Heart Rate In Supine Position Research Articles

Gastrocnemius Muscle Contraction and Its Role in Orthostatic Anti-Gravity Adjustment – The Effects of Body Mass Index

BACKGROUND: Obesity is a global concern with severe detrimental health and economic effect. Body mass index (BMI) is an inexpensive, non-invasive indicator for different diseases, and associated with abnormal weight. AIM: The aim of the study was to investigate the relationship between BMI and the contraction of gastrocnemius muscle (GM) and its possible role in peripheral muscle pump activity and pathogenesis of orthostatic intolerance. METHODS: One hundred and four volunteers (63 women and 41 men, mean age 39 ± 14 years) were divided into three subgroups according to their BMI values (with normal weight, overweight, and obesity). Changes in the transverse diameter and pennation angle of GM at rest and during maximal active plantar flexion (MAPF) were measured with multimodal ultrasound imaging. An active orthostatic test was performed and changes in systemic blood pressure and heart rate in supine position and active standing on the 1st, 5th, and 10th min were monitored. The results were statistically processed with alternative, variational, and correlational analysis. RESULTS: Patients with abnormal BMI were significantly older and had higher anthropometrical parameters compared to the subgroup with normal weight. They showed a significantly larger diameter and pennation angles at rest and during maximal active plantar flexion of GM bilaterally, which was more pronounced for the dominant right leg. However, the amount of changes in the GM diameter and pennation angles was similar in the different subgroups. CONCLUSION: The study showed that BMI affects predominantly the initial values of GM parameters at rest and MAPF without influence on its antigravity contractility associated with active straightening.

Impaired cerebral oxygenation in heart failure patients at rest and during head-up tilt testing.

AimsHeart failure (HF) confers potentially negative effects on the brain and autonomic nervous system. The measurement cerebral tissue oxygen saturation (SctO2) may aid in understanding such effects. We aimed to investigate if compensated HF affects SctO2 at rest and during orthostatic challenge.Methods and resultsNon‐invasive haemodynamic monitoring and near‐infrared spectroscopy were applied during head‐up tilt (HUT) in 61 HF patients [mean (SD) 71 (11) years, 82% male, New York Heart Association (NYHA) class I–III] and 60 controls [60 (12) years, 42% male). Group differences in continuous variables were compared using Student's t‐test. Associations between HF and SctO2 were studied using multivariable linear regression models adjusted for age, sex, diabetes, smoking, systolic blood pressure (SBP), and heart rate in supine position and after 10 min of HUT.Mean SctO2 was lower in HF patients compared with controls both in the supine position (67 vs. 71%; P < 0.001) and after 10 min of HUT (64 vs. 69%; P < 0.001). The HUT‐induced SctO2 decrease was greater in HF patients compared with controls (P = 0.026). SBP did not change in neither HF patients nor controls during HUT, whereas diastolic blood pressure and heart rate increased in both groups. HF was associated with lower SctO2 in supine (B = −2.5%, P = 0.023) and after 10 min of HUT (B = −2.6%, P = 0.007) after multivariable adjustments.ConclusionsCerebral tissue oxygenation is lower in HF patients both at rest and during orthostasis compared with subjects without HF. Future studies should test if the lower cerebral oxygenation associates with negative prognosis and with impaired cognitive function.

Association Of The Autonomous Nervous System And The Neuromuscular Performance In The Vertical Jump

The interactions between neuromuscular and metabolic processes can produce muscular contraction; Thus, the sympathetic nervous system takes special relevance because of its contribution in the autonomic control, which participates in the energetic supply of the muscular fibers and in the neuromuscular performance. This performance can be evaluated by using the vertical jump test, and its relationship with autonomous regulation is determined by the analysis of heart rate variability (HRV). PURPOSE: The aim of this study is to describe correlations between HRV and jump performance variables in young female professional soccer players. METHODS: Thirteen professional female soccer players (Aged: 20.7 +/- 2.6 years; Weight: 60.9 +/- 4.4 Kg) were analyzed, we evaluated HRV to determine autonomic regulation, we also evaluated neuromuscular performance during countermovement (CMJ) and squat jump (SJ) using tri-axial force platform. A statistical analyses was calculated to determine associations between variables of autonomic regulation and jump performance. RESULTS: Positive associations were found between CMJ contraction time and maximal heart rate (HR) during standing position (p=0.01, r2=0.4), SJ peak concentric velocity and LF/HF index in immediate postural change (P =0, 0453, r2= 0, 2739). Additionally, negative correlations were observed in CMJ concentric force and Stress Index (p=0.001, r2=0.42), sympathetic index (p=0.001, r2=0.41), average HR (P= 0.002 r2=0.58) and minimum HR in supine position (p=0.005, r2=0.52) and SJ peak concentric velocity and LF/HF index in orthostatic postural change (P =0, 0453, r2= 0, 2739). CONCLUSIONS: There is an inverse correlation between concentric contraction force and sympathetic modulation. Likewise, a positive association was found between some parameters related to neuromuscular power and variables of sympathetic activity, evidencing the existence of an influence of sympathetic system in explosive sports. According to this correlation, we suggest the use of HRV parameters that reflect sympathetic activity in the monitoring of training loads.

