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O. Girard, J.-P. Micallef and G.P. Millet

Purpose:

This study aimed at examining the influence of different playing surfaces on in-shoe loading patterns in each foot (back and front) separately during the first serve in tennis.

Methods:

Ten competitive tennis players completed randomly five frst (ie, fat) serves on two different playing surfaces: clay vs GreenSet. Maximum and mean force, peak and mean pressure, mean area, contact area and relative load were recorded by Pedar insoles divided into 9 areas for analysis.

Results:

Mean pressure was significantly lower (123 ± 30 vs 98 ± 26 kPa; -18.5%; P < .05) on clay than on GreenSet when examining the entire back foot. GreenSet induced higher mean pressures under the medial forefoot, lateral forefoot and hallux of the back foot (+9.9%, +3.5% and +15.9%, respectively; both P < .01) in conjunction with a trend toward higher maximal forces in the back hallux (+15.1%, P = .08). Peak pressures recorded under the central and lateral forefoot (+21.8% and +25.1%; P < .05) of the front foot but also the mean area values measured on the back medial and lateral midfoot were higher (P < .05) on clay. No significant interaction between foot region and playing surface on relative load was found.

Conclusions:

It is suggested that in-shoe loading parameters characterizing the first serve in tennis are adjusted according to the ground type surface. A lesser asymmetry in peak (P < .01) and mean (P < .001) pressures between the two feet was found on clay, suggesting a greater need for stability on this surface.

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Patrick F. Curran, Russell D. Fiore and Joseph J. Crisco

Context:

Self-myofascial release (SMR) is a technique used to treat myofascial restrictions and restore soft-tissue extensibility.

Purpose:

To determine whether the pressure and contact area on the lateral thigh differ between a Multilevel rigid roller (MRR) and a Bio-Foam roller (BFR) for participants performing SMR.

Participants:

Ten healthy young men and women.

Methods:

Participants performed an SMR technique on the lateral thigh using both myofascial rollers. Thin-film pressure sensels recorded pressure and contact area during each SMR trial.

Results:

Mean sensel pressure exerted on the soft tissue of the lateral thigh by the MRR (51.8 ± 10.7 kPa) was significantly (P < .001) greater than that of the conventional BFR (33.4 ± 6.4 kPa). Mean contact area of the MRR (47.0 ± 16.1 cm2) was significantly (P < .005) less than that of the BFR (68.4 ± 25.3 cm2).

Conclusion:

The significantly higher pressure and isolated contact area with the MRR suggest a potential benefit in SMR.

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Juliane P. Hernandez, Kristin Roever and Tonya Seed

This investigation attempted to determine whether heart-rate and blood pressure responses to maximal acute lower body negative pressure (LBNP) are exacerbated compared with maximal graded LBNP in active older (n = 9, 70 ± 7 yr) and endurance-trained younger (n = 10, 23 ± 3 yr) individuals. Heart rate increased earlier during graded LBNP in the younger group (−40 mm Hg vs. tolerance) and was significantly higher than that of the older adults at the point of tolerance. Mean arterial pressure (MAP) decreased more in the older than the younger individuals during graded LBNP. LBNP-tolerance index was significantly greater in the younger group (309 ± 52 vs. 255.6 ± 48 mm Hg/min). Acute doses of LBNP elicited slower heart-rate responses in the older group. Despite these age-related differences, MAP responses were not different between groups with acute LBNP, so age per se does not appear to predispose individuals to orthostatic intolerance.

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Tim Berrett and Trevor Slack

Sport sponsorship is frequently described as a strategic activity, and thus, it is influenced by both competitive and institutional forces. Using a sample of 28 Canadian companies, this study explores the influence of competitive and institutional pressures on those individuals who make decisions about their company's sport sponsorship initiatives. The results show that the sponsorship activities of rival companies were influential in a company's sponsorship choices. This was particularly the case in highly concentrated industries. We also show some evidence of a first-mover advantage in sponsorship decision-making but found preemptive strategies to yield little competitive advantage. In addition to these pressures from the competitive environment, institutional pressures from companies in the same geographic area, in the form of mimetic activity, in the form of involvement in social networks, and through the occupational training of the decision makers—all played a role in the choices made about what activities to sponsor.

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Ewald M. Hennig and Thomas L. Milani

Discrete pressure sensors were used to examine the influence of shoe construction on the local forces under the foot. Measurements were performed at eight locations under the feet of 22 subjects wearing 19 different models of running shoes. Mechanical properties of shoe soles were assessed with an impacter device. Pressure distribution, ground reaction force, and acceleration data were collected simultaneously during running at 3.3 m/s. Early lateral loading of the rearfoot was followed by increasing medial forefoot loads. In the later phase of pushoff the load was almost entirely carried by the first metatarsal head and the hallux. Substantial differences in plantar foot pressures and relative loads among shoe models indicated that footwear construction has a substantial influence on the loading behavior of the foot during ground contact. Finally, the chosen sensor locations under the foot were found to be adequate to estimate the vertical ground reaction force.

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Riann M. Palmieri, Christopher D. Ingersoll, Marcus B. Stone and B. Andrew Krause

Objective:

To define the numerous center-of-pressure derivatives used in the assessment of postural control and discuss what value each might provide in the assessment of balance.

