Wouter Welling

The effects of attentional focus on jump performance and knee joint kinematics in patients after ACL reconstruction

OBJECTIVES The purpose of this study was to determine the effect of an internal and external attentional focus on single leg hop jump distance and knee kinematics in patients after ACL reconstruction (ACLR). DESIGN Experimental. SETTING Outpatient physical therapy facility. PARTICIPANTS Sixteen patients after ACLR. MAIN OUTCOME MEASURES Patients received either an instruction with an internal focus or an external focus before performing a single leg hop jump. The jump distance, knee valgus angle at initial contact, peak knee valgus angle, knee flexion angle at initial contact, peak knee flexion angle, total ROM and time to peak angles for the injured and non-injured legs were recorded. A repeated measures MANOVA was used to determine significance between the experimental conditions with the primary outcome measures as dependent variables. RESULTS The external focus group had significant larger knee flexion angles at initial contact, peak knee flexion, total ROM and time to peak knee flexion for the injured legs. CONCLUSIONS This study demonstrates the applicability of using an external focus during rehabilitation of patients after ACLR to enhance safer movement patterns compared to an internal focus of attention and subsequently may help to reduce second ACL injury risk.

Novel methods of instruction in ACL injury prevention programs, a systematic review

Anterior cruciate ligament (ACL) injury prevention programs have been successful in the short term. Motor learning strategies with an internal focus (IF) to body movements have traditionally been utilized, but may be less suitable than an external focus (EF) for the acquisition and control of complex motor skills required for sport. To investigate the available literature and provide an overview of the effect of IF and EF instructions on jump landing technique. Systematic searches were conducted in PubMed (1966 to May 2014), CINAHL (1981 to May 2014) and PsycInfo (1989 to May 2014). A priori defined inclusion criteria were: (i) full text; (ii) published in English, German or Dutch; (iii) healthy adult subjects (mean age ≥18 years); (iv) jump and landing performance tested and (v) study used comparison between an EF and IF. Performance (jump height and distance) and technique (kinematics and kinetics) were the primary outcome variables of interest. Nine papers were included. Significant better motor performance and movement technique was found with an EF compared to an IF. Considering the beneficial results in the included studies when utilizing an EF, it is suggested to implement these strategies into ACL injury prevention programs.

Enhanced retention of drop vertical jump landing technique: A randomized controlled trial

External focus instructions have been shown to result in superior motor performance compared to internal focus instructions. Using an EF may help to optimize current anterior cruciate ligament (ACL) injury prevention programs. The purpose of the current study was to investigate the effects of instructions on landing technique and performance by comparing an external focus (EF), internal focus (IF), video (VI) and control (CTRL) group. Subjects (age 22.50±1.62years, height 179.70±10.43cm, mass 73.98±12.68kg) were randomly assigned to IF (n=10), EF (n=10), VI (n=10) or CTRL group (n=10). Landing was assessed from a drop vertical jump (DVJ) in five sessions: pretest, two training blocks (TR1 and TR2) and directly after the training sessions (post test) and retention test 1week later. Group specific instructions were offered in TR1 and TR2. Landing technique was assessed with the Landing Error Scoring System (LESS) and jump height was taken as performance measure. The results show that males in the VI group and females both in the VI and EF groups significantly improved jump-landing technique. Retention was achieved and jump height was maintained for males in the VI group and females both in the VI and EF groups. It is therefore concluded that EF and VI instructions have great potential in ACL injury prevention.

A critical analysis of limb symmetry indices of hop tests in athletes after anterior cruciate ligament reconstruction: A case control study

