bluuebunny/crossref_metadata_2025 huggingface dataset:
Replication Efficiency of Soil-Bound Prions Varies with Soil Type
Authors: Saunders Samuel E. , Shikiya Ronald A. , Langenfeld Katie , Bartelt-Hunt Shannon L. , Bartz Jason C.
Published: March 2011

Prion sorption to soil is thought to play an important role in the transmission of scrapie and chronic wasting disease (CWD) via the environment. Sorption of PrP to soil and soil minerals is influenced by the strain and species of PrP
Sc
and by soil characteristics. However, the ability of soil-bound prions to convert PrP
c
to PrP
Sc
under these wide-ranging conditions remains poorly understood. We developed a semiquantitative protein misfolding cyclic amplification (PMCA) protocol to evaluate replication efficiency of soil-bound prions. Binding of the hyper (HY) strain of transmissible mink encephalopathy (TME) (hamster) prions to a silty clay loam soil yielded a greater-than-1-log decrease in PMCA replication efficiency with a corresponding 1.3-log reduction in titer. The increased binding of PrP
Sc
to soil over time corresponded with a decrease in PMCA replication efficiency. The PMCA efficiency of bound prions varied with soil type, where prions bound to clay and organic surfaces exhibited significantly lower replication efficiencies while prions bound to sand exhibited no apparent difference in replication efficiency compared to unbound controls. PMCA results from hamster and CWD agent-infected elk prions yielded similar findings. Given that PrP
Sc
adsorption affinity varies with soil type, the overall balance between prion adsorption affinity and replication efficiency for the dominant soil types of an area may be a significant determinant in the environmental transmission of prion diseases.
Intersection of the Multivesicular Body Pathway and Lipid Homeostasis in RNA Replication by a Positive-Strand RNA Virus
Authors: Wang Xiaofeng , Diaz Arturo , Hao Linhui , Gancarz Brandi , den Boon Johan A. , Ahlquist Paul
Published: March 2011

Like many positive-strand RNA viruses, brome mosaic virus (BMV) RNA replication occurs in membrane-invaginated vesicular compartments. BMV RNA replication compartments show parallels with membrane-enveloped, budding retrovirus virions, whose release depends on the cellular multivesicular body (MVB) sorting pathway. BMV RNA replication compartments are not released from their parent membranes, but might depend on MVB functions for membrane invagination. Prior results show that BMV RNA replication is severely inhibited by deletion of the crucial MVB gene
DOA4
or
BRO1
. We report here that involvement of
DOA4
and
BRO1
in BMV RNA replication is not dependent on the MVB pathway's membrane-shaping functions but rather is due to their roles in recycling ubiquitin from MVB cargos. We show that deleting
DOA4
or
BRO1
inhibits the ubiquitination- and proteasome-dependent activation of homologous transcription factors Mga2p and Spt23p, which regulate many lipid metabolism genes, including the fatty acid desaturase gene
OLE1
, which is essential for BMV RNA replication. However, Mga2p processing and BMV RNA replication are restored by supplementing free ubiquitin, which is depleted in
doa4
Δ and
bro1
Δ cells. The results identify Mga2p and Spt23p processing and lipid regulation as sensitive targets of ubiquitin depletion and correctly predict multiple effects of modulating additional host genes
RFU1
,
UBP6
, and
UFD3
. Our results also show that BMV RNA replication depends on additional Mga2p-regulated genes likely involved in lipid metabolism beyond
OLE1
. Among other points, these findings show the potential for blocking viral RNA replication by modulating lipid synthesis at multiple levels.
Antiviral Stilbene 1,2-Diamines Prevent Initiation of Hepatitis C Virus RNA Replication at the Outset of Infection
Authors: Gastaminza Pablo , Pitram Suresh M. , Dreux Marlene , Krasnova Larissa B. , Whitten-Bauer Christina , Dong Jiajia , Chung Josan , Fokin Valery V. , Sharpless K. Barry , Chisari Francis V.
Published: March 2011

The recent development of a cell culture model of hepatitis C virus (HCV) infection based on the JFH-1 molecular clone has enabled discovery of new antiviral agents. Using a cell-based colorimetric screening assay to interrogate a 1,200-compound chemical library for anti-HCV activity, we identified a family of 1,2-diamines derived from
trans
-stilbene oxide that prevent HCV infection at nontoxic, low micromolar concentrations in cell culture. Structure-activity relationship analysis of ∼300 derivatives synthesized using click chemistry yielded compounds with greatly enhanced low nanomolar potency and a >1,000:1 therapeutic ratio. Using surrogate models of HCV infection, we showed that the compounds selectively block the initiation of replication of incoming HCV RNA but have no impact on viral entry, primary translation, or ongoing HCV RNA replication, nor do they suppress persistent HCV infection. Selection of an escape variant revealed that NS5A is directly or indirectly targeted by this compound. In summary, we have identified a family of HCV inhibitors that target a critical step in the establishment of HCV infection in which NS5A translated
de novo
from an incoming genomic HCV RNA template is required to initiate the replication of this important human pathogen.
Sequential Immunization with a Subtype B HIV-1 Envelope Quasispecies Partially Mimics the In Vivo Development of Neutralizing Antibodies
Authors: Malherbe Delphine C. , Doria-Rose Nicole A. , Misher Lynda , Beckett Travis , Puryear Wendy Blay , Schuman Jason T. , Kraft Zane , O'Malley Jean , Mori Motomi , Srivastava Indresh , Barnett Susan , Stamatatos Leonidas , Haigwood Nancy L.
Published: March 2011

