Positional Differences in Running Distance and Speed Among Collegiate Rugby 7s Players

Rugby sevens (7s) is an anaerobic contact sport consisting of seven players per team, with two 7-minute halves per match played in tournament style with several matches over up to a three-day event. However, due to the nature of the collegiate game, less funding, and their academic schedule, the tournaments are commonly consolidated into one day (minimum 3, as many as 6 matches). While there are six positions in 7s, this study divided them into three groups: Forwards (FW), Backs (BK), and Scrum halves (SH). Purpose: The purpose of this investigation was to identify the physiological and physical demands between positions of Indiana University 7s club players. Methods: Data was retrospectively analyzed from male (n = 15) collegiate rugby 7s players. Data was collected at Indiana University using GameTraka (Sports Performance Tracking, Victoria, Australia) and data represented here are from one tournament consisting of 5 matches on the same day. Participants wore Global Positioning System (GPS) units from which information on distances run per minute by each position group (FW, BK, and SH) was measured within six different speed zones. A one-way ANOVA was used to determine between group differences by each half of play with Tukey post-hoc analyses to reveal differences between positions. A two-way repeated measures ANOVA was used to determine if differences existed across matches by player position. A p-value of \u3c0.05 was set to determine the level of statistical significance. Results: During the first half no significant differences were seen. In the second half of match #1, significant differences were found in Zone 1 running (p = 0.004) indicating that BK ran more than both FW (p = 0.003) and SH (p = 0.05). No significant differences were found in the second half of matches 2-4. Match #5 second half results indicated significant difference in distance per minute (p = 0.022) with both FW (p = 0.036) and SH (p = 0.041) covering more distance than BK. A main effect for zone 1 (p = 0.015) and zone 4 (p = 0.003) were observed with both FW (p = 0.029) and SH (p = 0.003) higher than BK. No significant differences were found across the five matches between position groups. GPS data indicate that the primary differences between position groups are observed in the second halves of rugby 7s matches. Data suggests that FW and SH have a higher distance covered per minute and spend more time in the different running zones as the number of matches increases. This could be a byproduct of a change in the quality of play as peripheral fatigue sets in as the match progresses. Conclusion: Data presented here can affect the training approaches for the various position groups as the data suggests a greater amount of physiological exertion is present in the later matches of tournament play. Data also may be useful to coaches in the strategic utilization of substituting players as substitutions per match are capped in rugby 7s

Twelve Weeks of Nitrate, Beta-Alanine, or Combined Treatment in NCAA Division III Male Soccer Players

In a sport of long duration, such as soccer, with many high-intensity bouts interspersed within the match, enhancing performance to last the duration of the match and maintain high levels of intensity is paramount. Thus, with proper nutrition and physical preparation, supplements such as beta-alanine (due to its intracellular buffering capacity) and nitrate (due to its vasodilatory and ergogenic effects in endurance exercise) may have value in this population. PURPOSE: The purpose of this investigation was to examine the effects of chronic supplementation with nitrate, beta-alanine, or combined treatment in NCAA Division III male soccer players. METHODS: Twenty-two NCAA Division III male soccer players (age: 19.1 ± 1.1yrs; mass: 74.8 ± 8.0kg; body fat: 13.6 ± 4.0%) were randomly assigned into one of four groups: nitrate plus placebo (NIT), beta-alanine plus placebo (BA), placebo (PLA), or active treatments (ACT) and participated in this 12-week double-blind, placebo-controlled study. At pre-intervention testing, participants completed body composition measures, VO2 max, 30-second Wingate test on day one, and 40-yard dash and Yo-Yo Intermittent Recovery: Level 2 (YOYOIR2) on day two and testing sessions were repeated at 6- and 12-weeks post training and supplementation. A 4x3 repeated measures ANOVA was used to analyze the data with a-priori p value set at ≤0.05. RESULTS: There was a significant time effect for the following variables indicating that the training protocol induced performance adaptations: VO2 max (p = 0.0), Wingate peak power and mean power (p = 0.04; p = 0.006), 40-yard dash (p = 0.003), and YOYOIR2 (p = 0.0). Change in performance over time (% change) for VO2 max was NIT: 9%, BA: 7%, ACT: 12% vs PLA: 8%. Wingate mean power % change was NIT: 17%, BA: 6%, ACT: 4% vs PLA: 5%. Wingate peak power % change was NIT: 10%, BA: 11%, ACT: 10% vs PLA: 9%. YOYOIR2 % change was NIT: 48%, BA: 54%, ACT: 74% vs PLA: 10%. Despite this, there were no significant group by time effects for any variables. CONCLUSION: Although further research is warranted, addition of these supplements may be beneficial to soccer players

