× About the Journal Scope of the Journal Contact Editor-in-Chief Editorial Board Current Issue Archive Abstracting And Indexing Submit Article Advertise Join As Reviewer Publishing Ethics

JAPER is indexed in SCOPUS

Effect of physical activity level on vitamin D in teenagers

Lamiaa Elsayyad 1, Alaa Shafie 2, 3, Mazen almehmadi 2, 3, Khadiga Ahmed Ismail2, 5, Yaser O. Abu Asi 1,Hatem H. Allam 1,4*

1 Physical Therapy Department, College of Applied Medical Sciences, Taif University, Saudi Arabia. 2 Clinical Laboratory Department, College of Applied Medical Sciences, Taif University, Saudi Arabia. 3 High Altitude Research Center, Taif University, Saudi Arabia. 4 Faculty of physical therapy, Misr University for sciences and technology, Egypt. 5 Medical Parasitology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt.


Background: Vitamin D has a dramatic effect on health and a significant role in disease prevention. Inadequate dietary system and decreased sun exposure are the most important causes of vitamin D deficiency. The traditional intervention for vitamin D deficiency is supplements. Aim: The aim of our study was to evaluate the vitamin D status in teenagers and investigate the influence of activity level on vitamin D in this age group. Materials and methods: 204 male teenagers were recruited from Taif secondary schools. Their age ranged from 14 to 16 years, they had the same pubertal stage. They had not used vitamin D or calcium supplements for four months. Physical activities were measured using the piezoelectric pedometer. Dietary intake was calculated using the food frequency questionnaire. Also, sun exposure was calculated by the number of day hours spent outdoor. Results: There were no significant differences among the groups regarding sun exposure and dietary intake (P<0.05). Regarding vitamin D level, there was a significant increase in the more active groups, (active and highly active groups) (P>0.05), when compared with the less active groups. Also, the Pearson correlation showed highly significant correlation between the activity level and vitamin D level (r=0.418) and significance value of. 0.000. Conclusion: Physical activity level can affect vitamin D serum levels when the effect of sun exposure and dietary intake is controlled. There is a highly significant correlation between physical activity level and serum vitamin D level‎.

Keywords: Physical activity, vitamin D, teenager.


 Vitamin D deficiency is a common problem all over the world. Vitamin D deficiency not only has an impact on bone health but also it is related to many other diseases such as diabetes, cancer, and heart disease [1-6]. Also, vitamin D was found to be an important factor in psychological health in young adults. Increased sun exposure was recommended to improve mental health by improving vitamin D status [5, 7, 8]

It was observed that vitamin D deficiency is a common health problem among children of sunny cities such as Jeddah, Kingdom of Saudi Arabia, which is associated with health problems such as rickets [9, 10]. Also, Vitamin D status was found to be inversely correlated to age in children and teenagers. This may be due to a decrease in the activity level, inappropriate diet or decreased sun exposure [11, 12].

Muscular tissue and muscular activities were found to have a significant effect on 25(OH)D plasma levels. It was proved that a certain exercise program can improve 25(OH)D levels. The muscular tissue is considered a pool for 25(OH)D, which protects it from hepatic catabolism and can release it to blood after muscular activities [13, 14].

Vitamin D status is assessed by serum 25-OH levels, which are classified according to the following struts: ≤10, 11–20, and 21–30 and >30 ng/mL, and they are demarcated as a severe deficiency, deficiency, insufficiency, and sufficiency, respectively, according to previously recognized guidelines for bone health. [15-17]

So, the aim of the current study was to evaluate the vitamin D status in teenagers and investigate the influence of activity level on vitamin D in this age group. Other factors, which may affect vitamin D status such as diet and sun exposure were evaluated to ensure that any change in vitamin D status was due to change in the physical activities.

Materials and Methods

204 male students were recruited from the Taif secondary public schools. The enrollment was done by telephone calls to their parents to illustrate the nature and importance of the study. After that, we interviewed the parents and their sons to take the anthropometric parameters, illustrate to them the steps of the study, signing a consent form, take a medical history, and train them on how to use the pedometer, and food frequency questionnaire (FFQ). This study was ethically approved by the Ethical Committee at Taif University with application No. 41-34-0041. The sample size was determined using the G power program at medium effect size (0.25), power of (0.85) and alpha level of (0.05) [18]. This study was conducted at the college of applied medical sciences, Taif University, Saudi Arabia. The study started on January 1, 2020, and last for one month.


The subjects' inclusion criteria were: age ranged from 14-16 years, having the same pubertal stage (one to two year after the onset of puberty), body mass index (BMI) ranged from 15-22 (which is considered normal BMI according to WHO [19], free from any systemic diseases, having no previous major surgeries, taking no vitamin D or calcium supplements during last four months, the main portion of the dietary intake was homemade.