A major goal of human immunodeficiency virus type 1 (HIV-1) vaccine efforts is the design of Envelope (Env)-based immunogens effective at eliciting heterologous or broad neutralizing antibodies (NAbs). We hypothesized that programming the B-cell response could be achieved by sequentially exposing the host to a collection of
env
variants representing the viral quasispecies members isolated from an individual that developed broad NAbs over time. This ordered vaccine approach (sequential) was compared to exposure to a cocktail of
env
clones (mixture) and to a single
env
variant (clonal). The three strategies induced comparable levels of the autologous and heterologous neutralization of tier 1 pseudoviruses. Sequential and mixture exposure to quasispecies led to epitope targeting similar to that observed in the simian-human immunodeficiency virus (SHIV)-infected animal from which the
env
variants were cloned, while clonal and sequential exposure led to greater antibody maturation than the mixture. Therefore, the sequential vaccine approach best replicated the features of the NAb response observed in that animal. This study is the first to explore the use of a collection of HIV-1
env
quasispecies variants as immunogens and to present evidence that it is possible to educate the B-cell response by sequential exposure to native HIV-1 quasispecies
env
variants derived from an individual with a broadened NAb response.
A simple clinical screening test can identify elite female football players with increased knee valgus angles
Authors: Nilstad A , Kristianslund E , Krosshaug T , Steffen K , Myklebust G , Bahr R , Andersen T E
Published: March 2011

Background

A link has been suggested between increased dynamic knee valgus and the risk of anterior cruciate ligament (ACL) injuries in female athletes. However, these findings are based on complex time-consuming 3D motion analysis. There is a need for simple screening tools to identify athletes at increased risk of an ACL rupture.

Objective

To assess whether an experienced clinician can identify athletes with increased valgus angles and moments during a vertical drop jump using a simple screening test.

Design

Cross-sectional study.

Participants

Elite female football players.

Methods

Players in the Norwegian elite league (12 teams) were screened for potential risk factors for ACL injuries. Knee kinematics and kinetics in the landing phase of a 30 cm vertical drop jump were calculated using 3D motion analysis. Using a similar jump task, a physiotherapist assessed how well players stabilised their knees, and scored their knee control as ‘good’, ‘reduced’ or ‘poor’.

Results

Of the 136 players included, 38% were classified as ‘good’, 34% had ‘reduced’ control and 28% were scored as ‘poor’. Players with good control had significantly lower maximal valgus angles compared to players with poor control (0.5° vs 6.8°, p≤0.001). There were no differences in valgus moments (0.28 Nm/kg vs 0.28 Nm/kg, p=1.0). One-fifth of all players (17.6%) displayed valgus angles more than one SD above the mean in the 3D analyses (3.1° ±4.5°). The screening test captured 87.5% of these players. 22 (16.2%) players were classified in the ‘poor’ group without displaying high valgus angles.

Conclusion

The screening test identified 87.5% of players with increased valgus angles. No correlation was found between valgus angles and moments, and the test could not identify players with high valgus moments. Further investigations are needed to determine the cut-off value for defining high- versus low-risk groups, as well as the predictive value of the test.
What is more dangerous – football, skiing or snowboarding?
Authors: Flørenes T , Bjørneboe J , Andersen T E , Heir S , Bahr R
Published: March 2011

Background

It is well known that professional football has a high injury risk. The FIS Injury Surveillance System increases our knowledge of injuries to elite skiers and snowboarders. But what is more dangerous?

Objective

To compare the injury risk in World Cup (WC) skiing and snowboarding with Norwegian professional football (Tippeligaen).

Design/Setting

We conducted season-ending interviews with athletes from selected WC-teams in alpine skiing, freestyle skiing and snowboarding during the 2006–2007 and 2007–2008 winter seasons on acute injuries sustained (November through mid-March). Injury information was prospectively collected from medical staff in all Tippeliga-teams (n=16) and extracted from mid-March through July for the 2007 and 2008 seasons to best imitate the skiing/snowboarding season. Injury rate was calculated as number of injuries per 100 athletes per season.

Results

Among 521 alpine, 416 freestyle and 421 snowboard athletes we registered 155, 115 and 159 time-loss injuries, corresponding to 29.8 (95% CI 25.1 to 34.4), 27.6 (22.6–32.7) and 37.8 (31.9–43.6) injuries per 100 athletes per season. In Tippeligaen, 308 time-loss injuries were recorded among 440 players, corresponding to 70.0 (62.2–77.8) injuries per 100 players (RR: 2.4 (1.9–2.9) vs alpine, 2.5 (2.0–3.2) vs freestyle and 1.9 (1.5–2.2) vs snowboard). The rate of severe injuries (absence >28 days) was 11.3 (8.4–14.2), 13.8 (10.2–17.3), and 14.4 (10.8–18.1) injuries per 100 alpine, snowboard and freestyle athletes per season and 9.3 (6.5–12.2) in football. The rate of severe injuries was higher in freestyle skiing compared to football (RR: 1.5, 1.0–2.3) while no difference was found between football and alpine skiing (RR: 0.8, 0.6–1.2) or snowboarding (RR: 0.7, 0.5–1.0).

