Randomised controlled trials (RCTs) in sports injury research: authors-please report the compliance with the intervention.

BACKGROUND: In randomised controlled trials (RCTs) of interventions that aim to prevent sports injuries, the intention-to-treat principle is a recommended analysis method and one emphasised in the Consolidated Standards of Reporting Trials (CONSORT) statement that guides quality reporting of such trials. However, an important element of injury prevention trials-compliance with the intervention-is not always well-reported. The purpose of the present educational review was to describe the compliance during follow-up in eight large-scale sports injury trials and address compliance issues that surfaced. Then, we discuss how readers and researchers might consider interpreting results from intention-to-treat analyses depending on the observed compliance with the intervention. METHODS: Data from seven different randomised trials and one experimental study were included in the present educational review. In the trials that used training programme as an intervention, we defined full compliance as having completed the programme within ±10% of the prescribed running distance (ProjectRun21 (PR21), RUNCLEVER, Start 2 Run) or time-spent-running in minutes (Groningen Novice Running (GRONORUN)) for each planned training session. In the trials using running shoes as the intervention, full compliance was defined as wearing the prescribed running shoe in all running sessions the participants completed during follow-up. RESULTS: In the trials that used a running programme intervention, the number of participants who had been fully compliant was 0 of 839 (0%) at 24-week follow-up in RUNCLEVER, 0 of 612 (0%) at 14-week follow-up in PR21, 12 of 56 (21%) at 4-week follow-up in Start 2 Run and 8 of 532 (1%) at 8-week follow-up in GRONORUN. In the trials using a shoe-related intervention, the numbers of participants who had been fully compliant at the end of follow-up were 207 of 304 (68%) in the 21 week trial, and 322 of 423 (76%), 521 of 577 (90%), 753 of 874 (86%) after 24-week follow-up in the other three trials, respectively. CONCLUSION: The proportion of runners compliant at the end of follow-up ranged from 0% to 21% in the trials using running programme as intervention and from 68% to 90% in the trials using running shoes as intervention. We encourage sports injury researchers to carefully assess and report the compliance with intervention in their articles, use appropriate analytical approaches and take compliance into account when drawing study conclusions. In studies with low compliance, G-estimation may be a useful analytical tool provided certain assumptions are met.

Biomechanics of running with rocker shoes.

OBJECTIVES: Load reduction is an important consideration in conservative management of tendon overuse injuries such as Achilles tendinopathy. Previous research has shown that the use of rocker shoes can reduce the positive ankle power and plantar flexion moment which might help in unloading the Achilles tendon. Despite this promising implication of rocker shoes, the effects on hip and knee biomechanics remain unclear. Moreover, the effect of wearing rocker shoes on different running strike types is unexplored. The aim of this study was to investigate biomechanics of the ankle, knee and hip joints and the role of strike type on these outcomes. DESIGN: Randomized cross-over study. METHODS: In this study, 16 female endurance runners underwent three-dimensional gait analysis wearing rocker shoes and standard shoes. We examined work, moments, and angles of the ankle, knee and hip during the stance phase of running. RESULTS: In comparison with standard shoes, running with rocker shoes significantly (p<0.001) reduced the positive (16%), and negative (32%) work at the ankle joint. Plantar flexion moment peak and impulse were also reduced by 11% and 12%, respectively. Reduction in these variables was almost two times larger for midfoot strikers than for rearfoot strikers. At the knee joint running with rocker shoes significantly increased the positive work (14%), extension moment peak (6%), and extension moment impulse (12%). CONCLUSIONS: These findings indicate that although running with rocker shoes might lower mechanical load on the Achilles tendon, it could increase the risk of overuse injuries of the knee joint.

Do runners who suffer injuries have higher vertical ground reaction forces than those who remain injury-free? A systematic review and meta-analysis.

