Morph.Age (yrs)

Height (cm) Weight (kg)Fat %

PLX (cm) MIX

Mean SD Mean SD Mean SD Mean SD Mean SD Mean

SD

Athletes 9.55 1.32140.6

68.17 33.20 6.39 13.92 5.49 64.90 3.86

-1.53

0.24

Non-athletes

11.17

1.51148.5

29.62 43.93

11.91

20.47 7.73 69.96 4.84-

1.550.37

Younger 9.19 1.26 138.3 7.56 32.90 8.30 14.82 6.49 64.65 4.50-

1.480.28

Older11.1

81.20

149.33

7.61 41.35 9.78 17.53 7.33 68.89 4.11-

1.620.29

INTRODUCTION

MATERIAL AND METHODS

RESULTS AND DISCUSSION

SUMMARY

Table 1Table 1. . summarizesummarizes ts the he basic statsbasic stats of of the anthropometric variablesthe anthropometric variables..There were moderate significant relationships between age, stature, There were moderate significant relationships between age, stature, plastic index and SOS, BUA, BQI for the total sample. In non-athletes plastic index and SOS, BUA, BQI for the total sample. In non-athletes every bone parameter correlated with age significantly and no significant every bone parameter correlated with age significantly and no significant correlation was found in athletes but for SOS (Table 2, Figure 1).correlation was found in athletes but for SOS (Table 2, Figure 1).

The subjects were non-athletic (n=34) and soccer player The subjects were non-athletic (n=34) and soccer player prepubertal boys (n=76), grouped also as younger (9-10yrs, n=64) prepubertal boys (n=76), grouped also as younger (9-10yrs, n=64) and older (11-12yrs, n=46) ones. They had a 1.5 to 4 years sport and older (11-12yrs, n=46) ones. They had a 1.5 to 4 years sport related experience. related experience.

Anthropometric measurements were taken by the suggestion of Anthropometric measurements were taken by the suggestion of the IBP (Weiner and Lourie 1969), including estimated body fat the IBP (Weiner and Lourie 1969), including estimated body fat percentage (percentage (Pařižková 1961)Pařižková 1961) and physique was characterised by and physique was characterised by Conrad's growth type (1963)Conrad's growth type (1963).. Biological age was assessed by Biological age was assessed by anthropometric measurements using the method of Mészáros and anthropometric measurements using the method of Mészáros and Mohácsi (1983). Mohácsi (1983).

Calcaneal quantitative ultrasound parameters were registered by a Calcaneal quantitative ultrasound parameters were registered by a Sonost 3000 bone densitometer. The analysis included speed of Sonost 3000 bone densitometer. The analysis included speed of sound (SOS, m/s), broadband ultrasound attenuation (BUA, dB/MHz) sound (SOS, m/s), broadband ultrasound attenuation (BUA, dB/MHz) and the calculated bone quantity index (BQI=αSOS+βBUA, αβ: and the calculated bone quantity index (BQI=αSOS+βBUA, αβ: temperature corrections).temperature corrections).

Correlation patterns of anthropometric variables and bone Correlation patterns of anthropometric variables and bone characteristics for total sample and for subgroups were analyzed. characteristics for total sample and for subgroups were analyzed. Differences between athletic and non-athletic boys were tested by Differences between athletic and non-athletic boys were tested by Student Student tt-test; and -test; and if the F-test of ANOVA was significant for the if the F-test of ANOVA was significant for the respective means (age and physical activity), Tukey's post-hoc test respective means (age and physical activity), Tukey's post-hoc test was used at the 5% level of effective random error.was used at the 5% level of effective random error.

The bone variables did not significantly differ in athletes and in non-The bone variables did not significantly differ in athletes and in non-athletic prepubertal boys, similar to Cvijetić athletic prepubertal boys, similar to Cvijetić et alet al. (2003), in contrast to . (2003), in contrast to Falk Falk et alet al. (2003) and Mentzel . (2003) and Mentzel et al.et al. (2005). (2005). It seems that quantity bone parameters depend on the chronological as It seems that quantity bone parameters depend on the chronological as well as biological age. Although the bone parameters were related with well as biological age. Although the bone parameters were related with antropometric variables no difference was found at the same age even antropometric variables no difference was found at the same age even with various body size.with various body size. That means that age had the strongest effect on bone parameters in That means that age had the strongest effect on bone parameters in prepubertal boys.prepubertal boys. The older boys had larger values, so that favourable characteristics of The older boys had larger values, so that favourable characteristics of bone in this sample, irrespective to body size.bone in this sample, irrespective to body size.

