A reduced exposure heated tobacco product was introduced then abruptly taken off United States shelves: results from a tobacco harm reduction natural experiment.

BACKGROUND: A heated tobacco product (HTP) authorized for purchase in the United States by the Food and Drug Administration as a reduced harm product was removed from the market after about 2 years of sales. Adults who used the HTP were surveyed to determine the impact of the introduction and removal of the HTP on past and current tobacco behaviors. METHODS: Adults who were using the HTP before its United States market removal (n = 502) completed a cross-sectional online survey to determine their tobacco use behaviors at three timepoints: prior to HTP initiation, just before HTP market removal, and at the time of the survey which was administered approximately 10 months post-removal. Descriptive statistics summarized outcome variables and paired bivariate testing was used to compare percent change between timepoints. Multivariable logistic regression and general linear models estimated associations of tobacco use behaviors and cigarette consumption. RESULTS: Overall, significantly fewer adults consumed cigarettes while using HTP than before they tried the product (63.0% vs. 89.9%, p value < 0.0001) and the number of cigarettes consumed per week (CPW) decreased (106.3-39.0, p value < 0.0001). After HTP removal, the percent of adults who consumed cigarettes increased non-significantly (63.0-67.5%, p value = 0.0544) while CPW increased significantly (39.0-76.6 CPW, p value < 0.0001). At the time of the survey, over 25% of the sample continued to use the HTP and 7.2% reported use of no tobacco products. Electronic nicotine delivery system use had increased significantly from the prior period (27.4% increase, p value < 0.0001). CONCLUSION: This study demonstrates reduction or elimination of combustible cigarette smoking while adults were using HTPs and some increased smoking after market removal, albeit at lower levels. If unable to find satisfying alternatives, adults who smoke and transition to reduced harm products may return to smoking or purchase products illicitly if their preferred products are removed from the regulated market.

Exploration of collective tactical variables in elite netball: An analysis of team and sub-group positioning behaviours.

Collective tactical behaviours are aspects of player interactions that are particularly important in netball, due to its unique restrictions on player movement (players unable to move when in possession of the ball and positional spatial restrictions). The aim of this study was to explore variables representing collective tactical behaviours in netball. A local positioning system provided player positions of one team throughout seven elite-level netball matches. The positions were analysed to provide mean, variability (standard deviation) and irregularity (normalised approximate entropy) for each attack and defence possession (470 and 423, respectively) for the team and positional subgroups (forwards, midcourts and defenders) for 10 position-related variables. Correlational analyses showed collective tactical variables could be grouped as lateral and longitudinal dispersion variables. The variables were each analysed after log transformation with a linear mixed model to compare attack and defence and to estimate standardised effects on attack and defence of possession outcome, possession duration, score difference, match time, opposition strength and season time. During attack, the team and all sub-groups adopted greater lateral dispersion between players, while on defence there was generally greater longitudinal dispersion. The team also showed increased longitudinal dispersion when home and opposition possessions ended in a score. Additionally, greater irregularity was observed in active sub-groups (forwards on attack, defenders on defence). Score difference and opposition strength had trivial-small but generally unclear effects. In conclusion, these effects show that analysis of player positions on attack and defence is a promising avenue for coaches and analysts to modify collective tactical behaviours in netball.

The introduction of the six-again rule has increased acceleration intensity across all positions in the National Rugby League competition.

The impact of the six-again rule change on the movement of National Rugby League (NRL) athletes was examined. Player Global Navigation Satellite System (GNSS) data (10 Hz) was collected from 42 athletes who competed in 56 matches across the 2019 to 2021 NRL seasons. Maximal mean speed (m·min-1) and acceleration (m·s-2) were established across a 10 s to 10-min duration via raw GNSS files, with subsequent intercept (mean estimates) and slope values determined via power law analysis. The distributions of match distance (m) and impulse (kN·s-1) were established during ball-in-play time. To determine the significance between positions and seasons under different rules, linear mixed models were used. Effects were described using standardised effect sizes (ES) with 90% confidence limits (CL). Acceleration intercepts (power law-derived) across all positions were substantially greater (>0.6 SD) following the introduction of the six-again rule in the 2020 (mean ± SD; 1.02 ± 0.10 m·s-2) and 2021 seasons (1.05 ± 0.08 m·s-2) compared to the 2019 season (0.91 ± 0.07 m·s-2). Mean acceleration during ball-in-play time was greater in 2020 (ES; 90% CL = 0.75; ± 0.32) compared to 2019. The acceleration requirements of rugby league increased across all positional groups following the modification in NRL competition rules. Practitioners should tailor training programs for athletes to reflect the increased acceleration intensity found under the revised competition format.

