Karine Monteil

Contralateral limb deficit seven months after ACL-reconstruction: an analysis of single-leg hop tests.

BACKGROUNDnFollowing ACL-reconstruction, the non-injured leg (NIL) is used as a reference to assess injured leg (IL) recovery. However, deficits have been reported in the NIL questioning its use as a reference. The aim of this study is to assess whether NIL deficits are present while jumping after ACL-reconstruction.nnnMETHODSnThirteen males who had undergone ACL-reconstruction and 16 healthy subjects took part in the experiment. Jumping performance was assessed during a single and a triple hop for distance. Jumping performance, kinematic and kinetic data were recorded during single leg squat jumps. Values for both the NIL and the IL were compared to those of a control group (CG).nnnRESULTSnJumping performance for single and triple hop for distance and single leg squat jump was lower in the NIL than in the CG (p=0.004, p=0.002, and p=0.016, respectively). During the squat jump, the knee joint was more extended and the ankle plantar-flexion was greater at take-off while the peak total moment was 15% lower in the NIL than in the CG (p=0.002, p=0.002, and p=0.009, respectively). We found consistent evolutions in the NIL and the IL compared to the CG for jumping performance, initial joint angles, and peak total moment during the squat jump, but the opposite was found for the ankle and knee joint angles at squat jump take-off.nnnCONCLUSIONSnJumping strategies are impaired in the NIL after ACL-R during jump tasks with some deficits matching those observed in the IL and some specific to the NIL.nnnLEVEL OF EVIDENCEnIII, Case control study.

Asymmetries in joint work during multi‐joint movement after anterior cruciate ligament reconstruction: A pilot study

After anterior cruciate ligament reconstruction (ACL‐R), many studies have reported a deficit of performance on the injured leg during multi‐joint tasks. However, the total mechanical joint work (WTotal), parameter best related to the vertical displacement of the body mass center during vertical jumping, has not yet been studied. The aim of this research was to compare asymmetries between ACL‐R subjects and healthy matched subjects, through the analysis of the kinematics and kinetics during a single‐leg squat jump. Asymmetries are defined by the Limb Symmetry Index (LSI). A greater LSI was observed for WTotal in the ACL‐R group than in the healthy group. There was no difference in LSI for knee joint work between the two groups, while the LSI for hip and ankle joint work was significantly larger in the ACL‐R group. This was explained by greater LSI for the hip and ankle joint range of motion in the ACL‐R group than in the healthy group. After ACL‐R, patients exhibited greater asymmetries than healthy subjects during single‐leg squat jump. Physiotherapists should focus on quality execution of multi‐joint movement, especially on hip and ankle joints range of motion in order to reduce asymmetries and to improve vertical jumping performance.

Influence of lumbar spine extension on vertical jump height during maximal squat jumping

Abstract The purpose of this study was to determine the influence of lumbar spine extension and erector spinae muscle activation on vertical jump height during maximal squat jumping. Eight male athletes performed maximal squat jumps. Electromyograms of the erector spinae were recorded during these jumps. A simulation model of the musculoskeletal system was used to simulate maximal squat jumping with and without spine extension. The effect on vertical jump height of changing erector spinae strength was also tested through the simulated jumps. Concerning the participant jumps, the kinematics indicated a spine extension and erector spinae activation. Concerning the simulated jumps, vertical jump height was about 5.4 cm lower during squat jump without trunk extension compared to squat jump. These results were explained by greater total muscle work during squat jump, more especially by the erector spinae work (+119.5 J). The erector spinae may contribute to spine extension during maximal squat jumping. The simulated jumps confirmed this hypothesis showing that vertical jumping was decreased if this muscle was not taken into consideration in the model. Therefore it is concluded that the erector spinae should be considered as a trunk extensor, which enables to enhance total muscle work and consequently vertical jump height.

The effects of seat height and foot placement on lumbar spine load during sit-to-stand tasks

The purpose of this study was to determine the influence of seat height and foot position in the sagittal plane on L5-S1 joint load. Fourteen healthy male adults stood up from a chair with three different seat heights and positions of the feet in the sagittal plane. L5-S1 net joint torque, mechanical work, range of motion and electromyographic activity of the erector spinae muscle were measured. L5-S1 net joint work increased by about 50% from high to low seat position. The mean and peak L5-S1 net joint torques increased about 30% from foot-back to foot-neutral position. These results were reinforced by a greater integrated electromyography signal from the erector spinae from high to low seat position and from foot-back to foot-neutral position. A high chair and placement of the feet behind the knees may be advisable to lessen lumbar load during sit-to-stand movements. Practitioner Summary: This study evaluated the effect of seat height and foot position on L5-S1 joint work and erector spinae activation during sit-to-stand movements. A high seat with the feet positioned further back decreased L5-S1 joint torque and erector spinae activation. These outcomes may help to reduce spine load during sit-to-stand movements.

Explosive movement in the older men: analysis and comparative study of vertical jump

BackgroundLoss of power has been demonstrated to have severe functional consequences to perform physical daily living tasks in old age.PurposeThis study aimed to assess how moment and velocity were affected for each joint of the lower limbs during squat jumping for older men in comparison with young adults.MethodsTwenty-one healthy older men (74.5xa0±xa04.6xa0years) and 22 young men (21.8xa0±xa02.8xa0years) performed maximal squat jumps. Inverse dynamics procedure was used to compute the net joint power, moment and velocity produced at the hip, knee and ankle joints.Results and discussionVertical jump height of the elderly was 64xa0% lower than the young adults. The maximal power of the body mass center (Pmaxbmc) was 57xa0% lower in the older population. For the instant at Pmaxbmc, the vertical ground reaction force and the vertical velocity of the body mass center were 26xa0% and 35xa0% less in the older adults than in the young adults, respectively (pxa0<xa00.05; ESxa0=xa0−1.64 for vertical ground reaction force; pxa0<xa00.05; ESxa0=xa0−1.10). A lower value of the hip (−60xa0%), knee (−72xa0%) and ankle (−68xa0%) joint powers was observed in older adults. This was explained by both lower values of joint moments (−64, −57 and −61xa0% for the hip, knee and ankle, respectively) and angular velocities (−59, −49 and −52xa0% for the hip, knee and ankle, respectively).ConclusionThis study showed a lower joint power when performing vertical jump. This smaller power resulted from both a lower moment and angular velocity produced at each joint.