Caffeine and Sprint Performance in Habitual and Caffeine Naive Participants

Caffeine is thought to provide ergogenic benefits during endurance performance. However, there is limited research on the effects of caffeine on anaerobic sports performance. The purpose of this study was to examine the effects of 6 mg·kg-1 of caffeine on repeated sprint performance. The sample included active college students (N = 18), classified as habitual caffeine or caffeine naïve users. Participants completed a 12 x 30-m sprint test with 35 s rest intervals between sprints. Ratings of Perceived Exertion were collected every 3rd sprint. Height and body mass were measured and participants accommodated to the sprint test on Day 1. Participants were randomly assigned to the placebo or caffeine condition on Day 2 and the treatment was reversed on Day 3. Caffeine was ingested in a sports drink 1 h prior to performing the sprints. Caffeine produced a significantly faster best sprint time compared to the placebo trial, F (1, 17) = 7.38, MSE = .02, H-F p = .02. However, no significant difference was found between caffeine supplementation and placebo on time to complete the total sprint test. Additionally, no significant difference was found in sprint times with caffeine supplementation by sex or between caffeine-naïve and habitual caffeine users. Finally, a significantly higher average RPE was found with caffeine supplementation as compared to the placebo, t (1, 17) = 2.92, d = .38, p = .01. Caffeine has the potential to enhance sprint performance however, further research with women and habitual caffeine consumers is needed

Eccentric Resistance Training in Adults with and without Spinal Cord Injuries

International Journal of Exercise Science 10(1): 154-165, 2017 The purpose of this study was to examine the effects of active lower body eccentric resistance training (ERT) in individuals with incomplete spinal cord injury (iSCI) and controls (CON). Specifically, the study was designed to determine if those with iSCI adapt similarly to ERT as CON participants as well as the overall safety and efficacy of ERT in this population. This pilot investigation involved the recruitment of persons with iSCI (n = 3) and age- and sex-matched able-bodied CON (n = 3). The 8-week intervention focused on building lower extremity eccentric strength by progressively increasing the duration and intensity of training sessions. Control participants completed the same training intervention. Main outcome measures were eccentric strength (eccentric ergometer), isometric strength (hand held dynamometer), and leg muscle mass (DEXA). All participants completed the ERT. At posttest, eccentric strength improved from pretest (p = .044, ηp2 = .68) with similar changes between groups (p \u3e .05). The percent improvement in isometric strength for those with iSCI (41.5%) was different than CON (-2.8%) after training (p = .044). Neither group demonstrated muscle mass gains at posttest (p \u3e .05). Active lower body ERT is well tolerated and effective at increasing lower extremity strength in those with iSCI. These adaptations are likely attributable to neuromuscular development rather than a hypertrophic response

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on Agility Performance in Elite Youth Soccer Players

Int J Exerc Sci 5(2) : 97-105, 2012. A warm-up is an important part of preparation for a soccer match. Stretching is typically part of the warm-up however, debate exists as to the most appropriate type of stretching to perform. The purpose of this study was to examine the effects of static and proprioceptive neuromuscular facilitation (PNF) stretching on soccer-specific agility performance in 14 male elite, premier league youth soccer players. Participants completed 4 trials of the Balsom agility test while dribbling a soccer ball. Height, age, and body mass were collected in trial 1 and participants were accommodated to the agility test during trials 1 and 2. Trials 3 and 4 were the static and PNF treatment trials that were administered after a standardized warm-up (control) in a randomized and counterbalanced manner. There were no significant differences between the difference scores of the static and PNF stretching conditions, P = .66. Furthermore, no significant differences were found between the control and stretching trials for static stretching, P = .15 or between the control and stretching trials for PNF stretching, P = .58. Neither mode of stretching significantly affected agility performance. More research is needed to determine the chronic effects of PNF stretching on agility performance

Validation of the Actiheart Monitor for the Measurement of Physical Activity

The Actiheart monitor uniquely allows simultaneous measurement of heart rate and movement counts. The purpose of this study was to establish validity evidence for the Actiheart monitor under laboratory and free-living conditions. A total of 34 college students (17 males and 17 females, age = 21.8 ± 3.6 years) participated in the study. In the laboratory environment, the participants completed three, 5 min bouts of treadmill walking and/or running at speeds of 3.2, 6.4, and 9.6 km/h. Outside the laboratory, participants were asked to perform free-living physical activity for 30 min. For validation, energy expenditure, movement counts, and heart rate measurements from the Actiheart monitor were compared with an AEI Moxus Metabolic Cart, Actigraph accelerometer, Polar heart rate monitor (HRM), and electrocardiogram (ECG), respectively. The Actiheart underestimated energy expenditure only at the highest workload in the laboratory environment compared with the metabolic cart (p = .009). Actiheart heart rate (HR) was similar to the HR measured by ECG at all workloads. Under free-living conditions, the Actiheart energy expenditure was highly correlated (r = .81) with the Actigraph energy expenditure with no significant differences (t(33) =.26; p = .80). Actiheart heart rate was also highly correlated with HR from the Polar HRM (r = .93), however, there was an overestimation of HR by the Actiheart monitor (t(33) = 3.00; p = .005) under free-living conditions. The Actiheart monitor appears to accurately measure physical activity under free-living conditions and at low and moderate intensities in the laboratory environment