Conclusion

The injury risk among WC skiers and snowboarders is high, but only half of that in elite Norwegian football. However, the risk for severe injuries is the same in alpine skiing and snowboarding as in football, and even higher in freestyle skiing.
Pre-season screening of core muscle balance and control tests in the lumbar spine in professional road cyclists can we prevent uncontrolled movement?
Authors: Hadala M , de Bernardo N , Vera P , Laíz C , Barrios C
Published: March 2011

Background

Asymptomatic musculoskeletal function, normal range of joint motion and normal muscle strength are considered not adequate star points to design a prevention injury program.

Objective

To assess core muscle balance and control in the lumbar spine using simple functional tests during low load activity and high load dynamic movements.

Design

Cross-sectional descriptive study.

Setting

Professional road cyclists.

Patients

51 elite road cyclists were functionally evaluated at the beginning of the 2010 season. All injuries affecting racers during previous seasons were recorded throughout a clinical oriented interview.

Interventions

Specific assessment of the site (lower back and pelvis) and direction of uncontrolled movement, under low and high loading within functionally orientated tasks.

Main outcome measurements

Three tests were conducted in the crook laying position: (1) double leg lift and lower, (2) single leg extension, (3) bridge+single leg extension. In two first tests the ‘stabilizer’ pressure biofeedback unit was used to measure the influence of the global muscle system on trunk stability. Muscle functional extensibility of iliopsoas, tensor fasciae late, anterior rectus femoris and hamstrings were also evaluated.

Results

Uncontrolled movements in lower back in low load test were found in flexion (57% of cyclist) and extension test (67%). Passive and active restriction of hamstrings while sitting showed significant correlation with impaired low back movements in flexion test (p<0.05). Weakness of the gluteus maximus correlated with uncontrolled movement in low back extension at high loading. Impaired movements in pelvic girdle (70%) showed a statistically significant relationship with asymmetrical passive restriction of rectus anterior muscle (p<0.03).

Conclusion

Muscle imbalance between hamstrings and hip flexors together with weak hip extensors provoke uncontrolled movements in the low back of cyclists, predisposing them to more overuse injuries. A specific preventive program should be desirable.
Longitudinal study of dynamic lower limb alignment during landing in pubescent children
Authors: Kimura Y , Ishibashi Y , Tsuda E , Yamamoto Y , Maeda S , Hayashi Y , Sasaki S
Published: March 2011

Background

Female athletes have increased risk of anterior cruciate ligament (ACL) injury after puberty. It has been demonstrated that female athletes have greater valgus lower limb alignment than males during landing, and this may contribute to the gender disparity in ACL injury risks. In early teens, however, the gender difference in lower limb alignment has not been elucidated.

Objective

The purpose of this study was to examine whether dynamic lower limb alignment alters during the pubertal stage in girls and boys, in a longitudinal survey.

Design

Cohort study.

Settings

Elementary school students with no lower extremity complaints.

Participants

33 females and 27 males aged 10 to 11 years old were evaluated and followed for three consecutive years.

Assessment of risk factor

The subjects performed a drop-vertical-jump by dropping directly down off a box, and immediately performing a maximum vertical jump. The frontal view of the lower limb was recorded with a digital video camera and the images at deepest point of body (landing) were captured.

Main outcome measurement

The separate distances between right and left hips and knees were measured. The knee separation distances normalised by the hip separation distance (K/H ratio) were used as a parameter representing the valgus/varus lower limb alignment.

Results

At landing, K/H ratio in females was 0.41±0.10 in the first year, 0.39±0.11 in the second year, 0.36±0.10 in the third year. In males, the ratios were 0.60±0.21, 0.52±0.17, 0.55±0.19. Knee valgus alignment in females increased with maturation, with significant difference between first year and third year. However, there were no significant changes in males.

Conclusion

Different changing pattern of lower limb alignment during landing was seen between boys and girls, and it may be related to the gender difference in incidence of ACL injury.
Musculoskeletal pain in recreational runners prior to race participation: a cross-sectional survey in 1049 runners
Authors: Lopes A D , Saragiotto B T , Yamato T P , Adami F , Costa L O P
Published: March 2011

Background

We know that high-performance sports place high stress in the musculoskeletal system, often resulting in injury, pain, or other complaints. It is not unusual for athletes to decide to participate in important competitions, despite an ongoing disability or injury. However, we are unaware of any study that has presented any clear information about this issue in recreational runners.

Objective

The aims of this study were to calculate the prevalence of presence of musculoskeletal pain in amateur runners immediately before a race and to identify possible factors that could be associated with presence of musculoskeletal pain in this population.

Design

This is a cross-sectional survey study.

Setting

These runners were recreational athletes that participated in different races in São Paulo (Brazil), the distance of these races ranged from 5.000/10.000 meters.

Participants

A convenience sample of 1049 runners, 24.1% women (n=253) and 75.9% men (n=796).

