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Nathan G. Versey, Shona L. Halson and Brian T. Dawson

Purpose:

To investigate whether contrast water therapy (CWT) assists acute recovery from high-intensity running and whether a dose-response relationship exists.

Methods:

Ten trained male runners completed 4 trials, each commencing with a 3000-m time trial, followed by 8 × 400-m intervals with 1 min of recovery. Ten minutes postexercise, participants performed 1 of 4 recovery protocols: CWT, by alternating 1 min hot (38°C) and 1 min cold (15°C) for 6 (CWT6), 12 (CWT12), or 18 min (CWT18), or a seated rest control trial. The 3000-m time trial was repeated 2 h later.

Results:

3000-m performance slowed from 632 ± 4 to 647 ± 4 s in control, 631 ± 4 to 642 ± 4 s in CWT6, 633 ± 4 to 648 ± 4 s in CWT12, and 631 ± 4 to 647 ± 4 s in CWT18. Following CWT6, performance (smallest worthwhile change of 0.3%) was substantially faster than control (87% probability, 0.8 ± 0.8% mean ± 90% confidence limit), however, there was no effect for CWT12 (34%, 0.0 ± 1.0%) or CWT18 (34%, –0.1 ± 0.8%). There were no substantial differences between conditions in exercise heart rates, or postexercise calf and thigh girths. Algometer thigh pain threshold during CWT12 was higher at all time points compared with control. Subjective measures of thermal sensation and muscle soreness were lower in all CWT conditions at some post-water-immersion time points compared with control; however, there were no consistent differences in whole body fatigue following CWT.

Conclusions:

Contrast water therapy for 6 min assisted acute recovery from high-intensity running; however, CWT duration did not have a dose-response effect on recovery of running performance.

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Alan Barr and David Hawkins

An anatomical database was constructed containing three-dimensional geometric representations of the structures comprising the lower extremity. The database was constructed by digitizing 100 high-resolution digital photographic images supplied from the National Library of Medicine’s Visual Human Male (VHM) project. These images were taken of sequential transverse cross-sectional slices of the leg. Slices were located 1 cm apart between a location approximately 3 mm below the superior aspect of the ilium and approximately 2 mm below the distal end of the fibula. Image Tool Software (v. 2.0) was used to manually digitize the perimeters of muscles, tendons, and bones of the pelvis, thigh, and shank from the right leg of the VHM. Additionally, the perimeter of the leg and the inner aspect of the superficial fat layer were digitized. The pelvis was digitized as a hemi-pelvis. Tissue perimeters were characterized using between 10 and 151 nodes within each slice; the number of nodes varied depending on the tissue’s size. Transverse cross-sectional slice number, structure identification, node number, and the two-dimensional coordinates of each node were stored in a data file. The information contained in this file is unique and provides a database that researchers can use to investigate questions related to tissue anatomy and movement mechanics that cannot be considered using existing musculoskeletal data sets.

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Gertjan J.C. Ettema, Steinar Bråten and Maarten F. Bobbert

A ski jumper tries to maintain an aerodynamic position in the in-run during changing environmental forces. The purpose of this study was to analyze the mechanical demands on a ski jumper taking the in-run in a static position. We simulated the in-run in ski jumping with a 4-segment forward dynamic model (foot, leg, thigh, and upper body). The curved path of the in-run was used as kinematic constraint, and drag, lift, and snow friction were incorporated. Drag and snow friction created a forward rotating moment that had to be counteracted by a plantar flexion moment and caused the line of action of the normal force to pass anteriorly to the center of mass continuously. The normal force increased from 0.88G on the first straight to 1.65G in the curve. The required knee joint moment increased more because of an altered center of pressure. During the transition from the straight to the curve there was a rapid forward shift of the center of pressure under the foot, reflecting a short but high angular acceleration. Because unrealistically high rates of change of moment are required, an athlete cannot do this without changing body configuration which reduces the required rate of moment changes.

