Table 1.
Summary of equations for estimating maturity and maturation status in youth soccer players.
| Author (publication year) | Equation for boys | Equation for girls | Population used to formulate/validate equation | Suggested limit thresholds | Considerations | Available for use via supplementary spreadsheets |
|---|---|---|---|---|---|---|
| Fransen et al. (2018)47 | Maturity ratio = – 6.986547255416 + (0.115802846632 × CA) + (0.001450825199 × CA2) + (0.004518400406 × BM) − (0.000034086447 × BM2) − (0.151951447289 × S) + (0.000932836659 × S2) − (0.000001656585 × S3) + (0.032198263733 × LL) − (0.000269025264 × LL2) − (0.000760897942 × (S × CA)) |
Unavailable | Reanalysis of Mirwald et al.43 dataset (n = 251) plus (n = 1330) high-level male youth soccer players (8.0–17.0 years old) from Belgian soccer academies and from various ethnic backgrounds, with the majority of players of Caucasian descent (n = 1581) | ±1 year (but reduced error for early and late maturers) | Sample of 1330 high-level youth soccer players (8.0–17.0 years old) of various ethnic backgrounds recruited from Belgian soccer academies offers validation within a sport-specific population Builds on the previous maturity offset calculations by applying a polynomial model Has been accused of artificially inflating the explained variance (Nevill and Burton48) |
Yes |
| Moore et al. (2015)45 | Maturity offset = –8.128741 + (0.0070346 × (CA × SH)) Maturity offset = –7999994 + (0.0036124 × (CA × S)) |
Maturity offset = –7.709133 + (0.0042232 × (CA × S)) | Participants’ data were used from the Paediatric Bone Mineral Accrual Study (PBMAS) (1991–1997) (n = 79 boys and n = 72 girls; 10.3–15.6 years old), the Healthy Bones Study III (1999–2012) (n = 42 boys and n = 39 girls; 10.5–15.9 years old) and the Harpenden Growth Study (1948–1971) (n = 38 boys and n = 32 girls; 9.8–16.2 years old) Equations later validated by Koziel and Malina 46 using data used from Wrocław Growth Study (1961–1972), n = 193 boys (8–18 years old) and n = 198 girls (8–16 years old) |
±1 year | Offers equation without utilizing sitting height due to previous growth studies not always including this data Suggested to be of less use to those individuals who are early or late maturing, offering less sensitivity and leading to mean regression Recently validated by Koziel and Malina46 or average maturing boys close to onset of PHV |
Yes |
| Mirwald et al. (2002)43 | Maturity offset = –9.236 + (0.0002708 × (LL × SH)) + (–0.001663 × (CA × LL)) + (0.007216 × (CA × SH)) + (0.02292 × (BM/S)) |
Maturity offset = –9.376+ (0.0001882 × (LL × SH)) + (-0.0022 × (CA × LL)) + (0.005841 × CA × SH)) − (0.002658 × CA × BM)) + (0.07693 × (BM/S)) |
n = 152 Canadian children aged 8–16 years (n = 79 boys and n = 73 girls) followed for 7 years (1991−1997) | ±1 year | Accused of producing predicted PHV ages that are overestimated for early-maturing children and underestimated for late-maturing children, reducing efficacy for those at the extremes of maturation (e.g., regression to the mean) (Malina and Koziel44; Koziel and Malina46) Adjusted equations included within the Koziel and Malina46 study, including the final element of the equation multiplied by 100 Boys maturity offset = –9.236 + (0.0002708 × (LL × SH)) + (–0.001663 × (CA × LL)) + (0.007216 × (CA × SH)) + (0.02292 × (BM/S × 100)) Girls maturity offset = –9.376 + (0.0001882 × (LL × SH)) + (–0.0022 × (CA × LL)) + (0.005841 × (CA × SH)) − (0.002658 × (CA × BM)) + (0.07693 × (BM/S × 100)) |
No |
| Khamis and Roche (1994)31 | Predicted adult stature = β0 + β1 × stature+ β2 × weight + β3 × mid-parent height β1, β2, and β3 are the coefficients β0 see smoothed regression coefficients for boys and girls within Khamis and Roche31 |
Predicted adult stature = β0 + β1 × stature+ β2 × weight + β3 × mid-parent height β1, β2, and β3 are the coefficients β0 see smoothed regression coefficients for boys and girls within Khamis and Roche31 |
n = 223 males and n = 210 females, with stature measured at 18 years old, participating within the FELS Longitudinal Study | Boys: 2.1–5.3 cm (50th percentile), 2.4–7.3 cm (90th percentile) Girls: 1.7–2.2 cm (50th percentile), 2.1–4.4 cm (90th percentile) |
Validated against white, middle-class Americans only using hand-wrist X-rays | Yes |
Abbreviations: BM = body mass (kg); CA = calendar age; LL = leg length (m); PHV = peak height velocity; S = standing height (m) and/or stature (m); SH = seated height.