Sports experience related bone tissue mineralization specifics in skiers

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PhD, Associate Professor R.V. Kuchin1
PhD, Associate Professor N.D. Nenenko1
PhD, Associate Professor N.V. Chernitsyna1
Dr. Biol., Associate Professor M.V. Stogov1
Associate Professor T.A. Maksimova1
1Yugra State University, Khanty-Mansiysk

Keywords: bone mineral density, cross-country skiing, sporting experience, young males.

Background. Studies of the bone tissue and mineral metabolism in athletes are in high priority in the modern sport theory and practice [1, 2] although the study findings are still quite contradictory at this juncture on how the sporting lifestyles affect the bone mineralization processes [4, 6]. It is commonly acknowledged, however, that these processes are sport-, gender-, age- (and other factors) specific [3, 5].
Objective of the study was to profile the bone mineral density versus the sporting experiences in the modern cross-country skiing sport.
Methods and structure of the study. Sampled for the study were the KMAO-Yugra permanent residents (including native-born) split up into the following four groups; Experimental Group 1 (EG1, n=7) of the 19.0±0.5 year-olds with the 3-4-year experiences; Experimental Group 2 (EG2, n=8) of the 19.1±0.8 year-olds with the 7-8-year experiences; Experimental Group 3 (EG3, n=7) of the 19,5±0,5 year-olds with the 11-12-year experiences; and Reference Group (RG, n=9) of the 19.8±1.0 year-old unsporting individuals. As required by the ethical provisions of the Helsinki Declaration, every subject gave an informed consent for the tests. The bone mineral content and mineral density of the skeleton segments were rated by a dual energy X-ray absorptiometry using an Lunar Prodigy GE Medical Systems X-ray bone densitometer at the Khanty-Mansiysk Regional Clinical Hospital. The test data are given in Tables hereunder with the arithmetic means and standard deviations (Xi ± SD). Significance of the EG versus RG differences in the data arrays were rated using either the parametric Student t-test or the non-parametric Wilcoxon W-test.
Results and discussion. The tests found a few total bone mineral content and bone mineral density sagging trends in the EG1-3 versus the RG (see Table 1), with the differences rated significant at р<0.05. It should be noted that EG1/2/3 were tested with the higher muscle masses than the RG.

Table 1. Total bone mineralization in the sample (Xi±SD)

Group

BMC, kg

BMD, g/ cm2

Muscle mass, kg

EG1

2,92±0,14*

1,187±0,018*

58,7±1,0*

EG2

3,07±0,21

1,217±0,057

58,2±2,4*

EG3

3,01±0,33

1,214±0,041

58,1±2,5*

RG

3,17±0,19

1,239±0,030

55,3±2,7

 
Note: BMC bone mineral content, BMD bone mineral density, * р<0.05.

Segmental bone mineralization analysis found the average bone mineral content and bone mineral density in EG1 being significantly lower than in the RG. The average bone mineral content and bone mineral density in EG2/3 were found lower in the upper limbs and higher in the lower limbs than in the RG: see Table 2.

Table 2. Segmental bone mineralization in the sample (Xi±SD)

Segment

Rate

EG1

EG2

EG3

RG

Upper limbs

BMC, kg

0,40±0,01*

0,41±0,02*

0,44±0,06

0,45±0,03

BMD, g/ cm2

0,921±0,018*

0,953±0,065

0,964±0,053

0,985±0,041

Lower limbs

BMC, kg

1,13±0,04*

1,19±0,11

1,18±0,10

1,26±0,05

BMD, g/ cm2

1,402±0,010

1,429±0,042

1,445±0,055

1,421±0,044

Trunk

BMC, kg

0,93±0,02

1,01±0,10

0,95±0,17

0,99±0,11

BMD, g/ cm2

0,955±0,022

0,999±0,056

0,968±0,043

0,992±0,051

Pelvis

BMC, kg

0,40±0,02

0,46±0,04

0,43±0,09

0,41±0,04

BMD, g/ cm2

1,216±0,037

1,262±0,046

1,216±0,072

1,221±0,070

Spine

BMC, kg

0,24±0,02

0,25±0,03

0,24±0,04

0,26±0,03

BMD, g/ cm2

1,029±0,061

1,059±0,076

1,033±0,097

1,062±0,081

 
Note: BMC bone mineral content, BMD bone mineral density, * р<0.05

Table 3. Bone mass density in specific anatomic elements (Xi±SD)

Element

EG1

EG2

EG3

RG

Femoral neck

1,096±0,071

1,225±0,071*

1,176±0,089

1,107±0,095

Thigh diaphysis

1,402±0,080

1,406±0,077

1,326±0,051

1,372±0,098

Femur

1,164±0,068

1,198±0,051

1,156±0,052

1,145±0,098

L1-L4 average

1,180±0,088

1,232±0,088

1,211±0,073

1,163±0,093

Note: L1-L4 – lumbar vertebrae 1-4; * р<0.05.

The average bone mineral density values in EG1/2 in every anatomic element under the study were higher than in the RG: see Table 3; with the only exclusion for the femoral neck bone mineral density in EG2 that was significantly higher than in the RG. Furthermore, the bone mineral density was tested lower in EG1 than in the unsporting RG. The BN and bone mineral density rates in the higher-experienced EG2/3 were found to grow in the lower limbs and fall in the upper limbs with the experience versus RG. The bone mineral density was found to redistribute in the spine with the sporting record, with some bone mineral density growth in the lumbar segment.
Our study data and analyses showed that the cross-country skiers tend to lag behind their unsporting peers in the bone mineralization rates, and this negative process needs to be countered by special efforts to cover the calcium deficiency, particularly in the Northern areas. We believe that special diets may not be sufficient for this purpose and special administration of the minerals is recommended for the sporting groups.
Conclusion. The study found redistributions of the bone mineral content rates with the sporting experience, with the bone mineral density generally falling in the upper limbs and upper spinal segments and grow in the lower limbs and lumbar segment.

References
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3. Vlachopoulos D. et al. Longitudinal Adaptations of Bone Mass, Geometry, and Metabolism in Adolescent Male Athletes: The PRO-BONE Study  J. Bone Miner. Res. 2017. Vol. 32, No 11. pp. 2269-2277.
4. Dias Quiterio A.L. et al. Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports. J. Strength Cond. Res. 2011.  Vol. 25, No 12. pp. 3439-3447.
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Corresponding author: kuchin_r@mail.ru

Abstract
The paper is devoted to the study of the peculiarities of bone mineralization in skiers depending on their sports experience. Four Experimental Groups were formed: Group 1 (n=7) was made of the young males involved in cross-country skiing with 3-4 years of sports experience; Group 2 (n=8) – male cross-country skiers with 7-8 years of sports experience; Group 3 (n=7) - male cross-country skiers with 11-12 years of sports experience. The Control Group (n=9) involved the non-sporting young males. The young males of Group 1 were found to have a decrease in the total level of bone mineralization and bone mineral density as opposed to the Control Group. The young males of Groups 2 and 3 were observed to have an increase in mineralization of the lower limb bones and a decrease in that of the upper limb ones. In Groups 2 and 3, there was an increase in bone mineral density in the femur neck, diaphysis of femur, and lumbar vertebrae. Therefore, with growing sports experience, there occurs functional redistribution of bone minerals. The marked delay in bone mineralization among the young males involved in cross-country skiing requires nutritional correction with calcium supplements.