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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.

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David Diggin, Ross Anderson and Andrew J. Harrison

Evidence suggests reports describing the reliability of leg-spring (kleg) and joint stiffness (kjoint) measures are contaminated by artifacts originating from digital filtering procedures. In addition, the intraday reliability of kleg and kjoint requires investigation. This study examined the effects of experimental procedures on the inter- and intraday reliability of kleg and kjoint. Thirty-two participants completed 2 trials of single-legged hopping at 1.5, 2.2, and 3.0 Hz at the same time of day across 3 days. On the final test day a fourth experimental bout took place 6 hours before or after participants’ typical testing time. Kinematic and kinetic data were collected throughout. Stiffness was calculated using models of kleg and kjoint. Classifications of measurement agreement were established using thresholds for absolute and relative reliability statistics. Results illustrated that kleg and kankle exhibited strong agreement. In contrast, kknee and khip demonstrated weak-to-moderate consistency. Results suggest limits in kjoint reliability persist despite employment of appropriate filtering procedures. Furthermore, diurnal fluctuations in lower-limb muscle-tendon stiffness exhibit little effect on intraday reliability. The present findings support the existence of kleg as an attractor state during hopping, achieved through fluctuations in kjoint variables. Limits to kjoint reliability appear to represent biological function rather than measurement artifact.

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Cindy Y. Lin, Liang-Ching Tsai, Joel Press, Yupeng Ren, Sun G. Chung and Li-Qun Zhang

Context:

Gluteal-muscle strength has been identified as an important component of injury prevention and rehabilitation in several common knee injuries. However, many conventionally prescribed gluteal-strengthening exercises are not performed during dynamic weight-bearing activities, which is when most injuries occur.

Objectives:

To compare lower-limb muscle-activation patterns between conventional gluteal-strengthening exercises and off-axis elliptical exercises with motorized foot-plate perturbations designed to activate gluteal muscles during dynamic exercise.

Evidence Acquisition:

Twelve healthy volunteers (26.1 ± 4.7 y) participated in the study. They performed 3 conventional exercises (single-leg squat, forward lunge, and clamshell) and 3 elliptical exercises (regular, while resisting an adduction force, and while resisting an internal-rotation torque). Gluteus medius (GMed) and maximus (GMax), quadriceps, hamstrings, and gastrocnemius muscle activations during each exercise were recorded using surface electromyography (EMG) and normalized to maximal voluntary isometric contraction (MVIC).

Evidence Synthesis:

Normalized GMed EMG was the highest during the adduction-resistance elliptical exercise (22.4% ± 14.8% MVIC), significantly greater than forward lunge (8.2% ± 3.8% MVIC) and regular elliptical (6.4% ± 2.5% MVIC) and similar to clamshell (19.1% ± 8.8% MVIC) and single-leg squat (18.4% ± 7.9% MVIC). Normalized GMax EMG during adduction-resistance (11.1% ± 7.6% MVIC) and internal-rotation-resistance elliptical (7.4% ± 3.8% MVIC) was significantly greater than regular elliptical (4.4% ± 2.4% MVIC) and was similar to conventional exercises. The single-leg squat required more muscle activation from the quadriceps and gastrocnemius than the elliptical exercises.

Conclusions:

Off-axis elliptical exercise while resisting an adduction force or internal-rotation torque activates gluteal muscles dynamically while avoiding excessive quadriceps activation during a functional weight-bearing activity compared with conventional gluteal-strengthening exercises.