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The aim of this study was to examine the aerobic fitness status of top-class male soccer officials using a cross-sectional design and known population group constructs. Fifty-two field referees (FRs, age 38.4 ± 3.3 years; height 181 ± 5.6 cm; body mass 76.8 ± 6.8 kg; body mass index [BMI] 23.4 ± 1.7 kg·m-2; body fat 20.4 ± 3.6%; and international refereeing experience 5 ± 3.5 years) and 104 assistant referees (ARs, age 37.8 ± 4.1 years; height 176.9 ± 7.5 cm; body mass 72.1 ± 7.4 kg; BMI 23 ± 1.6 kg·m-2; body fat 19.2 ± 3.6%; and international refereeing experience 7 ± 3.8 years) from 53 National Football Associations worldwide, and candidates of the preliminary open-list developed by the FIFA Refereeing Department for the 2014 World Cup Final Tournament, were tested for aerobic fitness in laboratory conditions with a progressive speed treadmill test to exhaustion. Large (+8.54%, d = 0.8) and small (+3.1%, d = 0.3) differences in absolute (L·min-1) and relative (ml·kg-1·min-1) Vo2max were found between FR and AR, respectively. Trivial differences (d = 0.07) were shown in running economy (RE) (6 minutes at 8 km·h-1) between AR and FR. Using the scaling notation (b = 0.64), medium and significant differences were found between match officials for Vo2max and RE (FR > AR; d = 0.6 and 0.67, respectively). Using receiver operating characteristic curve statistics, cutoff values of 3.93 L·min-1 and 50.6 ml·kg-1·min-1 were detected in absolute and relative Vo2max for the FR and the AR (FR > AR), respectively. The FR showed superior aerobic fitness compared with AR. Training prescription should consider intensities at anaerobic threshold speed (14 km·h-1, 91% heart rate max) when aerobic fitness development is the aim in elite officials. [ABSTRACT FROM AUTHOR]

