Psychological predictors of sport injuries among junior soccer players.

Scand J Med Sci Sports. 2010 Jan 22. [Epub ahead of print]

Previous researches have established models that specify psychological factors that could predict sport injuries. One example is Williams and Andersen's stress-injury model stressing factors such as anxiety, negative life stress and few coping resources. The purpose of the current study was to find psychological factors that could lead to an increased injury risk among junior soccer players, in addition to construct an empirical model of injury risk factors for soccer players. The participants were 108 male and female soccer players (m=17, 6) studying at soccer high schools in southwest Sweden. Five questionnaires were used, State Trait Anxiety Inventory, Sport Anxiety Scale, Life Events Survey for Collegiate Athletes, Athletic Coping Skills Inventory-28 and Swedish universities Scales of Personality. Injury record was collected by athletic trainers at the schools during a period of 8 months. The result suggested four significant predictors that together could explain 23% of injury occurrence. The main factors are life event stress, somatic trait anxiety, mistrust and ineffective coping. These findings partly support Williams and Andersen's stress-injury model and are organized into an empirical model. Recommendations are given to sport medicine teams and coaches concerning issues in sport injury prevention.

Monitoring Load, Recovery, and Performance in Young Elite Soccer Players.

J Strength Cond Res. 2010 Feb 9. [Epub ahead of print] 

Monitoring load, recovery, and performance in young elite soccer players. J Strength Cond Res 24(x): 000-000, 2010-The purpose of this study was to investigate the relation between training load, recovery, and monthly field test performance in young elite soccer players to develop training guidelines to enhance performance. In a prospective, nonexperimental cohort design, 18 young elite soccer players registered training and match duration for a full competitive season by means of daily training logs. Furthermore, session rating of perceived exertion (RPE) and total quality of recovery (TQR) scores were recorded. Weekly duration (TLd), load (duration x session RPE = TLrpe), and TQR scores were calculated for 1 and 2 weeks before a monthly submaximal interval shuttle run tests to determine interval endurance capacity. Participants spent on average 394.4 +/- 134.9 minutes per week on training and game play with an average session RPE of 14.4 +/- 1.2 (somewhat hard) and TQR of 14.7 +/- 1.3 (good recovery). Random intercept models showed that every extra hour training or game play resulted in enhanced field test performance (p < 0.05). Session RPE and TQR scores did not contribute to the prediction of performance. The duration of training and game play in the week before field test performance is most strongly related to interval endurance capacity. Therefore, coaches should focus on training duration to improve interval endurance capacity in elite soccer players. To evaluate the group and individual training response, field tests should be frequently executed and be incorporated in the training program.

BJSM reviews: A-Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance Part 5.

Br J Sports Med. 2010 Jan;44(1):77-8.
 BUFFERS: SODIUM BICARBONATE AND SODIUM CITRATE; b-ALANINE AND CARNOSINE
The biochemistry of exercise-induced metabolic acidosis has been of considerable interest for many years. We now accept that the fatigue associated with high rates of anaerobic glycolysis is caused not by the accumulation of lactate but by the imbalance between the rate of proton release and the rate of proton buffering and removal. It is 70 years since formal investigations into acid–base balance and exercise began. Some carefully controlled studies in the 1980s suggested that ingestion of sodium bicarbonate (NaHCO3) could be effective in enhancing the performance of events such as an 800 m track run, via an improved capacity to buffer metabolic acidosis which then reduced or delayed the onset of the accompanying fatigue This topic remains of considerable interest with regular additions to the literature. The authors of the following brief reviews have a long history of involvement in investigating the ergogenic effects of buffers on athletes.

A–Z of nutritional supplements: Part 4

Br J Sports Med. 2009 Dec;43(14):1088-90.
In Part 4, the review takes us from aspartame, a sweetening ingredient found in many foods and drinks, to BCAA, the three branched chain essential amino acids; then onto bee pollen, marketed as a ‘‘superfood,’’  followed by the ultra trace element boron, known more for its association with bone health, and finally to L-carnitine, a supplement which is widely used in the sporting arena and seems to be gaining in popularity.

Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors

Knee Surg Sports Traumatol Arthrosc (2009) 17:705–729
Soccer is the most commonly played sport in the world, with an estimated 265 million active soccer players by 2006. Inherent to this sport is the higher risk of injury to the anterior cruciate ligament (ACL) relative to other sports. ACL injury causes the most time lost from competition in soccer which has influenced a strong research focus to determine the risk factors for injury. This research emphasis has afforded a rapid influx of literature defining potential modifiable and non-modifiable risk factors that increase the risk of injury. The purpose of the current review is to sequence the most recent literature that reports potential mechanisms and risk factors for non-contact ACL injury in soccer players. Most ACL tears in soccer players are non-contact in nature. Common playing situations precluding a non-contact ACL injury include: change of direction or cutting maneuvers combined with deceleration, landing from a jump in or near full extension, and pivoting with knee near full extension and a planted foot. The most common non-contact ACL injury mechanism include a deceleration task with high knee internal extension torque (with or without perturbation) combined with dynamic valgus rotation with the body weight shifted over the injured leg and the plantar surface of the foot fixed flat on the playing surface. Potential extrinsic non-contact ACL injury risk factors include: dry weather and surface, and artificial surface instead of natural grass. Commonly purported intrinsic risk factors include: generalized and specific knee joint laxity, small and narrow intercondylar notch width (ratio of notch width to the diameter and cross sectional area of the ACL), pre-ovulatory phase of menstrual cycle in females not using oral contraceptives, decreased relative (to quadriceps) hamstring strength and recruitment, muscular fatigue by altering neuromuscular control, decreased “core” strength and proprioception, low trunk, hip, and knee flexion angles, and high dorsiflexion of the ankle when performing sport tasks, lateral trunk displacement and hip adduction combined with increased knee abduction moments (dynamic knee valgus), and increased hip internal rotation and tibial external rotation with or without foot pronation. The identified mechanisms and risk factors for non-contact ACL injuries have been mainly studied in female soccer players; thus, further research in male players is warranted. Non-contact ACL injuries in soccer players likely has a multi-factorial etiology. The identification of those athletes at increased risk may be a salient first step before designing and implementing specific pre-season and in-season training programs aimed to modify the identified risk factors and to decrease ACL injury rates. Current evidence indicates that this crucial step to prevent ACL injury is the only option to effectively prevent the sequelae of osteoarthritis associated with this traumatic injury.

Platelet-Rich Plasma

The American Journal of Sports Medicine 37:2259-2272 (2009)
Platelet-rich plasma (PRP) has been utilized in surgery for 2 decades; there has been a recent interest in the use of PRP for the treatment of sports-related injuries. PRP contains growth factors and bioactive proteins that influence the healing of tendon, ligament, muscle, and bone. This article examines the basic science of PRP, and it describes the current clinical applications in sports medicine. This study reviews and evaluates the human studies that have been published in the orthopaedic surgery and sports medicine literature. The use of PRP in amateur and professional sports is reviewed, and the regulation of PRP by antidoping agencies is discussed.

Recreational soccer is an effective health-promoting activity for untrained men

British Journal of Sports Medicine 2009;43:825-831
To examine the effects of regular participation in recreational soccer on health profile, 36 healthy untrained Danish men aged 20–43 years were randomised into a soccer group, a running group and a control group. Training was performed for 1 h two or three times per week for 12 weeks.
In conclusion, participation in regular recreational soccer training, organised as small-sided drills, has significant beneficial effects on health profile and physical capacity for untrained men, and in some aspects it is superior to frequent moderate-intensity running.