Elsevier

Journal of Clinical Densitometry

Volume 12, Issue 1, January–March 2009, Pages 28-34
Journal of Clinical Densitometry

Original Article
Is Osteopenia a Health Risk in Professional Cyclists?

https://doi.org/10.1016/j.jocd.2008.07.057Get rights and content

Abstract

Bone mineral content (BMC) and bone mineral density (BMD) were measured by dual-energy X-ray absorptiometry Lunar DPX-NT, SV 4.0 in 23 professional male cyclists (age: 28.5 ± 3.9 yr; height: 179 ± 6.8 cm; weight: 70.9 ± 7.1 kg−1). Eight subjects had normal L1–L4 T-score values (−0.19 ± 0.62) and 15 had low values (−1.57 ± 0.45). Correlations between: L1–L4 T-scores and body weight, fat mass (FM) and % FM (r = 0.40, p < 0.05; r = 0.65, p < 0.001; r = 0.59, p < 0.01). Regression analysis: L1–L4 T-score and FM (R2 = 0.42; p < 0.001); total BMC and fat-free mass (FFM) (R2 = 0.60; p < 0.0001); and total BMD and BMI (R2 = 0.25; p < 0.05). Climbers had lower arms BMD (0.85 ± 0.04; p < 0.05). Flat-terrain cyclist had lower right leg FFM (9.7 ± 0.8 kg; p < 0.05). Time trialists had higher body weight (76.7 ± 4.4 kg; p < 0.05), total FFM (68.3 ± 4.7 kg), total BMC (3.1 ± 0.3; p < 0.03), right and left leg BMC (0.60 ± 0.1; 0.60 ± 0.1; p < 0.05), and spinal BMD (1.09 ± 0.1; p < 0.05). In conclusion, two-thirds of professional cyclists had abnormally low BMD values.

Introduction

The peak bone mineral content (BMC) achieved during the first decade of adulthood is a key determinant of BMC later in life. In addition to genetic makeup and hormonal status, nutrition and exercise influence BMC. Bone architecture varies with the mechanical loads imposed on the skeleton. Osteogenic effects are greatest for activities associated with high-strength, high-frequency loading distributed unevenly over the skeleton (1). However, clinical studies of bone mineral density (BMD) changes induced by exercise have produced inconsistent or contradictory results. Jumping and running in children (2) and adults (3), as well as many other athletic activities, are associated with an increase in BMC 4, 5, 6, 7, 8. By contrast, non–weight-bearing exercise does not seem to increase spinal BMD. Thus, swimming and cycling may not improve bone status in young adults 9, 10, 11, 12, 13, 14, 15. When used alone, prolonged non–weight-bearing activities may adversely affect bone status (16). To the best of our knowledge, BMC has not been investigated in professional cyclists. The objective of the present study was to assess BMC and BMD in the whole body and regions of interest in professional cyclists.

Section snippets

Cyclists

We studied 23 healthy male highly trained road cyclists belonging to the same professional team, part of the Top 10 International Cycling Union Pro Tour, tested in the context of the mandatory medical monitoring required by the French Cycling Federation and the International Cycling Union (ICU). The measurements were obtained during a routine fitness evaluation, in December 2003, just after the rest season and the start of training. Mean age, height, and body weight were, respectively, 28.5 ± 3.9 

Results

Table 1 shows the results of mean daily dietary intakes during the start of training (time of testing) and the competition period (June). Compared to the French Recommended Dietary Allowances (RDAs), the intake of kilocalories, % carbohydrate, calcium, phosphorous, and magnesium were all significantly greater (p < 0.001) than the RDA for the French population, with the exception of % fat intake which was lower in the training and the competition groups, the % fat intake was 21 ± 5.8 and 13 ± 3.6 (p < 

Discussion

The most significant finding in this study is that two-thirds of a professional cycling team had abnormally low BMD values. Time-trial cyclists had higher values for whole-body, lower-limb, and spinal BMD. The lowest values of arm BMD were found in the mountain-race subgroup.

In both men and women, BMC and BMD increase throughout childhood and adolescence until they reach a peak, usually in the third decade. About 90% of the peak BMC is accrued within the period of skeletal maturation (19).

Conclusion

In conclusion, two-thirds of the professional cyclist team that were studied had abnormally low BMD values. This, together with the high risk of trauma-related fractures caused by falls or nontraumatic stress fractures induced by overtraining (fatigue fractures), warrants a recommendation that BMD be monitored. Cyclists whose T-scores in lumbar spine are low should receive dietary advice about calcium and other nutrients required for osteosynthesis, perform in addition to cycling training

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