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Maurice R. Yeadon and Mark A. King

The use of computer simulation models in studies of human movement is now widespread. Most of these models, however, have not been evaluated in a quantitative manner in order to establish the level of accuracy that may be expected. Without such an evaluation, little credence should be given to the published results and conclusions. This paper presents a simulation model of tumbling takeoffs which is evaluated by comparing the simulation output with an actual performance of an elite gymnast. A five-segment planar model was developed to simulate tumbling takeoffs. The model comprised rigid foot, leg, thigh, trunk + head, and arm segments with two damped linear springs to represent the elasticity of the tumbling track/ gymnast interface. Torque generators were included at the ankle, knee, hip, and shoulder joints in order to allow each joint to open actively during the takeoff. The model was customized to the elite gymnast by determining subject-specific inertia and torque parameters. Good agreement was found between actual and simulated tumbling performances of a double layout somersault with 1% difference in the linear and angular momenta at takeoff. Allowing the activation timings of the four torque generators to vary resulted in an optimized simulation that was some 0.32 m higher than the evaluation simulation. These simulations suggest the model is a realistic representation of the elite gymnast, since otherwise the model would either fail to reproduce the double layout somersault or would produce a very different optimized solution.

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John W. Chow, Warren G. Darling and James C. Ehrhardt

The purpose of this study was to determine the coordinates of the origin and insertion, muscle volumes, lengths, lines of action, and effective moment arm of the quadriceps muscles in vivo using magnetic resonance imaging (MRI) and radiography for a pilot study involving musculoskeletal modeling. Two magnetic resonance scans were performed, and axial images were obtained for the left thigh of a female subject in the anatomical position to measure muscle volume, coordinates of the origin and insertion, and muscle belly length at the anatomical position of each quadriceps muscle. Six knee radiographs were used to determine the effective moment arm of the quadriceps force at different knee flexion angles. A combination of MRI and radiography data was used to compute the muscle lengths at different knee flexion angles. The coordinates of the vastus lateralis, muscle volumes of individual quadriceps muscles, and effective moment arms were clearly different from the corresponding values from cadaver data reported in the literature. These comparisons demonstrate the advantages of using personalized muscle parameters instead of those collected from cadavers and dry-bone specimens.

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Adam M. Fullenkamp, Brian M. Campbell, C. Matthew Laurent and Amanda Paige Lane

To date, biomechanical analyses of soccer kicking have focused predominantly on lower-extremity motions, with little emphasis on the trunk and upper body. The purpose of this study was to evaluate differences in trunk axial kinematics between novice (n = 10) and skilled (n = 10) participants, as well as to establish the relationship of trunk axial motion and sagittal plane thigh rotation to poststrike ball velocity. Three-dimensional body segmental motion data were captured using high-resolution motion analysis (120 Hz) while each participant completed 5 maximal instep soccer-style kicks. The results demonstrate that skilled participants use 53% greater axial trunk range of motion compared with novice participants (P < .01), as well as 62% greater peak trunk rotation velocity (P < .01). The results also show a moderate, positive correlation of peak trunk rotation velocity with poststrike ball velocity (r = .57; P < .01), and peak hip flexion velocity with poststrike ball velocity (r = .63; P < .01). The current study highlights the potential for trunk rotation-specific training to improve maximum instep kick velocity in developing soccer athletes.

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Bryan C. Heiderscheit, Joseph Hamill and Richard E.A. van Emmerik

The purpose of this investigation was to determine whether individuals with patellofemoral pain (PFP) display a reduction in intralimb joint coordination variability compared to nonimpaired persons. In addition, it was hypothesized that the variability of the stride characteristics would be similar between groups. Eight individuals with unilateral PFP and 8 nonimpaired participants ran on a treadmill at a fixed (2.68 m·s–1) and preferred speed while stride characteristics and 3-D kinematics of the bilateral lower extremities were recorded. Intralimb coordination variability was measured using a vector coding technique applied to relative motion plots of various joint couplings. The PFP group displayed greater stride length variability during running at the preferred speed. However, this was not the case during running at the fixed speed. When averaging across the entire stride cycle, coordination variability for all joint couplings was consistent between the two groups. However, further analysis about heel-strike revealed reduced joint coordination variability for the thigh rotation/leg rotation coupling of the PFP group’s injured limb compared to that of the nonimpaired group. With the exception of the transverse plane rotations at heel-strike, it would appear that the level of pain experienced by the PFP participants may not be great enough to produce a change in the intralimb coordination patterns during running.

