Effect of Dolphin Kick Timing on Breaststroke Pullout Performance

Breaststroke pullouts are now permitted to include a dolphin kick. Two variations of the pullout are distinguished by the timing of the dolphin kick within the movement. One variation uses an early-initiation of the dolphin kick (performed before the initiation of the arm pull) while a second variation uses a late-initiation of the dolphin kick (performed at the completion of the arm pull). PURPOSE: To compare the performance of two variations of breaststroke pullouts that incorporate a dolphin kick. METHODS: Fourteen collegiate swimmers (18.9 ± 1.17 years, 73.7 ± 8.54 kg, 174.5 ± 9.88 cm) who compete in breaststroke or IM races, volunteered to participate in this study and provided informed consent prior to beginning participation. Participants completed four 45.7 m (50 yd) trials of breaststroke swimming in a 22.8 m pool. In each trial, swimming speed was increased to maximum as they approached the midpoint of the swim. After completing a turn, swimmers performed one of the two designated pullout techniques and maintained maximal effort through two complete stroke cycles. Two trials of each pullout technique were completed and filmed at 60 Hz using a calibrated underwater camera. Using 12 digitized body landmarks, a 13-segment model of the body was defined and used to compute whole body center of mass location. Two-way repeated measures ANOVA’s were used to compare the time needed to travel specified distances from either the wall or the initiation of movement. Pairwise comparisons were used to follow-up any significant main effects. RESULTS: Time to 6 m from the wall was 0.12 s (pCONCLUSION:These data suggest that the early dolphin kick variation is superior by covering distance in less time after initiation of movement and increasing the distance covered underwater

Binge Drinking Effects on EEG in Young Adult Humans

Young adult (N = 96) university students who varied in their binge drinking history were assessed by electroencephalography (EEG) recording during passive viewing. Groups consisted of male and female non-binge drinkers (>1 to 5/4 drinks/ounces in under two hours), low-binge drinkers (5/4–7/6 drinks/ounces in under two hours), and high-binge drinkers (≥ 10 drinks/ounces in under two hours), who had been drinking alcohol at their respective levels for an average of 3 years. The non- and low-binge drinkers exhibited less spectral power than the high-binge drinkers in the delta (0–4 Hz) and fast-beta (20–35 Hz) bands. Binge drinking appears to be associated with a specific pattern of brain electrical activity in young adults that may reflect the future development of alcoholism

Kinematic Comparison of Underwater Dolphin and Flutter Kicking Performed in a Prone and Supine Body Position

Despite an increasing emphasis on underwater dolphin kicking in competitive swimming, little objective research exists to explain its preference over flutter kicking. PURPOSE: To examine kinematic characteristics of flutter and dolphin kicking performed in prone and supine body positions. METHODS: Ten collegiate swimmers (1.77±0.07 m, 72.4±7.6 kg, 19.8±1.0 yrs) experienced with dolphin and flutter kicking completed eight 10 m maximal effort underwater kicking trials. Body position and kicking style were randomly varied between trials such that half of all trials were performed using each kicking style and each body position. A calibrated underwater camera was used to record each trial at 60 Hz. Six body landmarks were digitized for three complete kicking cycles to determine linear and angular kinematic measurements. Whole body speed was defined as horizontal hip velocity. Kicking amplitude and frequency were determined using vertical toe movements. The Strouhal number, a dimensionless index related to the efficiency of underwater undulatory movement, was computed using the kicking amplitude, frequency and velocity. Kinematic measures were compared between kicking style and body positions using a 2x2 (kick x position) repeated measures ANOVA. RESULTS: Dolphin kicking velocity (1.22±0.18 m/s) was faster (p\u3c0.001, h2=0.88) than flutter kicking velocity (0.99±0.12 m/s). Dolphin kicking amplitude (0.58±0.10 m) was larger (p\u3c0.001, h2=0.93) than flutter kicking amplitude (0.48±0.08 m). Dolphin kicking frequency (1.85±0.34 Hz) was lower (p=0.002, h2=0.68) than flutter kicking frequency (2.33±0.33 Hz). Dolphin kicking (0.88±0.12) was more efficient as indicated by a lower Strouhal number (p=0.001, h2=0.71) than flutter kicking (1.11±0.21). Body position had no effect on any measure of kicking performance (p\u3e0.05). CONCLUSION: For these participants, dolphin kicking was a faster, more efficient form of underwater kicking. However, body position had little effect on the ability of these participants to perform the respective kicking style

Corneal thickness and anterior chamber depth of the normal adult horse as measured by ultrasound biomicroscopy

ObjectiveTo determine corneal thickness (CT) and axial anterior chamber depth (ACD) using ultrasound biomicroscopy (UBM) in normal adult horses. To compare corneal thickness measurements between UBM and ultrasonic pachymetry.Animals studiedSixty eyes of 30 healthy adult horses aged 8-24 years.ProceduresUltrasonic pachymetry (velocity of 1640 m/s) was utilized to obtain measurements of the central, superior, temporal, inferior, and nasal cornea. Triplicate images of the same corneal locations were acquired using UBM (50 MHz). Images of the axial anterior chamber were used to measure ACD. Intraocular pressure (IOP) was estimated using rebound tonometry, and axial globe length was measured using ultrasonographic biometry.ResultsCT (mean ± SD µm) measured by UBM was 854 ± 61 (central), 994 ± 58 (superior), 930 ± 57 (temporal), 979 ± 55 (inferior), and 898 ± 48 (nasal). CT measured by UBM was greater than that measured by ultrasonic pachymetry at all locations and was statistically significant at all locations except inferior (p = 0.0006-0.048). No sex nor age effect was detected for CT at any location. The repeatability of ultrasonic pachymetry was superior to that of UBM. Mean ± SD ACD was 5.74 ± 0.41 mm. A weak positive correlation was identified between central CT and IOP and between central CT and axial globe length.ConclusionsNormal data for CT and ACD of the adult horse obtained using UBM are provided. CT determined by UBM was greater relative to pachymetry at all corneal locations