Ruta Brazdzionyte

Background and Objectives: Controlled breathing can influence autonomic regulation and haemodynamics; however, the role of its timing relative to exercise remains unclear. Materials and Methods: Fourteen healthy, physically active men (mean age 21.8 ± 0.7 years; body mass index within the normal range) participated in this randomised crossover study. Each session consisted of five 5 min cycling bouts at 50% of heart-rate reserve, interspersed with 3 min passive recovery periods. The three conditions were: control (no structured breathing), 30 s hyperventilation (approximately 30 breaths·min⁻¹) performed before each bout, and the same hyperventilation performed after each bout. Resting heart rate variability spectra (low-frequency [LF], high-frequency [HF]) were assessed pre- and post-session; arterial blood pressure was measured stage-wise; quadriceps muscle oxygen saturation (StO₂) was monitored using near-infrared spectroscopy; and a discriminant co-integration index (Dsk) was calculated to integrate multisystem responses. Results: Compared with baseline, LF power increased and HF power decreased after exercise in the control and post-exercise hyperventilation conditions (p < 0.05), whereas pre-exercise hyperventilation attenuated these shifts. Post-exercise hyperventilation blunted the rise in systolic blood pressure and reduced diastolic blood pressure compared with control (p < 0.05). Both breathing interventions accelerated StO₂ recovery, with higher early recovery StO₂ following pre-exercise hyperventilation and sustained advantages after post-exercise hyperventilation (moderate-to-extensive effects). Dsk values were consistently highest after exercise, indicating stronger and more coherent multisystem coupling. Conclusions: In this acute crossover study of healthy young men, hyperventilation performed before or after exercise induced distinct short-term cardiovascular and muscular responses, reflecting respiratory-driven modulation of haemodynamic and autonomic processes. The timing of hyperventilation influenced these responses, suggesting that deliberate hyperventilation may acutely modify exercise-related regulatory mechanisms.

Background and Objectives: Cardiovascular diseases (CVDs) remain the leading cause of mortality worldwide. Regular physical activity (PA) represents a key modifiable factor in CVD prevention. Methods: Fifty-two healthy adult males participated in this study, divided into two groups: aged up to 45 years and over 45 years. The subjects performed a bicycle ergometer exercise and a standardised back muscle workload protocol. ECG, arterial blood pressure (ABP), and muscle oxygen saturation (StO₂) measurements were obtained during workload and recovery. Results: During bicycle ergometer workload, heart rate (HR) at minute 2 was significantly lower in participants over 45 years of age compared to the younger group (126.8–109.8 bpm), while diastolic blood pressure (dBP) was significantly lower in the under-45 group during maximal workload (65.4–71.9 mmHg) and the first minute of recovery (54.6–69.3 mmHg). During workload for back muscles, the over-45 group showed significantly lower dBP at the third rest period (87–74.7 mmHg), while StO₂ was significantly lower in the over-45 group compared to the under-45 group (54.4–77.8%). Conclusions: The findings of this study demonstrate that both bicycle ergometer exercise and standardised back muscle workload had a significant influence on cardiovascular system (CVS) responses, particularly when stratified by age. Participants over the age of 45 exhibited a higher incidence of functional myocardial ischaemia, reduced StO₂ and more pronounced increases in HR during and following exertion.

Background and Objectives: Cardiovascular diseases (CVD) are the primary causes of death throughout the world. Engaging in physical activity (PA) is crucial for the prevention of CVD, as a lack of exercise significantly impacts global health. For health promotion purposes, it is important to optimize PA and develop the main physical components. Multimodal exercise program (MEP) interventions cause unique cardiac changes that can be systematically analyzed using advanced ECG techniques. Using algebraic co-integration methods, this study examined the physiological cardiac adaptations of a 6-week MEP compared to sedentary control subjects. Materials and Methods: A total of 50 physically inactive males, aged 20–35 years, were recruited for a 6-week MEP. The intervention group (IG) consisted of 28 participants, while the control group (CG) included 22 participants. The MEP included balance, endurance, muscle strength, and flexibility exercises in one session. The cardiovascular system (CVS) was assessed using electrocardiography (ECG) and arterial blood pressure during an incremental cycle ergometer test, both before and after the 6-week period. Results: After the post-MEP, the IG’s resting HR showed a slight but insignificant decrease, from 84.5 to 82 bpm, with improved recovery rates at minute 1 (113.1–104.7 bpm). The CG showed a similar trend. pBP in IG significantly increased post-MEP during recovery at minute 1 (73–81) and minute 2 (65–72), where the CG showed a slight but significant difference. DskJT-QRS in IG post-MEP increased significantly during recovery in minutes 1–4, with all values showing p < 0.05. CG showed significance only at minute 3. Conclusions: Both the 6-week MEP and control had a positive impact on the CVS. The statement refers to changes in dynamic interactions between ECG parameters registered during the incremental exercise test and especially during the recovery after workload. Algebraic data co-integration analysis of ECG parameters demonstrated a sensitive assessment of the influence of exercising on the cardiovascular system.