Whether Duration of Physical Activity Influences Body Mass Index in Obese Adolescents

The principles of statistics play a major role in disseminating and analyzing research data. Statistical data is broadly classified into two types; descriptive and inferential. Descriptive statistics are estimated to represent the statistics of location and statistics of dispersion. On the other hand, inferential statistics is used to test a research hypothesis. The present article reflects an analysis of a research question based on the estimation of different descriptive and inferential statistics.

Statement of Task

The prevalence of obesity is a growing concern across parents and healthcare professionals around the globe. Hence, obesity is quite appropriately recognized as a “global epidemic.” Obesity is a metabolic disorder that is featured by an increase in body weight or a high body mass index (BMI). Technically, an individual is classified as “obese,” if his or her BMI exceeds 29.9 kg/m2. The disorder stems from an increased deposition of fats in the subcutaneous tissues of the body. Different studies suggest that inappropriate dietary patterns and a lack of physical activity predispose the risk of obesity. On the contrary, certain authors have reflected the importance of gene-environment interactions in the genesis of obesity. It is contended that mutations in certain genes are responsible for the genesis of childhood obesity (Yanovski and Yanovski 74-86).

Such genes are inherited from one generation to another, which forms the genetic basis of the disease. Moreover, obesity itself predisposes the risk of type-2 diabetes mellitus and different cardiovascular disorders.

For this reason, there has been a global consensus in reducing the prevalence of childhood and adult obesity. However, studies suggest that appropriate dietary and lifestyle behaviors could reduce the prevalence of obesity across an at-risk population. In fact, different school-based obesity mitigation programs have been launched across different nations. The major aim of such programs is to inculcate healthy dietary pattern and appropriate physical activity across concerned stakeholders (Yanovski and Yanovski 74-86).

Although different studies have recognized the role of physical activity in reducing the risk of obesity, however; there is inconclusive evidence regarding the duration of physical activity that is required to reduce the risk of obesity. Hence, the present study explored one primary research question “whether the duration of physical activity is significantly correlated with the reduction in body mass index in concerned stakeholders?” The findings of the present study would be beneficial for parents, healthcare professionals, and policy makers in designing obesity mitigation programs for at-risk populations (Yanovski and Yanovski 74-86).

Study Design and Sampling

The present study was conducted in a prospective and randomized manner. Purposive sampling was undertaken to select the study participants. This means individuals presenting with different grades of obesity were only considered for the trial. The study participants (n=60, males= 30 and females=30) were selected from community settings through an online invitation. Individuals, those who presented with a body mass index of > 29.9 kg/m2 at baseline, were only included in the trial. To recall, obesity is defined by a BMI > 29.9 kg/m2. All the study participants were otherwise healthy and belonged to the age range of 16 to 18 years. Body mass index was calculated as the ratio between body weight (measured in kilograms) and the square of the height of the individual (measured in meters).

Procedure

The study participants were randomly allocated into different experimental groups according to the duration of physical activity. Hence, all the study participants were exposed to two physical exercise regimes. The exercise regimes include running on a treadmill at 2.5mph for 15 minutes and 23 minutes respectively for males. On the other hand, the female study participants performed the same exercise regimes for eight minutes and 13 minutes respectively.

Statistical Tests and Software

The findings of the present study were presented as descriptive and inferential statistics. The descriptive statistics were used to plot bar diagrams for a visual depiction of the raw data. The detailed data for the present study is provided in Appendix-1. The descriptive statistics (mean and standard deviation) were further used to determine the inferential statistics. The inferential statistics that were undertaken for the present study include two-tailed paired t-tests. Two-tailed paired t-tests were used to compare the body mass index of the respective study participants before and after the end of the trial. A t-test is a statistical test of inference that is used to compare the arithmetic means between two groups. The computed t-score is compared with the critical t-score at a chosen level of significance. The t-score is computed as follows:
t = [Mean of group 1- Mean of Group 2]/standard error of the difference between the means
On the other hand, standard error of difference between means (SEM) is estimated as follows;
SEM= (standard deviation of group 1)/(square root of sample size of group 1) + (standard deviation of group 1)/(square root of sample size of group 1)
However, all statistical tests for the present study were conducted with MS-Excel and www.graphpad.com software.