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Trampas M. TenBroek, Pedro A. Rodrigues, Edward C. Frederick and Joseph Hamill

The purpose of this study was to: (1) investigate how kinematic patterns are adjusted while running in footwear with THIN, MEDIUM, and THICK midsole thicknesses and (2) determine if these patterns are adjusted over time during a sustained run in footwear of different thicknesses. Ten male heel-toe runners performed treadmill runs in specially constructed footwear (THIN, MEDIUM, and THICK midsoles) on separate days. Standard lower extremity kinematics and acceleration at the tibia and head were captured. Time epochs were created using data from every 5 minutes of the run. Repeated-measures ANOVA was used (P < .05) to determine differences across footwear and time. At touchdown, kinematics were similar for the THIN and MEDIUM conditions distal to the knee, whereas only the THIN condition was isolated above the knee. No runners displayed midfoot or forefoot strike patterns in any condition. Peak accelerations were slightly increased with THIN and MEDIUM footwear as was eversion, as well as tibial and thigh internal rotation. It appears that participants may have been anticipating, very early in their run, a suitable kinematic pattern based on both the length of the run and the footwear condition.

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Thomas W. Balon, Jeffrey F. Horowitz and Karen M. Fitzsimmons

Bodybuilders have used different carbohydrate loading regimens in conjunction with resistance exercise prior to competition in the belief that this would result in increased muscle size. To investigate this possibility, muscle girth measurements were obtained from nine weight-trained males before and after a control (standard isocaloric diet) and an experimental trial (carbohydrate loading). The latter regimen consisted of 3 days of intense weight-lifting while the subjects ingested a diet of 10% carbohydrate (CHO), 57% fat (F), and 33% protein (P), followed by 3 days of light weight-lifting and a day of rest while ingesting a diet of 80% CHO, 5% F, and 15% P. The control trial consisted of an identical weight-lifting regimen while subjects ingested an isocaloric (45 kcal/kg BWIday) diet. Body weight and girths (forearm, upper arm, chest, thigh, waist, and calf) were obtained before and after each trial in a relaxed and flexed state. The results indicated that an exercise/carbohydrate loading regimen had no significant effect on muscle girth as compared to the control trial. It is concluded that CHO loading has no additional advantage to enhancing muscle girth in bodybuilders over weight-lifting alone.

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Keitaro Kubo, Takanori Teshima, Norikazu Hirose and Naoya Tsunoda

The purpose of this study was to compare the morphological and mechanical properties of the human patellar tendon among elementary school children (prepubertal), junior high school students (pubertal), and adults. Twenty-one elementary school children, 18 junior high school students, and 22 adults participated in this study. The maximal strain, stiffness, Young’s modulus, hysteresis, and cross-sectional area of the patellar tendon were measured using ultrasonography. No significant difference was observed in the relative length (to thigh length) or cross-sectional area (to body mass2/3) of the patellar tendon among the three groups. Stiffness and Young’s modulus were significantly lower in elementary school children than in the other groups, while no significant differences were observed between junior high school students and adults. No significant differences were observed in maximal strain or hysteresis among the three groups. These results suggest that the material property (Young’s modulus) of the patellar tendons of elementary school children was lower than that of the other groups, whereas that of junior high school students was already similar to that of adults. In addition, no significant differences were observed in the extensibility (maximal strain) or viscosity (hysteresis) of the patellar tendon among the three groups.