Assessment of risk factors

This questionnaire contained information on presence of musculoskeletal pain, demographic characteristics, weight, body mass index, running experience, running mileage/week, number of training sessions/week, predominant training surface and coaching utilisation. We used logistic regression analysis to indentify associations between possible factors and presence of musculoskeletal pain (p<0.05). The data were collected 1–2 h prior to the races.

Main outcome measurements

Presence of musculoskeletal pain.

Results

The prevalence of presence of musculoskeletal pain was 20% and 26.9% for men and women respectively. Running experience (OR=2.97, 95% CI 1.59 to 5.56) and weekly running distance (OR=1.88, 95% CI 1.02 to 3.48) were associated with presence of musculoskeletal pain in men prior to the race.

Conclusion

The prevalence of presence of musculoskeletal pain in amateur runners prior to the race was high. We have observed higher experience in running (ie, more than 10 years) and high training volumes (ie, more than 50 Km/week) were associated with presence of musculoskeletal pain.
Influence of a preventive training program on the lower limbs kinematics and vertical jump height of male volleyball athletes
Authors: Leporace G , Metsavaht L , Praxedes J , Pereira G , Pinto S , Chagas D , Chame F , Batista L A
Published: March 2011

Background

The effectiveness of preventive training programs (PTP) aiming at changing the biomechanical behaviour related to anterior cruciate ligament injuries is subject to pre-existing risk. However, these assumptions are based on studies in females. Moreover, it is unclear what influence this training has on performance of young male athletes.

Objective

To examine the influence of a PTP on changes in kinematics during landings and in maximum vertical jump height (VJH) in males.

Design

6 weeks prospective exercise intervention.

Setting

Young male volleyball athletes.

Participants

15 male volleyball athletes (13±0.7 years, 1.70±0.12 m, 60±12 kg).

Interventions

PTP consisting of plyometric, balance and core stability exercises three times per week for 6 weeks. Bilateral vertical jumps with double leg (DL) and single leg (SL) landings were performed to measure the effects of training.

Main outcome measurements

Kinematics of knee and hip before and after training and VJH attained during both tasks after training. The hypothesis was that the PTP would produce improvements in VJH, but would not generate great changes in biomechanical behaviour.

Results

The only change revealed for the SL was the longest duration of landing (p=0.0273), while in the DL was the largest angular displacement of the knee (p=0.0371). The training did not significantly alter the VJH in the SL (diff: 2.7 cm, p=0.3054) or DL condition (diff: 3.5 cm, p=0.3635).

Conclusion

Despite the alterations in the kinematics behaviour, the changes observed are specific for each landing task, which highlights the importance of the principle of specificity. Despite the absence of significant increases in the VJH after training, the absolute differences pre to post training showed an increase consistent with other studies that compared the results with control groups. The present study showed that short time PTP in low-risk populations, although generating little influence on the kinematics, are capable of enhancing performance.
Protocol for the dano-run study: a 1-year observational follow up study on running related injuries in 1000 novice runners
Authors: Nielsen R , Ramskov D , Sorensen H , Lind M , Rasmussen S , Buist I
Published: March 2011

Background

The knowledge on the relation between running patterns and Running Related Injuries (RRIs) is sparse. Studies have tried to document a relationship. However, no firm conclusions can be made. Still it is necessary to identify which running exposures increase the risk of injuries and which exposures might be considered safe.

Objective

The purpose of this study is to investigate the link between the running volume and the development of RRIs.

Design

Observational prospective follow up study.

Setting

Clinical setting on novice and recreational athletes.

Participants

Healthy individuals (N=1000) who have not been running the past 1 year is included. All participants receive a global positioning system (GPS) watch (Garmin FR 110) and a pair of neutral running shoes (Adidas Glide 2). They are instructed to start running as much as they want, two times a week as a minimum. They must wear their GPS watch at each training session and upload data to an internet based database. All participants are followed for 1 year.

Assessment of risk factors

Running volume measured as absolute number of kilometres and the graduation in kilometres pr. week over a period of 3 weeks.

Main outcome measurement

RRI is defined as any musculoskeletal complaint of the lower extremity or back causing a restriction of running for at least 1 week.

Results

Time to RRI is compared between groups with different absolute running volumes. In a similar way time to injury is compared between individuals with different weekly training graduations.

Conclusion

This study may be the first study to adequately measure running patterns reliably in a large sample. The exposure is quantified by GPS, which is not affected by subject recall and is therefore a clear methodological improvement compared to previous studies. If absolute volume or running graduation over time seems to lead to injury, the study findings and methodology create a solid foundation for future randomised controlled trials in this field.
‘At risk’ positioning and hip biomechanics of the peewee ice hockey sprint start
Authors: Philippon M J , Stull J D , LaPrade R F
Published: March 2011

Background

‘At risk’ motion of the hip is defined primarily by internal rotation during flexion, reportedly increasing vulnerability to labral injury and observed during the recovery phase of the adult ice hockey skating stride. No biomechanical analysis has focused on ‘at risk’ hip motion in youth hockey players sprint starts.

Objective

To investigate the biomechanics of the male youth ice hockey sprint start with attention to the hip and a previously identified ‘at risk’ position. We hypothesised that youth hockey players display ‘at risk’ hip motion during the sprint start.

