A low-volume Nordic hamstring curl programme improves change of direction ability, despite no architectural, strength or speed adaptations in elite youth soccer players.

Nordic hamstring curls (NHC) are a commonly used injury intervention method in amateur team sports. Seventeen elite male academy soccer players performed an 8-week low volume NHC programme. Pre-post intervention measures of isokinetic eccentric knee flexor (KF) strength, linear speed, COD performance, hamstring muscle thickness, pennation angle and fascicle length were recorded. No significant main effects were observed for measures of isokinetic KF strength (P ≥ 0.19), linear sprint speed (P ≥ 0.47) or hamstring muscle architecture (P ≥ 0.30). However, significance was noted for improved COD performance (P < 0.01; mean difference, -0.06, p = 0.001, 95% CI = 0.03 to 0.09; d = 0.80), exceeding the minimal detectable difference (MDD = 0.05 s). A low-volume NHC intervention may contribute to significant improvements in COD ability, independent of no significant changes in eccentric KF strength, linear sprint speed or muscle architectural properties in elite youth soccer players.

The effect of pre-exercise Nordic hamstring exercise on hamstring neuromuscular response during soccer-specific activity.

Background: The Nordic hamstring exercise (NHE) has emerged as a popular intervention for improving eccentric hamstring strength, however recent literature suggests there is a potential for an increase in injury risk during subsequent exercise.Methods: To quantify the influence of pre-exercise NHE on the electromyographical response of the hamstrings, 10 male soccer players completed an experimental trial comprising 6 sets x 5 repetitions of NHE prior to the completion of a 45 minute soccer-specific protocol. Post-exercise NHE were performed in the experimental and control (no pre-exercise NHE) trials. Electromyographic (EMG) response (integrated, mean and peak amplitude) of the biceps femoris to the pre- and post-exercise NHE and the soccer-specific exercise protocol was quantified.Results: Integrated (P= 0.025) and mean (P= 0.020) EMG elicited a significant main effect for time in the soccer-specific protocol with higher values during the first 15 mins indicative of a fatigue effect. However, there was no trial x time interaction (P ≥ 0.78). There was no difference between trials in the EMG response to pre-exercise (P≥ 0.30) or post-exercise (P≥ 0.16) NHE trials.Conclusions: Therefore, although previous studies suggest performing pre-exercise NHE might impair maximal strength metrics, the current study's results suggest that it does not impair the electromyographical response to subsequent soccer-specific exercise or NHE repetitions.

The Effects of a Soccer-Specific Fitness Test on Eccentric Knee Flexor Strength.

CONTEXT: Physiological fitness testing, such as the Yo-Yo Intermittent Recovery Test (YYIR) is a key requirement of the Elite Player Performance Plan, introduced by the English Premier League. Eccentric hamstring strength has been identified as a risk factor for hamstring injuries in soccer players, with fatigue highlighted to further exasperate this issue. OBJECTIVE: The aim of the current study was to examine the effect of the YYIR level 1 (YYIR1) on eccentric knee flexor strength assessed using the NordBord in youth soccer players. DESIGN: Experimental design. SETTING: Soccer club academy. PARTICIPANTS: A total of 67 male academy soccer players (age = 16.58 [0.57] y; height = 175.45 [5.85] cm; mass = 66.30 [8.21] kg) volunteered to participate in the current study during the English competitive soccer season. MAIN OUTCOME MEASURES: Participants conducted eccentric hamstring strength assessments using the NordBord prior to and immediately postcompletion of the YYIR1, with outcome measures of peak force and peak force relative to body mass recorded. RESULTS: Paired t tests highlighted increased absolute eccentric knee flexor strength values (P < .001) immediately post-YYIR1 for both the dominant and nondominant limbs, with the same trend (P < .001) observed for eccentric strength relative to body mass. CONCLUSIONS: The results of this study indicate that the YYIR1 does not induce eccentric knee flexor fatigue and as such is not a valid assessment method to assess the effects of fatigue on hamstring function. However, results do suggest that the NordBord may be considered a viable and more accessible alternative to detect pre-post fitness test/fatigue protocol differences in eccentric knee flexor peak strength while working in the field.

