Alongamento ativo excêntrico dos músculos flexores do joelho na postura em pé: efeito sobre a amplitude de movimento e torque muscular.
Abstract
The relation between flexibility alterations and muscular torque posstretching
is not so exploited in literature. There are many stretching
techniques and posture used in clinics and sportive activities. The technique of
eccentric active stretching in a standing posture, with weight unloading in the
stretched limb, is one of them. Thus, a better knowledge of the alterations
caused after its application will provide scientific support for its usage.
Objective: To evaluate the effects of an eccentric active stretching program of
the knee flexor muscles in the standing posture on the evaluated limb on: knee
extension ROM, passive torque of knee flexor muscles and isometric and
isokinetic concentric and eccentric torque of flexor and extensor muscles of
the knee. Methodology: 34 healthy and sedentary volunteers, both genders
(34,42 ± 9,3 years) were evaluated. All of them had 20° or more knee flexor
muscles shortening. The stretching program was performed twice a week, for
four weeks and consisted of 7 consecutive repetitions of 1 min each one with a
30s rest between them. Knee ROM and knee torque were evaluated using an
Isokinetic Dynamometer before and after four weeks of intervention. The
passive torque and knee ROM were measured passively, while the isometric,
concentric and eccentric torque of the flexor and extensor of the knee were
measured through maximal voluntary contractions (speeds 30°/s, 60°/s).
Results: There was an increase in the knee extensor ROM from 53,7 ± 13° to
30,1 ± 16° (p = 0,0001). No alteration occurred in the passive torque (from
11,2 ± 3N to 10,6 ± 3N; p = 0,09). The isometric extensor and flexor torque
increased from 68 ± 67,8N to 187,58 ± 73,5N (p = 0,006) and from 89,68 ±
32,62N to 93,87 ± 33,12N (p = 0,01), respectively. There was a gain of knee
extensor concentric torque at 60°/s from 144,44 ± 51,6N to 151,57 ± 58,2N (p
= 0,02) and knee extensor eccentric torque at 30°/s from 175,4 ± 71,6N to
189,9 ± 73,8N (p = 0,01). There was an improvement in the flexor eccentric
and concentric torque at 30º /s (from 100,3 ± 34,2N to 105,63 ± 35N; p = 0,02
and from 90,7 ± 31,7N to 96,7 ± 31,8N; p = 0,001, respectively).
Conclusions: The eccentric active stretching program of the knee flexor
muscles in a standing posture was effective to increase knee extension ROM,
improving flexibility in the knee flexor muscles, although there was no change
in the passive torque. It also improved the isometric and isokinetic peak torque
from the muscle group submitted to the stretching and its antagonist group.