Objective: To investigate the potential etiology of a loss of neck control injury in female standard ballroom dancers. The median frequency (MF) as measured by electromyography (EMG) of the left upper trapezius (UT), left splenius capitius (SPL), and right sternocleidomastoid (SCM) of injured dancers was compared to non-injured dancers. This comparison was performed to identify whether dancers with a history of loss of neck control have a greater amount of fatigue than those with no history of this particular injury. Design and Setting: A 2 x 6 factorial design was used for this investigation. The independent variables were group (injured vs. non-injured) and time (before and after the three rounds of dancing). The dependent variables were MF as measured by EMG, range of motion, and neck length. All testing was performed at the university biomechanics laboratory and ballroom dance studio. Subjects: Twenty female subjects (10 injured group {mean height 167.40 ± 4.12 cm and weight 59.30 ± 5.41 kg}, 10 non-injured group {mean height 166.76 ± 4.62 cm and weight 58.93 ± 5.30 kg}), with at least one year experience in competitive ballroom dancing, in the standard division participated in this study. All subjects competed at a Dancesport competition either in the novice, pre-championship, and/or amateur standard classifications. Inclusion criteria for the injured group included female ballroom dancers who had a loss of neck control episode. Measurements: Surface EMG activity was recorded from the left UT, left SPL, and right SCM muscles before and after dancing the five standard dances. Results: The decrease in EMG MF was not significant between groups. There was no difference in neck lengths from the external occipital protuberance to inferior angle of the scapula between groups. There were also no significant differences in range of motion of left and right lateral flexion and extension in either group from pre to post dancing. Conclusions: Based on the results of this study, subjects with a history of neuromuscular neck injury did not appear to have acute fatigue of the three muscles studied here following the routine used in this study.

Purpose: Reducing body temperature before exercise is called precooling. Past research suggests that reducing body core temperature (Tc) slightly can result in improved running performance. This study evaluated the effects that warming up, while wearing a cooling vest prior to an interval workout, had on Tc, and interval time in long-distance runners. Methods: Nineteen healthy male collegiate cross-country runners were recruited for this study. Each subject warmed up and exercised under two different conditions: (a) an experimental condition in which subjects wore a Nike PreCool® ice vest during warm-up and (b) a control condition. Subjects performed a warm-up followed by running eight 1000 m intervals separated by 90 s of rest. Heart rate (HR) and Tc were measured prior to warm-up, just prior to start of the first interval, and after each interval. Results: Tc measured directly prior to the first interval was significantly lower in the vest condition than the non-vest condition (difference = 0.37°C; P < 0.05). This difference persisted through the end of the sixth interval. Tc rose at a faster rate in the non-vest condition, though this difference was not significant (P = 0.07). Differences in HR and interval times were found to be nonsignificant between conditions for all intervals. Conclusion: Wearing an ice vest prior to and during warm-up effectively lowers Tc during long-distance interval training.

To measure the differences in ground reaction forces between running shoes, racing flats, and distance spikes, twenty intercollegiate distance runners ran across a force plate at 6.7m/s (for males) and 5.74m/s (for females) in each of the three types of shoes. In order to control for differences in foot strike, only subjects who had a heel strike were included in the data analysis (N=16). Repeated-measures ANOVA and Tukey's post-hoc test (p<0.05) revealed loading rate and impact peak to be significantly increased in the flats and spikes compared to running shoes. Stiffness in spikes was significantly higher than in running shoes. Stance time in spikes and flats was decreased. These results can be used to better inform competitive runners, coaches, and trainers of the risks and performance benefits when determining the frequency and duration of the use of competitive footwear in training.

The aim of this study was two-fold: 1) what the hammer throwing technique differences between sexes are and 2) what technique parameters help determine throw distance. The performances of the top 16 male and female throwers at the 2003 World Athletic Final and the top 13 male and female throwers from the 2003 USA Track and Field Nationals were examined. Video was captured using three Canon 60 Hz cameras. The best throws of each athlete were digitized and analyzed using the Peak Motus 8.2 motion analysis system. T-tests revealed that athlete mass, athlete height, velocity at release, timing components, and centripetal force were different between sexes. The separation between the shoulders and hips and between the shoulders and the hammer at particular positions during the throw, radius changes at certain phases of the throw, and generation of large centripetal forces helped determine throwing distance. Performance would be aided by working on the development of centripetal force, the magnitude of radius changes, the separation that occurs between the shoulders and hips, and the separation between the shoulders and hammer.

The purpose of this study was to determine children's and parents' activity levels, examine the relationship between mothers' and children's mean step counts, and fathers' and children's mean step counts, and determine if there are differences in physical activity levels among children with mothers who work full time, work part time, or are not employed. Fifty-eight families participated in this 12-day study. Each family member wore a Walk4Life LS 2525 or a Walk4Life LS 2505 pedometer to measure daily step counts. Additionally, all participants completed the pedometer step count logs each night, and parents completed a short demographic form. In looking at all children, males averaged more steps per day than females in all three age categories (5-10 years, male = 12,555 to female = 10,729; 11-13 years, male = 13,749 to female = 10,373; 14-18 years, 11,849 to female = 9,795). Additionally, fathers were more active than mothers (fathers' mean step counts averaged 9,490 and mothers' mean step counts averaged 8,715). Pearson correlations revealed that parents' physical activity levels were significantly correlated with children's activity levels (mothers to their children = .247, p = .003 & fathers to their children = .316, p = .000). Further analysis using Pearson correlations showed significant correlations between mothers and their female children (.291, p = .022) and between fathers and their male children (.342, p = .002). ANOVA (mothers' employment status x mean daily step count) was used to determine differences among the three groups (full time, part time, and not employed). No significant differences in children's mean step counts were found among any of the groups (F (2, 141) = 2.545, p = .082).

