THE EFFECT OF DRIBBLING ON KNEE LOADING WHEN FEMALE BASKETBALL PLAYERS PERFORM SIDE STEP CUTTING MANEUVERS

Knee injuries in females seem related to movements during sports specific, high risk activities such as cutting. Loading on knee when the players make side step cutting maneuvers has been considered to be a factor related to Anterior Cruciate Ligament (ACL) injuries. Our purpose was to examine differences in female players performing a side step cutting with and without dribbling. Using 10 elite female basketball players, three dimensional kinematic and kinetic data were assessed. Based on our investigation, elite female basketball players performing a side step cut with dribbling exhibited greater knee valgus angles and moments. Sport-specific neuromuscular training programs for basketball players could consider may adding ball control tasks

A review of recent perspectives on biomechanical risk factors associated with anterior cruciate ligament injury

There is considerable evidence to support a number of biomechanical risk factors associated with non-contact anterior cruciate ligament (ACL) injury. This paper aimed to review these biomechanical risk factors and highlight future directions relating to them. Current perspectives investigating trunk position and relationships between strength, muscle activity and biomechanics during landing/cutting highlight the importance of increasing hamstring muscle force during dynamic movements through altering strength, muscle activity, muscle length and contraction velocity. In particular, increased trunk flexion during landing/cutting and greater hamstring strength are likely to increase hamstring muscle force during landing and cutting which have been associated with reduced ACL injury risk. Decision making has also been shown to influence landing biomechanics and should be considered when designing tasks to assess landing/cutting biomechanics. Coaches should therefore promote hamstring strength training and active trunk flexion during landing and cutting in an attempt to reduce ACL injury risk.Peer reviewe

Differential neuromuscular training effects onACL injury risk factors in"high-risk" versus "low-risk" athletes

<p>Abstract</p> <p>Background</p> <p>Neuromuscular training may reduce risk factors that contribute to ACL injury incidence in female athletes. Multi-component, ACL injury prevention training programs can be time and labor intensive, which may ultimately limit training program utilization or compliance. The purpose of this study was to determine the effect of neuromuscular training on those classified as "high-risk" compared to those classified as "low-risk." The hypothesis was that high-risk athletes would decrease knee abduction moments while low-risk and control athletes would not show measurable changes.</p> <p>Methods</p> <p>Eighteen high school female athletes participated in neuromuscular training 3×/week over a 7-week period. Knee kinematics and kinetics were measured during a drop vertical jump (DVJ) test at pre/post training. External knee abduction moments were calculated using inverse dynamics. Logistic regression indicated maximal sensitivity and specificity for prediction of ACL injury risk using external knee abduction (25.25 Nm cutoff) during a DVJ. Based on these data, 12 study subjects (and 4 controls) were grouped into the high-risk (knee abduction moment >25.25 Nm) and 6 subjects (and 7 controls) were grouped into the low-risk (knee abduction <25.25 Nm) categories using mean right and left leg knee abduction moments. A mixed design repeated measures ANOVA was used to determine differences between athletes categorized as high or low-risk.</p> <p>Results</p> <p>Athletes classified as high-risk decreased their knee abduction moments by 13% following training (Dominant pre: 39.9 ± 15.8 Nm to 34.6 ± 9.6 Nm; Non-dominant pre: 37.1 ± 9.2 to 32.4 ± 10.7 Nm; p = 0.033 training X risk factor interaction). Athletes grouped into the low-risk category did not change their abduction moments following training (p > 0.05). Control subjects classified as either high or low-risk also did not significantly change from pre to post-testing.</p> <p>Conclusion</p> <p>These results indicate that "high-risk" female athletes decreased the magnitude of the previously identified risk factor to ACL injury following neuromuscular training. However, the mean values for the high-risk subjects were not reduced to levels similar to low-risk group following training. Targeting female athletes who demonstrate high-risk knee abduction loads during dynamic tasks may improve efficacy of neuromuscular training. Yet, increased training volume or more specific techniques may be necessary for high-risk athletes to substantially decrease ACL injury risk.</p

The Effects of Running Cadence Manipulation on Plantar Loading in Healthy Runners

Our purpose was to evaluate effects of cadence manipulation on plantar loading during running. Participants (n=38) ran on a treadmill at their preferred speed in 3 conditions: preferred, 5% increased, and 5% decreased while measured using in-shoe sensors. Data (contact time [CT], peak force [PF], force time integral [FTI], pressure time integral [PTI] and peak pressure [PP]) were recorded for 30 right footfalls. Multivariate analysis was performed to detect differences in loading between cadences in the total foot and 4 plantar regions. Differences in plantar loading occurred between cadence conditions. Total foot CT and PF were lower with a faster cadence, but no total foot PP differences were observed. Faster cadence reduced CT, pressure and force variables in both the heel and metatarsal regions. Increasing cadence did not elevate metatarsal loads; rather, total foot and all regions were reduced when healthy runners increased their cadence. If a 5% increase in cadence from preferred were maintained over each mile run the impulse at the heel would be reduced by an estimated 565 body weightss (BWs) and the metatarsals 140-170 BWs per mile run despite the increased steps taken. Increasing cadence may benefit overuse injuries associated with elevated plantar loading

