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Lukas D. Linde, Jessica Archibald, Eve C. Lampert and John Z. Srbely

better understand the mechanism of ACL injury with an aim toward improving ACL injury prevention in females. Gender differences in lower limb mechanics have been shown to predispose females to ACL injury. 3 , 4 A large prospective study, in which female basketball and soccer athletes were followed for 2

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Gilbert M. Willett, Gregory M. Karst, Ellen M. Canney, Derrick Gallant and Jodene M. Wees

The purpose of this study was to investigate the electromyographic (EMG) activity of selected lower limb muscles during forward- and backward-facing stair-stepping exercises using a hydraulic step ergometer and during step aerobics using a standard 8 in. high step. Surface electrodes recorded EMG data from the vastus lateralis (VL), vastus medialis obliquus (VMO), and biceps femoris (BF) muscles on the right lower limbs of 13 healthy subjects under each of the four exercise conditions. Normalized mean EMG amplitude data were used to test for activity-dependent differences. Results indicated that (a) the VL and VMO were significantly (p < .05) more active during step ergometry than during step aerobics, (b) the BF was significantly (p < .05) more active during step aerobics than during step ergometry, and (c) when forward- versus backward-facing positions were compared, there were no statistically significant differences in mean EMG activity for either of the activities. These findings provide information relevant to the use and progression of stepping exercises commonly used for knee muscle strengthening and knee injury rehabilitation programs.

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J.-M. John Wilson, D. Gordon E. Robertson and J. Peter Stothart

In an effort to seek further understanding of lower limb muscle function in the rowing movement, an electromyographic analysis was undertaken of rowers rowing on a Gjessing ergometer. A strain gauged transducer was inserted in the ergometer linkage between handle and flywheel to detect pulling force. Electrodes were placed on the following lower limb muscles: gluteus maximus, biceps femoris, rectus femoris, vastus lateralis, gastrocnemius, and tibialis anterior. Linear envelope electromyograms from each muscle and the force signals were sampled synchronously at 50 Hz. The results indicated that all six muscles were active from catch to finish of the drive phase. Biceps femoris, gluteus maximus, gastrocnemius, and vastus lateralis all began their activity at or just prior to catch and reached maximal excitation near peak force of the stroke. Rectus femoris and tibialis anterior activity began prior to the catch and reached maximal excitation subsequent to peak force. The coactivation of the five leg muscles, of which four were biarticular, included potentially antagonistic actions that would cancel each other’s effects. Clearly, however, other explanations must be considered. Both gastrocnemius and biceps femoris have been shown to act as knee extensors and may do so in the case of the rowing action. Furthermore, rectus femoris may act with unchanging length as a knee extensor by functioning as a rigid link between the pelvis and tibia. In this manner, energy created by the hip extensors is transferred across the knee joint via the isometrically contracting rectus femoris muscle.

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Mehrez Hammami, Rodrigo Ramirez-Campillo, Nawel Gaamouri, Gaith Aloui, Roy J. Shephard and Mohamed Souhaiel Chelly

existing drills within a regular in-season handball training program would enhance the high-intensity actions of young female handball players. A combined lower-limb (hurdle jump) and upper-limb (push-up) plyometric program was introduced into the normal in-season regimen of experimental subjects for 9

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Ali Jalalvand and Mehrdad Anbarian

GRFs acting on the body during landings have been associated with injury to the lower limb. 9 In addition, chronic low back pain (CLBP) can seriously impact functional ability. People with CLBP are at increased risk of LEI. As a result, a previous history of LBP is a significant predictor of ACL

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Rodrigo de Marche Baldon, Daniel Ferreira Moreira Lobato, Lívia Pinheiro Carvalho, Paulo Roberto Pereira Santiago, Benedito Galvão Benze and Fábio Viadanna Serrão

The purposes of this study were to compare lower-limb kinematics between genders, and determine the relationships among eccentric hip abductor and lateral rotator torques and lower-limb kinematics. The movements of the pelvis, femur, and knee were calculated for 16 women and 16 men during the single-leg squat. Eccentric hip abductor and lateral rotator torques were measured using an isokinetic dynamometer. The results showed that women had greater contralateral pelvic depression, femur adduction, and knee abduction than men. The eccentric hip abductor and lateral rotator torques were correlated with coronal plane femur and knee movements in the overall sample. When the genders were analyzed separately, it was observed that women with greater eccentric hip abductor torque exhibited less femur adduction and femur medial rotation, and greater knee adduction excursion. No significant relationship was observed between the isokinetic and kinematic variables in the male group. The differences between the genders help to explain the greater rate of knee disorders observed in women. Moreover, the eccentric hip abduction action seemed to be more important in women to control the lower-limb movements.

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Matthew J. Moncrieff and Lori A. Livingston

Context:

Structural and coronal-plane-alignment characteristics of the lower limb are frequently cited as factors contributing to knee pathologies.

