Douglas M. Kleiner
Erik E. Swartz
Column-editor : Michael G. Dolan
John Strickland and Grant Bevill
review of biomechanics literature demonstrates that only the protective equipment available to batters and catchers have been evaluated, 5 – 9 whereas, to the authors’ knowledge, no tests have been performed for the facemasks available for fielders. Data from studies examining catcher’s masks are
Matthieu M. de Wit, Rich S.W. Masters and John van der Kamp
Based upon evidence that vision for action has quicker access to visual information than vision for perception, we hypothesized that the two systems may have differentiated visual thresholds. There is also evidence that, unlike vision for perception, vision for action is insensitive to cognitive dual-task interference. Using visual masking, we determined the visual thresholds of 15 participants in a perception task, an action task and an action plus concurrent cognitive secondary task. There was no difference in threshold between the perception task and the action task, but the action plus concurrent secondary task was accompanied by a greater visual threshold than both the perception task and the action task alone, indicating dual-task interference. The action task was thus most likely informed by vision for perception. The implications of these results are reviewed in the context of recent discussions of the two visual systems model.
Lacey Nordsiden, Bonnie L. Van Lunen, Martha L. Walker, Nelson Cortes, Maria Pasquale and James A. Onate
Many styles of foot pads are commonly applied to reduce immediate pain and pressure under the foot.
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.
A 4 (pad) × 4 (mask) repeated-measures design.
University athletic training clinic and fitness facility.
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.
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.
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).
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.
Per-Ludvik Kjendlie and Robert Keig Stallman
The aims of this study were to compare drag in swimming children and adults, quantify technique using the technique drag index (TDI), and use the Froude number (Fr) to study whether children or adults reach hull speed at maximal velocity (v max). Active and passive drag was measured by the perturbation method and a velocity decay method, respectively, including 9 children aged 11.7 ± 0.8 and 13 adults aged 21.4 ± 3.7. The children had significantly lower active (k AD) and passive drag factor (k PD) compared with the adults. TDI (k AD/k PD) could not detect any differences in swimming technique between the two groups, owing to the adults swimming maximally at a higher Fr, increasing the wave drag component, and masking the effect of better technique. The children were found not to reach hull speed at v max, and their Fr were 0.37 ± 0.01 vs. the adults 0.42 ± 0.01, indicating adults’ larger wave-making component of resistance at v max compared with children. Fr is proposed as an evaluation tool for competitive swimmers.
Jane LaRiviere and Louis R. Osternig
Ice-induced anesthesia is often used to permit pain-free activity. However, icing before a skilled performance may distort the ability to acknowledge sensory stimuli and may thereby mask certain protective mechanisms. Inadequate peripheral feedback regarding position of a limb in space could expose the joint to injury. This study was designed to determine the effect of ice immersion on ankle joint position sense. Three different pretest conditions of no ice immersion, 5 min of ice immersion, and 20 min of ice immersion were administered to 31 subjects prior to joint angle replication testing with an electrogoniometer. Subjects completed eight repositioning trials (four at each of two test angles) following each condition. An analysis of variance (ANOVA) revealed no statistically significant difference between conditions, trials, or angles. The results suggest that joint position receptors in the ankle are resilient to this type of ice treatment, or that the affected receptors (i.e., skin and muscle) were adequately compensated for by other sensors such as joint receptors.
Matheus M. Gomes and José A. Barela
The purpose of this study was to examine the effects of visual and somatosensory information on body sway in individuals with Down syndrome (DS). Nine adults with DS (19–29 years old) and nine control subjects (CS) (19–29 years old) stood in the upright stance in four experimental conditions: no vision and no touch; vision and no touch; no vision and touch; and vision and touch. In the vision condition, participants looked at a target placed in front of them; in the no vision condition, participants wore a black cotton mask. In the touch condition, participants touched a stationary surface with their right index finger; in the no touch condition, participants kept their arms hanging alongside their bodies. A force plate was used to estimate center of pressure excursion for both anterior-posterior and medial-lateral directions. MANOVA revealed that both the individuals with DS and the control subjects used vision and touch to reduce overall body sway, although individuals with DS still oscillated more than did the CS. These results indicate that adults with DS are able to use sensory information to reduce body sway, and they demonstrate that there is no difference in sensory integration between the individuals with DS and the CS.
Xiao Bao, Jie-Wen Tan, Ying Long, Howe Liu and Hui-Yu Liu
informed consent. Intermittent Hypoxia Intervention Normobaric hypoxia condition was applied by exposing subjects to 5 cycles of 10% O 2 for 5 minutes followed by room air for 5 minutes. Subjects will inspire hypoxic air through an air-cushioned disposable face mask or room air directed by a 3-way valve