TABLE 2.
Model Estimates and Comparisons of Head Impact Exposure for Practices and Games Within Youth Tackle and Flag Football Athletes (n = 477)a
| Outcome | Estimatesb | Tackle | Flag |
|---|---|---|---|
| No. of impacts | Average rate of impact per athletic exposurec | ||
| Game | 12.97 (11.36 to 14.73) | 0.77 (0.53 to 1.06) | |
| Practice | 6.51 (5.75 to 7.37) | 0.37 (0.20 to 0.60) | |
| Rate ratio | |||
| Game to practice | 2.00 (1.74 to 2.29) | 2.06 (1.29 to 3.58) | |
| Probability ≥1 impact | |||
| Game | 0.92 (0.90 to 0.94) | 0.53 (0.41 to 0.64) | |
| Practice | 0.92 (0.90 to 0.94) | 0.31 (0.18 to 0.45) | |
| Linear acceleration (50%) | Average 50th percentile | ||
| Game | 18.37 (18.17 to 18.57) | 16.69 (15.26 to 18.31) | |
| Practice | 18.08 (17.87 to 18.29) | 16.19 (15.04 to 17.42) | |
| Increase in 50th percentile | |||
| Game vs practice | 0.29 (0.09 to 0.49) | 0.49 (−1.10 to 2.32) | |
| Degrees of freedom | 2 (2 to 2) | 2 (2 to 4) | |
| Probability 50th percentile greater during gamesd | |||
| Game ≥practice | 1 | 0.72 | |
| Linear acceleration (95%) | Average 95th percentile | ||
| Game | 50.17 (48.57 to 51.77) | 32.46 (26.61 to 38.50) | |
| Practice | 50.09 (48.49 to 51.69) | 23.69 (18.84 to 29.19) | |
| Increase in 95th percentile | |||
| Game vs practice | 0.09 (–1.59 to 1.77) | 8.69 (1.51 to 15.83) | |
| Degrees of freedom | 3 (2 to 4) | 5 (2 to 21) | |
| Probability 95th percentile greater during gamesd | |||
| Game ≥ practice | 0.54 | 0.99 | |
| High-magnitude impacts (≥40g) | Average rate of impact per athletic exposure | ||
| Game | 1.43 (1.24 to 1.64) | — | |
| Practice | 0.70 (0.61 to 0.79) | — | |
| Rate ratio | |||
| Game to practice | 2.06 (1.80 to 2.34) | — | |
| Probability ≥1 impact | |||
| Game | 0.75 (0.70 to 0.79) | — | |
| Practice | 0.50 (0.45 to 0.54) | — | |
Estimates and comparisons were for those aged 6 to 14 years, by outcome variable (number of impacts, 50th percentile of linear acceleration, 95% percentile of linear acceleration, and high-magnitude impacts [≥40g]), in New York, 2017 and 2018. Data in parentheses are 95% CI. Dashes indicate that models were not stable and results were not calculated.
Estimates may differ slightly when the data are stratified by type of football played (ie, tackle, flag) and games versus practices.
Athletic exposure is defined as a youth football practice or game.
Reported value is the proportion of posterior samples in which estimate for games exceeded that for practice. Therefore, no CI is reported.