Chronic restraint stress increases sensitivity to punishment during cocaine self-administration via a dopamine D1-like receptor-mediated mechanism in prelimbic medial prefrontal cortex.

We recently reported that male rats displayed less sensitivity to punishment during cocaine self-administration compared to females. Moreover, daily restraint stress increased sensitivity to punishment in males, while having no effect in females. The purpose of the present study was to extend these findings by determining whether chronic stress-induced dopamine release in prelimbic medial prefrontal cortex mediates the effect of stress on punished cocaine self-administration. Thus, male rats were trained to press a lever for i.v. cocaine infusions (0.50 mg/kg/infusion) paired with a discrete tone + light cue in daily 3-hr sessions. Subsequently, 50 % of the lever presses were punished by a mild footshock that gradually increased in intensity over 7 days. During the punishment phase, rats were exposed to a chronic restraint stress procedure (3 h/day) or control procedure (unstressed). Rats also received bilateral microinjections of the D1-like receptor antagonist SCH-23390 (0.25 µg/0.5 µl/side) or vehicle (0.5 µl/side) delivered to prelimbic cortex prior to daily treatments. Relapse tests were conducted 1 and 8 days after the last punishment session. Chronically stressed rats displayed reduced cocaine self-administration during punishment relative to unstressed rats, an effect prevented by co-administration of SCH-23390 to prelimbic cortex with daily restraint. Neither stress nor SCH-23390 treatment had significant effects on subsequent relapse-like behavior. These results establish a specific role for prelimbic D1-like receptors in chronic stress-induced suppression of punished cocaine self-administration in male rats. As such, these findings may inform novel methods to facilitate self-imposed abstinence in cocaine-dependent men.

Challenges and considerations in determining the quality of electronic performance & tracking systems for team sports.

Electronic performance & tracking systems (EPTS) are commonly used to track the location and velocity of athletes in many team sports. A range of associated applications using the derived data exist, such as assessment of athlete characteristics, informing training design, assisting match adjudication and providing fan insights for broadcast. Consequently the quality of such systems is of importance to a range of stakeholders. The influence of both systematic and methodological factors such as hardware, software settings, sample rate and filtering on this resulting quality is non-trivial. Highlighting these allows for the user to understand their strengths and limitations in various decision-making processes, as well as identify areas for research and development. In this paper, a number of challenges and considerations relating to the determination of EPTS validity for team sport are outlined and discussed. The aim of this paper is to draw attention of these factors to both researchers and practitioners looking to inform their decision-making in the EPTS area. Addressing some of the posited considerations in future work may represent best practice; others may require further investigation, have multiple potential solutions or currently be intractable.

Understanding the effects of ball orientation in Rugby Union place kicking: the preferences of international kickers and the kinematics of the foot-ball impact.

Rugby Union place kicking is influential to match outcome. Previous research has analysed kicker motion prior to ball contact in detail, but ball orientation and the impact phase are typically ignored. This study aims to firstly identify the ball orientations used by international place kickers, and secondly to experimentally analyse the foot-ball interaction in trained kickers using different ball orientations. Overall, 25.5% of the international kickers used an upright ball orientation, 27.5% used a diagonal orientation and 47.1% used a horizontal orientation. However, ball orientation preference was not significant in predicting kick outcome in a binomial logistic regression model. To address the second aim, ball orientation was experimentally manipulated and lower limb and ball kinematics were captured using high-speed (4000 Hz) video. Whilst the impact location on the ball differed significantly between most ball orientation conditions, the impact location relative to the global vertical was largely consistent across all conditions. This was likely due to kickers adopting very consistent lower limb kinematics, although the shank and ankle angles at impact were affected by ball orientation conditions for some kickers. Impact durations also differed between some conditions, although this did not appear to affect the impact efficiency.

