Within- and between-day loading response to ballet choreography.

Overuse pathologies are prevalent in ballet injury. Ten amateur ballet dancers (age: 23.20 ± 3.08 years) completed a progressive 5-stage choreographed routine on two consecutive days. Tri-axial accelerometers positioned at C7 and the dominant and non-dominant lower-limb were used to calculate accumulated PlayerLoadTM (PLTOTAL) and uni-axial contributions of the anterior-posterior (PLAP), medial-lateral (PLML), and vertical (PLV) planes. PLTOTAL increased significantly (p = 0.001) as a function of exercise duration within-trial, however there was no significant change between trials (p = 0.18). PLTOTAL at C7 was significantly (p = 0.001) lower than both lower-limbs, with no bilateral asymmetry evident (p = 0.97). Planar contributions to PLTOTAL were significantly greater in PLV than PLAP and PLML (p = 0.001). PlayerLoadTM demonstrated within-trial sensitivity to the progressive routine, however no residual fatigue effect was observed between trials. The results of this study suggest that accelerometers have efficacy in athlete monitoring and injury screening protocols, however unit placement should be considered for practical interpretation.

Isokinetic ankle eversion and inversion strength profiling of female ballet dancers.

Ankle injuries are highly prevalent in ballet, with strength highlighted as a primary risk factor. To profile ankle strength, fourteen female ballet dancers (age: 19.29 ± 1.59 years) completed an isokinetic testing protocol comprising concentric eversion (CONEV) and inversion (CONINV), and, eccentric inversion (ECCINV) trials at four angular velocities (30° · s-1, 60° · s-1, 90° · s-1, 120° · s-1) for both the dominant and non-dominant limb. In addition to Peak Torque (PT) and the corresponding Dynamic Control Ratios (DCRs), angle-specific derivatives of strength (AST) and Functional Range (FR) were calculated. There was no evidence of any significant bilateral strength asymmetry (p = 0.90) across all metrics, and no significant interactions with limb and contraction mode or velocity. A significant main effect for contraction mode (p = 0.001) highlighted greater ECCINV strength - which was maintained with increasing isokinetic velocity - in contrast to reductions in CONEV and CONINV strength. Specifically, dancers are ECCINV dominant at angular velocities greater than 60° · s-1, which is likely to be characteristic of most functional tasks. The lack of bilateral asymmetry may be attributed to dance training interventions that facilitate bilateral development, but ipsilateral mode and velocity-specific asymmetries have implications for injury risk and the training needs of female ballet dancers.

Lumbar- and Cervicothoracic-Spine Loading During a Fast-Bowling Spell.

CONTEXT: Epidemiological studies highlight a prevalence of lumbar vertebrae injuries in cricket fast bowlers, with governing bodies implementing rules to reduce exposure. Analysis typically requires complex and laboratory-based biomechanical analyses, lacking ecological validity. Developments in GPS microtechnologies facilitate on-field measures of mechanical intensity, facilitating screening toward prevention and rehabilitation. OBJECTIVE: To examine the efficacy of using GPS-mounted triaxial accelerometers to quantify accumulated body load and to investigate the effect of GPS-unit placement in relation to epidemiological observations. DESIGN: Repeated measures, field-based. SETTING: Regulation cricket pitch. PARTICIPANTS: 10 male injury-free participants recruited from a cricket academy (18.1 ± 0.6 y). INTERVENTION: Each participant was fitted with 2 GPS units placed at the cervicothoracic and lumbar spines to measure triaxial acceleration (100 Hz). Participants were instructed to deliver a 7-over spell of fast bowling, as dictated by governing-body guidelines. MAIN OUTCOME MEASURES: Triaxial total accumulated body and the relative uniaxial contributions were calculated for each over. RESULTS: There was no significant main effect for overs bowled, in either total load or the triaxial contributions to total load. This finding suggests no cumulative fatigue effect across the 10-over spell. However, there was a significant main effect for GPS-unit location, with the lumbar unit exposed to significantly greater load than the cervicothoracic unit in each of the triaxial planes. CONCLUSIONS: There was no evidence to suggest that accumulated load significantly increased as a result of spell duration. In this respect the governing-body guidelines for this age group can be considered safe, or potentially even conservative. However, the observation of higher body load at the lumbar spine than at the cervicothoracic spine supports epidemiological observations of injury incidence. GPS microtechnologies might therefore be considered in screening and monitoring of players toward injury prevention and/or during rehabilitation.