Background: The FIFA 11+ injury prevention program has been shown to decrease the risk of soccer injuries in men and women. The program has also been shown to decrease time loss resulting from injury. However, previous studies have not specifically investigated how the program might impact the rate of anterior cruciate ligament (ACL) injury in male soccer players.Questions/purposes: The purpose of this study was to examine if the FIFA 11+ injury prevention program can (1) reduce the overall number of ACL injuries in men who play competitive college soccer and whether any potential reduction in rate of ACL injuries differed based on (2) game versus practice setting; (3) player position; (4) level of play (Division I or II); or (5) field type.Methods: This study was a prospective cluster randomized controlled trial, which was conducted in 61 Division I and Division II National Collegiate Athletic Association men's soccer teams over the course of one competitive soccer season. The FIFA 11+ is a 15- to 20-minute on-the-field dynamic warm-up program used before training and games and was utilized as the intervention throughout the entire competitive season. Sixty-five teams were randomized: 34 to the control group (850 players) and 31 to the intervention group (675 players). Four intervention teams did not complete the study and did not submit their data, noting insufficient time to complete the program, reducing the number for per-protocol analysis to 61. Compliance to the FIFA 11+ program, athletic exposures, specific injuries, ACL injuries, and time loss resulting from injury were collected and recorded using a secure Internet-based system. At the end of the season, the data in the injury surveillance system were crosshatched with each individual institution's internal database. At that time, the certified athletic trainer signed off on the injury collection data to confirm their accuracy and completeness.Results: A lower proportion of athletes in the intervention group experienced knee injuries (25% [34 of 136]) compared with the control group (75% [102 of 136]; relative risk [RR], 0.42; 95% confidence interval [CI], 0.29-0.61; p < 0.001). When the data were stratified for ACL injury, fewer ACL injuries were reported in the intervention group (16% [three of 19]) compared with the control group (84% [16 of 19]), accounting for a 4.25-fold reduction in the likelihood of incurring ACL injury (RR, 0.236; 95% CI, 0.193-0.93; number needed to treat = 70; p < 0.001). With the numbers available, there was no difference between the ACL injury rate within the FIFA 11+ group and the control group with respect to game and practice sessions (games-intervention: 1.055% [three of 15] versus control: 1.80% [12 of 15]; RR, 0.31; 95% CI, 0.09-1.11; p = 0.073 and practices-intervention: 0% [zero of four] versus control: 0.60% [four of four]; RR, 0.14; 95% CI, 0.01-2.59; p = 0.186). With the data that were available, there were no differences in incidence rate (IR) or injury by player position for forwards (IR control = 0.339 versus IR intervention = 0), midfielders (IR control = 0.54 versus IR intervention = 0.227), defenders (IR control = 0.339 versus IR intervention = 0.085), and goalkeepers (IR control = 0.0 versus IR intervention = 0.0) (p = 0.327). There were no differences in the number of ACL injuries for the Division I intervention group (0.70% [two of nine]) compared with the control group (1.05% [seven of nine]; RR, 0.30; CI, 0.06-1.45; p = 0.136). However, there were fewer ACL injuries incurred in the Division II intervention group (0.35% [one of 10]) compared with the control group (1.35% [nine of 10]; RR, 0.12; CI, 0.02-0.93; p = 0.042). There was no difference between the number of ACL injuries in the control group versus in the intervention group that occurred on grass versus turf (Wald chi square [1] = 0.473, b = 0.147, SE = 0.21, p = 0.492). However, there were more ACL injuries that occurred on artificial turf identified in the control group (1.35% [nine of 10]) versus the intervention group (0.35% [one of 10]; RR, 0.14; 95% CI, 0.02-1.10; p = 0.049).Conclusions: This program, if implemented correctly, has the potential to decrease the rate of ACL injury in competitive soccer players. In addition, this may also enhance the development and dissemination of injury prevention protocols and may mitigate risk to athletes who utilize the program consistently. Further studies are necessary to analyze the cost-effectiveness of the program implementation and to analyze the efficacy of the FIFA 11+ in the female collegiate soccer cohort.Level Of Evidence: Level I, therapeutic study. [ABSTRACT FROM AUTHOR]

The article presents the results of a study which investigated the usefulness of a field test for assistant soccer referees, designed to assess their ability to change direction. An overview of related previous research is provided, along with details of the experimental protocol. The field test was found to possess statistical significance and reliability.

Background: Quadriceps muscle strength, which is essential for the function and stability of the knee, has been found to be impaired even years after arthroscopic partial meniscectomy. However, the neuromuscular alterations that could account for such muscle weakness remain unclear.Questions/purposes: We investigated (1) the side-to-side asymmetries in quadriceps muscle strength 6 months after arthroscopic partial meniscectomy, (2) the physiologic mechanisms (neural versus muscular) underlying muscle weakness, and (3) the impact of quadriceps weakness on muscle control at submaximal force levels.Patients and Methods: We tested 14 volunteers (10 men, four women) with an average age of 44 +/- 9 years (range, 24-59 years) at 6 +/- 1 months after unilateral medial arthroscopic partial meniscectomy. We measured maximal voluntary strength and muscle activation during isometric, concentric, and eccentric contractions using isokinetic dynamometry and surface EMG, respectively. We assessed vastus lateralis muscle size and architecture using ultrasonography. We measured muscle control at submaximal force levels with a repositioning test (knee proprioception) and a low-force target-tracking task (steadiness, accuracy).Results: Isometric and concentric quadriceps strength and vastus lateralis EMG activity were lower on the involved than on the uninvolved side. Muscle architecture and muscle control did not differ between the involved and uninvolved sides.Conclusions: Our results showed quadriceps weakness exists 6 months after arthroscopic partial meniscectomy. As suggested by the EMG results, this is likely attributable to neural impairments (activation failure) that affect muscle control at maximal but not submaximal force outputs.Level Of Evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