Design

Descriptive in vivo laboratory study.

Setting

The study was conducted in a biomechanics laboratory on 6.4 mm acrylic surface manufactured specifically for ice hockey skate testing.

Participants

12 healthy male Peewee ice hockey players (mean age: 10.8 (± 0.6 years)).

Assessment of risk factors

Participants were assessed for hip flexion at maximum internal rotation by 10 high-speed infrared cameras that recorded 35 anatomical identifiers to assess the 3-D biomechanics of the ice hockey sprint start over 100 time-segments comprising the sprint stride.

Main outcome measurements

Data was collected for hip flexion, extension, abduction, adduction, external and internal rotation.

Results

During the recovery phase of the sprint start, maximum internal rotation in each hip occurred simultaneously to that hip approaching maximum flexion (Push leg; 5.6° internal rotation with 44.2° flexion; Lead leg; 10.8° internal rotation with 35.1° flexion). As the sprint start progressed, ‘at risk’ motion was increasingly exaggerated by increased hip rotation speed (Lead leg;+2.7° flexion/time-segment during recovery phase over the final 14% of the sprint).

Conclusion

During the sprint start, youth ice hockey players internally rotate while proceeding through hip flexion, displaying ‘at risk’ hip motion. This knowledge could be applied with related future findings to aid potential prevention of hip overuse injuries as youth hockey players mature and increase in skill level.
Translating theory into practice (and practice into theory) – does context influence sports injury prevention research?
Authors: Richardson P
Published: March 2011

Background

Sports injury prevention research, like many other fields, has difficulty translating research-based evidence into real-world practice. The ubiquitous theory-practice gap, historically portrayed as a ‘one-way’ knowledge-transfer issue, has recently been reconceptualised as a knowledge-production problem, suggesting a mismatch between the reductionist sense-making strategies which researchers and ‘real-world’ practitioners adopt to deal with the complexities of change, choice, communication, and culture. Sport, injury, prevention and research are dynamic, ecological phenomena occurring within socially-constructed communities of practice. Contextual factors influence the adoption of evidence-based recommendations in real-world settings, but do the theories that underpin sports injury prevention research practice take context into account?

Objective

This paper will explore the role of context in the theories commonly used to inform sports injury prevention research practice.

Design

Peer-reviewed literature and major reference texts were searched to identify the theories and models most commonly cited and recommended for application in sports injury prevention research. The theory-practice gap literature from a range of other fields was also reviewed. The ‘contextual content’ of the theories used to inform sports injury prevention research was compared and contrasted with a number of contextual dimensions identified as consistent barriers to translation of evidence into practice in trans-disciplinary perspectives.

Results

The theories most commonly cited by sports injury prevention researchers include behavioural, ecological and social dimensions that do reflect an understanding of the need to consider ‘context’ when trying to understand how to prevent sports injuries.

Conclusion

Although contextual elements are incorporated in the theories frequently cited by sports injury prevention researchers, lack of contextual ‘fit’ is still considered the major barrier to translating research knowledge into real-world practice. Is the ‘translation gap’ in the research process a problem of theory use or theory utility?
Posterior shear force and posterior tibial displacement using a sling bridge in patients with posterior cruciate ligament insufficiency
Authors: Sakai T , Koyanagi M , Nakata K , Fujisaki H , Yamagata T , Hidaka K , Suzuki Y , Nakamura N
Published: March 2011

Background

Rehabilitation training of hamstring muscle with deep knee flexion should be restricted following the posterior cruciate ligament (PCL) reconstruction because it stresses the PCL graft. To perform rehabilitation training of the hamstring muscle without the stress to the PCL, we have developed a sling bridge exercise (SB), which is a hamstring exercise with a sling at a lower leg to lift the buttocks in a supine position. Our hypothesis is that anterior traction force generated by a sling decrease strain on the PCL during SB.

Objective

To analyze posterior shear force and amount of posterior tibial displacement by the SB and compare with those by the conventional bridge (CB) exercise.

Design

Quasi-experimental study.

Setting

Controlled laboratory research.

Participants

Five healthy male volunteers and one patient with PCL insufficiency.

Intervention

Position of physical segments and force on floor were analyzed by a 3D motion capture system and force plate. Posterior tibial displacement was measured by lateral XP view of the knee during the exercises.

Main outcome measurements

Posterior shear force of the knee was calculated by using a biomechanical musculoskeletal model. Posterior tibial displacement was measured by digitised XP.

Results

Posterior shear force of the healthy volunteers was 849.0 ± 322.5 N during CB and 360.6 ± 75.5 N during SB. In a patient with the PCL insufficiency, side-to side difference in posterior tibial displacement by SB (1.2 mm) was smaller than that of CB (3.3 mm).

