Examinando por Autor "Delextrat, Anne"

Mostrando 1 - 7 de 7
  • Publicación
    Acceso abierto
    Angle-specific eccentric hamstring fatigue after simulated soccer
    (2015) Cohen, Daniel Dylan; Zhao, Bingnan; Okwera, Brian; Matthews, Martyn J.; Delextrat, Anne
    To evaluate the effect of simulated soccer on the hamstrings eccentric torque-angle profile and angle of peak torque (APTeccH), and on the hamstrings:quadriceps torque ratio at specific joint angles (ASHecc:Qcon). Methods: The authors assessed dominant-limb isokinetic concentric and eccentric knee flexion and concentric knee extension at 120°/s in 9 semiprofessional male soccer players immediately before and after they completed the Loughborough Intermittent Shuttle Test (LIST). Results: The LIST resulted in significant decreases in eccentric hamstrings torque at 60°, 50°, and 10° and a significant (21.8%) decrease in ASHecc:Qcon at 10° (P < .05). APTeccH increased from 7.1° ± 1.0° to 18.8° ± 4.2° (P < .05). Eccentric hamstrings peak torque significantly declined from 185.1 ± 70.4 N·m pre-LIST to 150.9 ± 58.5 N·m post-LIST (P = .002), but there were no significant changes in hamstrings or quadriceps concentric peak torque (P = .312, .169, respectively). Conclusions: Simulated soccer results in a selective loss of eccentric hamstrings torque and hamstrings-to-quadriceps muscle balance at an extended joint position and a shift in the eccentric hamstrings APT to a shorter length, changes that could increase vulnerability to hamstrings injury. These findings suggest that injury-risk screening could be improved by evaluating the eccentric hamstrings torque-angle profile and hamstrings strength-endurance and that the development of hamstrings fatigue resistance and long-length eccentric strength may reduce injury incidence.
  • Publicación
    Acceso abierto
    Changes in Torque-Angle Profiles of the Hamstrings and Hamstrings-to-Quadriceps Ratio After Two Hamstring Strengthening Exercise Interventions in Female Hockey Players
    (2020-02-05) Delextrat, Anne; Bateman, James; Ross, Chris; Harman, John; Davis, Lois; Vanrenterghem, Jos; Cohen, Daniel Dylan; Salud Comunidudes
    Delextrat, A, Bateman, J, Ross, C, Harman, J, Davis, L, Vanrenterghem, J, and Cohen, DD. Changes in torque-angle profiles of the hamstrings and hamstrings-to-quadriceps ratio after two hamstring strengthening exercise interventions in female hockey players. J Strength Cond Res 34(2): 396–405, 2020—The aim of this study was to compare the effects of 2 hamstring strengthening interventions (Nordic hamstrings [NHE] vs. eccentric leg curl [ELC]) on the hamstring torque-angle profiles and functional hamstrings-to-quadriceps ratio (Hecc:Qcon) in female hockey players. Female university-level players were randomly allocated to an NHE group (n = 9, 19.7 ± 1.4 years; 168.4 ± 4.4 cm; 66.2 ± 7.2 kg, 26.0 ± 4.4%), an ELC group (n = 8, 19.5 ± 1.0 years; 168.1 ± 3.4 cm; 66.7 ± 4.5 kg, 24.8 ± 3.5%), or a control (C) group (n = 8, 19.6 ± 1.4 years; 169.9 ± 7.5 cm; 70.7 ± 13.0 kg, 25.9 ± 5.2%). They performed baseline isokinetic concentric strength tests of the quadriceps (Qcon) and eccentric strength of the hamstrings (Hecc) at 120°·s−1, followed by a 6-week intervention with exercises (NHE or ELC) performed 3 times weekly, before post-tests. Analyses of variance with repeated measures were used to assess the effects of knee position angle (from 90° of knee flexion to 10° close to extension), group, and time on Qcon, Hecc, and Hecc:Qcon. There were no interactions between independent variables. Significant increases in Hecc and Hecc:Qcon were shown after NHE (+29.9 and +27.8%) and ELC (+30.5 and +38.3%) in the nondominant leg only. Furthermore, significant shifts in the hamstring eccentric angle of peak torque toward a longer muscle length were shown in both legs (14.3–28.6%). These findings suggest that NHE and ELC both resulted in significant improvements in peak and muscle-length–specific neuromuscular risk factors in the nondominant (ND) limb, thereby reducing interlimb peak strength asymmetries. Strength and conditioning specialists could therefore use both the NHE and ELC exercises in female hockey players.
