depends on Stimulation Frequency
2017
International audience; PURPOSE: This study analyzed the impact of several protocols of neuromuscular electrical stimulation (NMES), matched with a similar total torque-time integral, on muscle activation pathways and neuromuscular fatigue.METHODS: Ten young healthy participants (age: 24.6 +/- 4.2) performed 3 randomized NMES sessions on the triceps surae muscles with 20 Hz, 60 Hz or 100 Hz stimulation frequencies (pulse duration: 1 ms), with pulse amplitude (IES) set at 20 % of isometric maximal voluntary contraction (MVC). Muscle activity during NMES was assessed by means of the twitch, the soleus H-reflex and M wave responses evoked by single muscle stimulation at IES. Neuromuscular fati…
Contractile Impairment After Quadriceps Strength Training Via Electrical Stimulation
2010
The purpose of this study was to investigate the neural and muscular changes associated with electrical stimulation (ES) training and subsequent detraining. Twenty healthy active men were randomized to receive (intervention group) or not (control group) 4 weeks of ES strength training followed by 4 weeks of detraining. Quadriceps ES training sessions (20 minutes per session, 4 sessions per week) were completed under isometric loading conditions. Quadriceps maximal voluntary contraction (MVC) strength, activation level, maximal electromyographic (EMG) activity, and excitation-contraction coupling properties were assessed before training, after training, and after detraining. Maximal voluntar…
Validity and reliability of isometric, isokinetic and isoinertial modalities for the assessment of quadriceps muscle strength in patients with total …
2013
Reliability of isometric, isokinetic and isoinertial modalities for quadriceps strength evaluation, and the relation between quadriceps strength and physical function was investigated in 29 total knee arthroplasty (TKA) patients, with an average age of 63 years. Isometric maximal voluntary contraction torque, isokinetic peak torque, and isoinertial one-repetition maximum load of the involved and uninvolved quadriceps were evaluated as well as objective (walking parameters) and subjective physical function (WOMAC). Reliability was good and comparable for the isometric, isokinetic, and isoinertial strength outcomes on both sides (intraclass correlation coefficient range: 0.947-0.966; standard…