Differences in Impact and Load During Collegiate Rugby 7s

Rugby 7s is a sport played with seven players, and two, 7-minute halves, played on a standard rugby field of 100 meters long by 70 meters wide. Impacts with forces greater than 10.0 Gs are an often occurrence in rugby 7s, and the occurrence can be quite frequent in such a short period of time (14 minutes of match play). Multiple matches are played in a day or throughout a weekend in tournament format thus adding to the load on players and current research on the amount of impact and load players experience is lacking in a U.S. collegiate population. Purpose: The purpose of this investigation was to assess differences in impact and load during collegiate rugby 7s matches. Methods: Data was collected at Indiana University from male collegiate rugby 7s players (n = 15) by their head coach using GameTraka (Sports Performance Tracking, Victoria, Australia) during their 2019 season. Participants wore GPS units that collected data on impact and load by position groups forwards (FW), backs (BK), and scrum halves (SH). A one-way ANOVA was used to determine between group differences by each half of play with Tukey post-hoc analyses to reveal differences between positions. A two-way repeated measures ANOVA was used to determine if differences existed across matches by player position. A p-value of \u3c0.05 was set to determine the level of statistical significance. Results: Data analyses revealed a significant difference in number of impacts during the first half of match 1 (p = 0.014). Post-hoc analyses indicated FW incurred a significantly higher number of impacts than BK (p = 0.046), as well as more impacts than SH (p = 0.012). During the second half of play, the only match with a significant difference was match 5. Both summation of horizontal forces (loading 2D) as well as summation of horizontal and vertical forces (loading 3D) to the athlete revealed significant main effects. For the loading 2D and loading 3D during match 5, post-hoc analyses revealed significant differences between BK and SH at p = 0.048 and p = 0.045, respectively. In comparison of position across matches, no significant differences were found for impacts, 2D, or 3D loading. No significant differences were found across the five matches. Conclusion: This data suggests that the number of impacts is higher in the first half, with FW having significantly more impacts when compared to BK and SH. This is likely explained by task differences between FW, BK, and SH as FW are required to compete in scrums and more rucks than either BK or SH and tend to encounter contact more frequently. Differences in the second half occurred only in match 5 with SH being subjected to more forces than BK. This effect is likely a result of the positional differences as SH follow the course of play much more so than BK. This data supports that FW incur the greatest amount of collisions in rugby 7s compared to other positions also being a byproduct of the role that FW play in rugby 7s. There was no significant difference in loading and impact across matches

Phytoplankton blooms weakly influence the cloud forming ability of sea spray aerosol

After many field studies, the establishment of connections between marine microbiological processes, sea spray aerosol (SSA) composition, and cloud condensation nuclei (CCN) has remained an elusive challenge. In this study, we induced algae blooms to probe how complex changes in seawater composition impact the ability of nascent SSA to act as CCN, quantified by using the apparent hygroscopicity parameter (κapp). Throughout all blooms, κapp ranged between 0.7 and 1.4 (average 0.95 ± 0.15), consistent with laboratory investigations using algae‐produced organic matter, but differing from climate model parameterizations and in situ SSA generation studies. The size distribution of nascent SSA dictates that changes in κapp associated with biological processing induce less than 3% change in expected CCN concentrations for typical marine cloud supersaturations. The insignificant effect of hygroscopicity on CCN concentrations suggests that the SSA production flux and/or secondary aerosol chemistry may be more important factors linking ocean biogeochemistry and marine clouds.Key PointsChanges in seawater and sea spray composition did not strongly affect expected CCN concentrationsBlooms may impact clouds more strongly through changes in aerosol flux or secondary chemistryModel parameterizations likely overestimate changes in cloud nuclei due to primary marine organicsPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/1/grl54978_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/2/grl54978-sup-0001-supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134444/3/grl54978.pd