  • Publicación
    Acceso abierto
    Etiology of musculoskeletal injuries in amateur breakdancers
    (2015-10) Joka, T.; Clarke, N. D.; Cohen, Daniel Dylan; Delextrat, Anne
    Aim. The aim of this study was to assess the incidence of musculoskeletal injuries in breakdancers and investigate the association with training habits. Methods. Forty-six males and 16 females completed a questionnaire regarding their training and competition habits (frequency, warm-up and stretching, strength training, protective equipment, move types and supervision) and the musculoskeletal injuries sustained as a result of breakdancing in the previous 12 months. The effects of training habits and sex on injury rates were analyzed by a Mann Whitney Test and a Kruskal Wallis Test, while a stepwise linear regression analysis assessed the link between injury rates and quantitative risk factors. Results. The injury rate was 4.02 injuries per 1000 h, with no significant difference between males and females (P>0.05). The main injuries affected were the knee (23.4%) and wrist (15.3%), and females were characterized by a significantly greater number of finger injuries and a lower number of shoulder injuries that males (P<0.05). In addition, of all the risk factors evaluated, only the amount of time spent performing breakdance training showed a significant association with injury rate (P<0.05). Conclusion. These results suggest that interventions should focus on protecting specific body parts and improving training quality and recovery.
  • Publicación
    Restringido
    Physical fitness characteristics of Omani primary school children according to body mass index
    (2019-03) Delextrat, Anne; Hayes, Lawrence; Al Ghannami, Samia S; Ming, Yoeju; Hussein, Izzeldin; Al Oufi, Hamed; Ghebremeskel, Kebreab; Cohen, Daniel Dylan
    Background: There is evidence that children with high cardiorespiratory fitness and normal body mass index (BMI) have less risk of non-communicable diseases (NCDs), however limited research was undertaken in Omani children. Therefore the aims of the present study were to describe body composition and physical fitness of a large cohort of Omani school children of both genders, and to investigate the effects of weight status on physical fitness. Methods: Three hundred and fourteen Omani school children aged 9 to 10 years old took part in anthropometric assessments, body composition and fitness tests, including handgrip strength, the basketball chest pass, broad jump, 20-m sprint, four 10-m shuttle agility, 30-s sit-up, and multistage fitness test (MSFT). Results: Obese boys and girls performed worse than normal-weight children in sprint, agility and endurance. In addition, fitness measures in the overweight group and underweight groups were not significantly different from other groups, except a better handgrip strength and poorer MSFT in overweight compared to normal weight girls, and poorer agility performance in underweight girls compared to the three other groups. Conclusions: Most fitness measures are lower in obese Omani children, which suggests that they will be more at risk of developing NCDs later in life.
  • Publicación
    Acceso abierto
    Physical fitness characteristics of Omani primary school children according to body mass index
    (2019-03-05) Delextrat, Anne; Hayes, Lawrence D.; Al Ghannami, Samia S.; Min, Yoeju; Hussein, Izzeldin; Al Oufi, Hamed; Cohen, Daniel Dylan; Ghebremeskel, Kebreab; Salud Comuniudes
    BACKGROUND: There is evidence that children with high cardiorespiratory fitness and normal body mass index (BMI) have less risk of non-communicable diseases (NCDs), however limited research was undertaken in Omani children. Therefore the aims of the present study were to describe body composition and physical fitness of a large cohort of Omani school children of both genders, and to investigate the effects of weight status on physical fitness. METHODS: Three hundred and fourteen Omani school children aged 9 to 10 years old took part in anthropometric assessments, body composition and fitness tests, including handgrip strength, the basketball chest pass, broad jump, 20-m sprint, four 10-m shuttle agility, 30-s sit-up, and multistage fitness test (MSFT). RESULTS: Obese boys and girls performed worse than normal-weight children in sprint, agility and endurance. In addition, fitness measures in the overweight group and underweight groups were not significantly different from other groups, except a better handgrip strength and poorer MSFT in overweight compared to normal weight girls, and poorer agility performance in underweight girls compared to the three other groups. CONCLUSIONS: Most fitness measures are lower in obese Omani children, which suggests that they will be more at risk of developing NCDs later in life.
