What are the differences in heart activity between males and females?
Introduction
This report will investigate the differences in heart activity between males and females, focusing specially on two research questions of
- whether males have a higher heart rate than females
- whether males have a higher systemic blood pressure than females.
To do so, this report will examine data from the Framington Heart Study. This is a long term prospective study of the etiology of cardiovascular disease that began in 1948, and is now on its fourth generation of studied participants.
heartData <-read.csv("http://www.maths.usyd.edu.au/u/ellisp/AMED3002/data/frmgham.csv")
summary(heartData)## RANDID SEX TOTCHOL AGE
## Min. : 2448 Min. :1.000 Min. :107.0 Min. :32.00
## 1st Qu.:2474378 1st Qu.:1.000 1st Qu.:210.0 1st Qu.:48.00
## Median :5006008 Median :2.000 Median :238.0 Median :54.00
## Mean :5004741 Mean :1.568 Mean :241.2 Mean :54.79
## 3rd Qu.:7472730 3rd Qu.:2.000 3rd Qu.:268.0 3rd Qu.:62.00
## Max. :9999312 Max. :2.000 Max. :696.0 Max. :81.00
## NA's :409
## SYSBP DIABP CURSMOKE CIGPDAY
## Min. : 83.5 Min. : 30.00 Min. :0.0000 Min. : 0.00
## 1st Qu.:120.0 1st Qu.: 75.00 1st Qu.:0.0000 1st Qu.: 0.00
## Median :132.0 Median : 82.00 Median :0.0000 Median : 0.00
## Mean :136.3 Mean : 83.04 Mean :0.4325 Mean : 8.25
## 3rd Qu.:149.0 3rd Qu.: 90.00 3rd Qu.:1.0000 3rd Qu.:20.00
## Max. :295.0 Max. :150.00 Max. :1.0000 Max. :90.00
## NA's :79
## BMI DIABETES BPMEDS HEARTRTE
## Min. :14.43 Min. :0.00000 Min. :0.0000 Min. : 37.00
## 1st Qu.:23.09 1st Qu.:0.00000 1st Qu.:0.0000 1st Qu.: 69.00
## Median :25.48 Median :0.00000 Median :0.0000 Median : 75.00
## Mean :25.88 Mean :0.04558 Mean :0.0856 Mean : 76.78
## 3rd Qu.:28.07 3rd Qu.:0.00000 3rd Qu.:0.0000 3rd Qu.: 85.00
## Max. :56.80 Max. :1.00000 Max. :1.0000 Max. :220.00
## NA's :52 NA's :593 NA's :6
## GLUCOSE educ PREVCHD PREVAP
## Min. : 39.00 Min. :1.00 Min. :0.00000 Min. :0.00000
## 1st Qu.: 72.00 1st Qu.:1.00 1st Qu.:0.00000 1st Qu.:0.00000
## Median : 80.00 Median :2.00 Median :0.00000 Median :0.00000
## Mean : 84.12 Mean :1.99 Mean :0.07242 Mean :0.05393
## 3rd Qu.: 89.00 3rd Qu.:3.00 3rd Qu.:0.00000 3rd Qu.:0.00000
## Max. :478.00 Max. :4.00 Max. :1.00000 Max. :1.00000
## NA's :1440 NA's :295
## PREVMI PREVSTRK PREVHYP TIME
## Min. :0.00000 Min. :0.00000 Min. :0.0000 Min. : 0
## 1st Qu.:0.00000 1st Qu.:0.00000 1st Qu.:0.0000 1st Qu.: 0
## Median :0.00000 Median :0.00000 Median :0.0000 Median :2156
## Mean :0.03217 Mean :0.01307 Mean :0.4596 Mean :1957
## 3rd Qu.:0.00000 3rd Qu.:0.00000 3rd Qu.:1.0000 3rd Qu.:4252
## Max. :1.00000 Max. :1.00000 Max. :1.0000 Max. :4854
##
## PERIOD HDLC LDLC DEATH
## Min. :1.000 Min. : 10.00 Min. : 20.0 Min. :0.0000
## 1st Qu.:1.000 1st Qu.: 39.00 1st Qu.:145.0 1st Qu.:0.0000
## Median :2.000 Median : 48.00 Median :173.0 Median :0.0000
## Mean :1.899 Mean : 49.37 Mean :176.5 Mean :0.3033
## 3rd Qu.:3.000 3rd Qu.: 58.00 3rd Qu.:205.0 3rd Qu.:1.0000
## Max. :3.000 Max. :189.00 Max. :565.0 Max. :1.0000
## NA's :8600 NA's :8601
## ANGINA HOSPMI MI_FCHD ANYCHD
## Min. :0.0000 Min. :0.00000 Min. :0.0000 Min. :0.0000
## 1st Qu.:0.0000 1st Qu.:0.00000 1st Qu.:0.0000 1st Qu.:0.0000
## Median :0.0000 Median :0.00000 Median :0.0000 Median :0.0000
## Mean :0.1636 Mean :0.09925 Mean :0.1538 Mean :0.2716
## 3rd Qu.:0.0000 3rd Qu.:0.00000 3rd Qu.:0.0000 3rd Qu.:1.0000
## Max. :1.0000 Max. :1.00000 Max. :1.0000 Max. :1.0000
##
## STROKE CVD HYPERTEN TIMEAP
## Min. :0.00000 Min. :0.0000 Min. :0.0000 Min. : 0
## 1st Qu.:0.00000 1st Qu.:0.0000 1st Qu.:0.0000 1st Qu.:6224
## Median :0.00000 Median :0.0000 Median :1.0000 Median :8766
## Mean :0.09125 Mean :0.2493 Mean :0.7433 Mean :7242
## 3rd Qu.:0.00000 3rd Qu.:0.0000 3rd Qu.:1.0000 3rd Qu.:8766
## Max. :1.00000 Max. :1.0000 Max. :1.0000 Max. :8766
##
## TIMEMI TIMEMIFC TIMECHD TIMESTRK
## Min. : 0 Min. : 0 Min. : 0 Min. : 0
## 1st Qu.:7212 1st Qu.:7050 1st Qu.:5598 1st Qu.:7295
## Median :8766 Median :8766 Median :8766 Median :8766
## Mean :7594 Mean :7543 Mean :7008 Mean :7661
## 3rd Qu.:8766 3rd Qu.:8766 3rd Qu.:8766 3rd Qu.:8766
## Max. :8766 Max. :8766 Max. :8766 Max. :8766
##
## TIMECVD TIMEDTH TIMEHYP
## Min. : 0 Min. : 26 Min. : 0
## 1st Qu.:6004 1st Qu.:7798 1st Qu.: 0
## Median :8766 Median :8766 Median :2429
## Mean :7166 Mean :7854 Mean :3599
## 3rd Qu.:8766 3rd Qu.:8766 3rd Qu.:7329
## Max. :8766 Max. :8766 Max. :8766
## Results
hist(heartData$HEARTRTE, freq = FALSE,ylab = "Probabilities", col = "chocolate2", xlab= "Heart rates in beats per minute", main= "Histogram of heart rates of Framingham participants", xlim=c(25,150)) 