Data Sources:

MEDLINE and SPORTDiscus were searched with the terms balance, postural control, postural sway, and center of pressure. The remaining citations were collected from references of similar papers. A total of 67 references were studied.

Conclusions:

Understanding what is represented by each parameter used to assess postural control is crucial. At the present time the literature has failed to demonstrate how the variables reflect changes made by the postural-control system. Until it can be shown that the center of pressure and its derivatives actually reveal changes in the postural-control system, the value of using these measures to assess deficits in postural control is minimized.

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Larry J. Weber, Thomas M. Sherman and Carmen Tegano

In this research, faculty reported attempts to influence their academic decisions regarding student athletes. In most instances the pressure was not formal or frequently applied, and it appeared to have little influence on faculty judgments or their willingness to assist athletes. Except for isolated situations of a flagrant nature that are sensationalized by the media, the problem seems not to be a major one.

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Ewald M. Hennig and David J. Sanderson

Foot function and possible mechanisms for the etiology of frequently observed forefoot complaints in bicycling were studied. Pedal forces and in-shoe pressure distributions were measured with 29 subjects, who rode on a stationary bicycle with a cadence of 80 rpm at 100, 200, 300, and 400 W. The influence of footwear on foot loading was also investigated by comparing running and bicycling shoes at 400 W. The first metatarsal head and the hallux were identified as the major force-contributing structures of the foot. High pressures under the toes, midfoot, and under the heel showed that all foot areas contribute substantially to the generation of pedal forces. For increasing power outputs, higher peak pressures and relative loads under the medial forefoot were identified. These may cause pressure-related forefoot complaints and accompany increased foot pronation. As compared to the running shoe, the stiff bicycling shoe demonstrated a more evenly distributed load across the whole foot and showed a significantly increased index of effectiveness.

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Jessica Hill, Glyn Howatson, Ken van Someren, David Gaze, Hayley Legg, Jack Lineham and Charles Pedlar

Compression garments are frequently used to facilitate recovery from strenuous exercise.

Purpose:

To identify the effects of 2 different grades of compression garment on recovery indices after strenuous exercise.

Methods:

Forty-five recreationally active participants (n = 26 male and n = 19 female) completed an eccentric-exercise protocol consisting of 100 drop jumps, after which they were matched for body mass and randomly but equally assigned to a high-compression pressure (HI) group, a low-compression pressure (LOW) group, or a sham ultrasound group (SHAM). Participants in the HI and LOW groups wore the garments for 72 h postexercise; participants in the SHAM group received a single treatment of 10-min sham ultrasound. Measures of perceived muscle soreness, maximal voluntary contraction (MVC), countermovement-jump height (CMJ), creatine kinase (CK), C-reactive protein (CRP), and myoglobin (Mb) were assessed before the exercise protocol and again at 1, 24, 48, and 72 h postexercise. Data were analyzed using a repeated-measures ANOVA.

Results:

Recovery of MVC and CMJ was significantly improved with the HI compression garment (P < .05). A significant time-by-treatment interaction was also observed for jump height at 24 h postexercise (P < .05). No significant differences were observed for parameters of soreness and plasma CK, CRP, and Mb.

Conclusions:

The pressures exerted by a compression garment affect recovery after exercise-induced muscle damage, with higher pressure improving recovery of muscle function.

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Lacey Nordsiden, Bonnie L. Van Lunen, Martha L. Walker, Nelson Cortes, Maria Pasquale and James A. Onate

Context:

Many styles of foot pads are commonly applied to reduce immediate pain and pressure under the foot.

Objective:

To examine the effect of 3 different foot pads on peak plantar pressure (PPP) and mean plantar pressure (MPP) under the first metatarsophalangeal joint (MTPJ) during slow running.

Design:

A 4 (pad) × 4 (mask) repeated-measures design.

Setting:

University athletic training clinic and fitness facility.

Participants:

20 physically active participants, 12 men (19.7 ± 1.3 y, 181.5 ± 6.3 cm, 83.6 ± 12.3 kg) and 8 women (20.8 ± 1.5 y, 172.7 ± 11.2 cm, 69.9 ± 14.2 kg) with navicular drop greater than or equal to 10 mm, no history of surgery to the lower extremity, and no history of pain or injury to the first MTPJ in the past 6 months.

Interventions:

PPP and MPP were evaluated under 4 areas of the foot: the rear foot, lateral forefoot, medial forefoot, and first MTPJ. Four pad conditions (no pad, metatarsal dome, U-shaped pad, and donut-shaped pad) were evaluated during slow running. All measurements were taken on a standardized treadmill using the Pedar in-shoe pressure-measurement system.

Main Outcome Measures:

PPP and MPP in 4 designated foot masks during slow running.

Results:

The metatarsal dome produced significant decreases in MPP (163.07 ± 49.46) and PPP (228.73 ± 63.41) when compared with no pad (P < .001). The U-shaped pad significantly decreased MPP (168.68 ± 50.26) when compared with no pad (P < .001). The donut-shaped pad increased PPP compared with no pad (P < .001).

Conclusions:

The metatarsal dome was most effective in reducing both peak and mean plantar pressure. Other factors such as pad comfort, type of activity, and material availability must also be considered. Further research should be conducted on the applicability to other foot types and symptomatic subjects.