Physiological Changes in Heart Rate and Resting Arterial Pressure Because of Physical Activity

Abstract

Physical activity and different physiological variables have been shown to reduce resting arterial pressure and heart rate. The purpose of this study was to compare changes in systolic blood pressure, diastolic blood pressure and mean arterial blood pressure with different males and females partaking in the experiment. Furthermore, to establish a relationship with younger individuals and infer how that may affect older populations. Subjects waited for three minute resting intervals when obtaining the blood pressure measurements in order to collect the most accurate reading and thus, the average analysis kept. After measuring the height, weight and blood pressure of each individual, the class data was formulated into different statistical tests, a one-way ANOVA followed by specific contrasts using Dunnett’s test. The impact of physical activity on all dependent variables (age, height, weight, BMI, SBP, DBP and HR) except for MAP demonstrated statistically significant (p≤0.05) differences in the ANOVA test. Moreover, physical activity has been hypothesised to reduce resting arterial pressures, yet we cannot conclude definitively from these data that exercise training produces these results. Our results suggest that in a young, healthy population, the effect of exercise would be beneficial in preventing early cardiovascular diseases such as hypertension. A decreased heart rate does support this evidence which was provided throughout the results.

Introduction

In younger individuals, habitual physical activity is generally associated with a reduced resting arterial pressure and heart rate. As hypertension is one of the main leading causes of cardiac disease, almost one quarter of the world’s adult population is estimated to have hypertension (Kearney et al. 2005). Our arterial blood pressure and heart rate are influenced by range of different genetic and lifestyle factors such as physical exercise, diet and gender. Our arterial pressure, systolic and diastolic blood pressure tend to increase with age, so hypertension is often more prevalent in older people (Safar et al. 2011). Somers et al. (1991) observed that blood pressure levels are significantly lower than pre-exercise levels only during the first hour of recovery. Hypertension may not always present with symptoms, which is why it is often referred to as a silent killer (Bennett 2017). Because blood pressure and heart rate changes in response to physical exercise, it is possible that different intensities and frequency of exercise may help to decrease the risk of hypertension in adults. These changes in heart rate and resting arterial pressure can be linked to detecting and preventing early physiological changes. Physical exercise causes a series of physiological responses in the body systems, in particular the cardiovascular system. Regular aerobic exercise has a variety of effects which help to protect the heart against disease. It is possible that as a result of an increased cardiac output during exercise, both heart rate and stroke volume increase, thereby leading to a reduced resting arterial pressure. A reduction in blood pressure is healthy for individuals trying to live a healthier lifestyle although while blood pressure changes during exercise, it can vary quite a bit depending on the type of exercise. Nevertheless, there is still much to be investigated with emphasis on physical exercise and how this often leads to changes in an individual’s heart rate. The type and intensity of exercise is still controversial yet there is no doubt towards the beneficial results from exercise training on arterial pressure. Studies have shown a negative correlation in physical activity and hypertension. In 2004, it was demonstrated by a study conducted by Mokdad et al. that poor diet and physical inactivity was responsible for 16.6% of deaths in America. The relationship between physical activity and health is very important in establishing information pertinent to the causes of many specific cardiac diseases. Therefore, the goal of this study was to investigate the effect of exercise on young adults. It was to establish the relationship between the levels of physical activity and how in young adults, it reduces heart rate and resting arterial pressure. Totalling nearly one-billion people estimated to have hypertension, and with the worldwide prevalence of hypertension projected to increase 60% by 2025, the primary prevention of this cardiac disease has become a global public health challenge.

Methods 

1713 participants from the PHY2040 lab cohort, 626-633 males and 1071-1078 females participated in this study. In a group of four students, each individual had their blood pressure and heart rate measured in a quiet area using blood pressure (BP) machine making sure the cuff was positioned on the participants elbow 1-2cm above and aligned correctly. Fastening firmly and pressing the start/stop button on the Omron, the cuff will start to inflate automatically and a measurement and recording of systolic blood pressure (SYS), diastolic blood pressure (DIA) and pulse rate will appear on the screen. The participant was asked to rest three minutes between each measurement. Each subject’s systolic BP (mmHg), diastolic BP (mmHg), and heart rate (beats/min) were taken three times and an average of the three measurements kept.

The height of each participant was measured whilst footwear and all headgear are removed. Ask the participant to stand on the base of the stadiometer, face forwards, feet together and looking straight ahead so that their eyes are the same level as their ears and record the height (to the nearest cm) of each subject.

All patients had their weight measured (to the nearest 0.1 kg); removing all shoes and extra clothing. Each subject weighed themselves on a scale with one foot on each side, facing forward and standing still.