Kick proficiency and skill adaptability increase from an Australian football small-sided game intervention.

This investigation is the first to explore the effect of a 4 week small-sided game (SSG) and traditional training intervention on player kick proficiency and player adaptability in Australian football. Twenty-two amateur Australian football players (mean ± SD; age 22.3 ± 2.46; height 182.4 ± 5.25; weight 82.1 ± 6.10; years playing senior amateur football 3.86 ± 3.09) were randomly selected into either a traditional training group (n = 11) or a SSG group (n = 11). Traditional training involved activities where skills were generally executed in isolation and with minimal contact (e.g., kicking lane drill or possession football). The SSG training group participated in 5v6 competitive games on varied shaped areas (approximately 272 m2 per player) and changing constraints (e.g., game tempo, game rules). All players participated in the team training sessions; however, the SSG group participated in a 4 × 3min training protocol, with 60 seconds recovery, in the last 20-min of the session. The SSG group participated in these alternative sessions twice a week for 4 weeks. Results indicated only the SSG enhanced their kick proficiency (17%) and were found to be more adaptable. The intervention group executed more kicks over longer distances (i.e., 20-40 m), made quicker decisions (e.g., executing more kicks in < 1s), applied more pressure to the opposition when they were executing a skill and were more likely to "take the game on" by decreasing the amount of times a skill was executed from a stationary position. The results of this study can be used by coaches when designing and implementing training programs as different training strategies will elicit different player behavioral adaptations.

Sex-dependent effects of chronic stress on punished cocaine self-administration and cue-induced relapse to cocaine seeking.

We tested the effects of chronic stress on cocaine relapse after drug-reinforced responding was suppressed by punishment, an animal model of human relapse after self-imposed abstinence due to the negative consequences of drug use. Male rats displayed greater resistance to punishment than females, but daily stress decreased this resistance. Only female rats with a history of chronic stress displayed increased responding for cocaine cues from abstinence Day 1 to Day 8. Thus, the effects of chronic stress on punished cocaine self-administration and cue-induced relapse are dependent on biological sex, and may have implications for more targeted treatments for cocaine addiction.

Prelimbic medial prefrontal cortex has bidirectional control over the expression of behavioral sensitization to 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) depending on the context of drug administration.

Behavioral sensitization to MDMA is observed in the vast majority of rats if tested in the same environment in which previous MDMA exposure occurred, but not if tested in a novel, unpaired context. Previous studies have revealed a critical role for the prelimbic region of medial prefrontal cortex (PL) in the expression of sensitization to MDMA, but these studies assessed sensitization only in MDMA-paired environments. Given that PL activity can both facilitate and suppress behavior depending on context, we tested the hypothesis that PL has bidirectional control over the expression of locomotor sensitization to MDMA depending on the context of drug administration. Rats were treated with either saline or MDMA (5.0 mg/kg) twice daily for 5 days, in either their home cages (unpaired groups) or the activity monitors that were used for tests of sensitization on challenge days (paired groups). Prior to MDMA challenge injections (2.5 mg/kg; at âˆ¼ 2 weeks of withdrawal), rats received bilateral PL microinjections of either lidocaine (100 µg/0.5 µl/side) or physiological saline (0.5 µl/side). Locomotor activity in response to MDMA challenge was unaffected by PL inactivation in saline pretreated rats. However, PL inactivation caused a decrease in locomotion to the challenge injection in MDMA/paired rats and an increase in locomotion in MDMA/unpaired rats. These results establish a novel role for PL in suppressing the expression of behavioral sensitization when subjects are challenged in a drug-unpaired context, adding to the literature implicating PL activity in both the expression and inhibition of other drug-related behaviors.

Applying common filtering processes to Global Navigation Satellite System-derived acceleration during team sport locomotion.

