[The initial position of the contralateral leg affects the muscular power capability of testing and training on a leg press]. / Die Ausgangsstellung des kontralateralen Beines beeinflusst die muskuläre Kraftfähigkeit beim Testen und Trainieren auf einer Beinpresse.

There are numerous studies on the factors influencing the maximum isometric force. These include, among others, the activity of the contralateral extremities in unilateral measurements. With reference to this parameter, there is still disagreement. Some studies suggest that activation of the contralateral antagonist leads to an increase in force production of the tested limb. In contrast, other research groups came to the conclusion that simultaneous contraction of the contralateral agonists have this effect. The aim of this study was to find out how certain starting positions and contraction directions of the non-tested limb affect the force capability of the contralateral limb during unilateral maximum isometric force measurements on a leg press. In the course of the investigation, the unilateral isometric maximum force capacity of the lower limbs of 20 subjects in four different starting positions and forms of activation of the contralateral limb was tested. The non-tested leg was first loosely placed on the floor (starting position A), then it was held on the body in maximum knee and hip flexion (test situation G) and after that it had to perform maximal contraction exercises in extension (KE) and flexion (KF) each against a stabilisation bar. The results showed significantly (p < 0.05) lower force levels during the contralateral contraction KF compared to all other test situations. In the starting position A, the subjects reached the highest values. Compared to G and KF these differences in maximum force development were significant (p < 0.05). Both the initial position, and the activity of the contralateral limb has an impact on the maximum isometric extension strength of the tested leg at the leg press. Therefore, during the repeated execution of an isometric strength test on this apparatus, it should be taken care that the subject occupies the same starting position as the previous test. A voluntary activation of the contralateral side should be avoided during the measurement, or in the same way.

Motor task and muscle strength followed different adaptation patterns after anterior cruciate ligament reconstruction.

AIM: The aims of this study were: 1) to investigate the adaptations in walking, running and muscle strength after anterior cruciate ligament (ACL) reconstruction and 2) to examine the interaction between muscle strength and walking or running kinematics at different time intervals following an ACL reconstruction. METHODS: Eleven patients 3-6 months postsurgery, 11 patients 6-12 months postsurgery and 13 patients 12-24 months post surgery were filmed using two cameras (50 Hz) whilst walking (1 m/s) and running (2.5 m/s) on a treadmill. In addition, the strength of the muscles surrounding the knee, hip and ankle joints was tested using an isokinetic protocol (60 degrees/s). RESULTS: The comparison between the injured and the non-injured limbs revealed significant lower knee extension and flexion angles during the stance phase of the injured limb (P<0.05). This was found in the 3-6 month postsurgery period when walking and running and in the 6-12 month postsurgery period when mainly running. The analysis of the muscle strength revealed lower (P<0.05) maximal joint moments for the knee extensors, the knee flexors and the hip flexors of the injured limb during all the observed post surgery periods. CONCLUSION: The results of this study indicate that the adaptation of the motor task and the muscle strength follows different time patterns. This suggests that a decrease in muscle strength capabilities can be tolerated up to a certain extent by the patients when walking and during sub maximal running. However, when the decrease in muscle strength exceeds a certain threshold the biological system, being flexible, changes its locomotion strategy.

[Graft type-related versus graft type-unrelated ACL treatment: influence on adaptation of muscle strength and motor skills]. / Ersatzplastikabhängige vs. nicht ersatzplastikabhängige ACL-Behandlung. Einfluss auf die Adaptation der Muskelkräfte und den motorischen Aufgaben.

INTRODUCTION: The purposes of this study were to identify adaptational phenomena in running and walking characteristics as well as in muscle strength after an ACL injury and graft-type related ACL treatment in order to determine the effect of the different treatments on the regeneration of muscle capacity and functional motor skills for a given task. METHOD: The investigation was conducted on 11 patients with patella reconstructions (PT: patella tendon), 12 patients with semitendinosus reconstruction (ST: semitendinosus tendon) and 10 patients without reconstruction. Besides a clinical examination, the subject's walking (1 m/s) and running (2.5 m/s) characteristics were recorded by 2 cameras operating at 50 Hz. During the same test session, we determined the force potential of the muscles surrounding the hip, knee and ankle joints during isokinetic contractions. RESULTS: The comparison between injured and non-injured limbs revealed significant changes (p<0.05) only for the injured limb. For both types of reconstruction treatment the injured limb showed a significantly lower maximal knee extension joint moment as well as a lower angular displacement of the knee joint during the stance phase while walking and running (p<0.05). Furthermore, patients with PT reconstruction showed lower maximal knee flexion and hip flexion joint moments, and a lower angular displacement of the knee joint in flexion during the stance phase while running (p<0.05). The ratios of the maximal isokinetic knee extension moments between the injured and non injured limbs were lower for the reconstruction treatment compared to the treatment without reconstruction and further lower for the PT reconstructed compared to the ST reconstructed patients (p<0.05). CONCLUSIONS: The findings of the present study indicate that, using a similar regeneration programme, the muscle capacities and functional motor skills show faster regeneration processes for patients without reconstruction compared to a reconstruction treatment after an ACL injury. Concerning the reconstruction treatment, PT reconstructions seem to affect the degeneration process of the muscle capacities of the treated limb more than ST reconstructions.

