Normative Reference Values for High School–Aged American... : The Journal of Strength & Conditioning Research (2024)

Introduction

The 40-yd dash (40YD) and proagility (PA) are common field tests performed at the National Football League (NFL) scouting combine, as well as high school American football recruiting combines hosted across the United States. Typically, 10- and 20-yd split times (10YD and 20YD) are recorded during the 40YD, and a 10-yd split time is also recorded during the PA. Normative references values for the field tests performed at the NFL scouting combine have been previously reported (⁶). More recently, normative reference values for combine field tests have been reported based on a large sample of high school American football athletes (⁵). Another study provided comparisons among American football positions as well as high school grade levels for anthropometric and combine athletic performance results (⁴). However, neither of these reports includes 10YD, 20YD, or PA split times. Examining these field tests and their respective split times may provide insight into an athlete's acceleration and change of direction ability (^1,7).

It may be useful for younger athletes, their parents, and coaches to have normative reference values for 10YD, 20YD, and PA split times based on a large sample of peers. In addition, high school strength and conditioning professionals may use these values as a guide for realistic and attainable goal setting. This short report is a follow-up of the original report (⁵) with the purpose of providing position-specific normative reference values for the 10YD, 20YD, and PA split times based on a large, nationally representative sample of high school–aged American football athletes in their freshman, sophom*ore, and junior classes.

Methods

Experimental Approach to the Problem

The experimental approach has been previously reported in detail (⁵). Briefly, cross-sectional anthropometric and performance data were obtained from 12 different high school American football recruiting combines hosted by Zybek Sports (Boulder, CO, USA) between March 7, 2015, and January 9, 2016, across the United States. To determine normative reference values, data from all combines were aggregated into 1 sample and then segregated by high school class (freshman, sophom*ore, and junior). One combine held in Austin, TX, on March 15, 2015, did not measure the 20YD during the 40YD or the 10-yd split during PA. Therefore, the 603 athletes who completed the 40YD and PA did not present data for the 20YD or PA split. Very few high school seniors participated because these combines are typically used as tools for collegiate American football recruiting and many seniors had already committed to college programs. Thus, seniors were not included in this report.

Subjects

A sample of (n = 7,478) high school–aged American football athletes in their freshman (n = 1,185), sophom*ore (n = 2,514), and junior (n = 3,779) classes participated in these American football recruiting combines. The University of Nebraska-Lincoln's Institutional Review Board (IRB) in the office of Research and Economic Development determined that Institutional Review Board approval was unnecessary because these deidentified data provided by Zybek Sports do not constitute human subjects research (Institutional Review Board communication February 26, 2016).

Procedures

The methods have been previously reported in detail (⁵). In short, the 40YD and PA were measured in seconds using digital laser-beam actuated timing gates (fully automated Timing systems: Zybek Sports, Boulder, CO). Ten and 20YD split times (seconds) were measured during the 40YD. During the PA, the athlete passes the timing gates on 2 separate occasions: during the 10-yd sprint and again at the finish line; therefore, the PA split time is recorded during the first timing gate pass. The 40YD dash with 10 and 20YD split times and the PA have been explained in more detail elsewhere (^3,6).

Statistical Analyses

As in the original report (⁵), defensive end (n = 23) and tight end (n = 137) positions were grouped with linebacker for the 40YD and PA due to statistical commonality. Separate 1-way analyses of variance were performed to examine mean differences among grades for the 10YD, 20YD, and PA split for each position group. Descriptive statistics (mean values, SDs, and percentile ranks) were calculated for test- and position-specific absolute values (Tables 1–3). All analyses were performed using SPSS version 24 (IBM, Inc., Chicago, IL, USA). The type 1 error rate used to determine statistical significance (alpha) was set at p ≤ 0.05.

Results

Mean values, SDs, sample sizes (n), and percentile ranks for 10YD (seconds), 20YD (seconds), and PA (seconds) are reported in Tables 1–3. Mean differences were found among classes for all positions and all measurements (p ≤ 0.05) with 2 exceptions. For offensive linemen (OL) and quarterback (QB), no mean differences were found among classes for PA split (p > 0.05). Percent differences from freshman to sophom*ore and from sophom*ore to junior classes for the 10YD, 20YD, and PA split are presented in Figure 1.

Discussion

The original report of grade- and position-specific normative values included the 40YD and PA test results with no split times (⁵). Normative values previously reported for the NFL combine participants also did not include 10YD, 20YD, or PA split times (⁶). Nonetheless, high school and collegiate American football athletes, parents, and coaches may still use these measurements to evaluate performance ability. In fact, Teramoto et al (⁹) found 10YD times in the NFL Draft to be the most important predictor of rushing yards per attempt during the first 3 years of league play for running backs. It is possible that high school players or coaches may want similar types of normative comparisons. Thus, more realistic goal setting and expectations for athletic performance can be set by providing normative values for high school–aged football players based on peer comparisons, rather than comparisons to NFL combine participants.

The relevance of the 40YD to football has been criticized because the average football play requires considerably shorter sprints. It has been shown that most plays demand sprints of 5–20 yd (¹). Furthermore, the 40YD is only moderately correlated (r = 0.41) with 5-yd sprint time; thus, shorter sprint times may not be ideal for predicting 40YD performance (^2,8). However, examining the 40YD time alone gives little insight into the acceleration abilities of American football athletes, which is a critical component of sprint performance. Because of this, short sprints and the calculation of sprint acceleration are becoming increasingly popular tools to assess performance ability.

For all split times except PA split for OL and QB (Tables 1–3), mean differences were found among classes for all positions (p ≤ 0.05). The lack of difference in PA splits for OL and QB may reflect the relevance of the PA split to the demands of the OL and QB positions. However, for the average high school American football athlete, there were nonsignificant decreases in split times from freshman to sophom*ore to junior years (Tables 1 and 2). It is also important to note that the percent improvements for all split times from freshman to sophom*ore years were 1.67–4.67%, while from sophom*ore to junior years were 0.85–1.08% (Figure 1). These are consistent with the age-related improvements in the 40YD and PA as described previously (⁵). These findings suggest that a larger percent change is observed from freshman to sophom*ore years in lower-body speed and agility as a result of normal growth and development, compared with the transition from sophom*ore to junior years. This may be particularly insightful for high school strength and conditioning professionals who target specific outcomes in performance across years in high school. Improvements of greater than 10% were observed in the power push-up from freshmen to sophom*ore years and from sophom*ore to junior years (⁵). Thus, upper-body strength and power may be more adaptable for targeted improvements in these athletes than lower-body speed, power, and agility.

Practical Applications

Athletes, coaches, and parents should use the normative values for 10YD, 20YD, and PA split times in Tables 1–3 for more realistic comparisons based on results of their peers. These normative values may also be used by high school strength and conditioning professionals to set attainable goals and reward accomplishments for young American football athletes. There is also value in knowing the average percent differences between freshmen and sophom*ores and sophom*ores and juniors, so that tracking individual player progression can be monitored based on national averages.

References