CARDIOVASCULAR RESPONSE OF ATHLETES UNDER DIFFERENT TRAINING CONDITIONS

ABSTRACT Introduction: Improving cardiovascular function is one of the main training goals of many sports. Objective: To understand the characteristics of the cardiovascular response of athletes under different training conditions. Methods: Thirty male basketball students were enrolled. The subjects were divided into A and B groups according to their years of training, with 15 students in each group. Exercise fatigue tests were performed, starting at a low intensity and gradually increasing the load to a relatively high degree of fatigue. Results: The RMSSD value was 42.82±31.41ms in group A and 46.48±35.26ms in group B undera low fatigue state. The LF/HF value of the athletes in group A was 2.86±1.47 and the LF/HF value of the athletes in group B was 2.94±1.68. The RMSSD value was 40.78±31.17ms and 32.37±36.42ms for groups A and B, respectively, undera high fatigue state. Conclusions: Athletes with more years of training can mobilize more cardiac reserves to meet the increase in exercise load in a fatigue state and have better autonomic nervous regulation in the process of reaching a higher degree of fatigue state. Level of evidence II; Therapeutic studies - investigation of treatment results.

Vascular Responses to Simulated Breath-Hold Diving Involving Multiple Reflexes

Breath-hold diving evokes a complex cardiovascular response. The degrees of hypertension induced by the diving reflex are substantial and accentuated by the underwater swimming. This condition provides a circulatory challenge to properly buffer and cushion cardiac pulsations. We determined hemodynamic changes during the diving maneuver. A total of 20 healthy young adults were studied. Hemodynamics were measured during exercise on a cycle ergometer, apnea, face immersion in cold water (trigeminal stimulation), and simulated breath-hold diving. Dynamic arterial compliance (measured by changes in carotid artery diameter via ultrasound divided by changes in carotid blood pressure as assessed by arterial tonometry) increased with simulated diving compared with rest (p=0.007) and was elevated compared with exercise and apnea alone (p<0.01). A significant increase in heart rate was observed with exercise, apnea, and facial immersion when compared with rest (p<0.001). However, simulated diving brought the heart rate down to resting levels. Cardiac output increased with all conditions (p<0.001), with an attenuated response during simulated diving compared with exercise and facial immersion (p<0.05). Mean blood pressure was elevated during all conditions (p<0.001), with a further elevation observed during simulated diving compared with exercise (p<0.001), apnea (p=0.016), and facial immersion (p<0.001). Total peripheral resistance was decreased during exercise and facial immersion compared with rest (p<0.001) but was increased during simulated diving compared with exercise (p<0.001), apnea (p=0.008), and facial immersion (p=0.003). We concluded that central artery compliance is augmented during simulated breath-hold diving to help buffer cardiac pulsations.

Effects of daytime ingestion of melatonin on heart rate response during prolonged exercise

The current study sought to investigate the effect of melatonin consumption on cardiovascular response during submaximal exercise in healthy men. For this purpose, eight students (age: 21.8 ± 0.9) were asked to run for 45 minutes at submaximal intensity after melatonin-(6 mg) or placebo-ingestion, in a randomized and counterbalanced order. Heart rate (HR) and rectal temperature (Tre) evolution during exercise were measured. Blood samples were drawn twice (before and immediately after exercise) for the determination of triglycerides, total cholesterol, high-density lipoprotein cholesterol (HDL-c), lactate, protein, and superoxide dismutase concentrations. The results showed that melatonin may disturb thermoregulatory control by exerting an effect on HR at 10 min of exercise, reducing HR by 6.6% (9 bpm; P < 0.001), and this effect decreased to 3.6% at the end of exercise (P < 0.01). Melatonin has no effect on triglycerides total cholesterol, HDL-c, lactate, and protein at rest and post-exercise. Although melatonin administration did not present a risk for cardiovascular function in healthy men, melatonin at high doses could decrease superoxide dismutase concentrations owing to the alteration of redox balance. These findings suggest that a high concentration of antioxidants does not enhance cardiovascular performance and may impair thermoregulatory control during prolonged exercise.

