Getting a Grip on Strength Measurement in Children (6-13 Y): Impact of Typical Error of Measurement.

PURPOSE: To identify the smallest change in handgrip strength (HGS) in children that can be considered of practical significance. METHOD: A total of 290 male and female children, aged 6-13 years, performed a HGS testing protocol 3 times within a 7-day period. The typical error of measurement (TE), coefficient of variation, and smallest worthwhile change (SWC) were calculated for each sex and age group (grade). RESULTS: The TE for the combined group of grade 1 to 7 children was 1.3 kg. Changes in HGS associated with a small change were 1.3 kg, making it difficult for the HGS test to detect these changes. The TE was less than the medium (3.3 kg) and large (5.3 kg) changes in HGS for all the grades and sexes, making changes of these magnitudes more interpretable as they exceed the "noise" (TE) of the measurement. CONCLUSION: Changes in HGS greater than the TE and SWC can be considered real changes of practical significance. This provides researchers with an extra level of analysis when trying to determine the practical relevance of the observed changes.

Tackler and ball-carrier technique during moderate and severe injuries (≥8 days lost) compared with player-matched and team-matched injury-free controls in Elite Rugby Union.

OBJECTIVE: To analyse tackler and ball-carrier technical proficiency during moderate and severe contact injuries (≥8 days lost) in professional rugby union, and compare it with injury-free event-matched controls from the same player and from the same team. METHODS: Technical proficiency for 74 (n=74) (moderate and severe; ≥8 days lost) tackler and ball-carrier injuries during The Currie Cup (2014-2018) and 623 matched non-injury events (253 own controls, 370 team controls) were examined through video analysis using a standardised list of technical criteria. RESULTS: Mean technical proficiency score for injured tacklers during front-on tackles was 6.19/16 (arbitrary units (AU) 95% CI 4.89 to 7.48), which was significantly different to their own controls (8.90/16 AU, 95% CI 8.37 to 9.43, p<0.001, effect size (ES)=1.21, large) and team controls (9.93/16 AU, 95% CI 9.50 to 10.40, p<0.001, ES=1.71, large). Mean technical proficiency score for injured ball-carriers during front-on tackles was 5.60/14 AU (95% CI 4.65 to 6.55), which was significantly different to their own controls (8.08/14 AU, 95% CI 7.56 to 8.60, p<0.001, ES=1.16, moderate) and team controls (8.16/14 AU, 95% CI 7.75 to 8.57, p<0.001, ES=1.25, large). CONCLUSION: For the tackler and ball-carrier, for both front-on and side-on/behind tackles, overall technical proficiency scores were significantly lower for the injury-causing event, when compared with the player's own injury-free tackles and the team's injury-free tackles. Through analysing player and team controls, player technique deficiencies for the injured player and player technique deficiencies that expose all players to injury were highlighted, which may inform injury prevention strategies and policies, and assist coaches in optimising training to reduce tackle injury risk.

BokSmart rugby safety education courses are associated with improvements in behavioural determinants in attending coaches and referees: presurvey-postsurvey study.

BACKGROUND/AIM: BokSmart is a nationwide injury prevention programme that aims to reduce players' injury risk mainly through education of coaches and referees in mandatory biennial education courses. These courses are held throughout each rugby season. The objective of this cross-sectional study was to assess whether these courses were associated with improvements in attendees' behavioural determinants. METHODS: Coaches and referees completed a questionnaire based on the theory of planned behaviour, immediately before and after their 2012 BokSmart courses. Twelve behavioural determinants were assessed on a five-point Likert scale and open-ended questions. A meaningful change was defined as an improvement of ≥1 unit score supported by null hypothesis testing. Odds of improving by ≥1 unit score (compared with not improving) were assessed in attendees using multivariate logistic regression. RESULTS: In total, 390 coaches and 74 referees completed both questionnaires. 'Before' scores were high for most outcomes, except for knowledge. Although there was a significant (p<0.001) improvement in all 'after' course scores, the only meaningful change (=1 unit) was in knowledge of scrum techniques/rules. CONCLUSION: Although the only meaningful improvement in 2012 BokSmart course attendees was in one outcome, it should be noted that before-course scores were already high, reducing the questionnaire's ability to assess change because of a ceiling effect. Nonetheless, the knowledge acquisition of these courses was low and not related to previous course attendance or more years of rugby experience. These results justify the biennial nature of this safety course but also indicate that knowledge acquisition is generally low.