This study aimed to observe whether there were substantial differences in acceleration during team-sport locomotion between GNSS manufacturers. Speed and acceleration were obtained from 7 professional rugby league athletes via 2 GNSS manufacturers (GPSports EVO, 10 Hz and STATSports Apex, 10 Hz) worn together during the same training sessions (n = 13). Raw GNSS data were exported from respective proprietary software and a 1 Hz, 4th-order Butterworth filter applied, with differences in speed and acceleration calculated between manufacturers. To determine the difference in acceleration and speed, a root mean square deviation (RMSD) was used. Linear mixed models were used and no substantial differences were found between manufacturers in raw and filtered speed variables. RMSD for average acceleration (m · s-2) decreased from raw (RMSD: 1.77 ± 0.37 m · s-2) to those seen at the filtered (RMSD: 0.27 ± 0.23 m · s-2) and twice filtered (0.24 ± 0.23 m · s-2) variables. Raw average acceleration (m · s-2) was substantially higher in Apex compared to EVO (Difference (Diff); CI: -0.82; -0.84 to -0.80). Following application of the common filter there was no substantial difference between GNSS models for average acceleration (Diff; CI: -0.04; -0.04 to -0.04). Acceleration variables derived from each manufacturer's proprietary software were substantially different.

Prediction of 2000-m on-water rowing performance with measures derived from instrumented boats.

PURPOSE: Rowing instrumentation systems provide measures of stroke power, stroke rate, and boat velocity during rowing races, but how well these measures predict race performance has not been reported previously. METHODS: Data were collected per stroke from 45 2000-m races using Peach PowerLine and OptimEye S5 GPS units. The boat classes assessed were nine male singles, eight female singles, three male pairs, and six female pairs. Random effects and residuals from general linear mixed modeling of stroke velocity adjusted for stroke power, stroke rate, and mean headwind provided measures interpreted as technical efficiency, race conditions, and stroke-velocity variability. These measures, along with mean race power, mean stroke rate, and mean headwind were then included in multiple linear regressions to predict race velocity from official race times. Effects were assessed for 2 SD changes in predictors and interpreted using interval hypothesis tests. RESULTS: Effects of mean race power, mean stroke rate, and mean headwind on race velocity ranged from small to extremely large and were mostly decisively substantial. Effects of technical efficiency and race conditions ranged from trivial to extremely large but were generally unclear, while stroke-velocity variability had trivial-small and mostly unclear effects. Prediction error was small to moderate and decisively substantial. Men's pairs lacked sufficient data for analysis. CONCLUSION: On-water rowing race performance can be predicted with mean race values of power, stroke rate, and headwind. Estimates from stroke data are potentially useful predictors but require impractical numbers of boats and races to reduce their uncertainty.

Using Small-Sided Games in Field Hockey: Can They Be Used to Reach Match Intensity?

ABSTRACT: Duthie, GM, Thomas, EJ, Bahnisch, J, Thornton, HR, and Ball, K. Using small-sided games in field hockey: Can they be used to reach match intensity? J Strength Cond Res 36(2): 498-502, 2022-Small-sided games (SSGs) are commonly used in field hockey to replicate or overload physical and tactical competition demands; however, little evidence is available regarding if specific SSG formats achieve this. This research investigated how speed and acceleration differed between 5-minute SSG formats (2v2, 3v3, and 4v4) and also compared with competition. Elite male field hockey athletes (n = 10) participated in the SSGs with standard rules, on pitches of 30 × 20, 35 × 25, and 40 × 30 m, respectively (∼150 m2 per athlete excluding goal keepers). Global Positioning System devices measured speed (m·min-1) and acceleration (m·s-2). Differences between mean speed and acceleration during SSGs and 5-minute maximal mean values from competition (calculated using moving averages) were quantified using linear mixed models and described using standardized effect sizes (ES) and 90% confidence intervals. Between SSG formats, there were nonsubstantial differences for mean speed and acceleration (ES range -0.4 to 0.8). Compared with competition, mean speed was substantially lower for all SSG formats (ES range -1.4 to -1.8), whereas mean acceleration was higher (ES range 3.9-4.8). The SSG formats examined had a lower mean speed and higher mean acceleration than the maximal mean observed in competition. Therefore, these SSGs are an effective training drill for the development and overload of acceleration. However, manipulating SSG constraints to expose athletes to the maximal mean competition speed is required.

Dopamine D1-like receptors in prelimbic, but not infralimbic, medial prefrontal cortex contribute to chronic stress-induced increases in cue-induced relapse to palatable food seeking during forced abstinence.