Gender differences in lower limb frontal plane kinematics during landing

Original article can be found at: http://www.informaworld.com/ Copyright Informa / Taylor and Francis Group. DOI: 10.1080/14763140802233215The study aimed to investigate gender differences in knee valgus angle and inter-knee and inter-ankle distances in university volleyball players when performing opposed block jump landings. Six female and six male university volleyball players performed three dynamic trials each where subjects were instructed to jump up and block a volleyball suspended above a net set at the height of a standard volleyball net as it was spiked against them by an opposing player. Knee valgus/varus, inter-knee distance and inter-ankle distance (absolute and relative to height) were determined during landing using 3D motion analysis. Females displayed significantly greater maximum valgus angle and range of motion than males. This may increase the risk of ligament strain in females compared with males. Minimum absolute inter-knee distance was significantly smaller in females and absolute and relative inter-knee displacement during landing was significantly greater in females compared with males. Both absolute and relative inter-ankle displacement during landing was significantly greater in males than females. These findings suggest that the gender difference in the valgus angle of the knee during two-footed landing is influenced by gender differences in the linear movement of the ankles as well as the knees. Coaches should therefore develop training programmes to focus on movement of both the knee and ankle joints in the frontal plane in order to reduce the knee valgus angle during landing which in turn may reduce the risk of non-contact ACL injury.Peer reviewe

Hip-Abductor Fatigue and Single-Leg Landing Mechanics in Women Athletes

CONTEXT: Reduced hip-abductor strength and muscle activation may be associated with altered lower extremity mechanics, which are thought to increase the risk for anterior cruciate ligament injury. However, experimental evidence supporting this relationship is limited. OBJECTIVE: To examine the changes in single-leg landing mechanics and gluteus medius recruitment that occur after a hip-abductor fatigue protocol. DESIGN: Descriptive laboratory study. PATIENTS OR OTHER PARTICIPANTS: Twenty physically active women (age = 21.0 +/- 1.3 years). INTERVENTION(S): Participants were tested before (prefatigue) and after (postfatigue) a hip-abductor fatigue protocol consisting of repetitive side-lying hip abduction. MAIN OUTCOME MEASURE(S): Outcome measures included sagittal-plane and frontal-plane hip and knee kinematics at initial contact and at 60 milliseconds after initial contact during 5 single-leg landings from a height of 40 cm. Peak hip and knee sagittal-plane and frontal-plane joint moments during this time interval were also analyzed. Measures of gluteus medius activation, including latency, peak amplitude, and integrated signal, were recorded. RESULTS: A small (<1 degree) increase in hip-abduction angle at initial contact and a small (<1 degree) decrease in knee-abduction (valgus) angle at 60 milliseconds after contact were observed in the postfatigue landing condition. No other kinematic changes were noted for the knee or hip at initial contact or at 60 milliseconds after initial contact. Peak external knee-adduction moment decreased 27% and peak hip adduction moment decreased 24% during the postfatigue landing condition. Gluteus medius activation was delayed after the protocol, but no difference in peak or integrated signal was seen during the landing trials. CONCLUSIONS: Changes observed during single-leg landings after hip-abductor fatigue were not generally considered unfavorable to the integrity of the anterior cruciate ligament. Further work may be justified to study the role of hip-abductor activation in protecting the knee during landing

Differences between the sexes in knee kinetics during landing from volleyball block jumps

Original article can be found at: http://www.informaworld.com/smpp/title~content=t714592354~db=all Copyright Informa / Taylor and FrancisThe aim of the study was to assess frontal and sagittal plane kinetics (normalized ground reaction force and normalized knee moment) in male and female university volleyball players when performing opposed block jump landings. Females displayed a significantly lower normalized knee extension moment at the start of muscle latency than males. The greater normalized knee extension moment at the start of muscle latency in females suggests that, through practice, they may have developed a landing strategy that minimizes the moment acting about the knee in the sagittal plane to reduce the likely strain on the passive support structures. The time histories of the normalized knee moment in the frontal plane were different between males and females. The maximum normalized knee valgus moment was significantly greater in females than males. The significantly different maximum normalized knee valgus moment between males and females indicates a greater likelihood of overloading the muscles of the knee in females during landing, which, in turn, is likely to increase the strain on the passive support structures. The increased likely strain on the passive support structures of the knee in females could contribute to the higher incidence of non-contact anterior cruciate ligament injury in females compared with males.Peer reviewe