Respiratory and cardiovascular effects of ambient particulate matter from dust storm and non-dust storm periods in Kuwait

Epidemiological studies demonstrate a positive association between daily changes in concentrations of ambient airborne particulate matter (PM) and adverse respiratory and cardiovascular health effects. However, physicochemical properties of PM can vary greatly across geographical, atmospheric, and temporal conditions and influence the relative toxicity of airborne PM. The purpose of this study was to investigate the adverse pulmonary and cardiovascular health effects of ambient PM collected from discrete sampling sites in Kuwait during dust storm (DS) and non-dust storm (NDS) conditions. Collected dust samples were characterized for their chemical composition using atomic absorption, GC–MS, and HPLC–MS analyses. Male BALB/cJ mice were exposed to 100 µg of either NDS or dust storm (DS) PM in 50 µl of PBS by oropharyngeal aspiration. Lung function was measured and bronchoalveolar lavage was conducted at 1, 7, and 14 days post-exposure. Ischemia–reperfusion injury was performed 24 h after exposures by obstructing the left main coronary artery approximately 4 mm distal to its origin for 20 min, followed by 2 h. of reperfusion. Exposure to either NDS or DS PM resulted in airway hyperresponsiveness to acetylcholine compared to PBS controls. Total protein and cells in BAL fluid were elevated in both dust groups one day after exposure; however, DS PM induced a greater increase in cell numbers than did NDS PM, particularly in neutrophils, eosinophils, and lymphocytes. Representative lung sections exhibited positive staining for mucus in large airways at 7 days which resolved by 14 days in dust storm-exposed mice but persisted in NDS-exposed animals. Our findings suggest that NDS PM may be more effective in producing an adaptive immune response, while the early inflammation induced by DS PM may better resolve. We also observed a prolonged airway mucus response after exposure to NDS PM, suggesting it may produce more asthma-like features than dust storm PM. PM-induced changes to cardiac ischemia–reperfusion injury were not observed in this study. The lack of cardiovascular response may have been due to the limited exposure and single time point used in this study.

Effect of Standardized Yelling on Subjective Perception and Autonomic Nervous System Activity in Motion Sickness

This study investigated the effects of yelling intervention on symptoms and autonomic responses in motion sickness. Forty-two healthy participants were recruited, and they participated in Coriolis stimulation, a technique for inducing motion sickness. The experimental procedure comprised five 1-min rotating stimuli with 1-min rest after each stimulus. Then, the symptom severity was assessed using the Motion Sickness Symptom Rating (MSSR). The d2 Test of Attention scores and cardiovascular responses were recorded before and after Coriolis stimulation. The electrocardiogram results were documented to analyze heart rate variability (HRV). During Coriolis stimulus, the participants were required to yell 5–8 times in the experimental trial, and to keep quiet for each minute of rotation in the control trial. The yelling intervention significantly reduced the MSSR score (p < 0.001). Nevertheless, it did not significantly affect the d2 Test of Attention scores. Yelling while rotating did not significantly affect the heart rate nor blood pressure. However, it decreased the normalized low frequency of HRV (p = 0.036). Moreover, it improved motion sickness, but its effect on attention was not evident. Motion sickness could significantly affect cardiovascular responses and HRV. However, yelling did not affect cardiovascular response, and it reduced sympathetic nervous system activity.