Dietary intake and sun exposure:

Saudi (FFQ) was used, which is a modified form of food frequency questionnaire developed by the European prospective investigation into cancer and nutrition study (EPIC). It includes the food items that frequently consumed by the Saudi population [20]. This questionnaire was used to estimate the nutrients intake in mg especially vitamin D and calcium throughout the study period. The subjects documented the consumed food, its types and its estimated amount, for every meal. The documentation was done daily for one week then the data were submitted to the researchers by the end of the week. The FETA computer program was used to analyze the data obtained from the FFQ [21]. Monitoring and analysis of dietary intake were done by a trained dietitian. Sun exposure was calculated as the number of day hours spent outdoor reported by the participants of the study.


Omron HJ-324U digital pocket was used for one week including the weekend time. It is a simple, light-weight device that can be clipped easily and one can move with it everywhere. It can monitor the physical activities by counting the steps, and data for each day is stored separately. The memory can store data for seven days. The data are displayed on the screen by pressing the MEM button. the MEM button shows the results (days 1-7) in memory. The display changes with each press of the MEM button.

The procedures were conducted under the supervision of the primary researcher. She instructed the teenagers and their parents about the appropriate use of the pedometer. The pedometer was put on at the waist level using an elastic band that contained a pocket for the pedometer. It was put on all over the day except during bedtime, bathing or swimming. The subjects were instructed to practice their normal activities. If the subject removed the pedometer one hour or more during any day, the data of this day were excluded. Omron HJ-324U is one of the most accurate pedometers, which can be worn in different positions [22].

The data from the pedometer were collected by the end of the week. Data were processed by a personal computer for calculating the physical activities for each subject. Physical activities were classified as sedentary life, low active, somewhat active, active and highly active according to the number of steps as the following: <5,000 steps/day were classified as a sedentary lifestyle, 5,000–7,499 steps/day were classified as low active, 7,500–10,000 steps/day were classified as somewhat active, 10,000–12,499 steps/day were classified as active, and individuals walking >12,500 steps/day were considered as highly active [23, 24].

Vitamin D evaluation

ELISA reader:

ELISA (Enzyme-Linked ImmunoSorbent Assay) technique was used to detect 25(OH)D levels in plasma. Blood samples were withdrawn from all participants at the chemistry lab, faculty of Applied Medical Sciences, male section, Taif University after a week of data collection (diet, sun exposure, and physical activities). The samples were withdrawn at the same time from the day (9 AM) to avoid the effect of hormonal diurnal rhythm. Three cubic centimeters of blood were withdrawn after fasting more than 10 hours.

The current study was a case-control study. SPSS version 20 was used for statistical analysis. ANOVA was used to reveal any significant difference among the groups of different activity levels regarding sun exposure and dietary intake. After this step, we compared the vitamin D level (25(OH)D) among the groups of different activity levels. Also, the Pearson correlation test was used to declare the level of correlation between activity level and serum vitamin D. The alpha level of significance was set at 0.05.


The aim of the current study was to evaluate the vitamin D status in teenagers and investigate the influence of activity level on vitamin D in this age group. According to pedometer data, the samples were divided into four groups: 42 subjects low active, 55 subjects somewhat active, 86 subjects active, and 17 subjects highly active. According to the Shapiro Wilk test, skewness, kurtosis and their standard errors and inspection of stem and leaf graphs and QQ plots, our data showed almost normal distribution. ANOVA showed that there were not any significant differences between the four groups regarding age, stage of puberty, and BMI. The demographic data of the four groups are illustrated in Table (1).



Table 1: Demographic data of the four groups.


low active

No. 42

somewhat active

No. 55


No. 86

highly active

No. 17

F value


Age (M±SD)







Months after puberty (M±SD)
















Regarding the difference between the four groups in sun exposure and dietary intake, ANOVA revealed that there was no significant difference between the four groups in these two variables (Table 2).



Table 2: Difference between the four groups in sun exposure and dietary intake.










Low active

Somewhat active


Highly active



Sun exposure Mean ± SD







Vitamin D intake mg/day Mean ± SD











Table 3: Effect of physical activities on vitamin D serum level.



Low active

Somewhat active


Highly active



Vitamin D ng/ml Mean ± SD







Bonferroni test





low active vs. somewhat active


low active vs. active


low active vs. highly active


Active vs. highly active






The results of our study revealed that there were no significant differences between the groups of different activity levels regarding sun exposure. This may be attributed to the nearly equal time of sun exposure during a day, which is the break time in the school schedule in addition to physical activity lessons in the school. In Saudi Arabia, sun exposure does not play an important role in vitamin D status as customs and traditions make people wear clothes that almost cover the whole body, so there is not enough directly exposed skin [25]. Concerning the dietary intake of vitamin D, statistical analysis showed that the difference between the four groups was non-significant. This may be attributed to the fact that most of the dietary sources are fortified by vitamin D [26].