Results

In determining the relationships between body mass index, arterial pressure and heart rate as they vary according to the three categorical variables (gender, diet and level of physical activity), an analysis of covariance was used as seen in Table 7. There is strong evidence of an association between BMI and all three measures of arterial pressure as PBMI is always <0.001. Therefore, there is a positive relationship between BMI and all three measures of arterial pressure, indicating that BMI also has an independent association with systolic arterial pressure. Once this relationship is controlled there is no longer a significant association between activity and systolic pressure. This could be because BMI and unusual activity vary together as seen in Table 5.

 

Table 7: Outcomes of analysis of covariance.

___________________________________________________________________________

Dependent Variable

PGender

PBMI

PGender*BMI

___________________________________________________________________________

Systolic Arterial Pressure

0.03

<0.001

0.34

Diastolic Arterial Pressure

0.52

<0.001

0.39

Mean Arterial Pressure

0.15

<0.001

0.87

Heart Rate

0.001

0.61

0.009

___________________________________________________________________________

Dependent Variable

PActivity

PBMI

PActivity*BMI

___________________________________________________________________________

Systolic Arterial Pressure

0.24

<0.001

0.22

Diastolic Arterial Pressure

0.79

<0.001

0.60

Mean Arterial Pressure

0.97

<0.001

0.94

Heart Rate

0.06

0.68

0.27

Dependent Variable

PDiet

PBMI

PDiet*BMI

___________________________________________________________________________

Systolic Arterial Pressure

0.53

<0.001

0.36

Diastolic Arterial Pressure

0.05

<0.001

0.07

Mean Arterial Pressure

0.31

<0.001

0.45

Heart Rate

0.71

0.85

0.75

Values ≤ 0.05 are bolded.

Table 5:  Characteristics of participants according to their usual level of physical activity.

________________________________________________________________________________________________________________

 

No Exercise

1-2 TPW

3-5 TPW

> 5 TPW

 

Variable

n

Mean ± SD

n

Mean ± SD

n

Mean ± SD

n

Mean ± SD

P

________________________________________________________________________________________________________________

Age (years)

276

20.6 ± 1.4

610

20.6 ± 1.8

570

20.9 ± 2.1

250

21.0 ± 2.4**

0.02

Height (cm)

277

165.4 ± 9.4

610

166.7 ± 9.0

572

169.7 ± 9.0***

251

174.6 ± 9.1***

<0.001

Weight (kg)

273

61.5 ± 14.0

604

64.2 ± 13.8***

568

68.3 ± 12.8***

250

72.4 ± 12.3***

<0.001

BMI (kg/m2)

273

22.3 ± 3.6

603

23.0 ± 3.8***

568

23.6 ± 3.5***

250

23.6 ± 3.0***

<0.001

 

Systolic Pressure (mmHg)

277

110.7 ± 12.5

608

112.5 ± 12.4*

571

115.1 ± 12.6***

250

117.9 ± 12.2***

<0.001

Diastolic Pressure (mmHg)

277

70.2 ± 7.7

608

70.0 ± 8.1

571

68.9 ± 8.0*

250

67.5 ± 7.3***

<0.001

Mean Arterial Pressure (mmHg)

277

83.7 ± 8.2

608

84.2 ± 8.5

571

84.3 ± 8.3

250

84.3 ± 7.4

0.73

Heart Rate (beats/min)

276

79.5 ± 11.0

604

77.7 ± 11.2*

567

74.0 ± 10.8***

249

69.5 ± 11.9***

<0.001

__________________________________________________________________________________________________________________

Data are from a total of 1713 participants. P values are the outcomes of one-way analysis of variance and are shown in bold if ≤0.05. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001 for post hoc comparisons with ‘no exercise’ (Dunnett’s test). TPW = times per week, SD = standard deviation, BMI = body mass index.

According to the Mean ± SD for No Exercise in BMI (kg/m2)was 22.3 ± 3.6 and increased in the one-way analysis of variance for TPW.  There is also a tendency for fit people with a greater muscle mass to have lesser diastolic blood pressure which might confound the relationship between BMI and systolic pressure. In addition, there was also statistically significant differences seen in the Dunnett’s test within the amount of physical activity measured by “times per week (TPW)” for the same dependent variables. In particular, increasing the physical activity TPW was associated with a statistically significant greater SBP. In contrary, at lower physical activity (TPW ≤ 2), there was not a statistically significant difference in DBP. However, at higher physical activity (TPW greater or equal to 3), there was a statistically significant lower DBP. Systolic pressure is greater and both diastolic pressure and heart rate are progressively less, at progressively greater usual level of exercise. However, we cannot conclude solely from these data that exercise training produced these effects, although at least in the case of heart rate there is good evidence that this is the case. Furthermore, Table 5 illustrates that there is a significant relationship between BMI and systolic arterial pressure in comparison to the age, height and weight of males and females. The data in Table 5 infer that BMI can be influenced by different variables.