Chronic stress exposure causes increased vulnerability to future relapse-like behavior in male, but not female, rats with a history of palatable food self-administration. These effects are mediated by dopamine D1-like receptors, but the anatomical location of chronic stress' dopaminergic mechanism is not known. Thus, male rats were trained to respond for palatable food pellets in daily sessions. During subsequent forced abstinence from food self-administration, stress was manipulated (0 or 3 h restraint/day for 7 days). Rats also received bilateral microinjections of the D1-like receptor antagonist SCH-23390 (0.25 µg/0.5 µl/side) or vehicle (0.5 µl/side) delivered to either prelimbic or infralimbic medial prefrontal cortex prior to daily treatments. Relapse tests in the presence of food-associated cues were conducted 7 days after the last treatment. Stress caused an increase and a decrease in responding during relapse tests in rats that received prelimbic vehicle and SCH-23390 infusions, respectively, relative to unstressed rats. In rats receiving IL infusions, however, stress caused an increase in responding regardless of whether the infusion was vehicle or SCH-23390. These results establish a specific role for prelimbic D1-like receptors in chronic stress-potentiated relapse.

Concurrent Validity of Power From Three On-Water Rowing Instrumentation Systems and a Concept2 Ergometer.

Purpose: Instrumentation systems are increasingly used in rowing to measure training intensity and performance but have not been validated for measures of power. In this study, the concurrent validity of Peach PowerLine (six units), Nielsen-Kellerman EmPower (five units), Weba OarPowerMeter (three units), Concept2 model D ergometer (one unit), and a custom-built reference instrumentation system (Reference System; one unit) were investigated. Methods: Eight female and seven male rowers [age, 21 ± 2.5 years; rowing experience, 7.1 ± 2.6 years, mean ± standard deviation (SD)] performed a 30-s maximal test and a 7 × 4-min incremental test once per week for 5 weeks. Power per stroke was extracted concurrently from the Reference System (via chain force and velocity), the Concept2 itself, Weba (oar shaft-based), and either Peach or EmPower (oarlock-based). Differences from the Reference System in the mean (representing potential error) and the stroke-to-stroke variability (represented by its SD) of power per stroke for each stage and device, and between-unit differences, were estimated using general linear mixed modeling and interpreted using rejection of non-substantial and substantial hypotheses. Results: Potential error in mean power was decisively substantial for all devices (Concept2, -11 to -15%; Peach, -7.9 to -17%; EmPower, -32 to -48%; and Weba, -7.9 to -16%). Between-unit differences (as SD) in mean power lacked statistical precision but were substantial and consistent across stages (Peach, ∼5%; EmPower, ∼7%; and Weba, ∼2%). Most differences from the Reference System in stroke-to-stroke variability of power were possibly or likely trivial or small for Peach (-3.0 to -16%), and likely or decisively substantial for EmPower (9.7-57%), and mostly decisively substantial for Weba (61-139%) and the Concept2 (-28 to 177%). Conclusion: Potential negative error in mean power was evident for all devices and units, particularly EmPower. Stroke-to-stroke variation in power showed a lack of measurement sensitivity (apparent smoothing) that was minor for Peach but larger for the Concept2, whereas EmPower and Weba added random error. Peach is therefore recommended for measurement of mean and stroke power.

Relationships between measures of boat acceleration and performance in rowing, with and without controlling for stroke rate and power output.