Regarding the effect of physical activity on serum vitamin D level, our results revealed that the increase in the level of physical activities is associated with increased serum level of vitamin D. This comes in agreement with Wanner et al., 2015 [27], who found an association between the physical activity measured using Acti-Graph 7164 accelerometer and vitamin D level in individuals older than 18 years and they concluded that the physical activities may play a role in the improvement of vitamin D status. Also, Manios et al., 2018 [28], found a positive association between moderate physical activities more than 30 minutes measured by accelerometer and vitamin D level. The results of Elsayyad et al., 2019 [14] support our results as they found that conducting a selected treadmill exercise program for 12 weeks can improve vitamin D status in young adults. Gudjonsson et al., 2018 [29] found that there is an association between physical activity during leisure time and vitamin D level in normal and overweight older adults.

Our results contradict Gudici et al., 2017 [30], who conducted a cross-sectional study and found no association between physical activity level measured by international physical activity questionnaire and serum level of vitamin D. This contradiction may be attributed to the difference in the assessment tool between the current study and theirs. The results of Wanner et al., 2015 [27] showed that the association of physical activity and vitamin D depends on the assessment method of physical activities.


We concluded that physical activity level can affect vitamin D serum level when the effect of sun exposure and dietary intake is controlled. There is a highly significant correlation between physical activity level and serum vitamin D level.


This project was funded by Deanship of Scientific Research, Taif University on project no. 5647-438-1.


