Teaching People by Justifying Tree Search Decisions: An Empirical Study in Curling

In this research note we show that a simple justification system can be used to teach humans non-trivial strategies of the Olympic sport of curling. This is achieved by justifying the decisions of Kernel Regression UCT (KR-UCT), a tree search algorithm that derives curling strategies by playing the game with itself. Given an action returned by KR-UCT and the expected outcome of that action, we use a decision tree to produce a counterfactual justification of KR-UCT’s decision. The system samples other possible outcomes and selects for presentation the outcomes that are most similar to the expected outcome in terms of visual features and most different in terms of expected end-game value. A user study with 122 people shows that the participants who had access to the justifications produced by our system achieved much higher scores in a curling test than those who only observed the decision made by KR-UCT and those with access to the justifications of a baseline system. This is, to the best of our knowledge, the first work showing that a justification system is able to teach humans non-trivial strategies learned by an algorithm operating in self play.

Assessment of accelerometer-derived data in the context of seat height changes in cycling and the impact on running in triathlon

Triathlon has been an Olympic sport since the 2000 Sydney Olympics and has developed rapidly, leading to variations in race categories. Although running after cycling necessitates a postural change from a non-weight-bearing activity to a weight bearing one, no study has quantified the magnitude of trunk acceleration during cycling in different seat positions and the consequential effect on running. Therefore, this study was conducted to evaluate the effectiveness of a triaxial accelerometer to determine acceleration magnitudes of the trunk in a 20 km outdoor cycling event in two seat positions that were immediately followed by a 5 km overground run. Interpretation of data was evaluated based on cadence changes while triathletes cycled in an aerodynamic position in two seat positions. Running data was evaluated based on sinusoidal curves and foot strike peaks. The evaluation of accelerometer derived data within a characteristic overground setting suggests that cycling in an adjusted seat position significantly reduced trunk acceleration in both longitudinal and mediolateral directions with large effects ( p < 0.0001, d > 0.9). A significant and large effect was found in both longitudinal and anteroposterior trunk acceleration in post-cycle running between seat positions ( d > 0.9, p < 0.0001). In the longitudinal direction, a significant reduction in trunk acceleration occurred when running after the seat was adjusted with participants completing the 5 km run faster (21:55 ± 3:17 min compared to 22:05 ± 2:53 min). The results suggest that when the seat position is adjusted based on individual anthropometrics, overall trunk acceleration magnitude is reduced in both cycling and running. Accessible and practical sensor technology could be beneficial for postural considerations in triathlons.

Analysis on specific morfologic adaptation in the game of rugby in 7 - feminine, senior level

With the transition of rugby in 7 as an Olympic sport, performance standards have increased, the game becoming much faster and well structured, which also brings major changes in terms of the morphological profile of the player. The aim of this research is to achieve the morphological profile of rugby players from the first domestic league, and then the results to be compared with those of the players of professional leagues from countries with a tradition in the sport. The study took place in the pre-competition stage, on 24 professional rugby players, all active in the first league of the domestic championship in Romania and Ukraine respectively. The group represented by the team SC Politehnica Iasi, aged between 18-29 years-old and lot B components of the team from Ukraine, aged 18-31 years-old, both teams having rugby experience between 4-18 years-old. The research methods used in the study were: literature analysis, observation, pedagogical experiment, statistical, graphic representation method. The tests applied were: height, body mass, muscle mass, muscle fat tissue and mobility of the spine. The results of the analysis on compartments help to confirm the hypothesis, since following the study started, the players of the forwards compartment fall between the optimal values of the players of lot B, the back compartment recording values close to the optimal ones.