An atmospheric chemist in search of the tropopause

Delineating the boundary between troposphere and stratosphere in a chemistry transport model requires a state variable for each air mass that maps out the ever shifting, overlapping three-dimensional (3-D) boundary at each time step. Using an artificial tracer, e90, with surface sources and 90 day decay time, the model e90 tropopause matches the 1-D temperature lapse rate definition of the tropopause as well as the seasonal variation of ozone at this boundary. This approach works from equator to pole, over all seasons, unlike methods based on potential vorticity or ozone. By focusing on the time scales that separate stratosphere from troposphere, we examine the cause of ozone seasonality at the midlatitude tropopause, the oldest air in the troposphere (winter descent in the subtropics), and a north-south bias in the age of air of the lowermost stratosphere as evaluated using a northern tracer. The tracer e90 is invaluable in 3-D modeling, readily separating stratosphere from troposphere and a giving quantitative measure of the effective distance from the tropopause

Comparison of Bioimpedance Analysis and Dual Energy X-Ray Absorptiometry in Division III Football Athletes

Body composition is an integral component of physiology and pathology, as well as an indication of how the musculoskeletal system changes over time in response to training and/or nutritional modifications. Two common methods of estimating body composition include bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA). There is a debate regarding the agreement between these two methods, and it is thought that the population being tested may influence the similarity of estimates obtained by these technologies. Limited data comparing these two methodologies in athletic populations are available. PURPOSE: The purpose of this study was to take examine the agreement between BIA and DXA for estimates of body mass (BM) and body fat percentage (BF%). METHODS: Forty-three division III football players (mean ± SD; age: 19.9 ± 1.7 y; height: 179.7 ± 7.4 cm; BM: 100.3 ± 21.9 kg; DXA BF%: 21.8 ± 7.1%) reported to the Human Performance Lab after abstaining from exercise for the previous 24 hours and fasting from food/beverages (except water) for 12 hours. After an initial height assessment, BM and BF% were assessed using both BIA (Inbody 770) and DXA (Hologic Horizon W). BIA was performed in the standing position using an 8-point electrode arrangement. The electrode panels were placed at the hands and feet. DXA was performed with the participants in a supine position and hips internally rotated. Differences in BM and BF% from DXA and BIA were compared using paired-samples t-tests, Bland-Altman analysis, and validity metrics. RESULTS: BM detected by DXA was significantly lower than BM obtained from the BIA scale (DXA: 98.2 ± 20.8 kg, BIA: 100.3 ± 21.9 kg; p \u3c 0.001). Additionally, Bland-Altman analysis indicated significantly greater underestimation of BM by DXA in individuals with higher BM values (slope: 0.053; p \u3c 0.001). BF% did not significantly differ between DXA and BIA (DXA: 21.8 ± 7.1%, BIA: 21.8 ± 8.4%; p = 0.86). However, Bland-Altman analysis indicated significant proportional bias, with underestimations of BF% by BIA in leaner individuals but overestimations of BF% in those with higher BF% (slope: 0.176; p = 0.005). The total error and 95% limits of agreement for BF% were 3.2% and ± 6.4%, respectively. CONCLUSION: This study demonstrates that although DXA and BIA exhibit good group-level agreement for BF%, several inconsistencies between these methodologies are present. Estimates of BM differed between technologies. Additionally, proportional bias for BF% was observed indicating different levels of agreement between DXA and BIA depending on the body fat of the individuals being tested. Based on these findings, caution should be employed when interpreting data from DXA and BIA assessments in athletic populations

Associations of Changes in Body Composition and Athletic Performance in Collegiate American Football Players

