Comparison of gait speed reserve, usual gait speed, and maximum gait speed of adults aged 50+ in Ireland using explainable machine learning

Gait speed is a measure of general fitness. Changing from usual (UGS) to maximum (MGS) gait speed requires a general effort across many body systems. The difference, MGS − UGS, is defined as gait speed reserve (GSR). In the present study, using 3925 participants aged 50+ from Wave 3 of The Irish Longitudinal Study on Ageing (TILDA), we used a gradient boosted trees-based stepwise feature selection pipeline for the discovery of clinically relevant predictors of GSR, UGS, and MGS using a shortlist of 88 features across 5 categories (socio-demographics/anthropometrics/medical history; cardiovascular system; physical strength; sensory; and cognitive/psychological). The TreeSHAP explainable machine learning package was used to analyse the input-output relationships of the three models. The mean R2adj (SD) from 5-fold cross validation on training data and the R2adj score on test data for the models are: 0.38 (0.04) and 0.41 for UGS; 0.45 (0.04) and 0.46 for MGS; and 0.19 (0.02) and 0.21 for GSR. Features selected for the UGS model were: age, chair stands time, body mass index, grip strength, number of medications, resting state pulse interval, mean motor reaction time in the choice reaction time test, height, depression score, sit-to-stand difference in diastolic blood pressure, and left visual acuity. The features selected for the MGS model were: age, grip strength, repeated chair stands time, body mass index, education, mean motor reaction time in the choice reaction time test, number of medications, height, the standard deviation of the mean reaction time in the sustained attention to response task, mean heart rate at resting state, fear of falling, MOCA errors, orthostatic intolerance during active stand, smoking status, total heart beat power during paced breathing, the root mean square of successive differences between heartbeats during paced breathing, and visual acuity. Finally, the features chosen for the GSR model were: mean motor reaction time in the choice reaction time test, grip strength, education, chair stands time, MOCA errors, accuracy proportion in the sound induced flash illusion (two beeps and one flash with stimulus-onset asynchrony of +150 ms), fear of falling, height, age, sex, orthostatic intolerance, MMSE errors, and number of cardiovascular conditions. MGS and UGS were more explainable than GSR. All three models contain features from all five categories. There were common features to all three models (age, grip strength, chair stands time, mean motor reaction time in the choice reaction time test, and height), but also some features unique to each of them. Overall, findings on all three models were clinically plausible and support a network physiology approach to the understanding of predictors of performance-based tasks. By employing an explainable machine learning technique, our observations may help clinicians gain new insights into the multisystem predictors of gait speed and gait speed reserve in older adults.

Criteria for determining the preparedness of boxers and fencers of various qualifications

The study is devoted to determine the objective criteria characterizing the preparedness of boxers and fencers of various qualifications at the end of the preparatory period of the training macrocycle. It has been revealed that with the advanced training of combatants at the stages of long-term training, the number of correlations between time indicators of their specialized movements is growing. Scientists believe that certain components of the generally recognized system of training athletes can be improved and modified by the influence of certain factors. Especially when considering the issues of individualizing the training of highly skilled athletes. Sports form is a major factor in achieving high athletic performance. Formation, preservation and temporary loss of sportswear occur within the training cycle. The sports form is a purely individual state of the athlete's body. Sports are divided by objective and subjective attributes of determining the winner of the competition. The results of numerous measurements of the motor reaction time indicators, the time of boxers punches or fencers touches from close and long combat distances show that reliable relationships between certain indicators of specialized actions can be considered as one of the objective criteria for the training of combatants. For the purpose of pedagogical control at various stages of long-term training of athletes, it is advisable to determine their level of preparedness on the basis of specialized actions time indicators (time of motor reaction, time of punch or touche from close and long combat distance), as well as the presence of statistically significant relationships between time indicators of motor reaction, attacks time from close combat distance (punch or touche without moving on legs) and long combat distance (punch or touche with move forward). The purpose of preparing athletes for competitions is to obtain optimal readiness to achieve high results based on the harmonious unity of all parties.

Comparative Analysis of Starting Technique in Competitive Swimming and Finswimming

The study purpose was to determine time characteristics of the start phases: “jump” and “flight” performed by highly-skilled swimmers in competitive swimming and finswimming during the start from the starting block. Materials and methods. The participants of the pedagogical study were 8 competitive swimming female athletes, 7 – bifin swimming athletes, 4 – monofin swimmers. The swimmers were highly-skilled: among them were three international masters of sport, thirteen masters of sport of Ukraine, and three candidate masters of sport. The study recorded the following indicators: motor reaction time, horizontal flight speed (in different sections); flight acceleration (in different sections). Results. The difference in horizontal speed in the first section is not statistically significant (p > 0.05). The bifin swimming athletes show higher speed in sections 2 and 4; in section 3, higher speed is shown by the monofin swimmers (p < 0.001). The bifin swimmers show higher results in flight acceleration in sections 1, 2 and 4; in section 3, higher acceleration is shown by the monofin swimmers (p < 0.001). Conclusions. For comparative analysis of the starting technique, it is advisable to use such indicators as motor reaction time, horizontal flight speed, flight acceleration, and flight trajectory indicators as the main criteria. The study found that the time of motor reaction in competitive swimming is the shortest and it is the longest in monofin swimming. The athletes show the highest horizontal flight speed in section 3, the highest acceleration in section 2. The monofin swimming athletes show the highest acceleration in section 3. The second discriminant function with the emphasis on the most informative variables can be used to select the most rational starting technique in finswimming.