Conclusion

The SB hamstring exercise causes less posterior shear force and resulted in less posterior tibial displacement than a CB exercise. Therefore, a sling hamstring exercise is safer than a CB exercise in rehabilitation training for the patients with PCL reconstruction of the knee.
Atrial fibrillation in athletes: towards a changing therapeutic approach in the era of catheter ablation
Authors: Saoudi N , Arnoult M , Hugues T , Latcu D G , Popescu I , Ricard P , Rinaldi J P , Yaïci K , Zarqane N
Published: March 2011

Background

The Prevalence of atrial fibrillation (AF) is increasing and its incidence in professional and amateur athletes seems higher than in the general population (OR=2–10 after adjustment for other risk factors). A U shaped relationship of physical activity with incident AF suggests that the positive antiarrhythmic effects of sport are partially negated by prolonged heavy endurance exercise. AF is also more prevalent in middle-aged former competitive athletes.

Design

A review of the literature of AF in athletes is presented. AF may be due to sympathetic activity, volume load during exercise, vagotonia at rest but also atrial hypertrophy and dilatation. Anticoagulation cannot be used in sporting activities with a risk of bodily collision. Rate control during AF is difficult to reach in athletes: -blockers are not well tolerated or even prohibited in some competitive sports, and digoxin or calcium antagonists are poorly effective during exertion. In paroxysmal AF athletes, the flecainide or propafenone ‘pill-in the pocket approach’ can be used, but transient sport practice limitations ensue.

Intervention

Several reports of the new pulmonary vein catheter ablation have demonstrated encouraging results. Using radiofrequency current, the latter is as efficacious in lone AF amateur athletes as in controls. Representative examples from our AF ablation patient database will be presented.

Conclusion

A review of the literature and our own experience suggest that catheter ablation of AF in athletes will probably develop in the near future. This is also supported by the recent European guidelines which state that ‘where appropriate, AF ablation should be considered to prevent recurrent AF in athletes' without requiring prior drug therapy.
Effects of eccentric hamstring strength exercise on knee flexor strength
Authors: Sato K , Hosokawa T , Mitsueda S , Hosaki K , Okuyama M , Okada T , Kanisawa I , Tsuchiya A , Takahashi K , Sakai H
Published: March 2011

Background

Eccentric hamstring strength exercise has been adopted in lower extremity injury prevention programs extensively, but the study of its effect on knee flexor strength is limited.

Objective

The objective of this study was to examine the effects of eccentric hamstring strength exercise on knee flexor strength using three different measuring methods, and to compare the effects between men and women.

Design

Prospective cohort study.

Setting

The evaluation was performed in a rehabilitation laboratory.

Participants

18 healthy volunteers (10 men, 8 women) participated in this study.

Intervention

All subjects were asked to perform eccentric hamstring strength exercise (the so-called Nordic hamstring exercise) 3 days a week for 6 weeks.

Main outcome measurements

Concentric, eccentric and isometric knee flexor strengths were measured before and after the training periods using the Biodex dynamometer. Concentric and eccentric peak torques at 60 deg/sec, and isometric peak torque with 90° of knee flexion for 5 s, were measured. These were compared before and after intervention. The rate of increase was calculated and compared between men and women.

Results

The eccentric torque measurements for men after intervention were significantly higher than before intervention (p<0.05), while there was no significant difference in women. No significant differences between before and after intervention were shown for concentric and isometric torques in both sexes. The rate of increase for men (20.0%) was significantly higher than that for women (8.8%) in eccentric torque (p<0.05), while no significant differences were observed between men and women in concentric and isometric torque.

Conclusion

It seems that the effect of the eccentric hamstrings strength exercise in women was lower than in men. Therefore, careful attention should be paid in instructing the exercise to women.
Risk factors associated with exercise associated muscle cramping (EAMC) – a prospective cohort study in ironman triathletes
Authors: Schwellnus M , Collins M , Drew N
Published: March 2011

Background

Despite the high prevalence of Exercise Associated Muscle Cramping (EAMC) in endurance athletes, the aetiology and risk factors for this condition are not fully understood.

Objective

The objective of this prospective cohort study was to identify risk factors associated with EAMC in endurance triathletes.

Setting

Field study during an international Ironman triathlon.

Participants

210 triathletes competing in an Ironman triathlon.

Assessment

Prior to the race, subjects completed a detailed validated questionnaire and blood samples were taken for serum electrolytes. Immediately before the race, pre-race body weight was obtained. Body weight and blood samples for serum electrolyte concentrations were obtained immediately post-race. Clinical data on EAMC experienced during or immediately after the race were also collected.

Main outcome measurements

Training data, serum electrolyte and body weight changes were compared between 44 triathletes who reported EAMC (CR group) and 166 triathletes who did not report EAMC (NC group). A regression analysis was conducted to determine independent risk factors for EAMC in triathletes.

Results

There were no significant differences between groups in any pre-post race serum electrolyte concentrations and body weight changes. The development of EAMC was associated with faster predicted race times and faster actual race times, despite similarly matched preparation and performance histories in subjects from both groups. A regression analysis identified faster overall race time (and cycling time) and a past history of cramping (in the last 10 races) as the only two independent risk factors for EAMC.

Conclusion

The results from this study add to the evidence that dehydration and altered serum electrolyte balance are not causes for EAMC. Rather, endurance runners competing at a fast pace, which suggests that they exercise at a high intensity, are at risk for EAMC.
New device production for preventive measures against the hallux-valgus deformity
Authors: Urabe Y , Kamiya N , Yamanaka Y , Shintaku M
Published: March 2011

Background

Many athletes have foot deformity of hallux-valgus. These deformities lead to decrease of foot function and sports performance. The authors were developed a new device for decrease the angle of hallux-valgus. This device was socks and in use underwear in sports activity and daily living.