Nocturnal Heart Rate Variability and Morning Orthostatic Test as Tools to Monitor Training Load

Both the nocturnal heart rate variability (HRV) and the morning Orthostatic Test are widely used to monitor training load and recovery status of athletes. Both measurements have been observed to be associated with cardiac autonomic regulation. But less is known whether the measurements show similar responses to training load. PURPOSE: This study investigated the effects of easy and hard training days on the nocturnal HRV and the Orthostatic Test. In addition, the aim was to investigate relationships between nocturnal and morning HRV variables. METHODS: Thirty-four recreational endurance runners performed nocturnal R-R interval recordings and the morning Orthostatic test (5 min supine + 3 min standing) after an easy and a hard training day (moderate- or high-intensity endurance training). Nocturnal HRV was analyzed as four-hour period starting 30 min after going to bed for sleep. Morning HRV was analyzed over 4 min supine (00:30-04:30) and 2 min standing position (06:00-08:00). In addition, peak HR after stand-up and Orthostatic heart rate (HR) (HRstanding - HRsupine) were analyzed. RESULTS: Training load (session RPE) of hard training day (638 ± 638) was significantly (P < 0.001) greater compared to easy training day (50 ± 100). Nocturnal HR was lower (52 ± 6 vs. 57 ± 9, P < 0.001) and all nocturnal HRV variables were higher (Total power: 8.86 ± 0.63 vs, 8.41 ± 0.79, P < 0.001) after easy training day. HR in supine position was lower (53 ± 7 vs. 56 ± 7, P = 0.011) and high frequency power in supine position was higher (8.06 ± 0.89 vs. 7.74 ± 0.93, P = 0.027) after easy day. Other Orthostatic test variables were not different between easy and hard training days. Nocturnal HR and HRV variables showed moderate correlations (r = 0.62 - 0.78, P < 0.001) to the morning supine variables, but trivial and small correlations (0.19 - 0.39) to standing variables. CONCLUSIONS: Different training load after easy and hard training days can be observed in both nocturnal HRV and Orthostatic Test. However, the differences are greater in nocturnal HRV recordings compared the morning Orthostatic Test. In addition, it seems that standing variables are not able to evaluate the training load of the previous day. The results suggest that both nocturnal HRV and selected, supine variables of the Orthostatic test can be used in monitoring training load.

Effect of isometric hand grip on heart rate in normotensive and hypertensive individuals during head up tilt (300 and 600)

Objective: To study the effect of isometric hand grip exercise at 20% on normotensive, treated hypertensive, and non treated hypertensive in supine position, and at 30 0 and 60 0 head up tilt. Material and Methods: After recording heart rate in supine position, isometric hand grip exercise at 20% was conducted for 2 minutes with dominant hand and heart rate was recorded for 1 minute in all subjects after end of the exercise. The same maneuver was repeated before head up tilt in supine position and during head up tilt (30 0 and 60 0 ) in normotensive (n=104), treated hypertensive (n=76), and non treated (n=32) hypertensive individuals. Result: Isometric hand grip exercise at 20% resulted in mild increase in heart rate which was within normal limits of heart rate in all study groups. Similarly decrease in heart rate was observed in the some of the age groups. Conclusion: Isometric hand grip exercise at 20% caused marginal increase in heart rate in all study groups which was recorded within normal physiological range with decreased sympathetic stimulation and vagal modulation caused by isometric handgrip training.