 

Table 1: Characteristics of the sample: categorical variables

____________________________________

____________________________________  

Gender

Male

634

37.0

Female

1078

63.0

____________________________________ 

Diet

Vegetarian

139

8.1

Non-vegetarian

1573

91.9

____________________________________  

Level of  Physical Activity

None

276

16.1

1-2 Times Per Week

611

35.7

3-5 Times Per Week

573

33.5

>5 times per week

251

14.7

____________________________________

Data are compiled from a total of 1713 individuals.

Table 1 provides data for males and females and their diet choices versus their level of physical activity per week.  It can be noted that there is a strong correlation between individuals who exercise greater than >5 times per week alongside the data presented in Table 5 that BMI and usual physical activity vary together. On mechanistic ground, habitual physical activity may lead to greater systolic arterial pressure and lesser diastolic arterial pressure. BMI in habitual exercises is also likely to represent muscle mass more than fat mass as part of the relationship between BMI and systolic blood pressure might not be driven by adiposity but by the tendency for fit people with a lower resting hear rate, and greater stroke volume and systolic pressure to have a greater muscle mass.

Figure 3: Characteristics of participants according to usual level of physical activity. 1 = no regular exercise (n = 273-277), 2 = regular exercise 1-2 times per week (n = 603-610), 3 = regular exercise 3-5 times per week (n = 567-572), 4 = regular exercise > 5 times per week (n = 249-251). Columns and error bars represent mean ± standard deviation. P values are the outcomes of one way analysis of variance.  * P ≤ 0.05, ** P ≤ 0.01, *** P ≤ 0.001 for post hoc comparisons with ‘no regular exercise’ (Dunnett’s test).

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From the data provided in Figure 3, it was noted that the relationships between physical activity and arterial pressure contrasted those with what has been found previously in older populations of hypertensives. The relationships between BMI and the various measures of arterial pressure do not seem to differ as seen in Table 7. Furthermore, heart rate decreased with increased exercise and the mean arterial pressure remained the same across the levels. The mean arterial pressure is lower in women than it is in men.

Discussion

The main result of this study was to analyze the effects of exercise on the young adults and the way in which it helps to reduce blood pressure. It was effective in improving cardiorespiratory capacity, flexibility and reducing arterial pressure in hypertensive individuals. To increase awareness in hypertensive patients and improve cardiovascular strength, regular physical activity, using muscle strength and endurance help to adapt skeletal muscle. As arterial compliance is reduced as we age, our systolic pressure increases. In some people this causes isolated systolic hypertension. But the current view is that regular exercise can keep your arteries compliant. Improvement in diet and increase exercise may mediate indirectly to improvement in risk factors such as hypertension, obesity and diabetes. According to (Chobanian et al. 2003), hypertension is one of the most prominent cardiovascular diseases with a large impact on mortality. A strength of this study found that those who exercised more frequently showed a lower diastolic blood pressure but elevated pulse pressure. In younger individuals, regular exercise decreases our resting heart rate due to being fit and the heart is better apt to pumping blood around the body. Fewer beats are needed as larger amounts of blood are able to circulate. Variables such as gender, weight and height were also important in considering the way that they can affect blood pressure. Gender related differences in body size may affect the arterial hemodynamics such as systolic blood pressure (Yoshizaki et al. 2007). From the experiment, there is a significant relationship between BMI and systolic arterial pressure in comparison to males and females. Therefore, gender has an effect on this relationship. However, there is no significance between genders for mean or diastolic arterial pressure. There was no evidence in our study for BMI and diastolic arterial pressure having a difference in males and females. Leary et al. 2008, concluded that higher levels of physical activity were associated with lower blood pressure, and results suggested that the volume of activity may be more important than the intensity. The benefits of physical activity in the prevention and treatment of high blood pressure in adults have been very well described by Hagberg et al. and Whelton et al. Furthermore, aa large sample size of data collected increases the reliability of our results and interpretations in young adults. As seen in our study, most people fit the scope of our investigation. Some limitations of this study include a lack of accuracy due to human error in levelling off the most accurate height measurement by eye level. Additionally, some of the subjects may have eaten prior to, or not eaten breakfast before having their weight measured not giving a regular weight during the practical. Some of the subjects may have also been wearing heavier clothing than usual which could also affect their weight to the nearest 0.1kg. When the blood pressure was being measured, stress, agitation and distractions may have caused a spike or decrease in BP levels. Also, increasing the amount of repetitions in the experiments, decreases the chance of error and improves accuracy. Therefore, the goal of this study was to investigate the effect of exercise on young adults. It was to establish the relationship between the levels of physical activity and how in young adults, it reduces heart rate resting arterial pressure.

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