Research Questions and Hypothesis Testing

The research questions were explored based on appropriate hypotheses. The hypothesis testing was based on the acceptance or rejection of the null (Ho) or the alternative hypothesis respectively.

1st Research question: Whether there is a significant difference in mean BMI before and after the two exercise regimes across concerned stakeholders?

Ho= there is no significant difference in mean BMI across concerned stakeholders before and after either of the exercise regimes (p>0.05).
Ha= there is a significant difference in mean BMI across concerned stakeholders before and after either of the exercise regimes (p<0.05).
2nd Research question: Whether increased duration of physical activity significantly reduces BMI in concerned stakeholders?
Ho= increased duration of physical activity do not significantly reduce BMI in concerned stakeholders (p>0.05)
Ha= increased duration of physical activity significantly reduces BMI in concerned stakeholders (p<0.05).

Data Gathering

An online invitation was sent to individuals who were diagnosed with obesity. The study participants were asked to share their BMI before and after the end of the trial. The study was conducted for one month. The online invitation itself contained the BMI calculator as presented in table 1.
Please fill the relevant details(please note you can only participate in this study if you have access to a treadmill)
Age:
Sex:
BMI before the trial:
BMI after the trial:
** BMI= your body weight in kilograms/(your height in meters)2
Do you provide consent for participating in the study: Y/N
Has your physician permitted you to participate in the study?
Table 1: online invitation questionnaire
All study participants provided informed consent before initiation of the trial. Moreover, the study participants were only included in trial after due permission from their respective physicians. The study participants were personally approached, and the necessary body vitals were estimated. The body vitals (such as stature and body weight) were filled in by the study participants only to report their individual BMI.

Data Analysis

Descriptive statistics

Male before male after 15 mins Male before male after 23 mins females before females after 8 minutes females before females after 13 minutes
mean 32.26 30.88667 32.19333 29.60667 31.73333 30.54667 31.95333 29.69333
median 32.1 31.2 32.1 30.8 31.8 30.3 31.8 30.3
mode 31.8 30.1 31.8 31.1 32.1 31.1 32.1 27.1
standard deviation 1.499905 2.070841 1.313374 2.696947 1.57918 2.086305 1.717501 2.20987
maximum 36.4 34.4 35.4 32.4 36.4 36.4 37.4 32.3
minimum 30.3 27.1 30.3 22.7 30 27.8 30.3 26.7

Table 2: Reflects the descriptive statistics of the study participants

Graphical Presentations

Fig 1: BMI in male study participants before and after each exercise regime.

Fig 1: BMI in female study participants before and after each exercise regime.

Outputs of the t-tests

P value and statistical significance:   The two-tailed P value equals 0.0453   By conventional criteria, this difference is considered to be statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 1.3800   95% confidence interval of this difference: From 0.0311 to 2.7289 Intermediate values used in calculations:   t = 2.0956   df = 28   standard error of difference = 0.659
Table 3: t-test comparing the mean BMI between male study participants before and after the exercise regime of 15 minutes
P value and statistical significance:   The two-tailed P value equals 0.0023   By conventional criteria, this difference is considered to be very statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 2.5900   95% confidence interval of this difference: From 1.0075 to 4.1725 Intermediate values used in calculations:   t = 3.3526   df = 28   standard error of difference = 0.773
Table 4: t-test comparing the mean BMI between male study participants before and after the exercise regime of 23 minutes
P value and statistical significance:   The two-tailed P value equals 0.1553   By conventional criteria, this difference is considered to be not statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 1.2800   95% confidence interval of this difference: From -0.5152 to 3.0752 Intermediate values used in calculations:   t = 1.4605   df = 28   standard error of difference = 0.876
Table 5: t-test comparing the mean BMI between male study after the exercise regime of 15 and 23 minutes respectively
P value and statistical significance:   The two-tailed P value equals 0.0893   By conventional criteria, this difference is considered to be not quite statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 1.1900   95% confidence interval of this difference: From -0.1947 to 2.5747 Intermediate values used in calculations:   t = 1.7604   df = 28   standard error of difference = 0.676
Table 6: t-test comparing the mean BMI between female study participants before and after the exercise regime of 8 minutes
P value and statistical significance:   The two-tailed P value equals 0.0039   By conventional criteria, this difference is considered to be very statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 2.2600   95% confidence interval of this difference: From 0.7863 to 3.7337 Intermediate values used in calculations:   t = 3.1413   df = 28   standard error of difference = 0.71
Table 7: t-test comparing the mean BMI between female study participants before and after the exercise regime of 15 minutes
P value and statistical significance:   The two-tailed P value equals 0.2862   By conventional criteria, this difference is considered to be not statistically significant. Confidence interval:   The mean of Group One minus Group Two equals 0.8500   95% confidence interval of this difference: From -0.7513 to 2.4513 Intermediate values used in calculations:   t = 1.0873   df = 28   standard error of difference = 0.782
Table 8: t-test comparing the mean BMI between female study after the exercise regime of 8 and 15 minutes respectively.

