Search results for "hamstring"
showing 10 items of 57 documents
The effects of the Nordic hamstring exercise on sprint performance and eccentric knee flexor strength: A systematic review and meta-analysis of inter…
2021
Objectives: The primary aim of this study was to investigate the effects of the Nordic hamstring exercise (NHE) on sprint performance (i.e., 5, 10 and 20 m) and explore associations between study characteristics and sprint outcomes in team sport players. Secondary aims were to (1) investigate the effects of the NHE on eccentric strength of the knee flexors (ESKF) with categorical subgroup analysis to determine differences between recreationally, well-trained individuals and young athletes, (2) determine the relation between ESKF and sprint performance in team sport players, and (3) explore the effect of study characteristics (i.e., weekly volume, time duration and body mass) on ESKF.Methods…
Evidence of a preprogrammed deactivation of the hamstring muscles for triggering rapid changes of posture in humans
1997
Normal subjects were asked to make rapid flexions of the legs from a stationary initial standing posture in a self-paced mode. Because this movement implicates a rapid change in posture, questions were asked about the type of central command which must include the rupture of the erect posture and the accomplishment of the goal directed movement. Movements of the different segments of the body were recorded and analyzed using the optoelectronic ELITE system. Electromyographic (EMG) activities of 8 muscles of the lower limb on one side were recorded, rectified and integrated. The time relationships of the different EMG signals (activation or deactivation) were analyzed with respect to selecte…
Biceps Femoris Long Head Muscle Fascicles Actively Lengthen During the Nordic Hamstring Exercise
2021
Current debate exists around whether a presumed eccentric exercise, the Nordic hamstring exercise (NHE), actually causes active hamstring muscle lengthening. This is because of the decoupling that can occur between the muscle fascicle and muscle-tendon unit (MTU) length changes in relatively compliant human lower-limb MTUs, which results in MTU lengthening not necessarily causing muscle fascicle lengthening. This missing knowledge complicates the interpretation of why the NHE is effective at reducing running-related hamstring muscle injury risk in athletes previously unfamiliar with performing this exercise. The purpose of the study was therefore to investigate if the most-commonly injured …
Causas de la lesión de isquiosurales en fútbol: Una revisión bibliográfica desde las etapas formativas hasta la profesional
2021
espanolObjetivos: identificar las principales causas de lesion de isquiosurales en las diferentes etapas de formacion, desde la etapa sub-12 hasta la etapaprofesional, y establecer la influencia de la lesion previa de isquiosurales como causa principal de sufrir una nueva lesion.Metodo: la busqueda bibliografica se realizo en Dialnet, Pubmed, Web of Science, Scopus y SportDISCUS, entre las fechas de enero de 2010 hasta mayo de2020.Resultados: la busqueda concluyo que el patron de lesion isquiosural mas concurrido es el de jugador de edad avanzada, con mayores valores de fuerza ymenores valores de flexibilidad, y con un mayor grado de anteversion pelvica. El envejecimiento, los movimientos c…
Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance
2018
The purpose of the present study was to examine characteristics of muscle anatomical cross-sectional area (CSA) for different regions from proximal to distal parts of each muscle of the hamstring muscles in high-level sprinters, and to examine the relationship with those and the sprint performance. The CSA of the semitendinosus (ST), semimembranosus (SM), biceps femoris long head (BFL) and biceps femoris short head (BFS) at the four different region of hamstring muscles for twenty sprinters (SPRINT) and twenty healthy male control subjects (CTRL) were measured by using B-mode ultrasonography. The measured regions were divided into four parts from proximal to distal parts (PRO1, PRO2, DIS2, …
Neuromuscular fatigue induced by a 90-minute soccer game modeling.
2012
This study aimed to quantify neuromuscular fatigue induced by a soccer game. Eight amateur soccer players (age 20.4 ± 1.3 years, mass 70.4 ± 6.9 kg, and height 174.9 ± 5.2 cm) reproduced a 90-minute soccer game modeling composed of two 45-minute periods separated by a 15-minute rest. Torque of quadriceps and hamstring muscle groups associated with electromyography, sprint speed, and vertical jump height was assessed before, at halftime, and immediately after the modeling. Most physical qualities decreased throughout the game with greater decays at match end than at halftime. Contrarily to quadriceps muscles, hamstring torque impairments were not accompanied by electromyographic activity red…
Validity of an inertial system for measuring velocity, force, and power during hamstring exercises performed on a flywheel resistance training device
2020
Background Inertial hamstring exercises promote functional changes leading to lower rates of hamstring injuries. However, variable training measurement systems have not been specifically validated for hamstring exercises. Accordingly, this study aimed to evaluate the validity of the Inertial Measurement System (IMS) to measure the velocity, force, and power during the performance of different hamstring exercises on a flywheel resistance training device. Methods Fifteen males (average age: 22.4 ± 2.5 years; body mass: 77.3 ± 9.8 kg; height: 179.5 ± 7.4 cm; weekly physical activity: 434.0 ± 169.2 min; years of strength training: 4.3 ± 2.2 years) performed the bilateral stiff-leg deadlift (SD…
Children’s physical activity and sedentary time compared using assessments of accelerometry counts and muscle activity level
2018
Background This research compared accelerometry (ACC)-derived and muscle electromyography (EMG)-based estimates of physical activity (PA) and sedentary time in typical PA tasks and during the daily lives of children. Methods Data was included from two exploratory studies. In Study I, 6–7-year-old children (n = 11, 64% girls) were assessed for eight PA tasks (walking, stair negotiation, climbing, crawling, swinging, balancing, trampoline jumping and a game of tag). In Study II, 7–9-year-old children (n = 14, 38% girls) were assessed for six PA tasks (walking, sitting, static squat, single leg hops, jump for height and standing long jump), and daily PA during one day with and one day without…
Exercise with TENS does not augment gains in balance and strength for dancers
2020
Abstract Electrical stimulation modulates sensory feedback and improves motor performance, at least for individuals with compromised sensorimotor function. The purpose of this study was to determine the effectiveness of a 4-wk intervention with transcutaneous electrical nerve stimulation (TENS) at improving strength and balance in dancers. Nineteen dancers completed a timed, single-leg balance test, the Y-balance test, and contractions with the hip flexor and knee extensor muscles to assess maximal strength and force steadiness. They completed 4-wks of moderate-intensity bodyweight exercises (3x/wk) and were pseudo-randomized to either a Treatment or Sham group in a single-blind design. The…
Stability of pedalling mechanics during a prolonged cycling exercise performed at different cadences.
2005
The aim of this study was to analyse the effect of pedalling rate on the pattern of mechanical torque application and on neuromuscular fatigue during prolonged cycling exercise. Eleven well-trained individuals performed three 1-h pedalling sessions, at 50 rev.min-1, 110 rev.min-1 and a freely chosen cadence, at an intensity corresponding to 65% of their maximal aerobic power. The mechanical torque applied on the right pedal was recorded for 30 s every 5 min while pedalling. Contractile and neural properties of the quadriceps and hamstring muscles were analysed before and immediately after each of the three pedalling sessions. The post-exercise reduction in knee extensors maximal voluntary c…