Football practitioners ubiquitously employ offseason resistance training to improve on-field performance. Early offseason training is frequently designed to emphasize accretion of lean and total body mass. While this is a main objective of sport-specific conditioning, there are few investigations comparing correlated changes in body composition, maximal strength, and football-specific performance tests after an early-offseason training program. PURPOSE: The purpose of this analysis was to quantify the relationship between changes in athletic performance and body composition in collegiate American football players. METHODS: Before and after a 7-week offseason training program, body composition and athletic performance were assessed in NCAA Division III American football players. Body composition was estimated using dual-energy X-ray absorptiometry (DXA; Hologic Horizon). One-repetition maximum (1RM) strength was assessed for the barbell back squat and front squat exercises. Vertical jump height, 40-yard dash time, broad jump distance, and pro agility shuffle time were also assessed. The sample size ranged from 17 to 19, depending on the specific performance test. Using Pearson’s product-moment correlations, the relationships between percent changes in DXA variables and athletic performance outcomes were examined.RESULTS: A trend for a positive correlation between changes in lower body FFM and front squat 1RM (r: 0.43, p: 0.08), but not back squat 1RM (r: -0.03, p: 0.92), was observed. Additionally, a significant positive correlation was observed between pro agility shuffle time and DXA BM (r: 0.50, p: 0.03) and total FFM (r: 0.49, p: 0.04), but not FM (r: 0.06, p: 0.80). In contrast, no correlations between changes in body composition variables and changes in vertical jump height, 40-yard dash time, or broad jump height were observed (range of r: -0.36 to 0.31, p\u3e0.05 for all).CONCLUSION: Increases in FFM may predict improvements in front squat 1RM but impairments in pro agility shuffle performance, with no relationships observed for vertical jump height, 40-yard dash time or back squat. Additional phases of training that specialize in developing maximal power and velocity are likely necessary to maximize athletic development

Offseason Body Composition Changes Detected by Dual-Energy X-Ray Absorptiometry Versus Multifrequency Bioelectrical Impedance Analysis in Collegiate American Football Athletes

In American football, offseason training is designed to promote increases in muscle strength and size in athletes. Tracking changes in body composition may confer key information about the effectiveness of training programs to football practitioners. PURPOSE: The present study assessed the relationship between body composition changes estimated by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA) in football players during the initial period of an offseason training program. METHODS: Body composition in 29 NCAA Division III American football players (mean ± SD; age: 19.7 ± 1.5 y; height: 179.8 ± 6.6 cm; body mass [BM]: 96.1 ± 12.6 kg; DXA body fat: 20.9 ± 4.4%) was estimated using BIA (InBody 770) and DXA (Hologic Horizon) before and after a seven-week training intervention. Repeated measures analysis of variance, concordance correlation coefficients, and Bland-Altman analysis alongside linear regression were used to detect differences in cross-sectional estimates and change values, the strength of correlation, and determine the degree of proportional bias between methods, respectively. RESULTS: Significant method by time interactions were observed for BM (p = 0.03), arms fat-free mass (FFM) (p = 0.03), and legs FFM (p = 0.01). Post hoc comparisons indicated that DXA – but not BIA – detected increases in FFM of the arms and legs. Time main effects indicated an increase in total FFM (p = 0.004) and trunk FFM (p = 0.002) from pre to post. Finally, method main effects indicated higher leg FM values for DXA (p \u3c 0.001) and higher trunk FM values for BIA (p \u3c 0.001). No significant effects were observed for total FM (p = 0.92) or arms FM (p = 0.13). Changes in total BM (CCC = 0.96), FFM (CCC = 0.49), and fat mass (CCC = 0.50) were significantly correlated between BIA and DXA. CONCLUSION: DXA and BIA may similarly track increases in whole-body FFM in American collegiate football players; however, BIA may possess less sensitivity to detect segmental FFM increases, particularly in the appendages

The Effects of a Thermogenic Supplement on Metabolic and Hemodynamic Variables and Subjective Mood States