  1. Pasco JA, Henry MJ, Nicholson GC, Sanders KM, Kotowicz MA. Vitamin D status of women in the Geelong Osteoporosis Study: association with diet and casual exposure to sunlight. Medical Journal of Australia. 2001 Oct;175(8):401-5.
  2. Pittas AG, Dawson-Hughes B. Vitamin D and diabetes. The Journal of steroid biochemistry and molecular biology. 2010 Jul 1;121(1-2):425-9.
  3. Judd S, Tangpricha V. Vitamin D deficiency and risk for cardiovascular disease. Circulation. 2008 Jan 29;117(4):50
  4. Lappe J, Watson P, Travers-Gustafson D, Recker R, Garland C, Gorham E, Baggerly K, McDonnell SL. Effect of vitamin D and calcium supplementation on cancer incidence in older women: a randomized clinical trial. Jama. 2017 Mar 28;317(12):1234-43.
  5. Callegari ET, Reavley N, Garland SM, Gorelik A, Wark JD. Vitamin D status, bone mineral density and mental health in young Australian women: the Safe-D study. Journal of public health research. 2015 Nov 17;4(3).
  6. Alqudsi KK, Abdelaziz SA, Al-Agha AE. Association between Vitamin D Status and Type 1 Diabetes Mellitus in Saudi Adolescents. International Journal of Pharmaceutical Research & Allied Sciences. 2019 Jul 1;8(3).
  7. Nerhus M, Berg AO, Simonsen C, Haram M, Haatveit B, Dahl SR, Gurholt TP, Bjella TD, Ueland T, Andreassen OA, Melle I. Vitamin D Deficiency Associated With Cognitive Functioning in Psychotic Disorders. The Journal of clinical psychiatry. 2017 Jul;78(7):e750-
  8. Alabdulwahed RA, Khoja SO, Elshal MF, Bahlas S, AlGhamdi SA, Khojah SM. Modulation of CD28 and p38 Expression by Treatment with Vitamin D in Patients with Rheumatoid Arthritis. Journal of Biochemical Technology. 2019 Sep 1;10(3).
  9. Gamal M, Matyori A, Alkaibari M, Alzahrani T, Al-Sanea MM, Iqubal SS, Khan AA. Prevalence of Vitamin D Deficiency in Jeddah’s Children, Kingdom of Saudi Arabia. Journal of Pure and Applied Microbiology. 2018 Dec 1;12(4):1737-42.
  10. Muzaffar IH, Abdulsubhan MA, Baqasi AM, Bawazir OB, Aljohani RM, Alfadl YW, Alnoor MT, Atbay AA, Sangoura MI. Rickets among Saudi Infants in Jeddah, Saudi Arabia. The Egyptian Journal of Hospital Medicine. 2018 Apr 1;67(1):491-3.
  11. Saki F, Dabbaghmanesh MH, Omrani GR, Bakhshayeshkaram M. Vitamin D deficiency and its associated risk factors in children and adolescents in southern Iran. Public health nutrition. 2017 Jul;20(10):1851-6.
  12. Khoja SO, Al-Jehani RF, Bahlas SM, Algamdi SA, Attar S. Evaluation of Relationship between Vitamin D Receptor Gene Polymorphisms and Rheumatoid Arthritis in Saudi Population. Pharmacophore. 2018 Jan 1;9(1):85-94.
  13. Abboud M, Rybchyn MS, Ning YJ, Brennan-Speranza TC, Girgis CM, Gunton JE, Fraser DR, Mason RS. 1, 25-Dihydroxycholecalciferol (calcitriol) modifies uptake and release of 25-hydroxycholecalciferol in skeletal muscle cells in culture. The Journal of steroid biochemistry and molecular biology. 2018 Mar 1;177:109-15.
  14. Lamiaa Elsayyad, Alaa Shafie, Hatem H. Allam, Mazen almehmadi, Khadiga Ahmed Ismail and Yaser O. Abu Asi Effect of selected exercise program on vitamin D and parathyroid hormone level in high altitude residents, Bioscience Research, 2019 16(2): 1354-1362. 
  15. Holick MF. Vitamin D status: measurement, interpretation, and clinical application. Annals of epidemiology. 2009 Feb 1;19(2):73-8.
  16. Holick MF. Resurrection of vitamin D deficiency and rickets. The Journal of clinical investigation. 2006 Aug 1;116(8):2062-72.
  17. Stagi S, Lapi E, Romano S, Bargiacchi S, Brambilla A, Giglio S, Seminara S, de Martino M. Determinants of vitamin d levels in children and adolescents with down syndrome. International journal of endocrinology. 2015;2015.
  18. Faul, F., Erdfelder, E., Buchner, A., Lang, A.G. G* Power Version 3.1. 7 [computer software]. Uiversität Kiel, Germany. 2013.
  19. https://www.who.int/growthref/who2007_bmi_for_age/en/
  20. Gosadi IM, Alatar AA, Otayf MM, AlJahani DM, Ghabbani HM, AlRajban WA, Alrsheed AM, Al-Nasser KA. Development of a Saudi Food Frequency Questionnaire and testing its reliability and validity. Saudi medical journal. 2017 Jun;38(6):636.
  21. Mulligan AA, Luben RN, Bhaniani A, Parry-Smith DJ, O'Connor L, Khawaja AP, Forouhi NG, Khaw KT. A new tool for converting food frequency questionnaire data into nutrient and food group values: FETA research methods and availability. BMJ open. 2014 Mar 1;4(3):e004503.
  22. Park W, Lee VJ, Ku B, Tanaka H. Effect of walking speed and placement position interactions in determining the accuracy of various newer pedometers. Journal of Exercise Science & Fitness. 2014 Jun 1;12(1):31-7.
  23. Tudor-Locke C, Craig CL, Brown WJ, Clemes SA, De Cocker K, Giles-Corti B, Hatano Y, Inoue S, Matsudo SM, Mutrie N, Oppert JM. How many steps/day are enough? For adults. International Journal of Behavioral Nutrition and Physical Activity. 2011 Dec;8(1):79.
  24. Owoeye O, Tomori A, Akinbo S. Pedometer-determined physical activity profile of healthcare professionals in a Nigerian tertiary hospital. Nigerian medical journal: journal of the Nigeria Medical Association. 2016 Mar;57(2):99.
  25. Elsammak MY, Al-Wosaibi AA, Al-Howeish A, Alsaeed J. Vitamin d deficiency in Saudi Arabs. Hormone and metabolic research. 2010 May;42(05):364-8.
  26. Siddiqui A, Kamfar H. Prevalence of vitamin D deficiency rickets in adolescent school girls in Western region, Saudi Arabia. The Saudi Medical Journal. 2007;28(3).
  27. Wanner M, Richard A, Martin B, Linseisen J, Rohrmann S. Associations between objective and self-reported physical activity and vitamin D serum levels in the US population. Cancer Causes & Control. 2015 Jun 1;26(6):881-91.
  28. Manios Y, Moschonis G, Lambrinou CP, Mavrogianni C, Tsirigoti L, Hoeller U, Roos FF, Bendik I, Eggersdorfer M, Celis-Morales C, Livingstone KM. Associations of vitamin D status with dietary intakes and physical activity levels among adults from seven European countries: The Food4Me study. European journal of nutrition. 2018 Jun 1;57(4):1357-68.
  29. Gudjonsson MC, Geirsdottir O, Jonsson P, Thorsdottir I, Ramel A. Association between Physical Activity and Vitamin D According to Bmi Level Among Icelandic Older Adults. Innovation in Aging. 2018 Nov;2(Suppl 1):310.
  30. Giudici KV, Fisberg RM, Marchioni DM, Martini LA. Comparisons of physical activity, adipokines, vitamin D status and dietary vitamin D intake among adolescents. Journal of human nutrition and dietetics. 2017 Jun;30(3):369-77.

Contact SPER Publications

SPER Publications and Solutions Pvt. Ltd.

HD - 236,
Near The Shri Ram Millenium School,
Sector 135,
Noida-Greater Noida Expressway,
Noida-201301 [Delhi-NCR] India