3rd meeting of young researchers at UP 1 - IJUP - Universidade do ...

Warming-up before sporting activity improves knee position sense
T. Magalhães 1 , F. Ribeiro 1,2 and J. Oliveira 2
1 Department of Physiotherapy, Vale do Sousa Higher School of Health, Polytechnic Health Institute of
the North, Portugal.
2 Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto,
Portugal.
Introduction: The effects of warm-up in joint position sense are not clearly established. We
speculate that in response to mild exercise the sensitivity of mechanoreceptors would be
increased, hence increasing the reflex neuromuscular protective mechanisms, the motor
control, and the coordination, which in turn could be beneficial for performance and to
decrease the risk of injuries during sporting activities. Purpose: To evaluate the effects of a
warm-up program in knee JPS in karatekas. Additionally, this study also aims to compare the
proprioceptive acuity when assessed in open versus closed kinetic chain. Methods: Ten young
amateur karatekas (17.60 ± 4.03 years of age) participated in this study. Joint position sense
was evaluated through active repositioning of the knee in open kinetic chain (OKC) and closed
kinetic chain (CKC). The target and the repositioning joint angles were measured before and
immediately after the warm-up program. Knee angles were determined by computer analysis of
the videotape images and reported as absolute and relative angular error. The warm-up
program comprised 15 minutes of slow running, calisthenics and stretching exercises. Results:
At rest no differences were observed between OKC and CKC in absolute and relative angular
errors (Table 1). At rest, the karatekas showed a clear tendency to over-estimate the test
position in OKC and to under-estimate the test position in CKC. After the warm-up program, a
significant decrease in absolute angular error was observed only in CKC (p=0.04).
Additionally, in CKC the subjects reduced the relative angular error to approximately zero and
decrease the variability of the responses, expressed by the decrease in standard deviation of the
relative errors.
Table 1 Knee joint position sense (degrees) before and after the warm-up program (values are mean ±
standard deviation)
Absolute Error Relative Error
Baseline OKC 4.15 ± 1.57 2.43 ± 3.44
CKC 3.43 ± 1.99 2.05 ± 3.49
After warm-up program OKC 3.38 ± 2.03 3.25 ± 2.20
* Significantly different from baseline; p