Interpretation

The present study suggests that physical activity of 15 minutes and 23 minutes significantly reduced mean BMI of male study participants (p<0.05). However, there was no significant difference between the mean BMI of the male study participants regarding the two exercise regimes (p>0.05). Hence, it can be concluded that the duration of physical activity is a not a determining factor in reducing the BMI across male study participants. The study further showed that physical activity of 8 minutes did not reduce mean BMI across female study participants compared to their pre-exercise levels (p>0.05). However, there was a significant reduction in the mean BMI of the female study participants after engaging in the physical activity regime of 13 minutes (p<.0.05). Moreover, there was also no significant difference between the mean BMI of the female study participants in relation to the two exercise regimes (p>0.05). Hence, the present findings suggest that an optimum amount of physical activity is required for reducing BMI in concerned stakeholders. However, duration of physical exercise does not seem to influence BMI across the respective stakeholders.

Validity

The study was conducted with appropriate sample size and in an unbiased manner. Hence, the findings of the study are valid and reproducible. However, future studies should be conducted with face-to-face experimentation with researchers and their respective study participants.

Conclusion

The findings of the present study are aligned with earlier findings. To recall, earlier studies failed to draw a conclusive correlation between the duration of physical activity and reduction of body mass index or body weight across concerned stakeholders. However, the present study did reflect that an optimum duration of physical activity (13 minutes for females and 15 minutes for males) could significantly reduce their BMI from that at baseline.

Works Cited
Yanovski SZ and Yanovski JA .”Long-term drug treatment for obesity: a systematic and clinical review”  JAMA: the Journal of the American Medical Association (Review). 2014; (311.1): pp.74–86.
Appendix-1
Male before male after 15 mins Male before male after 23 mins females before females after 8 minutes females before females after 13 minutes
30.7 30.1 31.8 30.8 30.7 29.7 37.4 31.4
32.1 30.1 30.3 30.3 32.1 31.1 32.2 32.3
31.8 28.8 31.8 31.8 32.1 30.1 30.7 28.7
30.3 30.3 33 29.2 30.3 30.3 32.1 27.1
31.8 32.8 33.4 31.4 33.3 31.3 31.8 31.8
33 33 31.2 31.2 36.4 36.4 30.3 30.3
33.4 31.4 33.2 26.2 32.2 32.2 31.8 31.8
31.2 31.2 31.1 31.1 30.7 28.7 32 32
33.2 32.2 30.7 22.7 32.1 32.1 31.4 27.4
31.1 30.1 32.1 29.1 31.8 27.8 31.1 31.1
36.4 34.4 31.1 31.1 30.3 30.3 30.7 26.7
32.2 32.2 32.3 27.3 31.8 29.8 32.1 32.1
31.1 27.1 33.3 27.3 31.1 28.1 32.1 27.1
32.3 32.3 35.4 32.4 31.1 31.1 30.3 28.3
33.3 27.3 32.2 32.2 30 29.2 33.3 27.3