Cardiovascular Effect of Dorsal Periaqueductal Gray During LPS- Induced Hypotension

Introduction: The central mechanism responsible for cardiovascular response to lipopolysaccharide (LPS) - induced hypotension is not completely determined and it is suggested numerous brain areas such as dorsal periaqueductal gray (dPAG) are involved. In this study the cardiovascular effect of the dPAG during LPS-induced hypotension was evaluated. Methods: Twenty male Wistar rats divided into four groups including 1) Control (Saline microinjected into dPAG), 2) Lidocaine 2%, 3) LPS (intravenously injected), and 4) Lidocaine + LPS were used. Catheterization of the femoral artery and vein was performed for the recording of blood pressure and LPS injection, respectively. Saline and lidocaine were microinjected into the dPAG nucleus then, LPS injection was done. Cardiovascular responses throughout of experiments were recorded and changes (∆) of systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) were calculated over time and was compared with those control and LPS groups, using repeated measures ANOVA. Results: LPS significantly reduced ∆SBP and ∆MAP (P<0.05) and did not change the ∆HR than the control group. Lidocaine did not significantly affect basic ∆SBP, ∆MAP and ∆HR compared to the control. Injection of lidocaine before LPS significantly attenuated reduction of ∆SBP and ∆MAP evoked by LPS (P<0.05). Conclusion: Our data showed that blockade of the dPAG by lidocaine significantly ameliorates the hypotension induced by LPS. It confirms involvement of the dPAG in cardiovascular regulation during LPS-induced hypotension.

Electrophysiological assessment of peripheral nerves and neuro-muscular junctions in patients following self-poisoning with paraquat

Paraquat is neurotoxic. We aimed to study the electrophysiological effects of peripheral nerves and neuromuscular junction (NMJ) in the survivors of paraquat poisoning. A cohort study was conducted on patients following paraquat poisoning. Controls were recruited. The assessments were performed around one and six weeks after the exposure. Motor nerve conduction velocity (MNCV), amplitude of compound muscle action potential (CMAP), sensory nerve conduction velocity (SNCV), F-wave studies, cardiovascular response to different stimuli, sympathetic skin response (SSR) studies, and exercise modified supramaximal slow repetitive stimulation (RNS) and electromyography (EMG) were performed. There were 28 (21 males) patients and 56 controls. The mean (SD) age of the patients and the controls were 29 (12) and 31 (11) years. Significant impairment at the first assessment in the SNCV of ulnar nerve, amplitude of ulnar nerve CMAP on distal stimulation, and F-wave occurrence in median, ulnar and tibial nerves; change of systolic blood pressure three minutes after standing and SSR amplitude ( vs controls) was observed. All parameters reverted to normal at six weeks after the exposure. There was electrophysiological evidence for somatic nerve, autonomic, and NMJ dysfunction following acute paraquat poisoning which was not seen at six weeks after the exposure.

Cardiovascular and nitric oxide response after maximal voluntary isometric contraction in adolescents with and without Down Syndrome v1

Background This study was designed to compare the cardiovascular and nitric oxide (NO) responses to maximal voluntary isometric contraction (MVIC) with different muscle groups (leg press [LEP] and isometric handgrip [IHG] exercise) of adolescents with Down syndrome (DS) and age-matched non-DS peers. We also aimed to compare the absolute and relative IHG strength between groups. MethodsEleven adolescents with DS (14.1 ± 1.0 years) and ten without DS (13.7 ± 1.25 years)participants performed two experimental sessions of LEP and IHG exercises: 1) familiarization session and 2) 3 attempts x 5-sec contraction at MVIC with 3-min rest interval. Blood pressure (BP), heart rate (HR) and NO were collected at rest, immediately post-exercise session, and 10-min post-exercise. Results There were no differences for cardiovascular and NO responses between groups for MVIC test using different muscle groups. However, DS group displayed a lower but not significantly cardiovascular response at rest and after MVIC tests than controls. Furthermore, DS group displayed a higher NO- concentration at rest, recovery and after IHG when compared to controls (P< 0.05). In addition, DS adolescents displayed a significantly lower level in absolute and relative IHG strength when compared to controls (P = 0.001). Conclusions Individuals with DS display a lower cardiovascular response at rest and after MVIC tests than controls and higher NO response after exercise.