Lower Extremity Performance Measures in Athletes, Part 1
Lower Extremity Performance Measures in Athletes, Part 1
Using the PICO method, we established our research question as to whether individual PPTs of the lower extremity have any relationship to injury in athletes, age 12 years to adult (no limit). We then operationally defined PPTs as measures that assess components of sport function (strength, power, agility), determine readiness for return to sport, or predict injury of the lower extremity; and as measures that can be performed field side, courtside, or in a gym with affordable, portable and readily available equipment.
Specifically, this operational definition excluded studies that made use of three-dimensional motion capture, force plates, timing gates, treadmills, stationary bikes, metabolic carts or any other form of non-portable, unaffordable testing device. Also, this definition excluded tests of which the sole purpose was to judge movement quality or range of motion, such as the unloaded double leg squat.
We defined athletes as those individuals at level 5 or above on the Tegner scale. We chose level 5 because the predominance of literature on PPTs pertains to the knee, and level 5 is the lowest level in which competitive athletes are still encompassed. In articles where the Tegner scale was not used, we accepted the terms 'recreational athlete', 'sports participation', 'intramural athlete' as indicative of level 5 activity. We also included studies where 50% or more of the participants were at Tegner level 5 or above. For articles where there was confusion between the authors about inclusion or exclusion, a consensus was reached among all authors through discussion and majority vote.
We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist to critique the methodological quality of each paper.
After the fact and in order to make this review more publishable, we elected to divide the reporting into two subject categories: part 1, the knee; and part 2, the rest of the lower extremity. To be included in the knee review, the studies had to identify the knee or a knee injury as the focal point of the paper. In lieu of obvious identification of the knee as the primary focus, we reasoned that correlations with knee-related outcome measures or correlational studies with constructs, such as strength as measured by knee flexor and extensor torque, should be included.
A search was performed in PubMed, CINAHL and SportDiscus for all dates up to 13 January 2014. The full PubMed search strategy is described in online supplementary appendix A http://bjsm.bmj.com/content/49/10/642/suppl/DC1. Systematic reviews were then located using the 'Clinical Queries' option of PubMed and the references cited in these reviews were examined for appropriate articles for inclusion. Finally, after the selection of the final studies, as outlined below, citations from these articles that appeared pertinent were read in full to determine their appropriateness for inclusion.
The process by which studies were selected is outlined in figure 1. Two authors (EJH and CB) read the titles and abstracts of all citations from the three search engines in order to determine which articles to read in full. A third author (SM) resolved disputes between these authors. One author (EJH) then read the complete text of all remaining articles whereas all other authors read the same studies based on their area of expertise so that two researchers read all articles in full.
(Enlarge Image)
Figure 1.
Process for selecting studies.
Each of the studies included in the final analysis was read three times for the purposes of: (1) data extraction, (2) assessment of methodological quality and (3) assessment of the quality of the measurement properties of each PPT.
For data extraction, we chose to group the data in two ways. First, a 'Study Summary' was created (see online supplementary table S1 http://bjsm.bmj.com/content/49/10/642/suppl/DC1), which summarises the study population, PPTs, aims and results of each study. Next, we examined the names of the PPTs and the methodology of each study to determine whether certain tests were used more often, and if there was a consensus in how the tests were labelled and performed (see online supplementary table S2 http://bjsm.bmj.com/content/49/10/642/suppl/DC1).
Methodological quality was critiqued using the COSMIN four-point scoring system (excellent, good, fair, poor) designed for systematic reviews with the worst score serving as the global score in each subsection. In addition, we followed the adaptations to COSMIN for a review on PPTs as described previously (see online supplementary appendix B http://bjsm.bmj.com/content/49/10/642/suppl/DC1). Quality of measurement properties including reliability, measurement error, hypothesis testing/construct validity, criterion validity (including predictive validity) and responsiveness (both internal and external) were assessed using a rating scale of 'positive', 'indeterminate' and 'negative' for each property (see online supplementary appendix C http://bjsm.bmj.com/content/49/10/642/suppl/DC1). For both these steps, one author (EJH) applied the adapted COSMIN checklist for methodological quality and quality criteria to all final articles while each of the other authors did the same based on their area of expertise so that each article had at least two authors performing quality assessment. In the event that these two authors disagreed in their assessment, feedback was obtained from the other authors and a consensus was reached. Because there was a large volume of data accrued during this process, the final included studies were separated by region into hip, thigh, knee, ankle and entire lower extremity for the first three steps: data extraction, assessment of methodological quality and assessment of the quality of the measurement properties of each PPT. All studies pertaining to the knee are presented in this paper, whereas studies pertaining to the rest of the lower extremity are presented in part 2 of this series.
The fourth and final step, a best evidence synthesis, requires combining the information from findings regarding the methodological quality and the quality of measurement properties. The best evidence synthesis was subcategorised by PPT. In this grand summary, only studies with fair, good or excellent methodological quality were included, and the evidence for each test was rated as 'strong', 'moderate', 'limited', 'conflicting' and 'unknown'. We used 'unknown' to indicate that either there was no evidence of the statistical property or that there was evidence, but only in studies of poor methodological quality. Further, for the synthesis, only PPTs with somewhat consistent descriptions from study to study, across at least two studies, were considered for the synthesis. The evidence from studies with sample size less than 30 participants without an a priori power analysis was classified as limited evidence.