Research suggests declines in physical activity may occur after age 12. The purpose of this study was to determine the relationships between adolescent physical activity, BMI, and nutrition. Adolescents, ages 12-17 (N = 223), wore pedometers for 11 consecutive days and completed a nutrition survey, the Youth Adolescent Questionnaire. Activity levels did not differ among the ages of 12-17 year old adolescents, and boys were more active than girls. There was a low, but significant relationship between BMI and physical activity levels for both boys and girls. Energy intake was not related to BMI or physical activity levels in boys or girls.

The supine posture has been shown to limit exercise-induced plasma volume expansion. Differences in hydrostatic pressure gradients between the standing and seated position indicate that treadmill exercise might promote a greater plasma volume expansion than cycle ergometer exercise. To test this hypothesis ten subjects performed intermittent high intensity exercise (4 min at 85% VO2max, 5 min at 40% VO2max repeated 8 times) on separate days on the treadmill and cycle ergometer. Changes in plasma volume expansion were calculated from changes in hematocrit and hemoglobin. Stroke volume (SV), trans-thoracic impedance (Z0), HR, and arterial blood pressure (non-invasive arm cuff, SBP & DBP) were assessed in the seated position before and postexercise. Zo increased (p<0.05) as subjects started exercise (both treadmill and cycling), indicating a reduction in central blood volume (CBV), which returned to baseline towards the end of exercise. Postexercise Zo returned to control levels within 30 min regardless of the previous exercise mode. A significant post-exercise hypotension was observed following cycle ergometer exercise (p<0.05) but not following treadmill exercise. Plasma volume increased 6.1±1.0% and 7.0 ± 1.1% (p<0.05) following treadmill and cycle ergometer exercise, respectively. The increase in PV was similar for both exercise modes. Initial differences in central blood volume disappeared over the course of the exercise protocol and during recovery, possibly indicating that there is a postural threshold and moving beyond it yields no further effect. The lack of differences between modes of exercise on plasma albumin content and Z0 indicate that the upright postures were not different from each other. As such, PV expansion following high intensity intermittent exercise appears to be independent of upright exercise mode.

Research on physical activity and exercise in the elderly is limited. This study used the Participation Motivation Questionnaire for Older Adults (PMQOA) to assess reasons for engaging in regular physical activity of participants at the 2007 Huntsman World Senior Games. The 259 subjects ranged from ages 50 to 85 years and were divided into tertiles based on frequency of exercise, determined by self reported weekly exercise time and days for further comparison. The most commonly reported reasons for exercise were to stay healthy, keep physically fit, and stay in shape. A previously conducted factor analysis on the PMAOQ revealed six underlying factors given for engaging in regular exercise: social, fitness, recognition, challenge/benefits, medical and involvement. Analysis of variance indicated significant differences in reasons for exercise between exercise tertiles and three factors; social, fitness, and challenge/benefits. There were also significant differences in reasons given for exercise between gender for the medical and social factors. Bivariate correlations indicated associations between both fitness perceptions and BMI with some PMQOA factors. Additionally, significant correlations were found between the six PMQOA factors, the strongest being between challenge/benefits and recognition, involvement, and social.

As researchers explore the benefits of using pedometers to assess physical activity they are discovering that intensity of physical activity may be estimated from steps per minute (SPM). The purpose of this study was to determine the SPM and kilocalories (kcals) expended associated with moderate physical activity in middle school students (12 - 14 years old). Methods: Ninety-three (49 boys, 44 girls) middle school youth between the ages of 12 and 14, walked on a treadmill at four different speeds (4.0, 4.8, 5.64, and 6.4 km/h) for three minutes at each speed. Each participant wore a pedometer in order to obtain their steps per minute and a heart rate monitor to record their heart rate level during each test speed. Results: Moderate physical activity was reached, on average, by girls and boys at 122 SPM (5.64 km/h) and 115 SPM (4.8 km/h), respectively. At this SPM rate boys and girls expended 232.55 kcals and 176.66 kcals per hour. This study augments previous studies that explored ways to assess activity levels using SPM calculations.

The purpose of this study was to investigate the effect of same-day strength training on bat swing velocity of male collegiate baseball players. Sixteen male baseball players engaged in a preseason strength training program designed by the team's strength and conditioning coach. All subjects were tested for bat swing peak velocity immediately prior to ball impact for a non lifting day (NLD) by recording 10 swings with 30 seconds of rest in between swings. The next day, a lifting day (LD), all subjects tested on the NLD were tested four to six hours after the morning lifting session with the same amount of swings and rest. Six Vicon MX13+ infrared cameras (Vicon-Colorado, Centennial, Colorado), running at 400 Hz, were placed around the swinging area using Nexus 1.2 imaging software to download and determine bat swing peak velocity immediately prior to ball impact. The average of the top six bat swing peak velocity test results, for each subject, was compared to measures taken on the NLD and LD. A matched t-test revealed a significant difference in bat swing peak velocity between a NLD and a LD. A mean bat swing difference between NLD (69.18) and LD (70.86) of 1.68 was statistically different at better than the .05 level [p =.021]. This study suggests that male collegiate baseball players should be able to engage in a designed strength training program with a positive effect, and without any negative effect, on bat swing peak velocity when a strength training session is scheduled on the same day as a baseball competition.