Objective:

The purpose of this study was to determine the accuracy and reliability characteristics of a digital-photographic-goniometric method (DPGM) of measurement for 2-dimensional (2D) coronal-plane lower limb measurements of the quadriceps (Q) angle, tibiofemoral (TF) angle, and femur length in human participants adopting a self-selected- or Romberg-stance position.

Design:

Reliability study.

Setting:

University motion-analysis laboratory.

Participants:

A convenience sample of 20 healthy young adult men and women.

Main Outcome Measures:

Intraclass correlation coefficients (ICCs), 95% confidence intervals, and standard error of the measurements.

Results:

Intratester- and intertester-reliability coefficients for the Q angle (ICCs .458–845 and .257–737) were consistently lower than those for the TF angle (ICCs .627–.904 and .700–.839) or femur length (ICCs .867–.958 and .866–.944). Q angles were also significantly larger (13.4%) in the Romberg- vs self-selected-stance position (P < .001) and larger (20.2%) in the left limb than the right limb.

Conclusions:

The DPGM has the potential to produce accurate and reliable measurements of selected 2D lower limb measures. However, the reliability characteristics depend on the ability of the testers to correctly and repeatably landmark the anatomical sites used to define the measurements of interest and might be influenced by other factors such as the stance position adopted, the complexity of the variable (ie, number of anatomical landmarks and segments), and the size of the captured image. Further investigation of these latter factors is warranted.

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Scott C. White and David Winter

Repeat trials of a race walker were analyzed to ascertain the contribution to energy changes made by the lower limb muscles. A sagittal plane link segment model was used to calculate mechanical powers at the hip, knee and ankle. The ankle plantarflexors provided the major energy necessary to propel the body forward. Muscles about the hip contribute to a lesser extent via energy generation and transfer. At the knee, the muscles acted mainly as energy absorbers and did not contribute to forward propulsion. Mechanical powers calculated for the race walker were compared to other forms of locomotion. Patterns unique to the race walker were identified and discussed.

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Nicola Giovanelli, Paolo Taboga, Enrico Rejc, Bostjan Simunic, Guglielmo Antonutto and Stefano Lazzer

Purpose:

To investigate the effects of an uphill marathon (43 km, 3063-m elevation gain) on running mechanics and neuromuscular fatigue in lower-limb muscles.

Methods:

Maximal mechanical power of lower limbs (MMP), temporal tensiomyographic (TMG) parameters, and muscle-belly displacement (D m) were determined in the vastus lateralis muscle before and after the competition in 18 runners (age 42.8 ± 9.9 y, body mass 70.1 ± 7.3 kg, maximal oxygen uptake 55.5 ± 7.5 mL · kg−1 · min−1). Contact (t c) and aerial (t a) times, step frequency (f), and running velocity (v) were measured at 3, 14, and 30 km and after the finish line (POST). Peak vertical ground-reaction force (Fmax), vertical displacement of the center of mass (Δz), leg-length change (ΔL), and vertical (k vert) and leg (k leg) stiffness were calculated.

Results:

MMP was inversely related with race time (r = –.56, P = .016), t c (r = –.61, P = .008), and Δz (r = –.57, P = .012) and directly related with Fmax (r = .59, P = .010), t a (r = .48, P = .040), and k vert (r = .51, P = .027). In the fastest subgroup (n = 9) the following parameters were lower in POST (P < .05) than at km 3: t a (–14.1% ± 17.8%), Fmax (–6.2% ± 6.4%), k vert (–17.5% ± 17.2%), and k leg (–11.4% ± 10.9%). The slowest subgroup (n = 9) showed changes (P < .05) at km 30 and POST in Fmax (–5.5% ± 4.9% and –5.3% ± 4.1%), t a (–20.5% ± 16.2% and –21.5% ± 14.4%), t c (5.5% ± 7.5% and 3.2% ± 5.2%), k vert (–14.0% ± 12.8% and –11.8% ± 10.0%), and k leg (–8.9% ± 11.5% and –11.9% ± 12%). TMG temporal parameters decreased in all runners (–27.35% ± 18.0%, P < .001), while D m increased (24.0% ± 35.0%, P = .005), showing lower-limb stiffness and higher muscle sensibility to the electrical stimulus.

Conclusions:

Greater MMP was related with smaller changes in running mechanics induced by fatigue. Thus, lower-limb power training could improve running performance in uphill marathons.

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Bryce Dyer, Siamak Noroozi, Philip Sewell and Sabi Redwood

The purpose of this paper is to investigate the role of lower-limb running prostheses and stakeholders’ perceptions of fairness in relation to their use in competitive disability sport. A Delphi study was conducted over three rounds to solicit expert opinion in a developing area of knowledge. High levels of consensus were obtained. The findings suggest that the prosthesis is defined as a piece of sporting equipment to restore athletes’ function to enable them to take part in disability sport. In addition, the panel determined that the development of this technology should be considered to be integral to the sport’s ethos. Crucially, prostheses technology should be monitored and have limits placed upon it to ensure fairness for both participants and stakeholders.