A Cross-Sectional Study of Retired Great British Olympians (Berlin 1936–Sochi 2014): Olympic Career Injuries, Joint Health in Later Life, and Reasons for Retirement from Olympic Sport

Background The relationship between Olympic career sport injury and the long-term musculoskeletal health of the elite athlete remains unclear. This study describes the lifetime prevalence of medical attention injuries that occurred during training and/or competition as part of the athlete’s Olympic career, reasons for retirement from Olympic sport, and the point prevalence of pain and osteoarthritis (OA) among retired Great Britain’s (GB) Olympians. Methods This cross-sectional study involved distributing a questionnaire to retired GB Olympians who had competed at 36 Olympic Games between Berlin 1936 and Sochi 2014. The questionnaire captured Olympic career injury history (lasting ≥ 1 month), sport exposure, musculoskeletal pain (last 4 weeks), physician-diagnosed OA, and joint replacement. Injury prevalence was calculated for sports with a minimal of 15 respondents. Adjusted odds ratios (aOR) were estimated in logistic regression for pain, OA, and joint replacement. Models were adjusted for age, sex, BMI, and career duration. Results Six hundred fifty (57.8% male; 42.2% female) retired athletes representing 40 sports (29 summer; 11 winter), aged 60.5 years (range 23–97), completed the questionnaire. Overall, 721 injuries (368 athletes) were self-reported equating to a lifetime Olympic career injury prevalence of 56.6%. Injury prevalence was highest in field athletics (81.0%), gymnastics (75.0%), and track athletics (67.7%). Injuries most frequently occurred at the knee (19.0%), lower back (15.4%), and shoulder (11.5%). Of those injured, 19.5% retired from sport due to injury. Pain was most prevalent at the lumbar spine (32.8%), knee (25.3%), and hip (22.5%), and OA at the knee (13.4%), hip (10.4%), and lumbar spine (4.6%). Injury was associated with pain at the hip (aOR 4.88; 95% CI, 1.87–12.72, p = 0.001), knee (aOR 2.35; 95% CI, 1.45–3.81, p = 0.001), and lumbar spine (aOR 2.53; 95% CI, 1.63–3.92, p < 0.001); OA at the hip (aOR 5.97; 95% CI, 1.59–22.47, p = 0.008) and knee (aOR 3.91; 95% CI, 2.21–6.94, p < 0.001); and joint replacement at the hip (aOR 8.71; 95% CI, 2.13–35.63, p = 0.003) and knee (aOR 5.29; 95% CI, 2.39–11.74, p < 0.001). Conclusion The lifetime prevalence of Olympic career injury was 56.6%, with those injured more likely to self-report current pain and/or OA at the hip, knee, and lumbar spine and joint replacement at the hip and knee.

Analysis of vertical and horizontal impulsion in male handball athletes from joinville-sc

Handball has become a popular sport because it is easy to learn and very common in Brazilian schools, mostly, given that it is an Olympic sport. The goal of this study is to analyze the vertical and horizontal impulsion index in male handball athletes from Joinville. The sample counted 17 athletes with ages ranging from 14 to 18 years old. Seventeen athletes belonging to the handball team of the city of Joinville were investigated. For data collection the tests were used: Sargent Jump Test (Sargent, 1921) and Lower Limb Explosive Strength Test (GAYA, 2016), in all jumps three attempts were performed and only the highest of them was taken into account for validation. After the results in the tests the athletes obtained in the Jump Without Assistance (SSA), 47.05% of the athletes had a result considered GOOD, 35.29% were considered REGULAR and 17.64% in the VERY GOOD. In the Sargent Jump with aid of upper limbs, with the nomenclature Jump with Aid (SCA), 41.17% had jumps considered VERY GOOD, 35.29% considered GOOD, 11.76% considered GREAT and 5.88% considered REGULAR. In the lower limbs explosive strength test (TFEMI), 41.18% of the athletes were classified as VERY GOOD, 29.41% as GOOD, 23.52% as REASONABLE, and 5.88% as FAIL. After the conclusion of the data collection and analysis, the athletes in this study were classified with a jump considered good for their age group and most of the analyzed athletes had results higher than expected. The author highlights that with a more detailed study and with a more in-depth approach, so as to corroborate with other studies and with this one for future research.