Intermittent treadmill running induces kinematic compensations to maintain soccer kick foot speed despite no change in knee extensor strength

Kicking is a fundamental skill and a primary noncontact mechanism of injury in soccer, with injury incidence increasing during the latter stages of match-play. Ten male professional soccer players completed a 90-minute treadmill protocol based on the velocity profile of soccer match-play. Preexercise, and at 15-minute intervals, players completed a maximal velocity kick subjected to kinematic analysis at 200 Hz. Preexercise, and at the end of each half, players also completed isokinetic concentric knee extensor repetitions at 180°·s−1, 300°·s−1, and 60°·s−1. Kicking foot speed was maintained at ∼19 m·s−1, with no main effect for exercise duration. In relation to proximal–distal sequencing during the kicking action, there was a significant increase in the duration (but not magnitude) of thigh rotation, with a compensatory decrease in the duration (but not magnitude) of shank rotation during the latter stages of the exercise protocol. In relation to long-axis rotation, pelvic orientation at ball contact was maintained at ∼6°, representing a total pelvic rotation in the order of ∼15° during the kicking action. Peak knee extensor torque at all speeds was also maintained throughout the protocol, such that kinematic modifications are not attributable to a decline in knee extensor strength.</jats:p

Lumbar and cervico-thoracic spine loading during a fast bowling spell:Lumbar and cervico-thoracic 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

Temporal pattern of kinesiology tape efficacy on hamstring extensibility

BACKGROUND: Kinesiology tape has been advocated as a means of improving muscle flexibility, a potential modifiable risk factor for injury, over time. The epidemiology and etiology of hamstring injuries in sport have been well documented. PURPOSE: To compare the temporal pattern of efficacy of kinesiology tape and traditional stretching techniques on hamstring extensibility over a five day period. STUDY DESIGN: Controlled laboratory study. METHODS: Thirty recreationally active male participants (Mean ± SD: age 20.0 ± 1.55 years; height 179.3 ± 4.94 cm; mass 76.9 ± 7.57 kg) completed an active knee extension assessment (of the dominant leg) as a measure of hamstring extensibility. Three experimental interventions were applied in randomized order: Kinesiology tape (KT), static stretch (SS), proprioceptive neuromuscular facilitation (PNF). Measures were taken at baseline, +1min, + 30mins, + 3days and +5days days after each intervention. The temporal pattern of change in active knee extension was modelled as a range of regression polynomials for each intervention, quantified as the regression coefficient. RESULTS: Hamstring ROM with KT application at +3days was significantly greater than baseline (129.18 ± 15.46%, p = 0.01), SS (106.99 ± 9.84%, p = 0.03) and PNF (107.42 ± 136.13%, p = 0.03) interventions. The temporal pattern of changes in ROM for SS and PNF were best modelled by a negative linear function, although the strength of the correlation was weak in each case. In contrast, the KT data was optimised using a quadratic polynomial function (r(2) = 0.60), which yielded an optimum time of 2.76 days, eliciting a predicted ROM of 129.6% relative to baseline. CONCLUSION: Each intervention displayed a unique temporal pattern of changes in active knee extension. SS was best suited to immediate improvements, and PNF to +30 minutes in hamstring extensibility, whereas kinesiology tape offered advantages over a longer duration, peaking at 2.76 days. These findings have implications for the choice of intervention, timing and duration to assist clinicians in both a sporting and clinical context. LEVEL OF EVIDENCE: 2