Methods
Using the PICO method, we established our research question as to whether individual PPTs of the lower extremity have any relationship to injury in athletes, age 12 years to adult (no limit). We then operationally defined PPTs as measures that assess components of sport function (strength, power, agility), determine readiness for return to sport, or predict injury of the lower extremity; and as measures that can be performed field side, courtside, or in a gym with affordable, portable and readily available equipment.
Specifically, this operational definition excluded studies that made use of three-dimensional motion capture, force plates, timing gates, treadmills, stationary bikes, metabolic carts or any other form of non-portable, unaffordable testing device. Also, this definition excluded tests of which the sole purpose was to judge movement quality or range of motion, such as the unloaded double leg squat.
We defined athletes as those individuals at level 5 or above on the Tegner scale. We chose level 5 because the predominance of literature on PPTs pertains to the knee, and level 5 is the lowest level in which competitive athletes are still encompassed. In articles where the Tegner scale was not used, we accepted the terms 'recreational athlete', 'sports participation', 'intramural athlete' as indicative of level 5 activity. We also included studies where 50% or more of the participants were at Tegner level 5 or above. For articles where there was confusion between the authors about inclusion or exclusion, a consensus was reached among all authors through discussion and majority vote.
We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and the Consensus-based Standards for the selection of health Measurement Instruments (COSMIN) checklist to critique the methodological quality of each paper.
After the fact and in order to make this review more publishable, we elected to divide the reporting into two subject categories: part 1, the knee; and part 2, the rest of the lower extremity. To be included in the knee review, the studies had to identify the knee or a knee injury as the focal point of the paper. In lieu of obvious identification of the knee as the primary focus, we reasoned that correlations with knee-related outcome measures or correlational studies with constructs, such as strength as measured by knee flexor and extensor torque, should be included.
Search Strategy
A search was performed in PubMed, CINAHL and SportDiscus for all dates up to 13 January 2014. The full PubMed search strategy is described in online supplementary appendix A http://bjsm.bmj.com/content/49/10/642/suppl/DC1. Systematic reviews were then located using the 'Clinical Queries' option of PubMed and the references cited in these reviews were examined for appropriate articles for inclusion. Finally, after the selection of the final studies, as outlined below, citations from these articles that appeared pertinent were read in full to determine their appropriateness for inclusion.
Study Selection
The process by which studies were selected is outlined in figure 1. Two authors (EJH and CB) read the titles and abstracts of all citations from the three search engines in order to determine which articles to read in full. A third author (SM) resolved disputes between these authors. One author (EJH) then read the complete text of all remaining articles whereas all other authors read the same studies based on their area of expertise so that two researchers read all articles in full.
(Enlarge Image)
Figure 1.
Process for selecting studies.
Data Extraction and Analysis of Quality
Each of the studies included in the final analysis was read three times for the purposes of: (1) data extraction, (2) assessment of methodological quality and (3) assessment of the quality of the measurement properties of each PPT.
For data extraction, we chose to group the data in two ways. First, a 'Study Summary' was created (see online supplementary table S1 http://bjsm.bmj.com/content/49/10/642/suppl/DC1), which summarises the study population, PPTs, aims and results of each study. Next, we examined the names of the PPTs and the methodology of each study to determine whether certain tests were used more often, and if there was a consensus in how the tests were labelled and performed (see online supplementary table S2 http://bjsm.bmj.com/content/49/10/642/suppl/DC1).
Methodological quality was critiqued using the COSMIN four-point scoring system (excellent, good, fair, poor) designed for systematic reviews with the worst score serving as the global score in each subsection. In addition, we followed the adaptations to COSMIN for a review on PPTs as described previously (see online supplementary appendix B http://bjsm.bmj.com/content/49/10/642/suppl/DC1). Quality of measurement properties including reliability, measurement error, hypothesis testing/construct validity, criterion validity (including predictive validity) and responsiveness (both internal and external) were assessed using a rating scale of 'positive', 'indeterminate' and 'negative' for each property (see online supplementary appendix C http://bjsm.bmj.com/content/49/10/642/suppl/DC1). For both these steps, one author (EJH) applied the adapted COSMIN checklist for methodological quality and quality criteria to all final articles while each of the other authors did the same based on their area of expertise so that each article had at least two authors performing quality assessment. In the event that these two authors disagreed in their assessment, feedback was obtained from the other authors and a consensus was reached. Because there was a large volume of data accrued during this process, the final included studies were separated by region into hip, thigh, knee, ankle and entire lower extremity for the first three steps: data extraction, assessment of methodological quality and assessment of the quality of the measurement properties of each PPT. All studies pertaining to the knee are presented in this paper, whereas studies pertaining to the rest of the lower extremity are presented in part 2 of this series.
The fourth and final step, a best evidence synthesis, requires combining the information from findings regarding the methodological quality and the quality of measurement properties. The best evidence synthesis was subcategorised by PPT. In this grand summary, only studies with fair, good or excellent methodological quality were included, and the evidence for each test was rated as 'strong', 'moderate', 'limited', 'conflicting' and 'unknown'. We used 'unknown' to indicate that either there was no evidence of the statistical property or that there was evidence, but only in studies of poor methodological quality. Further, for the synthesis, only PPTs with somewhat consistent descriptions from study to study, across at least two studies, were considered for the synthesis. The evidence from studies with sample size less than 30 participants without an a priori power analysis was classified as limited evidence.
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