RAMB - JUNHO 2017

ssociation

between

physical

activity

and

vitamin

D: A

narrative

literature

review

ssoc

ras

2017; 63(6):550-556

553

Pagels et al. compared indoor and outdoor physical

activity among 179 children aged 7 to 14 years from

schools in Sweden, and found that outdoor physical activ-

ity led to a moderate and vigorous increase in physical

activity, during all seasons of the year.

This strong cor-

relation between the variables of moderate/vigorous

physical activity and outdoor environment was also found

in the studies by Sallis et al.

and Cooper et al.

These

authors did not, however, study the association with serum

levels of vitamin D.

22,29,30

Pagels et al., in another recent study, report that out-

door environment, due to suberythemal exposure to the

sun even at high latitudes, has a favorable health impact,

helping students to acquire vitamin D.

Therefore, mod-

erate exposure to ultraviolet rays in outdoor environment

during school days in northern European countries has

a positive impact on the immune system, bone mineral-

ization and, possibly, mental health.

Florez et al. conducted a cross-sectional study and

found an association between vitamin D levels, body

mass index and outdoor physical activity in white His-

panic, and non-Hispanic patients. In Hispanics, there

was a high prevalence of hypovitaminosis D among the

obese compared to non-obese individuals. The practice

of outdoor physical activity decreased the prevalence of

hypovitaminosis D, with individuals 47% less likely to

have this condition.

Valtueña et al. investigated 408 Spanish athletes from

34 different modalities, both male and female, and con-

cluded that 82% had suboptimal levels of plasma vitamin

D concentration, demonstrating that outdoor physical

training is the appropriate way to increase this concentra-

tion in athletes.

Some studies, however, mention high levels of phys-

ical activity associated with increases in vitamin D levels

in older adults over the years, regardless of outdoor prac-

tice. This, because indoor physical practice would also

result in increased levels of vitamin D, suggesting that

the concentration of vitamin D is not only attributed to

high sun exposure.

34-37

The findings of the analysis based on data from the

US National Health and Nutrition Examination Survey

(NHANES)

indicate that physical activity is associated

with high serum levels of vitamin D, regardless of indoor

or outdoor practice.

Scragg and Camargo conducted an

earlier study using the same database (NHANES III), and

found that the association between physical activity and

vitamin D was stronger in outdoor compared with indoor

environments.

Therefore, even though both studies have

reported associations between physical activity and vita-

min D in older individuals, and despite the fact that the

ability of vitamin D synthesis from sun exposure decreas-

es with age, the results were not replicated.

38,39

Independent effects on sun exposure during physi-

cal activity may be associated with increased plasma

concentrations of vitamin D. A French study by Touvier

et al. supports this claim, with findings of association

between physical activity and vitamin D after adjusting

for sun exposure and outdoor sports.

Maimoun and

Sultan also corroborate the hypothesis that other fac-

tors, which are known and altered by physical activity,

may contribute to elevated levels of vitamin D metabo-

lites in athletes, such as decreased serum phosphate and

ionized calcium.

41,42

In addition, Kimlin et al., in an Australian study, re-

ported that exposure to ultraviolet rays was responsible

for only 8% of the variation found in vitamin D concen-

tration, while the largest contribution was clothing cov-

erage (27%), followed by location (20%), season (17%),

supplementation (7%) and body mass index/physical

activity, with 4% each. These results suggest that modifi-

able factors related to sun exposure could help maintain

the healthy state of vitamin D, such as decreased clothing

coverage, rather than increasing the duration of exposure

to ultraviolet rays.

Van den Heuvel et al. evaluated the contribution of

different physical activity characteristics, such as duration,

intensity and location, in relation to plasma levels of vi-

tamin D and concluded that physical activity performed

at high intensity had the strongest positive association

with vitamin D levels.

It is important to emphasize that exposure of the

body to the sun during physical activity should have some

particularities in order to raise the plasma concentrations

of vitamin D, since it depends on the amount of melanin

present in the skin, the type of clothing and the use of

sunscreen, as well as hour of the day, season of the year,

latitude of the place and age of the individual.

28,45,46

The studies included in our narrative review are pre-

sented in Table 1 (outdoor physical activity and vitamin

D synthesis) and Table 2 (indoor physical activity and

vitamin D synthesis), and show sample size, study design

and their main findings.

Directed attention plays a fundamental role in cogni-

tive functions, but once it is weakened, the individual’s

ability to concentrate for certain tasks is reduced, leading

to mental fatigue.

The practice of physical activity in-

teracting with nature may be important for recovery of

this directed attention, which is closely linked to the pro-

cess of regaining balance.

48-51