BACKGROUND: Vertical ground reaction force (VGRF) parameters have been implicated as a cause of several running-related injuries. However, no systematic review has examined this relationship. AIM: We systematically reviewed evidence for a relation between VGRF parameters and specific running-related injuries. METHODS: MEDLINE, Web of Science and EMBASE databases were searched. Two independent assessors screened the articles and rated the methodological quality. The 3 key VGRF parameters we measured were vertical loading rate, impact/passive peak (Fz1) and propulsive/active peak (Fz2). Standardised mean differences of these parameters were calculated using a random-effects model. Meta-regression was performed using injury type, study type and methodological quality as factors. RESULTS: The search yielded 2016 citations and 18 met the inclusion criteria for the systematic review. The loading rate was higher in studies that included patients with a history of stress fractures and patients with all injury types, both compared with controls. Only studies that included patients with a history of symptoms at the time of kinetic data collection showed higher loading rates overall in cases than in controls. There were no differences between injured subjects and controls for the active and passive peaks of the VGRF. SUMMARY: The loading rate is higher in respondents with a history of stress fractures than in respondents without running injuries. Owing to the absence of prospective studies on other injury types, it is not possible to draw definite conclusions regarding their relation with loading rate.

Differences in kinetic variables between injured and noninjured novice runners: a prospective cohort study.

OBJECTIVES: This prospective study examined differences in kinetic variables between injured and noninjured novice female and male runners and their potential contribution to RRIs. DESIGN: A prospective cohort study. METHODS: At baseline vertical ground reaction forces were assessed with an instrumented treadmill equipped with three force measuring transducers. Female participants ran at 8 and 9kmh(-1) and male runners ran at 9 and 10kmh(-1). Primary outcome measure was a running related injury (RRI). Participants were novice female and male recreational runners and were followed during a 9-week running program with three running sessions a week. RESULTS: One hundred thirty three female and seventy seven male runners participated in this study. Mean age was 37.2years and the BMI was 23.9kgm(-2). During the nine week running program 16.2% of the participants sustained an injury and no difference in incidence between female and male runners was seen. In injured male runners loading rate was significantly higher compared to noninjured male runners at both running speeds and contact time in the injured male group was significantly shorter at 9kmh(-1). In the group of female injured and noninjured runners no differences on kinetic or spatio-temporal variables were observed. Female runners had significantly higher loading rates compared to male runners but this did not have an effect on the incidence of RRIs. CONCLUSIONS: This study showed that male injured runners had higher loading rates and shorter contact times than noninjured male runners. In female runners, however, no differences in kinetic or spatio-temporal variables were observed between injured and noninjured novice runners.

Comparison of vertical ground reaction forces during overground and treadmill running. A validation study.

BACKGROUND: One major drawback in measuring ground-reaction forces during running is that it is time consuming to get representative ground-reaction force (GRF) values with a traditional force platform. An instrumented force measuring treadmill can overcome the shortcomings inherent to overground testing. The purpose of the current study was to determine the validity of an instrumented force measuring treadmill for measuring vertical ground-reaction force parameters during running. METHODS: Vertical ground-reaction forces of experienced runners (12 male, 12 female) were obtained during overground and treadmill running at slow, preferred and fast self-selected running speeds. For each runner, 7 mean vertical ground-reaction force parameters of the right leg were calculated based on five successful overground steps and 30 seconds of treadmill running data. Intraclass correlations (ICC3,1) and ratio limits of agreement (RLOA) were used for further analysis. RESULTS: Qualitatively, the overground and treadmill ground-reaction force curves for heelstrike runners and non-heelstrike runners were very similar. Quantitatively, the time-related parameters and active peak showed excellent agreement (ICCs between 0.76 and 0.95, RLOA between 5.7% and 15.5%). Impact peak showed modest agreement (ICCs between 0.71 and 0.76, RLOA between 19.9% and 28.8%). The maximal and average loading-rate showed modest to excellent ICCs (between 0.70 and 0.89), but RLOA were higher (between 34.3% and 45.4%). CONCLUSIONS: The results of this study demonstrated that the treadmill is a moderate to highly valid tool for the assessment of vertical ground-reaction forces during running for runners who showed a consistent landing strategy during overground and treadmill running. The high stride-to-stride variance during both overground and treadmill running demonstrates the importance of measuring sufficient steps for representative ground-reaction force values. Therefore, an instrumented treadmill seems to be suitable for measuring representative vertical ground-reaction forces during running.

The effectiveness of a preconditioning programme on preventing running-related injuries in novice runners: a randomised controlled trial.