Thermogenic supplements are widely used in the general population to support attempted fat loss; however, the efficacy and safety of these supplements are questioned. PURPOSE: To determine whether a thermogenic supplement affects metabolic rate, hemodynamic responses, and mood states. METHODS: In a randomized double-blind crossover design, 23 females (22.2 ± 3.5 y; 164.8 ± 6.4 cm; 73.5 ± 6.9 kg) who were moderate caffeine consumers (\u3c150mg/day) reported to the lab on a 12-hour fast for baseline assessments of resting energy expenditure (REE) via indirect calorimetry, heart rate (HR), blood pressure (SBP and DBP), and hunger, satiety, and mood states. Thereafter, subjects ingested the assigned treatment (active treatment containing caffeine, micronutrients, and phytochemicals [TR] or placebo [PL]). All variables were reassessed at 30-, 60-, 120-, and 180-minutes post-ingestion. Subjects repeated the same protocol with ingestion of the opposite treatment on a separate day. All data were analyzed using a 2x5 ANOVA with repeated measures and significance was accepted a priori at p\u3c0.05. RESULTS: In the TR group, mean increases in REE of 121 to 166 kcal/d were observed at 30-, 60-, and 180-minutes post-ingestion (p\u3c0.01 for all). PL group mean decreases in REE of 72 to 91 kcal/d were observed at 60-, 120-, and 180-minutes (p\u3c0.05 for all). Similarly, TR resulted in mean increases in expired carbon dioxide of 13 to 19 mL/min at 30- and 60-minutes (p\u3c0.05 for both), and oxygen consumption increased by 12 to 24 mL/min at 30-, 60-, 120-, and 180-minutes (p\u3c0.05 for all) post-ingestion. Respiratory quotient decreased at 120- and 180-minutes in both treatments. A mean decrease in HR of 5 bpm was observed at 30-minutes post-ingestion of TR (p\u3c0.01). Slight increases in SBP of 3 to 4 mmHg were observed at 30-, 120-, and 180-minutes (p\u3c0.05 for all) post-ingestion of TR, while no effects were observed for DBP. Observed increases in SBP were within normal blood pressure ranges. TR decreased subjective fatigue with no other significant changes in mood states. CONCLUSION: These findings indicate that ingestion of a specific thermogenic supplement formulation produces a sustained increase in metabolic rate and caloric expenditure and reduces fatigue over three hours without producing adverse hemodynamic responses

Relationship Between Changes in Upper Body Fat-Free Mass and Bench Press Performance in American Football Players

Horizontal pushing strength and strength endurance are relevant attributes for blocking and block shedding in American football. Since most positions in American football require the ability to either block or shed a block, and since bench press repetitions to failure (RTF) with 225 pounds is a component of the NFL draft combine, improving horizontal pushing strength and strength endurance have been key areas of emphasis for strength and conditioning coaches working with these athletes. PURPOSE: The purpose of this analysis was to quantify the relationship between changes in upper body fat-free mass (FFM) and metrics of bench press performance in American football players. METHODS: Body composition and muscular performance were assessed in NCAA Division III American football players. Upper body FFM was obtained from dual-energy X-ray absorptiometry (DXA; Hologic Horizon) before and after a seven-week offseason training period. Barbell bench press one-repetition maximum (1RM), incline barbell bench press 1RM, and RTF with 225 pounds on the barbell bench press were also determined before and after the training period. Using Spearman’s rank correlations, the relationships between percent changes in upper body FFM and bench press 1RM (n=19), bench press RTF with 225 pounds (n=15), and incline bench press 1RM (n=18) were evaluated. RESULTS: Relative changes in bench press 1RM and DXA upper body FFM exhibited a weak, non-significant correlation (ρ: 0.38, p: 0.11). However, there was a moderate strength, significant correlation between relative changes in bench press RTF with 225 pounds and DXA upper body FFM (ρ: 0.53, p: 0.04). For relative changes in incline bench press 1RM, there was a weak, non-significant correlation with DXA upper body FFM (ρ: 0.24, p: 0.36). CONCLUSION: Of the performance tests assessed, only changes in bench press RTF with 225 pounds and changes in DXA upper body FFM were positively correlated. Therefore, strength and conditioning coaches working with athletes who plan on entering the NFL draft may want to consider dedicating time to increasing upper body FFM gains prior to the draft as it appears to be positively correlated with performance on this NFL combine test