BACKGROUND Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs. HYPOTHESIS Athletes after ACLR would achieve LSI>90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes. MATERIALS AND METHODS Fifty-two patients (38 males mean age 23.9±3.5years; 14 females mean age 21.7±3.5 years) who had undergone an ACLR participated in this study. Patients performed the 3 hop tests at a mean time of 7 months after ACLR. Hop distance, number of side hops and LSI were compared with normative data of 188 healthy athletes. RESULTS The differences between the involved limb and the uninvolved limb were significant in all hop tests (SLH P=0.003, TLH P=0.003, SH P=0.018). For females, only significant between limb differences were found in the SLH (P=0.049). For both the SLH and the TLH, significant differences were found between the involved limb and the normative data (males; SLH P<0.001, TLH P<0.001; females; SLH P<0.001, TLH P=0.006) and between the uninvolved limb and the normative data for both males and females (males; SLH P<0.001, TLH P<0.001; females; SLH P=0.003, TLH P=0.038). For the SH, only significant differences were found between the involved limb and the normative values in males (P=0.033). CONCLUSION Athletes who have undergone an ACLR demonstrate bilateral deficits on hop tests in comparison to age and sex matched normative data of healthy controls. Using the LSI may underestimate performance deficits and should therefore be analyzed with caution when used as a criterion for RTS after ACLR. LEVEL OF EVIDENCE III, case control study.

Low rates of patients meeting return to sport criteria 9 months after anterior cruciate ligament reconstruction: a prospective longitudinal study.

PurposeThe purpose of the current prospective study was to assess the changes over time in patients tested at 6 months and 9 months after anterior cruciate ligament reconstruction (ACLR) with a return to sport (RTS) test battery. It was hypothesized that more patients passed RTS criteria at 9 months compared to 6 months.MethodsSixty-two ACLR patients performed a test battery at an average of 6.5 ± 0.7 and 9.5 ± 0.9 months after ACLR. All patients underwent a standardized rehabilitation protocol. The test battery consisted of the following tests: a jump-landing task assessed with the Landing Error Scoring System (LESS), three single-leg hop tasks (single-leg hop test, triple-leg hop test, side hop test), isokinetic quadriceps and hamstring strength at 60, 180 and 300°/s and two questionnaires (IKDC and ACL–RSI). Cut off criteria were set as Limb Symmetry Index (LSI) > 90% (for isokinetic strength and for single-leg hop tasks), LESS < 5, IKDC score within 15th percentage of healthy subjects and ACL–RSI > 56 respectively.ResultsAt 6 months, two patients (3.2%) passed all criteria. At 9 months, seven patients (11.3%) passed all criteria. Patients improved in all RTS criteria over time except for the IKDC score. Twenty-nine patients (46.8%) did not pass the strength criterion at 60°/s at 9 months after ACLR.ConclusionsThe percentages of patients passing all RTS criteria were low at both 6 and 9 months after ACLR. Quadriceps strength revealed persistent deficits and the lack of improvement in the IKDC score questionnaires shows insufficient self-reported knee function for RTS.Level of evidenceIII.

Transfer of a jump-landing task to sidestep cutting: implications for ACL injury prevention

Background It is unknown if learned motor skills as practiced in ACL injury prevention training carry over to other tasks. Objective Determine if training of a jump-landing task results in transfer of improvement in lower extremity biomechanics during sidestep cutting. Design Randomized controlled trial. Setting Controlled laboratory setting, recreational athletes. Participants Twenty male and twenty female healthy team ball sport athletes were randomly assigned to a verbal internal focus (IF, n=10), verbal external focus (EF, n=10), video (VI, n=10) or control group (CTRL, n=10). Interventions A jump-landing task was performed at baseline followed by training blocks (TR1 and TR2), an immediate post-test and an one-week retention test. Subjects in the IF, EF and VI groups received group specific instructions in TR1 and TR2. Transfer was determined after one week with a 45° unanticipated sidestep cutting task. Main Outcome Measurements Hip and knee flexion range of motion (ROM). Results During sidestep cutting, males in the VI (5.1°±1.0) and CTRL (5.1°±1.0) group showed greater hip flexion ROM compared to the IF (3.7°±0.0) and EF (3.0°±1.5) groups (p<0.05). For females, the VI group (7.0°±1.0) showed greater hip flexion ROM compared to the IF (0.6°±0.0), EF (1.3°±0.7) and CTRL (2.7°±0.0) groups (p<0.05). The EF (males −15.8°±3.9, females −11.0°±3.0) and VI (males −15.1°±2.6, females −16.7°±1.8) groups showed greater knee flexion ROM compared to the IF (males −6.6°±3.9, females −6.0°±1.3) group (p<0.05). Conclusions Athletes who received VI instructions demonstrated transfer of improved movement technique from jump-landing to sidestep cutting. Adding visual instruction to ACL injury prevention programs seems promising for transfer to sport specific situations.