Figure 1. Histogram of heart rates of participants in Framingham study
boxplot(HEARTRTE ~ SEX, data = heartData, main = "Boxplot of heart rates for each gender", ylab = "Heart rate in beats per minute", col = "cornflowerblue", xlab = "Gender", names= c("Males", "Females"))
Figure 2. Boxplot of heart rates for each gender
hist(heartData$SYSBP, freq = FALSE,ylab = "Probabilities", col = "chocolate2", xlab= "Systemic blood pressure (mmHg)", main= "Histogram of systemic blood pressure of Framingham participants", xlim=c(40,260)) 
Figure 3. Histogram of systemic blood pressure of participants in Framingham study
boxplot(SYSBP ~ SEX, data = heartData, main = "Boxplot of systemic blood pressure for each gender", ylab = "Systemic blood pressure (mmHg)", col = "cornflowerblue", xlab = "Gender", names= c("Males", "Females"))
Figure 4. Boxplot of systemic blood pressure for each gender
Discussion
From figure 1. it can be seen that heart rates were usually between 70-80 beats per minute. From figure 2. it can be seen that females tended to have a higher heart rate than males, with a higher interquartile range and narrower and higher distribution of spread. This correlates with other studies that indicate women have a higher frequency heart rate spectral power, due to how the female heart is typically smaller. This results in it pumping less blood per beat, and thus requiring more heart beats per minute to sustain the body. (Golosheykin et al., 2017, Trujillo et al., 2019, Ramaekers et al., 1998)
From figure 3. it can be seen the median for systemic blood pressure was 132.0 mmHg. From figure 4, it can be seen that between the genders there is a slightly higher systemic blood pressure in females than men in terms of maximum values. Other studies have shown that higher blood pressure is common in women than men after the age of 55, whilst below the age of 55, higher blood pressure is more common in men than females. To further understand this, it is suggested to correlate blood pressure with different age brackets in female and men within the Framingham dataset. (Maranon et al., 2013, Wilkins et al., 2010,Voss et al., 2015) Age may be a confounding variable influencing these results.
Summary and Conclusion
Overall, results demonstrate that females have a slightly higher heart rate and systemic blood pressure than males, with factors such as a smaller heart volume influencing heart rate, and age potentially being a affecting these results. More analysis is suggested.
Bibliography
- Golosheykin, S., Grant, J.D., Novak, O.V., Heath, A.C. and Anokhin, A.P., 2017. Genetic influences on heart rate variability. International Journal of Psychophysiology, 115, pp.65-73.
- Maranon, R. and Reckelhoff, J.F., 2013. Sex and gender differences in control of blood pressure. Clinical science, 125(7), pp.311-318.
- Ramaekers, D., Ector, H., Aubert, A.E., Rubens, A., Van de Werf, F., 1998. Heart rate variability and heart rate in healthy volunteers. European Hear Journal, 19, pp. 1334-1341
- Trujillo, E., Rascon, J., Maddox, J., Morales-Acuna, F.J. and Gurovich, A.N., 2019. Heart Rate Differences in Males and Females during Similar Physiological Work. The FASEB Journal, 33(1_supplement), pp.534-5.
- Voss, A., Schroeder, R., Heitmann, A., Peters, A. and Perz, S., 2015. Short-term heart rate variability—influence of gender and age in healthy subjects. PloS one, 10(3).
- Wilkins, K., Campbell, N.R., Joffres, M.R., McAlister, F.A., Nichol, M., Quach, S., Johansen, H.L. and Tremblay, M.S., 2010. Blood pressure in Canadian adults. Health Reports, 21(1), p.37.