Reference: Hegedus EJ, McDonough S, Bleakley C, Cook CE, Baxter GD. Clinician-friendly lower extremity physical performance measures in athletes: a systematic review of measurement properties and correlation with injury. Part 1: the tests for knee function including the hop tests. Br J Sports Med. 2015;49(10):642-648.
Clinical question: Do individual physical performance tests (PPTs) used as measures for lower extremity function have any relationship to injuries in athletes aged 12 years or older?
Data sources: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to locate articles. The authors searched PubMed, EMBASE, and SPORTDiscus, in addition to searching by hand. The search strategy combined the terms athlete, lower extremity, and synonyms of performance test with the names of performance tests.
Study selection: Studies were included if they involved a test that met the operational definition for a PPT. The included studies assessed components of sport function (eg, speed, agility, and power), determined readiness for return to sport, or predicted injury to the lower extremity. All PPT measures could be performed on the field, courtside, or in a gym with affordable, portable, and readily available equipment. Studies were excluded if they made use of 3-dimensional motion capture, force platforms, timing gates, treadmills, stationary bikes, metabolic charts, or another nonportable, costly testing device. Athletes were categorized on the Tegner Scale at a minimum of level 5, which is the lowest level that still encompasses competitive athletes. Studies were included if 50% or more of the participants were rated above 5 on the Tegner Scale. Studies were excluded if the sole purpose was to judge movement quality or range of motion. Studies were selected if they identified the knee or a knee injury as a focal point of the paper.
Data extraction: The Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) was used to critique the methodologic quality of each paper with a 4-point Likert scale. The title and methods of each paper were extracted. Extracted data were summarized using ratings of unknown, conflicting, limited, moderate, and strong.
Main results: An initial search revealed 3379 original articles for consideration. After initial review, 169 full-text articles were evaluated and 29 articles were included in the systematic review. Six tests were examined for the best evidence of methodologic quality: (1) 1-legged single hop for distance, (2) 1-legged triple hop for distance, (3) 6-m timed hop, (4) crossover hop for distance, (5) triple jump, and (6) 1-legged vertical jump. A summary of the methodologic properties of the 6 tests showed fair/poor reliability, fair/poor hypothesis testing, good criterion validity, and good/poor responsiveness. No tests predicted knee injury in athletes.
Conclusions: Although numerous authors have evaluated PPTs at the knee, evidence for the measurement quality of these functional tests is limited and conflicting. Ample opportunity exists for researchers to further examine PPTs for the knee. Until more knowledge is gained about these PPTs, clinicians should exercise caution when making clinical decisions based on the results of these tests.
Keywords: functional test; hop test; injury prediction; reliability; single-legged hop.