  • Publicación
    Acceso abierto
    Strength and endurance training reduces the loss of eccentric hamstring torque observed after soccer specific fatigue
    (2017) Matthews, Martyn J.; Heron, Kate; Todd, Stefanie; Tomlinson, Andrew; Jones, Paul; Delextrat, Anne; Cohen, Daniel Dylan
    Objectives: To investigate the effect of two hamstring training protocols on eccentric peak torque before and after soccer specific fatigue. Participants: Twenty-two university male soccer players. Design: Isokinetic strength tests were performed at 60!/s pre and post fatigue, before and after 2 different training interventions. A 45-min soccer specific fatigue modified BEAST protocol (M-BEAST) was used to induce fatigue. Players were randomly assigned to a 4 week hamstrings conditioning intervention with either a maximum strength (STR) or a muscle endurance (END) emphasis. Main outcome measures: The following parameters were evaluated: Eccentric peak torque (EccPT), angle of peak torque (APT), and angle specific torques at knee joint angles of 10!, 20!, 30!, 40!, 50!, 60!, 70!, 80! and 90!. Results: There was a significant effect of the M-BEAST on the Eccentric torque angle profile before training as well as significant improvements in post-fatigue torque angle profile following the effects of both strength and muscle endurance interventions. Conclusions: Forty-five minutes of simulated soccer activity leads to reduced eccentric hamstring torque at longer muscle lengths. Short-term conditioning programs (4-weeks) with either a maximum strength or a muscular endurance emphasis can equally reduce fatigue induced loss of strength over this time period.
  • Publicación
    Restringido
    Strength-endurance training reduces the hamstrings strength decline following simulated football competition in female players
    (2018-08) Cohen, Daniel Dylan; Delextrat, Anne; Piquet, Jessica; Matthews, Martyn J.
    Hamstring strains are the most common injury in multiple sprint sports, with inadequate eccentric hamstring strength and fatigue identified as important risk factors. Resistance training interventions aimed at reducing injury risk typically focus on the development of maximum strength, while little is known about the impact of training on hamstring fatigue resistance. The present study compared the effects of strength endurance (SE) with a strength intervention (S) on the eccentric hamstring strength decline induced by a simulated soccer match. Twenty-one female soccer players were randomly assigned to a S group (n = 10) or a SE group (n = 11). Hamstrings and quadriceps isokinetic concentric and eccentric peak torque (PT) were assessed at 120°.s-1 and hamstrings-to-quadriceps ratio (HEcc:QCon) calculated, pre- and immediately post a 90-min simulated match (BEAST90). This was repeated following a 7-week intervention of either three to five sets of 6RM leg curl and stiff-leg deadlift with 3-min inter-set rest (S), or the same exercises performed using three sets of 12–20 RM with 45–90 s inter-set rest (SE). At baseline, the simulated match led to significant declines in hamstrings eccentric peak torque (EccPT) in both groups in both dominant (D) and non-dominant (ND) legs [SE: (D: -15.5, ND: -15.6%), P = 0.001 to 0.016; S: (D: -12.3%, ND: -15.5%), P = 0.001 to 0.018]. After the 7-week intervention, we observed a group∗intervention∗match interaction such that there was no significant decline in EccPT in the SE group following the simulated match (D: 5.3%, ND: 2.0%), but there remained significant declines in the S group (D: -14.2%, ND: -15.5%, P = 0.018–0.001). Similarly, in the SE group, there was a significant decrease in the HEcc:QCon in D before (-14.2%, P = 0.007), but not after the training intervention, whereas declines were observed in the S group both at baseline, and following the intervention (D: -13.9%, ND: -15.6%, P = 0.045). These results demonstrate that SE training can reduce the magnitude of the EccPT decline observed during soccer competition. As inadequate eccentric strength and fatigue are both risk factors for hamstring injury, SE training should be considered along with the development of peak eccentric strength, as a component of programs aimed at reducing injury risk in multiple-sprint sports.