Sandor L. Schmikli

Effectiveness of an injury prevention programme for adult male amateur soccer players: a cluster-randomised controlled trial

Background The incidence rate of soccer injuries is among the highest in sports, particularly for adult male soccer players. Purpose To investigate the effect of the ‘The11’ injury prevention programme on injury incidence and injury severity in adult male amateur soccer players. Study design Cluster-randomised controlled trial. Methods Teams from two high-level amateur soccer competitions were randomly assigned to an intervention (n=11 teams, 223 players) or control group (n=12 teams, 233 players). The intervention group was instructed to perform The11 in each practice session during one soccer season. The11 focuses on core stability, eccentric training of thigh muscles, proprioceptive training, dynamic stabilisation and plyometrics with straight leg alignment. All participants of the control group continued their practice sessions as usual. Results In total, 427 injuries were recorded, affecting 274 of 456 players (60.1%). Compliance with the intervention programme was good (team compliance=73%, player compliance=71%). Contrary to the hypothesis, injury incidences were almost equal between the two study groups: 9.6 per 1000 sports hours (8.4–11.0) for the intervention group and 9.7 (8.5–11.1) for the control group. No significant differences were found in injury severity, but a significant difference was observed in the location of the injuries: players in the intervention group sustained significantly less knee injuries. Conclusions This study did not find significant differences in the overall injury incidence or injury severity between the intervention and control group of adult male soccer players. More research is recommended, focusing on injury aetiology and risk factors in adult male amateur soccer players.

National survey on sports injuries in the Netherlands: target populations for sports injury prevention programs

Objective:To define target populations for sports injury prevention programs. Design:A computer-assisted telephone survey on sports injuries and sports participation during 2000-2005 using a 3-month recall period. Setting:Data obtained from a representative sample of Dutch citizens. Participants:Fifty-eight thousand four hundred five Dutch citizens aged older than 3 years. Assessment of Risk Factors:Age, gender, and type of sports were used to distinguish subgroups with a substantial contribution to sports injuries. Main Outcome Measures:The absolute number of sports injuries, the incidence of sports injuries per 10 000 hours, the severity, and costs of sports injuries. Results:Sports participation was associated with 1.5 million injuries per year and 10 injuries per 10 000 hours; of these, 50% had to be treated medically. Two-thirds of all medically treated sports injuries were associated with 9 sports (representing 18 subpopulations, all younger than 55 years): outdoor soccer (males 4-54 years and females 4-17 years), indoor soccer (males 18-34 years), tennis (males/females 35-54 years), volleyball (females 18-54 years), field hockey (males 18-34 years and females 4-17 years), running/jogging (males/females 35-54 years), gymnastics (males/females 4-17 years), skiing/snowboarding (males 4-17 years and females 18-34 years), and equestrian sports (females 18-34 years). These groups showed more than average injury rates and covered two-thirds of all direct and indirect costs (&U20AC;400 million). Conclusions:The survey identified the most important (sports-, age-, and gender-specific) target populations for injury prevention programs in the Netherlands. Sports participants aged older than 55 years were excluded from these target groups because of their limited contribution to the total sports injury problem.

Injury prevention target groups in soccer: Injury characteristics and incidence rates in male junior and senior players

To identify target groups for injury prevention in male amateur soccer players under 35 years of age. A computer-assisted telephone survey with a 12-month recall period for injuries in a representative sample of Dutch citizens from the Injuries and Physical Activity Netherlands (IPAN)-database. A comparison of the volume of soccer injuries, the incidence and the need for medical attention per level of exposure and age category. The incidence in seniors was twice that of juniors (17.5% versus 8.1%; odds ratio (OR=2.4). In juniors the overall incidence was lowest in the category with the least amount of soccer exposure time (0-3 h: 2.9%; 3-5 h: 13.0%; 5+ h: 12.3%). A comparable result was found in seniors: (0-3 h: 12.0%; 3-5 h: 21.6%; 5+ h: 21.5%). Within each level of soccer exposure, a different incidence was found in juniors and seniors (0-3 h: OR=4.6; 3-5 h: OR=1.8; 5+ h: OR=1.9). Ankle, knee and upper leg injuries were most common (59.9%). Contusions, strains and sprains dominated (78.1%). Body region and type of injuries were similar in both age categories. Medical treatment for injuries was equally necessary in both age groups. Senior male amateur soccer players and particularly the more skilled seniors (involved in soccer at least 3 h per week), should be primarily targeted for studies on injury risk factors and prevention programs.

Monitoring load, recovery and performance in young elite soccer players

Brink, MS, Nederhof, E, Visscher, C, Schmikli, SL, and Lemmink, KAPM. Monitoring load, recovery, and performance in young elite soccer players. J Strength Cond Res 24(3): 597-603, 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 × 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.

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.

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.

