The acute effects of multiple resisted sled-pull loads on subsequent sprint-running performances

Sled-pulling is a commonly implemented form of training for various sports. However, few studies have used sled-pulling as a means of acutely enhancing sprintrunning performances. The purpose of this study was to investigate how various sledpulling resistance loads (95% and 110% of body mass) effect subsequent, unloaded, sprint-running performances, possibly with aid from the effect known as Post-Activation Potentiation (PAP). PAP is a physiological phenomenon which increases the rate of force development of skeletal muscle which may result in the enhancement of power (speed-strength) dominant activities such as sprint-running and jumping. Participants were a mix of males (n = 11; age 23.3 ± 1.8 years) and females (n = 4; age = 23.0 ± 3.2 years) who were either recreationally trained, division I collegiate athletes, or strength and conditioning coaches, all of whom regularly employed sprintrunning as part of their normal training program. The participants of this study underwent 2 experimental sled-pulling conditions (95% and 110% of body mass, respectively) as well as a third, unresisted, testing day which acted as the control. Each session was performed on a seperate day. On each experimental day, the participants ran timed, unresisted, 30-meter sprint-runs both before (pre-testing) and after (post-testing) the implementation of the sled-pulling condition. The uinresisted (control) condition consisted of two unresisted 30-meter sprint runs. The first of these sprints acted as the pre-test and the second sprint acted as the post-test. All unresisted sprints were electronically timed at the 10-, 20-, and 30-meter split marks as well as through the duration of the sprint. A repeated-measures, pre-experimental design was used and the order in which the testing sessions were performed was randomized. Descriptive statistics (mean ± SD) were calculated for all performance variables. A 2X3 factorial MANOVA (time x pulling condition) was used to determine the effect of sled-pulling on sprint performance. Paired samples t-tests with Bonferronni adjustment were used as post hoc analysis when appropriate. The level of significance was set at p The results of the 2x3 repeated measures MANOVA indicated that there were no significant interactions (F(6,9)=0.31, p=0.92) therefore main effects were analyzed. There was no significant load effect (F(6,9)=1.15, p=0.41) indicating that the loading strategy had no effect on sprint performance. There was a significant time effect (F(3,12)=5.7, p=0.012). The post hoc analysis indicated that the post-testing sprint trial (regardless of loading strategy) was significantly slower than the pre-testing trial for first (F(1)=5.5, p=0.034) and second splits (F(1)=9.4, p=0.008). There was no difference between the pre- and post-testing trials for third split (F(1)=0.71, p=0.41). In conclusion, the heavy sled-pulling loads implemented in this study did not acutely enhance subsequent sprint-running performances. Furthermore, future studies implementing sled-pulling as a means of enhancing subsequent unresisted sprint-running performances can be directed at a wide variety of variables due to the limited amount of research that has been conducted in this area of sprint training

Poverty and Elimination of Urban Health Disparities Challenge and Opportunity

The aim of this article is to examine the intersection of race and poverty, two critical factors fueling persistent racial and ethnic health disparities among urban populations. From the morass of social determinants that shape the health of racial and ethnic communities in our urban centers, we will offer promising practices and potential solutions to eliminating racial and ethnic health disparities

The National Negro Health Week, 1915 to 1951: A Descriptive Account

In 1914, Booker T. Washington, founder of Tuskegee Institute, viewed the poor health status of black Americans as an obstacle to economic progress and issued a call for "the Negro people... to join in a movement which shall be known as Health Improvement Week" (Patterson, 1939). Health Improvement Week evolved into the National Negro Health Week, observed annually for 35 years. This article provides an overview of the structure and activities of the National Negro Health Week and suggests implications for public health in the black community today

Acute Vascular Effects of Aquatic and Land Treadmill Exercise

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The Tuskegee Syphilis Study, 1932 to 1972: Implications for HIV Education and AIDS Risk Education Programs in the Black Community

The Tuskegee study of untreated syphilis in the Negro male is the longest nontherapeutic experiment on human beings in medical history. The strategies used to recruit and retain participants were quite similar to those being advocated for HIV/AIDS preention programs today. Almost 60 years after the study began, there remains a trail of distrust and suspicion that hampers HIV education efforts in Black communities. The AIDS epidemic has exposed the Tuskegee study as a histotical marker for legitimate discontent of Blacks with the public health system. The belief that AIDS is a form of genocide is rooted in a social context in which Black Americans, faced with persistent inequality, believe in conspiracy theories about Whites against Blacks. These theories range from the belief that the government promotes drug abuse in Black communities to the belief that HIV is a manmade weapon of racial warfare. An open and honest discussion of the Tuskegee Syphilis Study can facilitate the process of rebuilding trust between the Black community and public health authorities. This dialogue can contribute to the development of HIV education programs that are scientifically sound, culturally sensitive, and ethnically acceptable

