Recreational football training decreases risk factors for bone fractures in untrained premenopausal women

The present intervention was designed to investigate whether a 14-week period of regular recreational association football (F) or endurance running (R) has an effect on the risk of falls and bone fractures due to gains in muscle function and volumetric bone mineral density (vBMD). Fifty healthy untrained Danish premenopausal women were randomized into two training groups (F and R) that trained 1.8+/-0.3 (+/-SD) and 1.9+/-0.3 h/week, respectively, and these groups were compared with an inactive control group (C). Jumping and dynamic muscle strength were tested and tibial vBMD was measured using peripheral quantitative computed tomography. Total vBMD in left and right tibia increased by 2.6+/-2.3% and 2.1+/-1.8% (P<0.005), respectively, in F and by 0.7+/-1.3% (P=0.05) and 1.1+/-1.5% (P<0.01), respectively, in R without any significant changes in C. Similar results were found for trabecular vBMD. In F, peak jump power increased by 3+/-6% (P<0.05), and hamstring strength during fast (240 degrees /s) and slow (30 degrees /s) contractions increased by 11+/-25% and 9+/-21%, respectively, (P<0.05) without any significant changes in R or C. In conclusion, 14 weeks of regular recreational football improved peak jump power, maximal hamstring strength and vBMD in the distal tibia, suggesting a decreased fracture risk due to stronger bones and a reduced risk of falling.