Differences in injury risk and characteristics between Dutch amateur and professional soccer players.

OBJECTIVES: To compare the incidence and characteristics of injuries between Dutch amateur and professional male soccer players during one entire competition season. DESIGN: A prospective two-cohort design. METHODS: During the 2009-2010 season, 456 Dutch male amateur soccer players and 217 professional players were prospectively followed. Information on injuries and individual exposure to all soccer activities were recorded in both cohorts. Injuries were recorded using the time-loss definition. RESULTS: In total, 424 injuries were recorded among 274 of the amateur players (60.1% injured players) and 286 injuries were sustained by 136 (62.7% injured players) of the professional players (p=0.52). Compared to the professionals, the injury incidence during training sessions was higher among amateurs (p=0.01), but the injury incidence among professionals was higher during matches (p<0.001). Professional players also had a higher incidence of minimal injuries (p<0.001), whereas the incidence of moderate and severe injuries was higher for amateurs (all p<0.001). Lastly, professional players sustained more overuse injuries (p=0.02), whereas amateurs reported more recurrent injuries (p<0.001). CONCLUSIONS: The above-mentioned differences in injury rates between amateur and professional players in the Netherlands might be explained by the difference in the level at which they play, since factors like the availability of medical support and/or the team size may influence the injury risk and characteristics.

Progression of mechanical properties during on-field sprint running after returning to sports from a hamstring muscle injury in soccer players.

The objectives of this study were to examine the consequences of an acute hamstring injury on performance and mechanical properties of sprint-running at the time of returning to sports and after the subsequent ~2 months of regular soccer training after return. 28 semi-professional male soccer players, 14 with a recent history of unilateral hamstring injury and 14 without prior injury, participated in the study. All players performed two 50-m maximal sprints when cleared to return to play (Test 1), and 11 injured players performed the same sprint test about 2 months after returning to play (Test 2). Sprint performance (i. e., speed) was measured via a radar gun and used to derive linear horizontal force-velocity relationships from which the following variables obtained: theoretical maximal velocity (V(0)), horizontal force (F(H0)) and horizontal power (Pmax). Upon returning to sports the injured players were moderately slower compared to the uninjured players. F H0 and Pmax were also substantially lower in the injured players. At Test 2, the injured players showed a very likely increase in F(H0) and Pmax concomitant with improvements in early acceleration performance. Practitioners should consider assessing and training horizontal force production during sprint running after acute hamstring injuries in soccer players before they return to sports.

A prospective study on MRI findings and prognostic factors in athletes with MTSS.

In medial tibial stress syndrome (MTSS) bone marrow and periosteal edema of the tibia on the magnetic resonance imaging (MRI) is frequently reported. The relationship between these MRI findings and recovery has not been previously studied. This prospective study describes MRI findings of 52 athletes with MTSS. Baseline characteristics were recorded and recovery was related to these parameters and MRI findings to examine for prognostic factors. Results showed that 43.5% of the symptomatic legs showed bone marrow or periosteal edema. Absence of periosteal and bone marrow edema on MRI was associated with longer recovery (P = 0.033 and P = 0.013). A clinical scoring system for sports activity (SARS score) was significantly higher in the presence of bone marrow edema (P = 0.027). When clinical scoring systems (SARS score and the Lower Extremity Functional Scale) were combined in a model, time to recovery could be predicted substantially (explaining 54% of variance, P = 0.006). In conclusion, in athletes with MTSS, bone marrow or periosteal edema is seen on MRI in 43,5% of the symptomatic legs. Furthermore, periosteal and bone marrow edema on MRI and clinical scoring systems are prognostic factors. Future studies should focus on MRI findings in symptomatic MTSS and compare these with a matched control group.

Shockwave treatment for medial tibial stress syndrome in athletes; a prospective controlled study.

Objective The purpose of this study was to describe the results of two treatment regimens for medial tibial stress syndrome (MTSS); a graded running programme and the same running programme with additional shockwave therapy (extracorporeal shockwave therapy; ESWT). Design A prospective observational controlled trial. Setting Two different sports medicine departments. Participants 42 athletes with MTSS were included. Intervention Patients from one hospital were treated with a graded running programme, while patients from the other hospital were treated with the same graded running programme and focused ESWT (five sessions in 9 weeks). Main Outcome Measures Time to full recovery (the endpoint was being able to run 18 min consecutively without pain at a fixed intensity). Results The time to full recovery was significantly faster in the ESWT group compared with the patients who only performed a graded running programme, respectively 59.7±25.8 and 91.6±43.0 days (p=0.008). Conclusions This prospective observational study showed that MTSS patients may benefit from ESWT in addition to a graded running programme. ESWT as an additional treatment warrants further investigation in a prospective controlled trial with the addition of randomisation and double blinding.

Recognising vascular causes of leg complaints in endurance athletes. Part 2: the value of patient history, physical examination, cycling exercise test and echo-Doppler examination.

UNLABELLED: Leg complaints at maximal exercise in endurance athletes may have many causes, including arterial flow limitations in the iliac arteries. Such flow limitations can evolve into serious health problems due to increasing intravascular obstruction or even complete obstruction as a result of dissection or thrombosis. Early detection is therefore of clinical importance, but conventional diagnostic tools often prove inadequate. In the current study simple sports-specific tests are examined for their diagnostic power. Test variables derived from patient history, physical examination, cycling exercise testing followed by arterial pressure measurements at the ankle, and echo-Doppler examination with provocative manoeuvres were tested in 92 symptomatic legs (80 patients). A validated clinical classification acted as a reference. Several test variables proved useful. However, no single test variable combined a high sensitivity with a high specificity. Multivariate testing resulted in the correct classification of 91 % of patients, reaching a sensitivity of 0.90 and specificity of 0.93 (kappa 0.76). Four patients wrongly classified as non-vascular suffered from kinking in the common iliac artery that could not be visualised using the diagnostic tools currently available in this study. IN CONCLUSION: simple sports-specific tests accurately diagnose iliac artery obstruction in endurance athletes.