Background: Hip abductors are the most important muscles around the hip joint. It is therefore essential to assess their function in a valid and reliable way. Since the optimal body posture for the assessment of hip abductor strength is unknown, we tested the validity and reliability of unilateral hip abductor strength assessment in three different body positions. We hypothesized that the validity would be better in the side-lying position because of the consistent stabilization of the contralateral (untested) hip. Methods: Sixteen healthy subjects participated in two identical testing sessions. Unilateral isometric hip abductor muscle strength was measured, with use of a stabilized commercial dynamometer, with the subject in the side-lying, supine, and standing positions. Construct validity was based on concomitant recordings of gluteus medius electromyographic activity from the tested and contralateral hips. The body position permitting greater muscle activation and abductor strength on the tested hip, while minimizing muscle activation in the contralateral hip (that is, lower contralateral-to-tested electromyographic ratio), was considered the most valid. Coefficients of variation, the Bland and Altman limits of agreement, and intraclass correlation coefficients were calculated to determine test-retest reliability of hip abductor strength. Results: Maximal hip abductor strength was significantly higher in the side-lying position compared with the standing and supine positions (p < 0.05). The contralateral-to-tested electromyographic ratio for the side-lying position was significantly lower than that for the supine and the standing position (p < 0.01). Test-retest reliability of strength measurements in terms of coefficients of variation (3.7% for side-lying, 6.1% for supine, and 4.2% for standing) and limits of agreement (±6.9% for side-lying, ±8.4% for supine, and ±7.5% for standing) was better in the side-lying position. All intraclass correlation coefficients were high to moderate (0.90 for side-lying, 0.83 for supine, and 0.88 for standing). Conclusions: The side-lying body position offers the most valid and reliable assessment of unilateral hip abductor strength. Clinical Relevance: We recommend the use of the side-lying body position whenever hip abductor function is assessed. [ABSTRACT FROM AUTHOR]

The article discusses a study which analyzes the extent and characteristics of injuries and musculoskeletal complaints of elite football referees and the difference between match referee (MR) and assistant referee (AR). The study highlighted hamstring strains and ankle sprains as the most frequent types of injuries incurred by elite referees during training because of their greater exposure in training than in matches, followed by knee cartilage lesions. The study assessed stretching before every match or training as the main injury prevention for referees and players. The study also found no difference between MR and AR in their level of experience as referees, however, they differ on the number of national matches that they had officiated.

The article presents the results of a study which investigated the impact of electro-stimulation (ES) on tennis players in terms of strength training. A description of the ES procedure, which involved a Compex unit from Medicompex SA, is provided. It was found that ES training produced detectable results in leg muscle strength.

Objectives: To analyze ligamentous stability and isokinetic strength of knee extensor and flexor muscles after anterior cruciate ligament reconstruction using 2 different autografts with identical fixation. Design: This study implements a comparative case series design. Setting: Schulthess Clinic, Switzerland. Patients: A total of 153 consecutive patients (n = 87 bone-patellar tendon-bone [BPTB]/66 quadruple semitendinosus/gracilis tendons [QSGT] patients) who underwent BPTB and QSGT surgery were functionally assessed. Intervention: All patients were functionally assessed (knee extension/flexion isokinetic strength and knee joint laxity) at a mean follow-up time of 11 months. Main Outcome Measurements: Laxity was measured utilizing the Kneelax arthrometer, whereas isokinetic strength of the knee extensor/flexor muscle groups was measured using the Biodex Multi Joint System 2 (180°/s and 300°/s). Results: The QSGT group had significantly greater knee joint laxity when compared with the BPTB group (P < 0.001). Furthermore, females in the QSGT group demonstrated the greatest knee joint laxity overall (P < 0.001). Additionally, a significant flexor torque deficiency was demonstrated in the QSGT group (P < 0.001); however, no differences in extensor torque were observed. Conclusions: The use of a BPTB autograft achieved better knee joint stability as well as greater knee flexor torque than the QSGT autograft. Both grafts exhibited a similar knee extensor torque deficit, indicating that only quadriceps strength is not graft-dependent. [ABSTRACT FROM AUTHOR]