Original Publication Information: The article "PREDICTING 40-YARD DASH TIME IN COLLEGE FOOTBALL PLAYERS " appeared in the spring, 1999 I.A.H.P.E.R.D. Journal.

INTRODUCTION

Performance in the 40-yd dash is often a major factor for selecting high school, college, or professional football players. While it is relatively simple to have players perform the 40-yd dash to determine their speed, it may be beneficial to identify performance and nonperformance variables which are highly associated with running speed. If certain variables are highly related to better sprint performance, it could provide a basis for designing training programs to enhance that particular component, thus potentially improving sprint speed. The purpose of this study was to determine the effectiveness of selected measures to predict 40-yd dash time in college football players.

METHODS

Forty-three NCAA Div II varsity college football players were measured for seven predictor variables at the conclusion of a 10-week winter conditioning program. Body composition analysis included determination of percent body fat estimated from skinfolds using an athletic equation.

Leg strength was assessed from a 1-RM squat. Each subject was allowed three attempts to reach his best lift, and the use of weight belts, knee wraps, and squat suits was permitted. While almost every player used a weight belt, only a few used knee wraps or squat suits. The bar was typically placed across the upper back distal to the cervical vertebrae. The player lifted the bar from a support rack, took one step backward into position, and lowered the bar until the bottoms of the thighs were parallel to the floor. Upon a signal from the strength coach, the lifter extended the legs to return the bar to the starting position.

Vertical jump was measured according to standard procedures (Adams, 1998:76:78). Initially the player reached as high as possible on a measuring tape with his dominant hand. He then jumped as high as possible from a flat-footed position to touch the measuring tape. Vertical jump power was calculated according to the newly developed procedure of Johnson and Bahamonde (1996) utilizing height, weight, and jump distance.

Time for a 40-yard dash for each subject was derived using a two-trial average obtained from two hand-held stop watches. Subjects ran in pairs to enhance the competitive nature of the effort. Each subject ran in athletic shoes and shorts on an artificial indoor rubber surface. Each subject started from a stationary three-point position, with each watch being started on the first movement of the subject.

RESULTS

Means and SDs for performance and nonperformance variables for the entire group are shown in Table 1.

TABLE 1. Physical and Performance Characteristics of the Subjects (n = 43).

Variable	Mean	SD	Correlation With 40-yd Dash (s)*
Height (cm)	184.7	4.4	0.19
Weight (kg)	102.2	36.7	0.78
LBM (kg)	87.5	11.6	0.65
%fat	13.2	3.5	0.83
Vertical Jump (cm)	64.8	2.9	-0.76
Jump Power (W)	3,764.7	440.3	0.33
1-RM Squat (kg)	199.4	51.8	0.18
40-yd Dash (s)	4.98	0.31	-

*r = 0.38 significant at p<0.01 >

Five of the seven variables were significantly correlated with 40-yd dash time in the composite group of players. However, when the players were separated into backs and linemen, the only significant correlations with 40-yd dash were for %fat and vertical jump in the two groups (Table 2).

TABLE 2. Correlations of Physical and Performance Variables with 40-yd Dash.

Variable

Correlation with 40-yd Dash (s):a

 

.

Backs (n = 24)

Linemen (n = 19)

 

.	ZOb	BMc	ZOb	BMc
Height (cm)	0.26	0.23	-0.44	-0.25
Weight (kg)	0.29	.	0.57	.
LBM (kg)	0.13	-0.64	0.42	-0.83
%fat	0.61	0.63	0.85	0.79
Vertical Jump (cm)	-0.59	-0.61	-0.73	-0.67
Jump Power (W)	-0.22	-0.64	0.14	-0.66
1-RM Squat (kg)	-0.14	-0.39	-0.18	-0.67

In both groups, the lower the %fat and the greater the vertical jump, the faster the 40-yd dash time.

If the differences for body weight among the backs was controlled statistically, LBM and jump power became significant without altering the relationships between 40-yd dash and %fat and vertical jump. Holding body weight constant in linemen produced similar changes, but with the addition of a significant relationship between 1-RM squat and 40-yd dash. Multiple regression analysis produced five significant equations to predict 40-yd dash from performance and nonperformance variables (Table 3).

TABLE 3. Prediction Equations to Estimate 40-yd Dash in College Football Players (n = 43).

Equation	R	R2 x 100	SEE
40-yd dash (s) = 6.56 -0.171 LBM (kg) + 0.144 Weight (kg) - 0.090 %fat	0.90	81.0	0.14
40-yd dash (s) = 6.13 - 0.148 LBM (kg) + 0.129 Weight (kg) - 0.082 %fat - 0.001 Squat	0.91	82.8	0.13
40-yd dash (s) = 4.97 - 0.110 %fat + 0.163 Weight (kg) - 0.195 LBM (kg) + 0.011 Height	0.91	82.8	0.13
40-yd dash (s) = 7.09 - 0.143 LBM (kg) - 0.083 %fat + 0.121 Weight (kg) - 0.030 Vertical Jump (cm)	0.92	84.6	0.13
40-yd dash (s) = 5.60 - 0.167 LBM (kg) - 0.102 %fat + 0.140 Weight (kg) - 0.029 Vertical Jump (cm) + 0.010 Height (cm)	0.93	86.5	0.12

DISCUSSION

The fundamental finding of this study indicated that the leaner yet more muscular the player, the faster the 40-yd dash time. This was true in the team as a composite or within the back and linemen subgroups. Ironically, leg strength was not highly related to sprint speed. The association between vertical jump and 40-yd dash might be indicative of a predominance of fast-twitch muscle fibers. Further research may be required to determine how much running speed can be increased by manipulating some of these factors.

REFERENCES

·       Adams, G. M. (1998). Exercise Physiology Laboratory Manual (3rd ed.). Boston, MA: McGraw-Hill.

·       Johnson, D. L. & Bahamonde, R. (1996). Power output estimate in university athletes.Journal of Strength and Conditioning Research, 10:161-166.