Recognising vascular causes of leg complaints in endurance athletes. Part 1: validation of a decision algorithm.

Flow limitations in the iliac arteries of endurance athletes during exercise were previously ascribed solely to intravascular lesions. We postulate that functional kinking of the arteries can also result in flow limitations. However, the diagnostic tools in routine practice are not effective in diagnosing such flow limitations in a substantial proportion of athletes, mainly because these diagnostic tools do not measure in the provocative situations. Ninety-two symptomatic legs in 80 endurance athletes were examined with newly developed, sports-specific vascular tests. Thirty-five asymptomatic cyclists matched for working capacity served as the control subjects. Legs were classified as vascular or non-vascular following a decision algorithm, based upon the results of these diagnostic tests, excluding orthopaedic causes by the effects of specific treatment. Independently of this clinical classification, an alternative method was applied to find stable characteristics in the total patient group using factor analysis. This characterisation was based on scores on 14 test variables deriving from diagnostic tests that were not used in the decision algorithm, thus avoiding dependency between the clinical categorisation and the statistical categorisation. The hypothesis was that these characteristics were sufficiently sensitive to classify patients with vascular and non-vascular complaints. If so, these characteristics should correspond with the one derived from the decision algorithm. Following the decision algorithm, 58 legs (63%) were classified as vascular, 29 (32%) as non-vascular and 5 (5%) as inconclusive. The latter were considered non-vascular. In a substantial proportion of the vascular patients, kinking of the iliac arteries was identified as the major cause of flow limitation. The characteristics derived from factor analysis proved to classify 87% in agreement with the decision algorithm (kappa 0.56). The agreement is sufficient for validation of the clinical classification. The algorithm can therefore be applied in clinical situations to diagnose endurance athletes with flow limitations due to both intravascular lesions and kinking of the arteries.

Color Doppler used to detect kinking and intravascular lesions in the iliac arteries in endurance athletes with claudication.

OBJECTIVE: In endurance athletes, flow limitations in the iliac arteries are commonly ascribed to mechanically induced intravascular lesions (endofibrosis). We hypothesize that kinking of the vessels, occurring during exercise, can also cause such flow limitations. Conventional diagnostic tests fail to demonstrate such kinking. METHODS: In the current study, the iliac arteries were examined in 50 endurance athletes suffering from flow limitations in the iliac arteries with color Doppler using provocative maneuvers of hip flexion, isometric psoas contraction and exercise. Five had both-sided complaints resulting in 55 symptomatic legs and 45 asymptomatic legs. Sixteen national level competitive cyclists served as control subjects resulting in 32 healthy reference legs. RESULTS: The iliac arteries could be visualized accurately in 127/132 (96%) of the legs. The legs with insufficient image quality were not scored in the further analysis. In the external iliac artery, kinks were detected in 21/54 symptomatic legs (39%) compared to none in 28 reference legs. Intravascular lesions could be detected in 33/54 symptomatic legs (61%) compared to only 1/28 reference legs (4%). In the symptomatic legs Doppler measurements showed significantly higher peak systolic velocities in all test conditions compared to the reference legs (P<0.05). These differences increased significantly with provocative maneuvers (P<0.05).In the common iliac artery, kinks were demonstrated in 3/54 symptomatic legs (6%) and an intravascular lesion in 2/54 symptomatic legs (4%) only. Neither kink nor intravascular lesions were demonstrated in the reference legs. Peak systolic velocity measurements in the common iliac artery were in line with these observations and did not show differences between symptomatic and reference legs. The incidence of intravascular lesions in the external and common iliac artery is as expected, however, the incidence of kinks in the common iliac artery is much lower than reported from magnetic resonance angiography. This discrepancy is most probably caused by the fact that kinks in the common iliac artery are predominantly situated in the coronal plane, which cannot be visualized by color Doppler. CONCLUSION: Both kinks and intravascular lesions are associated with flow limitations in the iliac arteries in endurance athletes. Color Doppler appears to be an effective technique to visualize and scale kinks and intravascular lesions in the external iliac artery and to visualize and scale intravascular lesions in the common iliac artery.

Injuries in male soccer players: team risk analysis.

Selection may be responsible for different characteristics of subgroups (teams) of soccer players resulting in different risks of injury and different injury patterns. In the present study injury rates of teams were analysed with respect to the factors age and level of play. In two Dutch non-professional soccer clubs 477 male players, active in teams of different age groups and at different levels of play, were prospectively followed during the second half of the 1986/1987 competitive season. Teams in the 17/18 years age group showed the highest incidence of injury per 1000 players hours in games. At a high level of play teams have a significantly (p < 0.01) higher risk of injury than teams at a low level of play. This difference is noticed within every age group with exception of the 15/16 years age group. At a high level of play teams of senior players have significantly (p < 0.005) more prevalent injuries than teams of junior players. Senior players, active at a high level of play, have significantly (p < 0.05) more overuse injuries than senior players of a low level of play. At a high level of play significantly (p < 0.05) more upper leg injuries are reported. In the total population of soccer players relatively more sprains are located in the ankle joint and relatively more strains are located on the upper leg. It is concluded that prevention of soccer injuries primarily should be aimed at teams and their environment and not at the individual soccer player.