[Conservative versus operative treatment after ACL-rupture: influence on the muscle strength capability of the lower extremity]. / Konservative vs. operative Behandlungsmethode nach einer ACL-Ruptur: Einfluss auf die muskulären Kraftfähigkeiten der unteren Extremität.

PURPOSE: In this study two groups of ACL-rupture patients having had a conservative or an operative treatment and a similar rehabilitation were compared regarding their muscle strength capabilities, and the clinical outcome. METHODS: Thirty-three patients (mean age 31 years) were selected according to the Lysholm-scores. Twelve patients were conservatively treated (Group I) and were examined between six and 16 months post trauma. Group II consisted of 21 operatively treated patients which were examined between 6 and 16 months post surgery. All patients underwent a clinical exam following the OAK evaluation form and were tested on a Cybex 6000 isokinetic machine. The subjects had to perform concentric contractions of the extensor and flexor muscles of the knee, hip and ankle at 60 and 120 degrees /s. In addition the knee musculature was isometrically tested at knee angles of 0 and 45 degrees . RESULTS: The clinical examination revealed significant (P < 0.05) differences between groups. The operatively treated patients scored better at the tests for ligamentous stability, whereas the testing of the muscular capabilities revealed significant differences (P < 0.05) favouring the conservatively treated patients in the isokinetic measures, (maximal concentric torque M (max,con)) of the knee extensors, knee flexors, and ankle plantarflexors. CONCLUSION: Whereas the clinical examination only revealed the ligamentous stability to be better results in the operatively treated patients, the conservatively treated patients showed better results in the isokinetik strength measures of the knee extensors, knee flexors, and ankle plantarflexors. The better muscular profiles found for the conservatively treated patients suggest that a better regeneration of the corresponding muscular capabilities after an ACL rupture is possible, provided a specific and controlled rehabilitation program is performed. This seems to be more difficult in operatively treated patients even six to 16 months after the surgical intervention.

[Development of muscle strength in knee, hip and ankle joints after ACL reconstruction]. / Entwicklung der muskulären Kraftfähigkeiten im Knie-, Hüft- und Fussgelenk nach einer ACL-Rekonstruktion.

INTRODUCTION: We searched for answers for following questions: How does the knee muscle strength change in dependence of post OP time after the same ACL-rehabilitation's program? Which changes in muscle strength occur in hip and ankle muscles after ACL? METHODS: In this study 69 patients with ACL-Reconstruction participated, mean 31 years. The Lysholm- and OAK-scores of all were good respectively very good. 28 patients were 3 - 6 months post OP (Gr. I), 20 were 6 - 12 months post OP (Gr. II), 21 was 12 - 24 months post OP (Gr. II). All patients were tested on the isokinetic Cybex 6000, for dynamic concentric strength and endurance. The evaluation parameters chosen were: max.moment at angle speed of 60 degrees /sec and endurance index at 120 degrees /sec, RESULTS: The analysis of the max. moment showed significant (P < 0.05) changes in both knee extension and flexion in all groups, in the hip flexors and extensors in group I, and hip flexors in group II and III. In the ankle joint we only found significant changes in the plantarflexors of group I. Looking at the endurance index we observed that many muscle groups of the injured leg presented higher values, however the difference is only significant in the knee flexors and extensors of group I and in the hip flexors of group III. CONCLUSION: Our study showed strength loss in both knee extensors and knee flexors in all patients who had undergone reconstruction surgery after the same ACL-rehabilitation's program. We can state that there is strength loss in hip and ankle muscles in 3 - 6 months post OP patients. A reduction of muscle strength at the hip flexor from all patients was seen after 12 months post-OP. It is suggested that the strength loss in the hip flexors could be due to bi-articular muscles surrounding the knee.This results has to be consider on the planning of strength training after ACL injuries.