Influence of CrossFit training on bone mineral density in athletes

The volume of physical activity (PA) is decreasing, including those types that would have an impact on bone mineral density (BMD). This leads to a search for suitable and accessible forms of PA with sufficient effects on BMD. CrossFit (CF) could be among these forms of PA. Exercises included in a CrossFit (CF) training program should contain stimuli that lead to bone mass remodeling and, therefore, could positively influence the development and maintenance of bone mineral density (BMD). However, the results verifying the effect of CF on BMD are inconsistent in the current studies. The aim of the study is to investigate the impact of CrossFit training with an average weekly volume of 511.3±124.4 and 202.5±34.2 minutes in middle-aged individuals on their BMD. Given the number of participants, this study is more of a case study.

This cross-sectional study included 36 males divided into three groups. Group G1 was inactive individuals who did not meet the WHO (2020) physical activity (PA) recommendations. Participants were from the 4HAIE project. Group G2 was CF recreational athletes and group G3 was CF competitive athletes. Participants G2 and G3 had been doing regular CF training for at least 2 years. The average duration of training in G2 was 4.0±2.1 years and in G3 5.9±2.4 years. The age of the participants ranged from 26 to 35 years (G1 31.3±2.5, G2 31.9±2.5, G3 29.9±2.3 years). BMD was measured using DXA.

The results showed that although the G2 group had higher BMD values than G1, the differences were not significant; the P values ranged from 0.180 to 0.617. The G3 group had significantly higher BMD values than G1 and G2. When comparing G3 and G2, the P values ranged from 0.000 to 0.048, while the difference in the lower limbs was not significant (P=0.053 and 0.146). When comparing G3 and G1, the P values ranged from 0.000 to 0.002.

Therefore, we can conclude that CF could have a positive effect on BMD, but only if training is performed over a long period and at a high volume, which aligns with the level of PA recommendations for additional health benefits (more than 300 min/week moderate-intensity, or 150 min/week vigorous-intensity) according to the WHO.