Assessing tackle performance using a novel collision sport simulator in comparison to a "live" one-on-one tackling drill.

It is necessary to study the rugby tackle as it is associated with successful performance outcomes and is responsible for the majority of contact injuries. A novel collision sport simulator was developed to study tackle performance. The main aim of this validation study was to assess tackle technique performance between two different conditions: simulator versus a standardised one-on-one tackle drill previously used to assess technique. Tackling proficiency was assessed using a list of technical criteria. Mean scores, standard deviations and Cohen's d effect sizes were calculated. Mean overall score for dynamic i.e. running simulator tackles was 7.78 (95%CI 7.58-7.99) (out of 9) or 87% (standard deviation or SD±8.94), and mean overall score for dynamic "live" tackles was 7.85 (95%CI 7.57-8.13) (out of 9) or 87% (SD±9.60) (effect size = 0.08; trivial; p > 0.05). Mean overall score for static i.e. standing simulator tackles was 7.45 (95%CI 7.20-7.69) (out of 9) or 83% (SD±10.71), and mean overall score for static "live" tackles was 8.05 (95%CI 7.83-8.27) (out of 9) or 89% (SD±7.53) (effect size = 0.72; moderate; p < 0.001). The simulator replicates dynamic tackle technique comparable to real-life tackle drills. It may be used for research analysing various aspects of the tackle in rugby and other contact sports.

'In a blink of an eye your life can change': experiences of players sustaining a rugby-related acute spinal cord injury.

BACKGROUND: Though rare, rugby union carries a risk for serious injuries such as acute spinal cord injuries (ASCI), which may result in permanent disability. Various studies have investigated injury mechanisms, prevention programmes and immediate medical management of these injuries. However, relatively scant attention has been placed on the player's experience of such an injury and the importance of context. AIM: The aim of this study was to explore the injury experience and its related context, as perceived by the catastrophically injured player. METHODS: A qualitative approach was followed to explore the immediate, postevent injury experience. Semi-structured interviews were conducted with 48 (n=48) players who had sustained a rugby-related ASCI. RESULTS: Four themes were derived from the data. Participants described the context around the injury incident, which may be valuable to help understand the mechanism of injury and potentially minimise risk. Participants also described certain contributing factors to their injury, which included descriptions of foul play and aggression, unaccustomed playing positions, pressure to perform and unpreparedness. The physical experience included signs and symptoms of ASCI that is important to recognise by first aiders, fellow teammates, coaches and referees. Lastly, participants described the emotional experience which has implications for all ASCI first responders. SIGNIFICANCE: All rugby stakeholders, including players, first responders, coaches and referees, may gain valuable information from the experiences of players who have sustained these injuries. This information is also relevant for rugby safety initiatives in shaping education and awareness interventions.

Coach-directed education is associated with injury-prevention behaviour in players: an ecological cross-sectional study.

BACKGROUND/AIM: Rugby union ('rugby') presents an above-average risk of injury to participants. BokSmart is a South African nationwide intervention that aims to reduce rugby-related injuries in players. This is achieved by educating coaches and referees to improve injury behaviour of players. Thus, the aim of this study was to assess if the receipt of injury-prevention education was associated with player behaviour. METHODS: Junior (n=2279) and senior (n=1642) players, who attended merit-based South African Rugby tournaments (2008-2012), completed an anonymous questionnaire. Logistic regressions investigated if player injury-prevention behaviours were associated with the receipt of education on the same topic. Additionally, players' preferred sources of education were explored through frequency and χ2 analyses. RESULTS: Of the 16 injury-prevention behaviours, 12 (75%) were associated with receiving education on that topic. The four behaviours not associated with education were: warming-up (before training and matches), and avoiding heat and massage post injury. Of the seven possible sources of this education, the majority of players chose either coaches or physiotherapists as their preferred media. In comparison with junior players, more senior players chose physiotherapists instead of coaches for warming-up and cooling-down education. CONCLUSIONS: The results of this study support, to a large degree, the strategy of BokSmart-influence of player behaviour through coach education. However, these findings also suggest that BokSmart could target team physiotherapists in addition to coaches and referees with their safety education. Also, players might have different preferences for this education depending on their age.