Light on the Shadow of the Syphilis Study at Tuskegee

In the 1940s, with the disclosure that Nazi doctors had conducted experiments on humans, the term research crime appeared for the first time. Most Americans believed such abuses could never happen here. On a hot day in July 1972, however, the national front-page news described an experiment sponsored by the U.S. government. In Macon County, Alabama, a large group of Black men had gone untreated for syphilis. Over 4 decades, as some of them died, the U.S. government went to great lengths to ensure that the men in the Tuskegee Study were denied treatment, even after penicillin had become the standard of care in the mid-1940

Vitamin D Deficiency in TAMU Female Basketball Players and Supplement Effectiveness

Purpose: Vitamin D deficiency has been defined by the Institute of Medicine (IOM) as a level of serum 25-OH vitamin D less than 20 ng/mL. The Endocrine Society went on to further define vitamin D insufficiency as a level between 21 and 29 ng/mL. Research suggests that vitamin D deficiency could increase fracture risk in athletes, especially females who are naturally prone to deficiency. Methods: Eight female athletes from the Texas A&M women’s basketball team (21 ± 1yrs; 88 ± 18 kg; 179 ± 16.5cm; BMI 26 ± 3 kg/m2; black female) were identified to have low vitamin D blood levels in April of 2012. Each of these women was ordered to supplement with 50,000 IU of vitamin D2 1x/week. After 8 weeks, the subjects were again evaluated in July 2012. Body composition information was also attained via DEXA scan. For each subject, the change in blood vitamin D levels (final – initial) and bone mineral density (BMD) difference was calculated. Data were analyzed for frequency and for pre-post significance by dependent t-test, [α=0.05 Conclusions: Vitamin D supplementation improved serum vitamin D levels significantly. 100% of the women were initially deficient in vitamin D. After intervention, 100% of the athletes were brought into the acceptable range as defined by the IOM (\u3e20 ng/mL), while 22.22% of the women improved to the standards to the standards of The Endocrine Society (\u3e 30ng/mL). The changes in pre-post vitamin D values were statistically significant after 8 weeks, while the BMD changes were not. Improvements in BMD may take longer than 8 weeks to become evident. Vitamin D assessment is critical to ensuring bone health and injury prevention in athletes, especially in black females

Resting and Post-Exercise Blood Pressure Response to Repeated Bouts of Aquatic Treadmill Exercise

Aerobic exercise is known to reduce resting blood pressure as well as induce and acute post-exercise hypotensive response. Purpose: Determine the effect of repeated bouts of aquatic treadmill exercise on consecutive days in physically untrained, pre-hypertensive men. Methods: Nine male subjects (SBP: 132 ± 8 mmHg; DBP: 79 ± 8 mmHG; 33 ± 8 years; 183 ± 7 cm; 103 ± 31 kg; 32 ± 10% Fat; 36 ± 7 ml·kg-1·min-1) participated in the study. All subjects completed an acute aquatic treadmill exercise session (60% VO2max; 300 kcal) on two consecutive days. Prior to each exercise session and following 10 minutes of seated rest, blood pressure and heart rate were automatically taken every 3 minutes for a total of 3 measurements. Following each exercise session, blood pressure and heart rate were measured automatically every 10-minutes from 20 to 60 minutes post while subjects were seated at rest. Pre-exercise and post-exercise measures were averaged. A dependent sample t-test was performed to compare the average values between the first (ATM1) and second (ATM2) exercise sessions. Results: Data are displayed in table below. Both pre-exercise and post-exercise systolic, diastolic, and mean arterial pressures were lower for ATM2. Conclusion: A single bout of ATM exercise resulted in reduced resting blood pressure 24-hours later. Furthermore, post-exercise blood pressure was lower following a second ATM exercise session. These data support both the efficacy of ATM exercise in regulating blood pressure and the cumulative benefit of repeated exercise bouts. Pre-Exercise Post-Exercise SBP DBP MAP HR SBP DBP MAP HR ATM1 Avg 126 78 96 72 124 77 93 83 SD 11 7 7 11 12 7 8 10 ATM2 Avg 121 74 92 70 120 75 91 80 SD 11 7 7 11 10 8 7 13 T-Test 0.035 0.005 0.003 0.113 0.047 0.028 0.034 0.058 All values represent mean ± SD. p-values compare ATM1 vs. ATM