Osteopenia and osteoporosis are common diseases in the world. It is well known, that bone degeneration can be prevented or Osteopenia and osteoporosis are common diseases in the world. It is well known, that bone degeneration can be prevented or decreased by regular physical activity. High-impact exercise, like football has been shown to be associated with higher bone mass. decreased by regular physical activity. High-impact exercise, like football has been shown to be associated with higher bone mass. Football involves running, kicking, jumping, tackling, turning, sprinting. During these movements the lower extremities are loaded Football involves running, kicking, jumping, tackling, turning, sprinting. During these movements the lower extremities are loaded with high-impact forces (Tarakçi and Oral 2009). with high-impact forces (Tarakçi and Oral 2009). A quantitative ultrasound measurements is relatively inexpensive, portable, non-invasive and radiation-free method of evaluating A quantitative ultrasound measurements is relatively inexpensive, portable, non-invasive and radiation-free method of evaluating bone status. The main aim of this pilot study was to analyze the relationships between different physical activity levels, bone status. The main aim of this pilot study was to analyze the relationships between different physical activity levels, anthropometric and bone parameters in prepubertal boys.anthropometric and bone parameters in prepubertal boys.

Figure 4:Figure 4: The calculated bone quantity index, means and SDThe calculated bone quantity index, means and SD

Table 1: Basic statistics of the anthropometric variablesTable 1: Basic statistics of the anthropometric variables

Figure 3:Figure 3: Speed of sound (SOS, m/s), means and SDSpeed of sound (SOS, m/s), means and SD

Figure 2:Figure 2: Broadband ultrasound attenuation (BUA, dB/MHz), means and SD Broadband ultrasound attenuation (BUA, dB/MHz), means and SD

Figure 1: Significant correlations between age, Figure 1: Significant correlations between age, stature, stature, plastic index and BQI in total sample plastic index and BQI in total sample

Age (yrs)Height (cm)

Weight (kg)

PLX (cm)

Total Sample

BUA 0.26 0.19 0.19 0.20

SOS 0.35 0.29 0.16 0.20

BQI 0.37 0.26 0.18 0.22

Athletes

BUA 0.06 0.02 0.06 0.07

SOS 0.24 0.18 0.16 0.16

BQI 0.20 0.16 0.17 0.19

Non-athletes

BUA 0.75 0.60 0.30 0.37

SOS 0.50 0.30 0.01 0.08

BQI 0.72 0.51 0.13 0.20

Table 2: Correlation pattern of anthropometric and bone Table 2: Correlation pattern of anthropometric and bone parameters parameters

(in blue italics: significant correlation coefficient)(in blue italics: significant correlation coefficient)

5055

6065

7075

8085

90

A NA

dB/MHz

505560657075808590

Y O

dB/MHz

*

148214861490149414981502150615101514

A NA

m/s

148214861490149414981502150615101514

Y O

m/s

*

50

55

60

65

70

75

80

A NA

50

55

60

65

70

75

80

Y O

*

r = 0.37

Age (yrs)

r = 0.29 r = 0.22

Stature (cm) Plastic index (cm)

In comparison of the activity-related subgroups the bone parameters In comparison of the activity-related subgroups the bone parameters i.e. BUA in dB/MHz (71.92±11.29 vs. 74.38±11.12), SOS in m/s (1493.4 i.e. BUA in dB/MHz (71.92±11.29 vs. 74.38±11.12), SOS in m/s (1493.4 ±10.78 vs. 1497.6±9.57) and BQI (60.16±11.17 vs. 63.00±10.87) did ±10.78 vs. 1497.6±9.57) and BQI (60.16±11.17 vs. 63.00±10.87) did not differ. not differ. Bone variables differed significantly by age: SOS (1491.59±9.69 vs. Bone variables differed significantly by age: SOS (1491.59±9.69 vs. 1499.09±10.24), BUA (70.11±10.69 vs. 76.26±11.13) and BQI 1499.09±10.24), BUA (70.11±10.69 vs. 76.26±11.13) and BQI (57.27±10.05 vs.66.27±10.45) (Figures 2-4).(57.27±10.05 vs.66.27±10.45) (Figures 2-4).

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