The BokSmart intervention programme is associated with improvements in injury prevention behaviours of rugby union players: an ecological cross-sectional study.

BACKGROUND/AIM: Participants of rugby union ('rugby') have an above-average risk of injury compared with other popular sports. Thus, BokSmart, a nationwide injury prevention programme for rugby, was introduced in South Africa in 2009. Improvements in injury-preventing behaviour of players are critical to the success of an intervention. The aim of this study was to assess whether BokSmart has been associated with improvements in rugby player behaviour. METHODS: An anonymous knowledge, attitude and self-reported behaviour questionnaire was completed by junior (under-18) and senior (adult) tournament players who attended merit-based tournaments (2008-2012). The questionnaire was completed by 2279 junior players (99% of total estimated population) from 111 teams and 1642 senior players (96% of population) from 81 teams. A generalised linear model assessed behavioural changes over this time period. RESULTS: Nine (50%) of the behaviours improved significantly (p<0.005) between 2008 and 2012 and the remaining behaviours remained unchanged. Improved behaviours included the targeted, catastrophic injury-preventing behaviours of the intervention: practising of tackling (adjusted overall improvement in odds: 56%) and scrummaging, in forwards only (58%), techniques. Other behaviours that improved significantly were postinjury compression and elevation as well as alcohol avoidance, mouthguard use (training and matches) and cooling down (training and matches). Practising of safe rucking techniques; warming up before training/matches; ice use; heat, massage and alcohol avoidance postinjury; and preseason and off-season conditioning remained unchanged. CONCLUSIONS: BokSmart is associated with improvements in targeted injury-preventing behaviours in players. Future research should ascertain whether self-reported behaviours reflect actual behaviour and whether the observed improvements translate into changes in injury rates.

Methods of prescribing relative exercise intensity: physiological and practical considerations.

Exercise prescribed according to relative intensity is a routine feature in the exercise science literature and is intended to produce an approximately equivalent exercise stress in individuals with different absolute exercise capacities. The traditional approach has been to prescribe exercise intensity as a percentage of maximal oxygen uptake (VO2max) or maximum heart rate (HRmax) and these methods remain common in the literature. However, exercise intensity prescribed at a %VO2max or %HRmax does not necessarily place individuals at an equivalent intensity above resting levels. Furthermore, some individuals may be above and others below metabolic thresholds such as the aerobic threshold (AerT) or anaerobic threshold (AnT) at the same %VO2max or %HRmax. For these reasons, some authors have recommended that exercise intensity be prescribed relative to oxygen consumption reserve (VO2R), heart rate reserve (HRR), the AerT, or the AnT rather than relative to VO2max or HRmax. The aim of this review was to compare the physiological and practical implications of using each of these methods of relative exercise intensity prescription for research trials or training sessions. It is well established that an exercise bout at a fixed %VO2max or %HRmax may produce interindividual variation in blood lactate accumulation and a similar effect has been shown when relating exercise intensity to VO2R or HRR. Although individual variation in other markers of metabolic stress have seldom been reported, it is assumed that these responses would be similarly heterogeneous at a %VO2max, %HRmax, %VO2R, or %HRR of moderate-to-high intensity. In contrast, exercise prescribed relative to the AerT or AnT would be expected to produce less individual variation in metabolic responses and less individual variation in time to exhaustion at a constant exercise intensity. Furthermore, it would be expected that training prescribed relative to the AerT or AnT would provide a more homogenous training stimulus than training prescribed as a %VO2max. However, many of these theoretical advantages of threshold-related exercise prescription have yet to be directly demonstrated. On a practical level, the use of threshold-related exercise prescription has distinct disadvantages compared to the use of %VO2max or %HRmax. Thresholds determined from single incremental tests cannot be assumed to be accurate in all individuals without verification trials. Verification trials would involve two or three additional laboratory visits and would add considerably to the testing burden on both the participant and researcher. Threshold determination and verification would also involve blood lactate sampling, which is aversive to some participants and has a number of intrinsic and extrinsic sources of variation. Threshold measurements also tend to show higher day-to-day variation than VO2max or HRmax. In summary, each method of prescribing relative exercise intensity has both advantages and disadvantages when both theoretical and practical considerations are taken into account. It follows that the most appropriate method of relative exercise intensity prescription may vary with factors such as exercise intensity, number of participants, and participant characteristics. Considering a method's limitations as well as advantages and increased reporting of individual exercise responses will facilitate accurate interpretation of findings and help to identify areas for further study.