OBJECTIVES: There is no consensus on the aetiology and prevention of running-related injuries in runners. Preconditioning studies among different athlete populations show positive effects on the incidence of sports injuries. HYPOTHESIS: A 4-week preconditioning programme in novice runners will reduce the incidence of running-related injuries. STUDY DESIGN: Randomised controlled clinical trial; level of evidence, 1. METHODS: Novice runners (N=432) prepared for a four-mile recreational running event. Participants were allocated to the 4-week preconditioning (PRECON) group (N=211) or the control group (N=221). The PRECON group started a 4-week training programme, prior to the running programme, with walking and hopping exercises. After the 4-week period both groups started a 9-week running programme. In both groups information was registered on running exposure and running-related injuries (RRIs) using an internet-based running log. Primary outcome measure was RRIs per 100 runners. An RRI was defined as any musculoskeletal complaint of the lower extremity or lower back causing restriction of running for at least a week. RESULTS: The incidence of RRIs was 15.2% in the PRECON group and 16.8% in the control group. The difference in RRIs between the groups was not significant (χ(2)=0.161, df=1, p=0.69). CONCLUSION: This prospective study demonstrated that a 4-week PRECON programme with walking and hopping exercises had no influence on the incidence of RRIs in novice runners.

The GRONORUN 2 study: effectiveness of a preconditioning program on preventing running related injuries in novice runners. The design of a randomized controlled trial.

BACKGROUND: Distance running is a popular recreational exercise. It is a beneficial activity for health and well being. However, running may also cause injuries, especially of the lower extremities. In literature there is no agreement what intrinsic and extrinsic factors cause running related injuries (RRIs). In theory, most RRIs are elicited by training errors, this too much, too soon. In a preconditioning program runners can adapt more gradually to the high mechanical loads of running and will be less susceptible to RRIs. In this study the effectiveness of a 4-week preconditioning program on the incidence of RRIs in novice runners prior to a training program will be studied. METHODS/DESIGN: The GRONORUN 2 (Groningen Novice Running) study is a two arm randomized controlled trial studying the effect of a 4-week preconditioning (PRECON) program in a group of novice runners. All participants wanted to train for the recreational Groningen 4-Mile running event. The PRECON group started a 4-week preconditioning program with walking and hopping exercises 4 weeks before the start of the training program. The control (CON) and PRECON group started a frequently used 9-week training program in preparation for the Groningen 4-Mile running event.During the follow up period participants registered their running exposure, other sporting activities and running related injuries in an Internet based running log. The primary outcome measure was the number of RRIs. RRI was defined as a musculoskeletal ailment or complaint of the lower extremities or back causing a restriction on running for at least three training sessions. DISCUSSION: The GRONORUN 2 study will add important information to the existing running science. The concept of preconditioning is easy to implement in existing training programs and will hopefully prevent RRIs especially in novice runners. TRIAL REGISTRATION: The Netherlands National Trial Register NTR1906. The NTR is part of the WHO Primary Registries.

Predictors of running-related injuries in novice runners enrolled in a systematic training program: a prospective cohort study.

BACKGROUND: The popularity of running is still growing. As participation increases, running-related injuries also increase. Until now, little is known about the predictors for injuries in novice runners. HYPOTHESIS: Predictors for running-related injuries (RRIs) will differ between male and female novice runners. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Participants were 532 novice runners (226 men, 306 women) preparing for a recreational 4-mile (6.7-km) running event. After completing a baseline questionnaire and undergoing an orthopaedic examination, they were followed during the training period of 13 weeks. An RRI was defined as any self-reported running-related musculoskeletal pain of the lower extremity or back causing a restriction of running for at least 1 week. RESULTS: Twenty-one percent of the novice runners had at least one RRI during follow-up. The multivariate adjusted Cox regression model for male participants showed that body mass index (BMI) (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.05-1.26), previous injury in the past year (HR, 2.7; 95% CI, 1.36-5.55), and previous participation in sports without axial load (HR, 2.05; 95% CI, 1.03-4.11) were associated with RRI. In female participants, only navicular drop (HR, 0.85; 95% CI, 0.75-0.97) remained a significant predictor for RRI in the multivariate Cox regression modeling. Type A behavior and range of motion (ROM) of the hip and ankle did not affect risk. CONCLUSION: Male and female novice runners have different risk profiles. Higher BMI, previous injury, and previous sports participation without axial loading are important predictors for RRI in male participants. Further research is needed to detect more predictors for female novice runners.

