Development of novel calibration model(s) to predict whole-body density in professional football players

ABSTRACT

Introduction

Questions continue to be raised about the validity that is in existence to estimate D_b, in professional male footballer players.

Methods

Phase 1: n = 28 anthropometric variables were used on n = 206 footballers, using regression analyses to determine standard error of estimate and R². A cut-off correlation coefficient set at r = 0.950 and 90% R². Phase 2: all variables (z-scores, $\bar{x}$ = 0.0, SD = ±1.0) to help reduce heteroscedasticity, β, r, t, significance of t and P-values were calculated. Phase 3: a forced stepwise–backwards regression analysis approach with nine predictors which met the acceptance criteria (r = 0.950, R² = 90% and β weights) was used to develop a ‘best fit’ and a ‘practical’ calibration model. Phase 4: cross-validation of the two newly developed calibration method using LoA.

Results

The ‘best fit’ model SEM (0.115 g ml⁻¹), the highest R² (6.6%) (P  ≤ 0.005), whereas the ‘practical’ calibration model SEM (0.115 g ml⁻¹), R² (4.7%) (P  ≤ 0.005) with r values = 0.271 and 0.596 and R² (%) coefficients = 0.3526 for the ‘best fit’ and ‘practical’ calibration models, respectively (P = 0.01).

Conclusions

The two calibration models supported an ecologically and statistically valid contribution and can provide sound judgements about professional footballers’ body composition.

KEYWORDS:

• Anthropometry
• calibration models
• whole-body density
• professional football players
• cross-validation

Disclosure statement

No potential conflict of interest was reported by the author(s).

Informed consent

All participants described in the paper have given written consent to the inclusion of material pertaining to themselves, that they acknowledge that they cannot be identified via the paper; and they have been fully anonymized.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.