Relationship between Football-Specific Training Characteristics and Tibial Bone Adaptation in Male Academy Football Players

We examined the relationship between football-specific training and changes in bone structural properties across a 12-week period in 15 male football players aged 16 years (Mean +/- 1 SD = 16.6 +/- 0.3 years) that belonged to a professional football academy. Tibial scans were performed at 4%, 14% and 38% sites using peripheral quantitative computed tomography immediately before and 12 weeks after increased football-specific training. Training was analysed using GPS to quantify peak speed, average speed, total distance and high-speed distance. Analyses were conducted with bias-corrected and accelerated bootstrapped 95% confidence intervals (BCa 95% CI). There were increases in bone mass at the 4% (mean increment = 0.15 g, BCa 95% CI = 0.07, 0.26 g, g = 0.72), 14% (mean increment = 0.04 g, BCa 95% CI = 0.02, 0.06 g, g = 1.20), and 38% sites (mean increment = 0.03 g, BCa 95% CI = 0.01, 0.05 g, g = 0.61). There were increases in trabecular density (4%), (mean increment = 3.57 mg center dot cm(-3), BCa 95% CI = 0.38, 7.05 mg center dot cm(-3), g = 0.53), cortical dentsity (14%) (mean increment = 5.08 mg center dot cm(-3), BCa 95% CI = 0.19, 9.92 mg center dot cm(-3), g = 0.49), and cortical density (38%) (mean increment = 6.32 mg center dot cm(-3), BCa 95% CI = 4.31, 8.90 mg center dot cm(-3), g = 1.22). Polar stress strain index (mean increment = 50.56 mm(3), BCa 95% CI = 10.52, 109.95 mm(3), g = 0.41), cortical area (mean increment = 2.12 mm(2), BCa 95% CI = 0.09, 4.37 mm(2), g = 0.48) and thickness (mean increment = 0.06 mm, BCa 95% CI = 0.01, 0.13 mm, g = 0.45) increased at the 38% site. Correlations revealed positive relationships between total distance and increased cortical density (38%) (r = 0.39, BCa 95% CI = 0.02, 0.66), and between peak speed and increased trabecular density (4%) (r = 0.43, BCa 95% CI = 0.03, 0.73). There were negative correlations between total (r = -0.21, BCa 95% CI = -0.65, -0.12) and high-speed distance (r = -0.29, BCa 95% CI = -0.57, -0.24) with increased polar stress strain index (38%). Results suggest that despite football training relating to increases in bone characteristics in male academy footballers, the specific training variables promoting adaptation over a 12-week period may vary. Further studies conducted over a longer period are required to fully elucidate the time-course of how certain football-specific training characteristics influence bone structural properties.

Automated summary

We investigated the relationship between football-specific training and changes in bone structural properties in 15 male football players aged 16 years over a 12-week period. Tibial scans were performed before and after increased football-specific training, and training parameters were analyzed using GPS. The results suggest that while football training is associated with increased bone characteristics in male academy footballers, the specific training variables influencing bone structural properties may vary over a 12-week period. Further research is needed to fully understand the time-course of how certain football-specific training characteristics affect bone adaptation.