Comparative Characteristics of Sensorimotor Reactions of Highly Qualified Athletes with Different Types of Heart Rate Regulation

The purpose of the study was a comparative analysis of sensorimotor reactions in highly trained athletes with different types of heart rate regulation. Materials and methods. 202 highly trained male athletes aged 22.6±2.8 years, who are engaged in acyclic sports – martial arts (karate, taekwondo, kickboxing, boxing, freestyle wrestling, Greco-Roman wrestling, judo, sambo) and games (water polo, soccer) were examined. The experience in sports was 10.3±3.1 years. All studies were conducted in the pre-competition period in the morning. Based on the study of heart rate variability in athletes, the type of heart rate regulation was determined. The basis for determining the types of regulation is the classification of heart rate variability indicators, taking into account their inclusion in certain limits. Heart rate variability indicators that reflect the dual-circuit model of heart rate regulation and are used for diagnosis include: total heart rate variability – total power (ms2), very low frequency (ms2), and stress-index (e.u.), which reflect the various chains of regulatory effects on heart rate. According to certain data types, 4 groups were formed. 1 group (type I) consisted of 42 athletes, 2 (type II) – 28 athletes, 3 (type III) – 88 athletes, 4 (type IV) – 44 athletes. The study of sensorimotor function was performed using the device KMM-3. Results and discussion. It is shown that the most balanced sensorimotor reactions are in athletes with type III regulation of heart rate. The most strain sensorimotor reactions are observed in type II regulation of heart rate, which is reflected in the pronounced central asymmetry of movement control with acceleration to the left against the background of deteriorating accuracy of right (due to flexors) and left (due to extensors) limbs, and the right-hand predominance. Sensorimotor reactions are quite strain in type IV of heart rate regulation, which is characterized by slow reactions at the synaptic and peripheral levels. In type I of heart rate regulation, the disorders observed at the central level of regulation relate to the asymmetry of short-term motor memory processes, which are significantly reduced in the left hemisphere. Conclusion. The study shows that the differences in the regulatory support of heart rate in highly qualified athletes are accompanied by characteristic differences in sensorimotor function. The latter can be useful for the diagnosis and further correction of conditions associated with the development of overexertion and overtraining

Improving Explainability of Major Risk Factors in Artificial Neural Networks for Auto Insurance Rate Regulation

In insurance rate-making, the use of statistical machine learning techniques such as artificial neural networks (ANN) is an emerging approach, and many insurance companies have been using them for pricing. However, due to the complexity of model specification and its implementation, model explainability may be essential to meet insurance pricing transparency for rate regulation purposes. This requirement may imply the need for estimating or evaluating the variable importance when complicated models are used. Furthermore, from both rate-making and rate-regulation perspectives, it is critical to investigate the impact of major risk factors on the response variables, such as claim frequency or claim severity. In this work, we consider the modelling problems of how claim counts, claim amounts and average loss per claim are related to major risk factors. ANN models are applied to meet this goal, and variable importance is measured to improve the model’s explainability due to the models’ complex nature. The results obtained from different variable importance measurements are compared, and dominant risk factors are identified. The contribution of this work is in making advanced mathematical models possible for applications in auto insurance rate regulation. This study focuses on analyzing major risks only, but the proposed method can be applied to more general insurance pricing problems when additional risk factors are being considered. In addition, the proposed methodology is useful for other business applications where statistical machine learning techniques are used.

Features of heart rate variability in patients with takotsubo syndrome

Funding Acknowledgements Type of funding sources: None. Main funding source(s): North-Western State Medical University named after I.I. Mechnikov Objective to study the features of autonomic regulation of sinus rhythm features of autonomic regulation of cardiac sinus rhythm in patients with Takotsubo syndrome (TTS) during inpatient stay in hospital. Materials and methods. The study included 25 female patients (the median age 57.5 ± 28.5 years) with TTS, diagnosis was based on the InterTAK criteria. On the 5-7th day after admission, the heart rate variability (HRV) was assessed both at rest and cardiac autonomic function tests: the deep breathing test (DBT) and active orthostatic test (AOT) with the usage of a computer diagnostic system «Valenta». RESULTS According to HRV data, initially at rest, the majority of the studied patients predominantly had a parasympathetic impact on the heart rate regulation: in 70% - increased parasympathetic influence, in 17% - increased sympathetic influence, in 13% - a balanced heart rate regulation. When performing a DBT, the predominance of the parasympathetic influence on the heart rate was noted both in spectral parameters and according to the data of time analysis (HF during DBT increased 1.8 times up to 489.6 ± 114.2 ms2 (p <0.05) ; LF decreased 1.7 times up to 254.1 ± 70.3 ms2 (p <0.05); VLF increased 2.8 times up to 402.3 ± 101.8 ms2 (p <0, 05); TP increased 1.4 times up to 1145.9 ± 251.3 ms2; CV increased 1.3 times up to 6.5 ± 0.7% (p <0.05); SDNN increased 1.3 times up to - 58.7 ± 6.6 ms (p <0.05). HRV measured during an AOT showed a paradoxical evaluation in the parasympathetic impact on the heart rate (HF increased by 1.8 times and reached - 488.0 ± 104.7 ms2 (p <0.05); LF decreased by 1.1 times up to 408 , 4 ± 103.6 ms2; VLF increased 1.2 times up to 166.4 ± 52.2 ms2; TP increased 1.3 times up to 1062.8 ± 181.1 ms2 (p <0.05); CV increased 1.6 times up to 8.0 ± 0.9% (p <0.05); SDNN increased 1.4 times up to 62.6 ± 7.5 ms (p <0.05)). Conclusions During the index hospital inpatient stays the majority of patients with TTS have a vegetative imbalance due to increased parasympathetic influence on the heart rate, both at rest and during a deep breathing test and an active orthostatic test. This fact is quite unexpected and requires further study.