Objective

The purpose of this study was following four points. Does this device can change the hallux-valgus angle? Does this device can change the foot pain? Does this device influence centre of pressure (COP) of the foot? Does this device can decrease the deformity for long-term use?

Design

Prospective and randomised controlled trial design.

Setting

This study was clinical setting for athletes.

Participants

The subjects were 34 female volunteer athletes. The hallux-valgus group was consisted 17 athletes, all who has hallux-valgus angle above 20° and complaint of foot pain. The control group was 17, all who has hallux-valgus angle below 19° and pain free of each foot.

Intervention

The subjects were used this socks 3 months of their daily life and sports activities.

Main outcome measurements

The hallux-valgus angle and COP of standing position were measured, and checked again after the 3 months.

Results

The hallux-valgus angle was decreased 7.1° at instance of wearing the socks with hallux-valgus group and 5.5° with control group. The foot pain was decreased 50% at instance of wearing socks with hallux-valgus group and 70% decrease at 2.3 months uses the socks. The COP of the body was changed 3.7% forward on the foot of hallux-valgus group. The 2.3 months later, hallux-valgus angle was decreased 4.7° of average at the bare foot with hallux-valgus group.

Conclusions

This study showed the hallux-valgus prevention socks were decreased not only deformity angle at instance but also use prolonged more angle decreased.
The epidemiology of shoulder injuries in rugby union football
Authors: Usman J , McIntosh A S , Best J P
Published: March 2011

Background

Shoulder injuries are a significant risk in rugby union football. However, the aetiology and the risk factors associated with shoulder injuries are not well understood.

Objective

To analyse the incidence and risk factors for shoulder injuries in rugby union football.

Design

A prospective shoulder injury study was carried out in 2009 using a recursive injury model framework.

Setting

Community level adult male rugby union players.

Participants

75 players at the start and 54 players at the end.

Assessment of risk factors

The effects of player size, age, injury history and usage of shoulder padding were assessed.

Main outcome measurements

Shoulder injury incidence rate (IIR). Performance on shoulder assessments using the Constant Score Protocol was measured pre-, mid- and end-season. Weekly training and shoulder impairment was measured.

Results

A total of 1138.1 player participation hours (pph) were recorded. The overall shoulder IIR was 4.4 injuries per 1000 pph with an average severity of 1.0 missed game. Previous injury and shoulder pads were the main observed intrinsic and extrinsic injury risk factors, respectively. An IIR of 3.5/1000 pph were recorded in players with no history of shoulder injury in the last 3 years (80%). There was a non-significant reduction in injury incidence for players wearing shoulder pads during a match. The tackle has been identified as the intrinsic factor that contributed to 67% of the total time loss to injury. Shoulder pain and impairment were reported by 41% of the players throughout the season but none caused the players to miss any games.

Conclusion

A recursive injury model was applied however shoulder pain and impairment did not appear to be correlated with injury risk. Recursiveness may not be relevant to the shoulder injuries observed in this cohort. Pre-season screening and appropriate rehabilitation may prevent repeat shoulder injury.
Risk factors for patellar tendinopathy in basketball and volleyball players: a cross-sectional survey
Authors: van der Worp H , van Ark M , Zwerver J , van den Akker-Scheek I
Published: March 2011

Background

Patellar tendinopathy has a multifactorial aetiology, and many potential risk factors have been described in the literature. Findings are conflicting though, and most research is conducted on elite athletes.

Objective

Aim of the study is to determine risk factors for patellar tendinopathy in a large representative sample of basketball and volleyball players.

Design

Cross-sectional survey using an online questionnaire.

Setting

Basketball and volleyball players of all playing levels.

Participants

All basketball and volleyball players between ages 18 and 35 years (n=7740) from the Dutch Basketball Association and the Dutch Volleyball Association were invited to complete the questionnaire. 1561 volleyball players completed the questionnaire.

Assessment of risk factors

The following independent variables were collected: Gender, age, body mass index, waist-to-hip ratio, years playing basketball/volleyball, hours of training during the last week, number of games during the last month, average hours of other sports per week, training increase compared to last year, playing surface, playing level and playing position.

Main outcome measurements

Presence of symptomatic patellar tendinopathy was the dependent variable.

Results

Risk factors for patellar tendinopathy were age, playing at the national level, being male and playing volleyball (compared to playing basketball). Risk factors for men and women were comparable. Among volleyball players outside hitters and middle blockers/hitters had an increased risk compared to setters. For basketball players no risk factors could be identified. No differences in risk factors were found between athletes with unilateral and bilateral patellar tendinopathy.

Conclusion

Several potential risk factors for patellar tendinopathy were identified. These findings should be taken into account for prevention and rehabilitation purposes.
A prospective study of injuries in elite soccer referees and assistant referees
Authors: Wilson F , Gissane C , Byrne A
Published: March 2011

Background

Injury incidence in soccer players has received wide attention, but there is a lack of information dealing with match officials.

Objective

To examine the profile and incidence of injury in soccer match officials.