No effect of a graded training program on the number of running-related injuries in novice runners: a randomized controlled trial.

BACKGROUND: Although running has positive effects on health and fitness, the incidence of a running-related injury (RRI) is high. Research on prevention of RRI is scarce; to date, no studies have involved novice runners. HYPOTHESIS: A graded training program for novice runners will lead to a decrease in the absolute number of RRIs compared with a standard training program. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: GRONORUN (Groningen Novice Running) is a 2-armed randomized controlled trial comparing a standard 8-week training program (control group) and an adapted, graded, 13-week training program (intervention group), on the risk of sustaining an RRI. Participants were novice runners (N = 532) preparing for a recreational 4-mile (6.7-km) running event. The graded 13-week training program was based on the 10% training rule. Both groups registered information on running characteristics and RRI using an Internet-based running log. The primary outcome measure was RRIs per 100 participants. An RRI was defined as any musculoskeletal complaint of the lower extremity or back causing a restriction of running for at least 1 week. RESULTS: The graded training program was not preventive for sustaining an RRI (chi(2) = 0.016, df = 1, P = .90). The incidence of RRI was 20.8% in the graded training program group and 20.3% in the standard training program group. CONCLUSIONS: This randomized controlled trial showed no effect of a graded training program (13 weeks) in novice runners, applying the 10% rule, on the incidence of RRI compared with a standard 8-week training program.

The GRONORUN study: is a graded training program for novice runners effective in preventing running related injuries? Design of a Randomized Controlled Trial.

BACKGROUND: Running is a popular form of recreational exercise. Beside the positive effects of running on health and fitness, the risk of a running related injury has to be considered. The incidence of injuries in runners is high and varies from 30-79%. However, few intervention studies on prevention of running related injuries have been performed and none of these studies involved novice runners. METHODS: GRONORUN (Groningen Novice Running) is a two armed randomized controlled trial, comparing the effects of two different training programs for novice runners on the incidence of running related injuries. Participants are novice runners, who want to train for a four mile running event. The control group will train according a standard 8 week training program. The intervention group will use a more gradual, 13 week training program which is based on "the ten percent training rule". During the thirteen week follow up participants register information on running and RRI's in an internet based running log. The primary outcome measure is RRI. An injury is defined as a musculoskeletal ailment of the lower extremity or back, causing a restriction of running for at least one week. DISCUSSION: The GRONORUN trial is the first randomized controlled trial to study a preventive intervention in novice runners. Many different training programs for novice runners are offered, but none are evidence based.

Relationship between landing strategy and patellar tendinopathy in volleyball.

OBJECTIVE: The aetiology of patellar tendinopathy (jumper's knee) remains unclear. To see whether landing strategy might be a risk factor for the development of this injury, this study examined whether landing dynamics from drop jumps differed among healthy volleyball players (CON) and volleyball players with a jumper's knee. The patients with jumper's knee were divided into an asymptomatic group with a previous jumper's knee (PJK) and a symptomatic group with a recent jumper's knee (RJK). METHODS: Inverse dynamics analyses were used to estimate lower extremity joint dynamics from 30, 50 and 70 cm drop jumps in the three groups (CON, n = 8; PJK, n = 7; RJK, n = 9). A univariate repeated measures analysis of variance was used to compare the different landing techniques. RESULTS: Data analysis of the landing dynamics revealed that PJK showed higher knee angular velocities (p<0.01), and higher ankle plantar flexion moment loading rate (p<0.01). Furthermore, strong tendencies of higher loading rate of vertical ground reaction force (p = 0.05) and higher knee extensor moment loading rate (p = 0.08) were found compared with CON. Higher values for peak knee moment, peak knee power and knee work (all p<0.01) were found for CON compared with RJK. The comparison of the two jumper's knee groups yielded higher knee angular velocities (p<0.01), together with higher ankle plantar flexion and knee extensor moment loading rate (p<0.01 and p<0.05, respectively). CONCLUSION: Where RJK used a landing technique to avoid high patellar tendon loading, PJK used a stiffer landing strategy, which may be a risk factor in the development of patellar tendinopathy.