Predicting Effects of Exercise Training in Patients With Heart Failure Secondary to Ischemic or Idiopathic Dilated Cardiomyopathy

The purpose of this study was to investigate which patient characteristics may predict training effects on maximal and submaximal exercise performance in patients with heart failure. Together with commonly used clinical and performance-related variables, oxygen uptake kinetics during exercise recovery were included as possible predictors. Fifty patients with heart failure (New York Heart Association class II or III) performed a 12-week training program (cycle interval and resistance training). Training effects were expressed as changes in peak oxygen uptake (Vo(2)), Vo(2) at ventilatory threshold (VT), and the time constant of Vo(2) recovery after submaximal exercise (tau-rec). After training, peak Vo(2), Vo(2) at VT, and tau-rec improved significantly, with a wide variety in training responses. Changes in peak Vo(2) were related to changes in VT (r = 0.79, p <0.001), but both changes were not related to changes in tau-rec. Using multivariate regression analyses, post-training changes in peak Vo(2) could be predicted by recovery halftime of peak Vo(2) (T1/2), peak Vo(2) (percentage of predicted), and peak respiratory exchange ratio (R(2) = 36%). Post-training changes in VT could be predicted by T1/2 and VT (predicted) (R(2) = 29%), whereas changes in tau-rec could be predicted only by tau-rec at baseline (R(2) = 34%). In conclusion, oxygen recovery kinetics after maximal and submaximal exercise substantially add to the prediction of training effects in patients with heart failure, presumably because of their relations with, respectively, central and peripheral impairments of exercise capacity. However, the explained variance in training effects is not sufficient to make a definite distinction between training responders and nonresponders.

Can we detect non-functional overreaching in young elite soccer players and middle-long distance runners using field performance tests?

Objective To study whether field performance tests can make a valid distinction between non-functionally overreaching (NFO) athletes and control athletes. Design Monthly field performance tests were used to determine a performance decrement (PD) throughout a season. Athletes with a minimum of 1 month PD were compared with control athletes without a PD on mood characteristics and resting levels of stress hormones. Setting Sporting field and sports medical laboratory. Participants 129 young elite athletes, 77 soccer players and 52 middle-long distance runners were followed prospectively during the 2006–2007 season. Fifteen of them were invited to the laboratory. Eight athletes showed a performance decrease lasting longer than 1 month, and seven athletes without a performance decrease acted as their controls. Main outcome measures Performance changes over time were measured using field tests. Profile of Mood States and resting levels of adrenocorticotrophic hormone (ACTH) and cortisol in blood were measured in the laboratory. Results PD athletes showed several symptoms typical of the non-functional state of overreaching (OR). The PD group scored higher on depression and anger than controls. They also showed a specific pattern of correlations between negative mood subscales (tension, fatigue and depression), which was absent in controls. ACTH levels at rest were similar, but lower cortisol levels in PD athletes pointed at a blunted cortisol response. Cortisol levels were decoupled from ACTH levels only in PD athletes. Conclusions Implementing performance-related criteria in field tests can help coaches and sports physicians to distinguish NFO athletes from athletes with balanced workload and recovery.

Monitoring performance, pituitary–adrenal hormones and mood profiles: how to diagnose non-functional over-reaching in male elite junior soccer players

Objective To verify if in male elite junior soccer players a minimum 1-month performance decrease is accompanied by a mood profile and hormone levels typical of non-functional over-reaching (NFOR). Design A prospective case-control study using a monthly performance monitor with a standardised field test to detect the performance changes. Players with a performance decrease lasting at least 1 month were compared with control players without a performance decrease on mood scores and pre-exercise and postexercise levels of stress hormones. Setting Sporting field and sports medical laboratory. Participants Ninety-four young elite soccer players were monitored during the 2006–2008 seasons. Twenty-one players were invited to the laboratory, seven of whom showed a significant performance decrease. Main outcome measures Performance change over time, scores on the profile of mood states and premaximal and postmaximal exercise serum levels of adrenocorticotropic hormone (ACTH), growth hormone (GH) and cortisol. Results Players with a performance decrease showed psychological and hormonal changes typical of the non-functional state of over-reaching. Scores were higher on depression and anger, whereas the resting GH levels and ACTH levels after maximal exercise were reduced. ACTH and GH were capable of classifying all but one player correctly as either NFOR or control. Conclusions Performance-related criteria in field tests are capable of identifying players with worsened mood and adaptations of the endocrine system that fit the definition of NFOR. Performance, mood and hormone levels may therefore be considered as valid instruments to diagnose NFOR in young elite soccer players.

Is an elevated submaximal heart rate associated with psychomotor slowness in young elite soccer players

Abstract The aim of the present study was to find early markers for overreaching that are applicable in sport practice. In a group of elite soccer players aged 15–18, the stress–recovery balance and reaction times before and after exercise were assessed. Overreaching was indicated by an elevated submaximal heart rate during a sport-specific field test. Submaximal changes in heart rate were prospectively monitored by means of monthly Interval Shuttle Run Tests during two competitive seasons. Out of 94 players, seven players with an elevated heart rate of at least one month could be included in the study, together with seven controls, matched for age, body composition, training and performance level. The stress–recovery balance was assessed with the Dutch version of the Recovery Stress Questionnaire (RESTQ-Sport). The soccer players with an elevated heart rate reported a disturbed stress–recovery balance (Mann–Whitney test, P<0.05). An ANOVA for repeated measures of reaction times revealed a significant main effect of time (F 1,12=13.87, P<0.01) indicating an improvement of psychomotor speed. No differences between groups were found. We conclude that soccer players with an elevated submaximal heart rate of at least one month share a disturbed stress–recovery balance, but they could not be distinguished from controls based on reaction time after strenuous exercise.