Joint Hypermobility as a Predictor of Mechanical Loading in Dancers.

CONTEXT: Dance requires the performance of complex movements that may exceed normal anatomical range. However, in hypermobile individuals, this may have implications for injury and performance. OBJECTIVES: The aim of the study was to investigate the efficacy of the Beighton score (BS) in predicting mechanical loading in dancers in hypermobile and nonhypermobile dancers with consideration of accelerometer placement and lumbar flexion hypermobility. DESIGN: Cohort study, clinical measurement. SETTING: University. PARTICIPANTS: A total of 34 dancers had their joint hypermobility assessed by the BS. Participants completed the Dance Aerobic Fitness Test with a global positioning device incorporating a triaxial accelerometer located at the cervico-thoracic junction (C7) and one at the midbelly of the gastrocnemius. MAIN OUTCOME MEASURES: Accelerometry data were used to calculate PlayerLoad total, PlayerLoad medial-lateral, PlayerLoad anterior-posterior, and PlayerLoad vertical. Physiological response was measured via heart rate and fatigue response by rate of perceived exertion. RESULTS: The total BS was a poor predictor of all mechanical loading directions with PlayerLoad anterior-posterior C7 (r = .15) and PlayerLoad total lower limb (r = .20) the highest values. Multiple linear regression was a better predictor with values of C7 (r = .43) and lower limb (r = .37). No significant difference existed between hypermobile and nonhypermobile subjects for mechanical loading values for all stages of the Dance Aerobic Fitness Test and for heart rate and fatigue responses. CONCLUSIONS: The BS is not a good predictor of mechanical loading which is similar in hypermobile and nonhypermobile dancers for all levels of the Dance Aerobic Fitness Test. Mechanical loading and fatigue responses are similar between hypermobile and nonhypermobile dancers.

Acute adaptations and subsequent preservation of strength and speed measures following a Nordic hamstring curl intervention: a randomised controlled trial.

This randomised controlled trial investigated changes in eccentric hamstring strength, 10m sprint speed, and change-of-direction (COD) performance immediately post Nordic hamstring curl (NHC) intervention and following a 3-week detraining period. Fourteen male team sports athletes were randomised to a do-as-usual control group (CG; n = 7) or to a NHC intervention group (NHC; n = 7). Isokinetic dynamometry at 180°/s evaluated eccentric hamstring strength immediately post-intervention as the primary outcome measure. Secondary outcomes included 10 m sprint time and COD. Each outcome was measured, pre, immediately post-intervention and following a 3-week detraining period. Immediately post-intervention significant group differences were observed in the NHC group for eccentric hamstring strength (31.81 Nm-1 vs. 6.44 Nm-1, P = 0.001), COD (-0.12 s vs. 0.20 s; P = 0.003) and sprint (- 0.06 s vs. 0.05 s; P = 0.024) performance. Performance improvements were maintained following a detraining period for COD (-0.11 s vs. 0.20 s; P = 0.014) and sprint (-0.05 s vs. 0.03 s, P = 0.031) but not eccentric hamstring strength (15.67 Nm-1 vs. 6.44 Nm-1, P = 0.145) These findings have important implications for training programmes designed to reduce hamstring injury incidence, whilst enhancing physical qualities critical to sport.

Functional Movement Screening as a Predictor of Mechanical Loading and Performance in Dancers.