PURPOSE: Boat acceleration profiles provide a valuable feedback tool by reflecting both rower technique and force application. Relationships between measures of boat acceleration and velocity to inform interpretation of boat acceleration profiles in rowing were investigated here. METHODS: Thirteen male singles, nine female singles, eight male pairs, and seven female pairs participated (national and international level, age 18-27 y). Data from each stroke for 74 2000-m races were collected using Peach PowerLine and OptimEye S5 GPS units. General linear mixed modelling established modifying effects on velocity of two within-crew SD of boat acceleration variables for each boat class, without and with adjustment for stroke rate and power, to identify potential performance-enhancement strategies for a given stroke rate and power. Measures of acceleration magnitude at six peaks or dips, and six measures of the rate of change (jerk) between these peaks and dips were analyzed. Results were interpreted using rejection of non-substantial and substantial hypotheses with a smallest substantial change in velocity of 0.3%. RESULTS: Several boat acceleration measures had decisively substantial effects (-2.4-2.5%) before adjustment for stroke rate and power. Most effect magnitudes reduced after adjustment for stroke rate and power, although maximum negative drive acceleration, peak drive acceleration, jerk during the mid-drive phase, and jerk in the late recovery remained decisively substantial (-1.8-1.9%) in some boat classes. CONCLUSION: Greater absolute values of maximum negative drive acceleration and jerk in the late recovery are related to improved performance, likely reflecting delayed rower centre-of-mass negative acceleration in preparation for the catch. Greater absolute values of peak drive acceleration, first peak acceleration, and jerk in the early and mid-drive are also associated with improved performance, likely reflecting propulsive force during the drive. These proposed mechanisms provide potential strategies for performance enhancement additional to increases in stroke rate and power output.

The Quantification of Acceleration Events in Elite Team Sport: a Systematic Review.

BACKGROUND: Wearable tracking devices are commonly utilised to quantify the external acceleration load of team sport athletes during training and competition. The ability to accelerate is an important attribute for athletes in many team sports. However, there are many different acceleration metrics that exist in team sport research. This review aimed to provide researchers and practitioners with a clear reporting framework on acceleration variables by outlining the different metrics and calculation processes that have been adopted to quantify acceleration loads in team sport research. METHODS: A systematic review of three electronic databases (CINAHL, MEDLINE, SPORTDiscus), was performed to identify peer-reviewed studies that published external acceleration load in elite team sports during training and/or competition. Articles published between January 2010 and April 2020 were identified using Boolean search phrases in relation to team sports (population), acceleration/deceleration (comparators), and competition and/or training (outcome). The included studies were required to present external acceleration and/or deceleration load (of any magnitude) from able-bodied athletes (mean age ≥ 18 years) via wearable technologies. RESULTS: A total of 124 research articles qualified for inclusion. In total, 113/124 studies utilised GPS/GNSS technology to outline the external acceleration load of athletes. Count-based metrics of acceleration were predominant of all metrics in this review (72%). There was a lack of information surrounding the calculation process of acceleration with 13% of studies specifying the filter used in the processing of athlete data, whilst 32% outlined the minimum effort duration (MED). Markers of GPS/GNSS data quality, including horizontal dilution of precision (HDOP) and the average number of satellites connected, were outlined in 24% and 27% of studies respectively. CONCLUSIONS: Team sport research has predominantly quantified external acceleration load in training and competition with count-based metrics. Despite the influence of data filtering processes and MEDs upon acceleration, this information is largely omitted from team sport research. Future research that outlines acceleration load should present filtering processes, MEDs, HDOP, and the number of connected satellites. For GPS/GNSS systems, satellite planning tools should document evidence of available satellites for data collection to analyse tracking device performance. The development of a consistent acceleration filtering method should be established to promote consistency in the research of external athlete acceleration loads.

Corrigendum: Technical Determinants of On-Water Rowing Performance.

[This corrects the article DOI: 10.3389/fspor.2020.589013.].

Classification of Australian football kick types in-situation via ankle-mounted inertial measurement units.

The utility of inertial measurement units (IMUs) for sporting skill and performance analysis during training and competition is advantageous for enhancing the objectivity of athlete monitoring. This study aimed to classify Australian Rules football (AF) kick types in an applied environment using ankle-mounted IMUs. IMUs and video capture of a controlled protocol, including four kick types at varying distances, were recorded during a single testing session with female AF athletes (n = 20). Processed IMU data were modelled using support vector machine classifier, random forest, and k-nearest neighbour algorithms under a 2-Kick, 4-Kick, and kick distance (10, 20, 30 m) conditions. The random forest model showed the highest results for overall classification accuracy (83% 2-Kick and 80% 4-Kick), test F1-score (0.76 2-Kick and 0.81 4-Kick), and AUC score (0.58 2-Kick and 0.60 4-Kick). Kick distance classification showed a model test and class weighted F1-score of 0.63 and overall accuracy of 64%, respectively. This study highlights the potential for an applied semi-automated AF training kick detection and type classification system using IMUs.