Perceptual cues in the regulation of exercise performance - physical sensations of exercise and awareness of effort interact as separate cues.

It has been argued that the physical sensations induced by exercise, measured as the ratings of perceived exertion (RPE), are distinct from the sense of effort. This study aimed to determine whether a new measure of task effort - the Task Effort and Awareness (TEA) score - is able to measure sensations distinct from those included in the conventional RPE scale. Seven well-trained cyclists completed a maximal effort 100 km time trial (TT) and a submaximal trial at 70% of the power sustained during the TT (70% TT). Five maximal 1 km sprints were included in both trials. Both the RPE related solely to physical sensation (P-RPE) and the TEA score increased during the TT and were linearly related. During the 70% TT, both P-RPE and TEA scores increased, but TEA increased significantly less than P-RPE (p<0.001). TEA scores reached maximal values in all 1 km sprints in both the maximal TT and 70% TT, whereas the RPE increased progressively, reaching a maximal value only in the final 1 km sprints in both the TT and the 70% TT. These results indicate that the physical sensations of effort measured as the P-RPE act as the template regulating performance during exercise and that deviation from that template produces an increase in the sense of effort measured by the TEA score. Together, these controls ensure that the chosen exercise intensity does not threaten bodily homeostasis. Our findings also explain why submaximal exercise conducted within the constraints of the template P-RPE does not produce any conscious awareness of effort.

Measuring training load in sports.

The principle of training can be reduced to a simple "dose-response" relationship. The "response" in this relationship can be measured as a change in performance or the adaptation of a physiological system. The "dose" of training, or physiological stress associated with the training load, is more difficult to measure as there is no absolute "gold standard" which can be used in the field, making it difficult to validate procedures. Attempts have been made to use heart rate as a marker of intensity during training, but the theoretical attractiveness of this method is not supported by the accuracy and the practicality of using this method during training or competition. The session RPE, based on the product of training duration and perceived intensity is more practical and can be used in a variety of sports. However, the score depends on a subjective assessment, and the intersubject comparisons may be inaccurate. The demands of different sports vary and therefore the methods of assessing training need to vary accordingly. The time has come to reach consensus on assessing training accurately in different sports. There is a precedent for this consensus approach with scientists having already done so for the assessment of physical activity, and for defining injuries in rugby, football and cricket. Standardizing these methods has resulted in the quality of research in these areas increasing exponentially.

The quantification of training load, the training response and the effect on performance.

Historically, the ability of coaches to prescribe training to achieve optimal athletic performance can be attributed to many years of personal experience. A more modern approach is to adopt scientific methods in the development of optimal training programmes. However, there is not much research in this area, particularly into the quantification of training programmes and their effects on physiological adaptation and subsequent performance. Several methods have been used to quantify training load, including questionnaires, diaries, physiological monitoring and direct observation. More recently, indices of training stress have been proposed, including the training impulse, which uses heart rate measurements and training load, and session rating of perceived exertion measurements, which utilizes subjective perception of effort scores and duration of exercise. Although physiological adaptations to training are well documented, their influence on performance has not been accurately quantified. To date, no single physiological marker has been identified that can measure the fitness and fatigue responses to exercise or accurately predict performance. Models attempting to quantify the relationship between training and performance have been proposed, many of which consider the athlete as a system in which the training load is the input and performance the system output. Although attractive in concept, the accuracy of these theoretical models has proven poor. A possible reason may be the absence of a measure of individuality in each athlete's response to training. Thus, in the future more attention should be directed towards measurements that reflect individual capacity to respond or adapt to exercise training rather than an absolute measure of changes in physiological variables that occur with training.