Dielectrophoretic discrimination of bovine red blood cell starvation age by buffer selection and membrane cross-linking

We report an interesting buffer electric relaxation time tuning technique, coupled with a glutaraldehyde cross-linking cell fixation reaction, which allows for sensitive dielectrophoretic analysis and discrimination of bovine red blood cell (bRBC) starvation age. The buffer composition is selected such that two easily accessible dielectrophoretic crossover frequencies (cof) exist. Low concentration glutaraldehyde fixation was observed to produce a threefold decrease in the higher cof with a comparable increase in the lower cof also witnessed. More importantly, increased glutaraldehyde fixation concentration significantly increased the higher cof by a factor found to be sensitive to the bRBC starvation age.     

Backstroke start performance: the impact of using the Omega OBL2 backstroke ledge

FINA recently approved the backstroke ledge (Omega OBL2) to improve backstroke start performance in competition, but its performance has not been thoroughly evaluated. The purpose of this study was to compare the mechanics of starts performed with and without the OBL2. Ten high-level backstroke swimmers performed three starts with, and three starts without, the OBL2. A wall-mounted force plate measured the lower limb horizontal impulse, vertical impulse, take-off velocity and take-off angle. Entry distance, time to 10 m and start of hip and knee extension were recorded using video cameras. Starts performed with the OBL2 had a 0.13 s lower time to 10 m, 2.5% less variability in time to 10 m and 0.14 m greater head entry distance. The OBL2 provides a performance advantage by allowing an increased head entry distance rather than larger horizontal impulse on the wall. This may be due to the swimmers assuming different body positions during the start manoeuvre. Additional studies are needed to evaluate factors that contribute to improved performance when using the OBL2. Swimmers should train with the OBL2 and use it in competition to ensure optimal start performance.     

Development,implementation and assessment of a concussion education programme for high school student-athletes

Although experts have noted that adolescent athletes should be educated about concussions to improve their safety, there is no agreement on the most effective strategy to disseminate concussion education. The purpose of this study was to develop, implement and assess a concussion education programme. More precisely, four interactive oral presentations were delivered to high school student-athletes (N = 35, M_age = 15.94, SD = 0.34) in a large urban centre. Participants completed a questionnaire at three time-points during the season to measure changes in their knowledge (CK) and attitudes (CA) of concussions, and focus group interviews were conducted following the concussion education programme. Questionnaire data revealed participants’ post-intervention CK scores were higher than their pre-intervention scores. During the focus groups, the student-athletes said they acquired CK about the role of protective equipment and symptom variability, and in terms of CA, they intended to avoid dangerous in-game collisions in the future. Our study was the first to create and deliver a concussion education intervention across multiple time-points, and to use mixed-methods in its assessment. These findings may be of interest to researchers, practitioners and stakeholders in sport who are invested in making the sport environment safer through concussion education and awareness.     

Corporate Support for Artistic and Cultural Activities: What Determines the Distribution of Corporate Giving?

This paper examines the allocation of corporate donations among variouscategories of recipients and the reasons underlying that allocation. Ananalytical model is utilized to determine the importance of profitability,firm size, advertising expenditures and type of business in determining thelevel of support for each activity. The results demonstrate that corporategiving to artistic/cultural activities is correlated with advertisingexpenditures, while donations to educational, civic and health causes are not.Thus, support for culture and the arts is a means of directly promoting thefirm, while giving to other causes fulfills the firm's goals throughalternative means.     

Initial foot contact and related kinematics affect impact loading rate in running

This study assessed kinematic differences between different foot strike patterns and their relationship with peak vertical instantaneous loading rate (VILR) of the ground reaction force (GRF). Fifty-two runners ran at 3.2 m · s^?1 while we recorded GRF and lower limb kinematics and determined foot strike pattern: Typical or Atypical rearfoot strike (RFS), midfoot strike (MFS) of forefoot strike (FFS). Typical RFS had longer contact times and a lower leg stiffness than Atypical RFS and MFS. Typical RFS showed a dorsiflexed ankle (7.2 ± 3.5°) and positive foot angle (20.4 ± 4.8°) at initial contact while MFS showed a plantar flexed ankle (?10.4 ± 6.3°) and more horizontal foot (1.6 ± 3.1°). Atypical RFS showed a plantar flexed ankle (?3.1 ± 4.4°) and a small foot angle (7.0 ± 5.1°) at initial contact and had the highest VILR. For the RFS (Typical and Atypical RFS), foot angle at initial contact showed the highest correlation with VILR (r = ?0.68). The observed higher VILR in Atypical RFS could be related to both ankle and foot kinematics and global running style that indicate a limited use of known kinematic impact absorbing “strategies” such as initial ankle dorsiflexion in MFS or initial ankle plantar flexion in Typical RFS.     

Can fast-twitch muscle fibres be selectively recruited during lengthening contractions? Review and applications to sport movements

Literature examining the recruitment order of motor units during lengthening (eccentric) contractions was reviewed to determine if fast-twitch motor units can be active while lower threshold slow-twitch motor units are not active. Studies utilizing surface electromyogram (EMG) amplitude, single motor unit activity, spike amplitude-frequency analyses, EMG power spectrum, mechanomyographic, and phosphocreatine-to-creatine ratio (PCr/Cr) techniques were reviewed. Only single motor unit and PCr/Cr data were found to be suitable to address the goals of this review. Nine of ten single motor unit studies, examining joint movement velocities up to 225 degrees/s and forces up to 53% of a maximum voluntary contraction, found that the size principle of motor unit recruitment applied during lengthening contractions. Deviation from the size principle was demonstrated by one study examining movements within a small range of low velocities and modest forces, although other studies examining similar low forces and lengthening velocities reported size-ordered recruitment. The PCr/Cr data demonstrated the activation of all fibre types in lengthening maximal contractions. Most evidence indicates that for lengthening contractions of a wide range of efforts and speeds, fast-twitch muscle fibres cannot be selectively recruited without activity of the slow-twitch fibres of the same muscle.