Dance requires effective functional movement for the prevention of injury, with implications for the biomechanical response to performance. This study investigated the efficacy of the Functional Movement Screening (FMS) in predicting mechanical loading during the Dance Aerobic Fitness Test (DAFT). Twenty-five university dancers (19 females; age: 20.3 ± 0.94 years; height: 162.55 ± 0.05 cm; mass: 58.73 ± 6.3 kg; and 6 males; age: 21.08 ± 2.01 years; height: 175 ± 6.54 cm; mass: 68.16 ± 4.97 kg) were screened using the FMS. Subjects then completed the DAFT with a GPS-mounted triaxial accelerometer located at the cervico-thoracic junction. Accelerometry data were sampled at 100 Hz and used to calculate total accumulated PlayerLoad, Playerload medial-lateral (PLML), PlayerLoad anterior-posterior (PLAP), and PlayerLoad vertical (PLV) over the duration of the DAFT. Linear regression analysis was used to determine the strength of correlation between FMS and PlayerLoad, PLML, PLAP, and PLV, and forward stepwise hierarchical modelling was performed to establish which FMS components were the primary predictors of mechanical loading. The Deep Squat (DS) demonstrated statistical significance for PLVTotal and PLTotal. The non-dominant Hurdle Step (HS) was a statistically significant predictor of PLMLTotal. The FMS composite score was a statistically significant predictor for PLVTotal. Forward stepwise regression analysis demonstrated that DS was the sole predictor for PLTotal and the primary predictor for PLVTotal. Non-dominant HS was identified as the primary predictor of PLMLTotal. It is concluded that the DS, non-dominant HS, and the FMS composite score can be used to predict mechanical loading in performance of the DAFT, which may have implications for dance performance and injury prevention.

The Influence of Fatigue on Star Excursion Balance Test Performance in Dancers.

Dance is associated with a high risk of injury and fatigue is often a contributing factor. The Star Excursion Balance Test (SEBT) has been used to identify alterations in normal movement that may contribute to injury risk; however, there has been limited investigation of the potential effects of fatigue. The aim of this study was to explore the influence of dance-specific fatigue on SEBT performance, with implications for injury and performance in dance. Thirty-five university dancers completed the modified SEBT in anterior, posterolateral, and posteromedial directions prior to and immediately following the Dance Aerobic Fitness Test (DAFT). The SEBT was completed for dominant and non-dominant legs. Heart rate and rate of perceived exertion were quantified as measures of fatigue. Post-DAFT, the mean SEBT percentage maximized reach distances for dominant and nondominant legs were non-significant compared to pre-DAFT scores. Lack of a main effect for exercise was observed in each of the anterior dominant and non-dominant, posterolateral dominant and non-dominant, and posteromedial dominant and non-dominant scores. It is concluded that the limited changes in the ability of dancers to perform the SEBT suggest that they were able to maintain SEBT performance in both dominant and non-dominant legs following exercise. This resistance to fatigue may demonstrate a dance-specific performance adaptation so that potential alterations in movement performance that may increase injury risk were not observed.

The efficacy of elastic therapeutic tape variations on measures of ankle function and performance.

OBJECTIVES: To investigate the effects of different variations of elastic therapeutic taping (ETT) on tests used to screen for ankle injury risk and function. DESIGN: Randomized crossover. SETTING: Laboratory. PARTICIPANTS: Twelve professional male soccer players completed three experimental trials: No tape (NT), RockTape™ (RT), and Kinesio™ Tape (KT) applied to the ankle complex. OUTCOME MEASURES: Clinical and functional ankle screening tests were used to assess the effects of ETT on measures of joint position sense, postural stability and ground reaction forces. RESULTS: KT (P = 0.04) and RT (P = 0.01) demonstrated significant improvements in end range joint position sense. When compared to NT, RT significantly (P = 0.02) improved mid-range joint position sense at 15°, and time to complete a drop landing task. No significant differences were observed for measures of postural stability (P ≥ 0.12) nor ground reaction force variables (P ≥ 0.33). CONCLUSIONS: Results advocate the use of ETT for proprioceptive and functional tasks when applied to the ankles of healthy male soccer players. However, a greater number of practical and significant differences were observed when RT only was applied, indicating that practitioners may potentially advocate the use of RT for tasks requiring proprioception and functional performance.