Dynamic stretching is effective as static stretching at increasing flexibility

This study examined the effect of dynamic and static (standard) stretching on hamstring flexibility. Twenty-five female volleyball players were randomly assigned to dynamic (n = 12) and standard (n = 13) stretching groups. The experimental group trained with repetitive dynamic stretching exercises, while the standard modality group trained with static stretching exercises. The stretching interventions were equivalent in the time at stretch and were performed three days a week for four weeks. Both stretching groups showed significant improvements (P < .001) in range of motion (ROM) during the intervention. However, no difference in gains in the range of motion between stretching groups was observed. It was concluded that both dynamic stretching and standard stretching are effective at increasing ROM

A Cross-Training Program Does Not Alter Self-Reported Physical Activity Levels in Elementary School Children

The purpose of the study was to examine the effects of a school-based cross-training program on body mass index (BMI), attitudes toward physical activity (ATPA), and physical activity (PA) levels of children in the 4th and 5th grades. Children (N = 118) were divided into control (n = 60) and experimental (n = 58) groups based on class availability. While the control group continued academic classes as usual, the experimental group participated in cross-training involving resistance training (RT), calisthenics, and stretching twice a week for 10 weeks. Pre- and post-intervention measures included height, mass, ATPA, and PA. BMI was calculated and ATPA and PA levels were assessed via questionnaire. The groups did not differ significantly (p \u3e .05) for either pre- or post-intervention regarding BMI, ATPA, and PA. However, BMI and PA levels significantly increased over time for both groups (p ≤ .05). Overall, cross-training in a school setting may be a safe and enjoyable option for physical activity participation. BMI and PA increases were likely the result of the natural growth process and seasonal weather pattern changes, respectively. Nevertheless, the cross-training did not detract from PA levels and may have led to an overall increase in PA levels. As subdomain analyses revealed decreased attitude toward health and fitness in the experimental group, shorter programs involving RT with various protocols are recommended

A Cross-Training Program Does Not Alter Self-Reported Physical Activity Levels in Elementary School Children

International Journal of Exercise Science 11(5): 308-318, 2018. The purpose of the study was to examine the effects of a school-based cross-training program on body mass index (BMI), attitudes toward physical activity (ATPA), and physical activity (PA) levels of children in the 4th and 5th grades. Children (N = 118) were divided into control (n = 60) and experimental (n = 58) groups based on class availability. While the control group continued academic classes as usual, the experimental group participated in cross-training involving resistance training (RT), calisthenics, and stretching twice a week for 10 weeks. Pre- and post-intervention measures included height, mass, ATPA, and PA. BMI was calculated and ATPA and PA levels were assessed via questionnaire. The groups did not differ significantly (p \u3e .05) for either pre- or post-intervention regarding BMI, ATPA, and PA. However, BMI and PA levels significantly increased over time for both groups (p ≤ .05). Overall, cross-training in a school setting may be a safe and enjoyable option for physical activity participation. BMI and PA increases were likely the result of the natural growth process and seasonal weather pattern changes, respectively. Nevertheless, the cross-training did not detract from PA levels and may have led to an overall increase in PA levels. As subdomain analyses revealed decreased attitude toward health and fitness in the experimental group, shorter programs involving RT with various protocols are recommended

The Impact of a Pilot Community Intervention on Health-Related Fitness Measures in Overweight Children

The purpose of this study was to pilot a 5-week community-based intervention on improving measures of health-related fitness in overweight children. Data were obtained from 8 overweight and obese 8- to 14-year-old children. Measurements included muscular fitness (curl-ups and modified pull-ups), aerobic capacity (20 meter progressive aerobic cardiovascular endurance run [PACER] test), body composition (tricep and calf skinfolds), body mass index (BMI), and flexibility (back saver sit-and-reach). A significant reduction in BMI was observed at post-test compared to baseline (p = .03). There was a significant decrease in body fat at post-test for boys (p = .013)

Relative Age Effect Among Elite Youth Female Soccer Players across the United States

The consequence of relative age eff ect (RAE) has been an overrepresentation of athletes born early in the cohort and an underrepresentation of athletes born late in the cohort. There are signifi cantly fewer studies that examine this phenomenon among female soccer players. Therefore, the purpose was to determine the existence of RAEs among elite youth female soccer players competing in the Elite Clubs National League (ECNL) during the 2012-2013 season. Player birthdates (U14-U18 N=7,294) were collected from the ECNL and compared to the birthdates distribution for the general population. Data revealed a RAE across all age groups (U14-U18) indicating a preference for the selection of the oldest in the cohort. An overrepresentation of players was observed in Q1 and an underrepresentation of players in Q4 among the U14-U17 age groups. Among the u18 age group, an overrepresentation of players was detected in Q2 and an underrepresentation of players in Q4. The birthdate distribution for the fi rst and second halves of the playing season showed strong RAEs among the U14-U17 age groups. No statistically signifi cant diff erence was found between the fi rst and second halves of the playing season among players in the U18 age group