Summary

The study aimed at establishing the correlation between muscle imbalance typical for ice-skating position and the anterior knee pain, often related to the patellar tendon enthesopathy. The key practical objective however, was to establish whether a complementary flexors strengthening protocol could successfully reduce the pain by reducing the muscle imbalance.

Abstract

Introduction

Speed skating is a sport requiring movement in a highly specific skating position. Most work is done by quadriceps and gluteus medius muscles, while the posterior leg muscles are far less involved. The correlation of the overloading the anterior thigh muscles during repetitive physical activity has been described and so has patellar tendon enthesopathy as being characteristic ailment of speedskaters.
OBJECTIVE/S
To assesses the correlation between the ratio of the muscle torque of the knee flexors to the extensors and the occurrence of patellar tendon enthesopathy combined with pain in the anterior knee compartment. Secondly, to evaluate the impact of corrective training aimed at strengthening the flexor muscles of the knee joint on the reduction of these symptoms.

Material And Methods

The study assessed 30 competitors of the national speed skating team (14 females, 16 males), divided into the study and control group based on the ultrasound examination and pain assessment (VAS scale). The study group included 14 players (mean age 26.4?6.8 years, height 175?7.5 cm, weight 82?5.9 kg) diagnosed with a chronic patellar tendon enthesopathy on ultrasound examination with pain above 3 on the VAS scale. The control group consisted of the remaining 16 competitors not presenting with enthesopathy and related symptoms (mean age 25.1?7.5 years, height 176?6.8 cm, weight 79?6.7 kg.
In both groups, the measurements of the muscle torque were done using the HUMAC NORM device during isometric contractions of the knee flexors and extensors, the ratio of the flexors to extensors torque was also calculated. Control measures were taken after 6 weeks.
Post-measurements, the study group participated in supplementary training sessions focused on strengthening the posterior thigh muscles (thrice a week). Gathered data was statistically analysed using the T-student, Mann-Whitney U and Pearson correlation tests.

Results

The analysis of the mean muscle torque values showed a statistically significant difference in the ratio of the knee extensors to flexors in both groups during the entry measurements.
The muscle imbalance between the flexors and extensors was significantly lower in the study group after the 6-week complementary training protocol, whereas the controls’ results did not significantly change.
The level of pain did significantly decrease in the study group while it remained on the same level in the control group.

Conclusions

Professional speed skaters present with the reduced muscle torque ratio of the knee flexors to extensors which is associated with the occurrence of patellar tendon enthesopathy. Additionally, excessive rectus femoris muscle tension in relation to the weakened flexors combined with excessive forces acting on PT in the skating position result in pain in the anterior knee compartment. Regular complementary training protocol focusing on strengthening and elasticising the posterior thigh muscles reduces the muscle imbalance between the anterior and posterior compartment of the leg limiting the chances of developing pain.