Reliability of a novel procedure to monitor the flexibility of lower limb muscle groups in highly-trained adolescent athletes.

OBJECTIVES

To evaluate the reliability level of an innovative method using a standardized stretch force to assess the flexibility of lower limb muscle groups in highly-trained adolescent athletes and to examine whether interchanging the examiners affects the reliability of the measures.

DESIGN

Randomized test-retest study.

SETTING AND PARTICIPANTS

In ten athletes, the flexibility of eight lower limb muscle groups was examined on two occasions on both sides and in two phases: a video capture by three distinct operators and an analysis by three distinct analysers. The reliability of the measures was assessed by the coefficient of variation (CV, 90% CI). Between-analysers and between-operators standardized differences (i.e., Cohen's d) were calculated.

RESULTS

CV (%, 90% CI) were 8.3% (7.5; 9.3) for quadriceps, 3.3% (3.0; 3.7) for hamstrings, 7.2% (6.5-8.0) for adductors, 5.7% (5.1; 6.3) for gastrocnemius, 4.5% (4.0; 5.0) for soleus, 2.6% (2.3; 2.9) for hip flexors, 9.6% (8.6; 10.8) for hip medial rotators and 12.4% (12.2; 14.0) for hip lateral rotators. There was no substantial (i.e., Cohen's d < 0.2) difference in CV between all the possible operators/analysers combinations.

CONCLUSION

This method has a moderate-to-good reliability level and is examiner-independent. It may be implemented in future injury prevention programs, in order to monitor the flexibility of highly-trained adolescent athletes.