Context: Asymmetries subsist after anterior cruciate ligament reconstruction (ACL-R), and it is unclear how lower limb motion is altered in the context of a dynamic movement.Objective: To highlight the alterations observed in the injured limb (IL) during the performance of a dynamic movement after ACL-R.Design: Cross-sectional study. Setting: Research laboratory. Patients or Other Participants: A total of 11 men (age ¼ 23.3 6 3.8 years, mass ¼ 81.2 6 17.0 kg) who underwent ACL-R took part in this study 7.3 6 1.1 months (range ¼ 6-9 months) after surgery.Intervention(s): Kinematic and kinetic analyses of a singlelegged squat jump were performed. The uninjured leg (UL) was used as the control variable.Main Outcome Measure(s): Kinematic and kinetic variables.Results: Jump height was 24% less for the IL than the UL (F 1,9 ¼ 23.3, P ¼ .001), whereas the push-off phase duration was similar for both lower limbs (P ¼ .96). Knee-joint extension (F 1,9 ¼ 11.4, P ¼ .009), and ankle plantar flexion (F 1,9 ¼ 22.6, P ¼ .001) were less at takeoff for the IL than the UL. The hip angle at takeoff was not different between lower limbs (P ¼ .09). We found that total moment was 14% less (F 1,9 ¼ 11.1, P ¼ .01) and total power was 35% less (F 1,9 ¼ 24.2, P ¼ .001) for the IL than the UL. Maximal hip (P ¼ .09) and knee (P ¼ .21) power was not different between legs. The IL had 34% less maximal ankle power (F 1,9 ¼ 11.3, P ¼ .009) and 31% less angular velocity of ankle plantar flexion (F 1,9 ¼ 17.8, P ¼ .004) than the UL.Conclusions: At 7.3 months after ACL-R, motion alterations were present in the IL, leading to a decrease in dynamic movement performance. Enhancing the tools for assessing articular and muscular variables during a multijoint movement would help to individualize rehabilitation protocols after ACL-R.Key Words: knee, dynamic movement, hop test, rehabilitation Key PointsKinematic and kinetic alterations were demonstrated in the injured leg at 7.3 months after anterior cruciate ligament reconstruction. These alterations led to decreased jump height during a single-legged squat jump in the injured leg. Enhancing tools for assessing articular and muscular variables during a multijoint movement would help to individualize rehabilitation protocols after anterior cruciate ligament reconstruction.

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The aim of this study was to determine the effect of wearing a triathlon wet suit on the technical parameters of the front crawl stroke. Eight highly trained male triathletes were filmed with underwater camcorders during two 1500-m swim tests: one with a wet suit (WS) and the other with a standard suit (SS). Two conditions were considered: Condition I (CI) and Condition XV (CXV), representing the 1st and the 15th 100-m, respectively. Views were synchronized and digitized using kinematic analysis software (Schleihauf, 1994) to obtain 3-D coordinates of the anatomical landmarks of the body. Results showed that the wet suit and duration of the exercise significantly influenced stroke parameters. The swim with WS was characterized by greater stroke length and a progressive increase in stroke frequency, resulting from a more extended elbow position during the stroke and from a decrease in the absolute and relative times of the propulsive phase. These changes indicated more efficient upper limb action. The duration of exercise modified the swim with WS and SS. The loss of velocity observed in CXV was related to a decrease in stroke length, or more precisely a reduction in lever arm length during the aquatic phase, insufficiently offset by a slight increase in stroke frequency. These two motor responses, a less extended elbow position and a stroke frequency increase, emerged as an easier motor solution for coping with the effect of fatigue. This solution could be regarded as an adaptation to the duration of the exercise.

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Arm swing helps to increase vertical jump height (VJH), in part by a greater hip joint muscle work. The force-velocity relationship has been put forward to explain the increase in hip joint work. Nevertheless, the efficacy ratio, muscle shortening length, and active state might be parameters that affect the effective energy and then VJH. The purpose of this study was to evaluate the influence of arm swing on effective energy in vertical jumping. Eight subjects performed maximal squat jumps with (SJ arm ) and without arm swing (SJ). A simulation model of the musculo-skeletal system was applied. For subjects and simulation, VJH was about 20% higher during SJ arm. In subjects, this was explained by the shoulder joint work (34%) and an increase of L5-S1 joint work (66%). In simulated jump, effective energy increase during SJ arm (+80.74 J) was related to an improvement of the total muscle work and not to the efficacy ratio. The increase in total muscle work was due to anterior deltoid work and to greater erector spinae, biceps femoris, and gluteus work. The greater muscle works were explained by a slower shortening velocity for all the muscles and by a greater shortening length and active state for the biceps femoris.