Design

A 12 month prospective cohort injury surveillance programme.

Setting

Elite soccer referees and assistant referees who were part of the Football Association of Ireland referee database.

Participants

31 participants (27 males and 4 females), mean age 33.2 (6.2) years old (69% of the available cohort).

Assessment of risk factors

Weekly web based survey, followed up by a telephone interview in those cases who reported injury.

Main outcome measurements

Details of training and match officiating. New injuries in terms of site of the body, type of injury, where, when and how it took place.

Results

Most activity time was spent training (61%) with 39% spent officiating. 38 injuries were recorded, (8.8/1000 h training (CI 6.2 to 12.0) and 16.4/1000 h for match officiating (CI 10.9 to 23.8), (RR 4.3, 2.1 to 8.9)). 55% (CI 40 to 70%) were injuries to muscles. 76% (CI 61 to 87) were to the lower leg. Overuse injuries represented 61% (CI 45 to 74%) of all cases. Achilles tendinopathy and hip/groin muscle strain were the most common injuries (18.4% of all injuries each). The proportion of overuse injuries that took place in matches (68%) and training (40%) were not significantly different (difference=28%, 95% CI −6 to 55). Only two injuries (5.3%, 95% CI 1.5 to 17.0) involved contact, both during training.

Conclusion

Elite match officials complete high volumes of training and officiating. Match officials are at risk of sustaining injury which in training, is similar to the incidence reported in soccer players.
Brain loading in concussive head impacts: implications for injury prevention
Authors: Patton D , McIntosh A , Kleiven S
Published: March 2011

Background

Concussion is a prominent injury risk in sport, but the mechanisms that cause concussion are unclear. An important debate centres on the roles of angular and linear head acceleration in the mechanism of concussion. Resolving this debate is a prerequisite for developing injury prevention methods.

Objective

To estimate the brain loading patterns in a case series of concussive and no-injury head impacts. To assess the relative affects of linear and angular acceleration on brain loading and injury.

Design

Biomechanical analysis of head impacts using the validated KTH human head finite element model to analyse brain loading patterns in reconstructed head impacts.

Setting

Professional male unhelmeted contact football.

Participants

Biomechanical data from a previous case series study of 40 male football players (concussed and no-injury).

Main outcome measurements

Maximum principle strain, a predictor of injury, was measured in discrete brain locations.

Results

The highest maximum principle strains were recorded in both the white and grey matter of the cerebrum. Strains in all brain regions were similar across all three grades of concussion (Cantu Revised Concussion Grading Guidelines), but lower (33–47%) for no-injury cases. Concussion was most correlated with strains in the brainstem and thalamus. Angular, rather than linear, resultant accelerations correlated higher to strains in all regions of the brain. Angular accelerations in the coronal plane and linear accelerations directed inferiorly had the greatest correlation to concussion and loss of consciousness. For linear accelerations, those directed laterally and inferiorly were most correlated with strain. Angular accelerations in the coronal plane correlated highly with strains in the brainstem, thalamus, and midbrain. Angular accelerations in the transverse plane correlated highly with strains in the cerebrum and corpus callosum.

Conclusion

Brain loading differences were observed between concussion and no-injury cases. Angular acceleration may play a more important role in the mechanism of concussion than linear acceleration.
Neuromuscular patterns in chronic ankle instability
Authors: Leumann A , Ebneter L , Von Tscharner V , Valderrabano V
Published: March 2011

Background

Ankle sprains are the most frequent injury in sports. Up to 40% of acute sprains develop chronic ankle instability (CAI). CAI may be seen either as mechanical (ligamentous) instability or functional (neuromuscular) instability. So far, no method is known to objectivate functional instability.

Purpose

To measure neuromuscular patterns in patients with mechanical ligamentous CAI.

Design

Prospective cohort study.

Setting and patients

15 Patients (age 15–58 years) were included evidencing chronic unilateral mechanical ankle instability undergoing ligament reconstruction. As control, the contralateral healthy ankle and 15 sex- and age-matched participants were used.

Interventions

Superficial Electromyography (EMG) analysis of four muscles were recorded: gastrocnemius medialis (GM), tibialis anterior (TA), peroneus longus (PL) and soleus (SO) while the patient performed single stance tests on a Biodex Balance System (BBS).

Main outcome measurements

EMG was analyzed by intensity and frequency using Wavelet Transformation. Neuromuscular controal was analyzed by the results of the BBS.

Results

CAI patients showed significantly decreased results in neuromuscular ankle joint control correlating to increased ankle pain. EMG analyses showed a significant decrease in frequency recruitment for the PL (average frequency, 138.3 Hz for the unstable ankle versus 158.3 Hz for the contralateral healthy side, p<0.001). Instead, no change in intensity was found for the PL. For the GM, TA, and SO, changes neither for intensity, nor frequency were found.

Conclusion

This shift of frequency in the PL muscle due to chronic ligamentous ankle instability is the sign of lower muscle activation coming along with type II muscle atrophy. This is the first study to report on the fact that functional ankle instability may be measured as muscle damage seen by a shift in EMG frequency. Therefore, prevention and rehabilitation of chronic ligamentous instability has to address also a functional chronic muscle damage.