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Number of Explosive Muscular Contractions Over 40 Yards

Mike Gittleson was the Director of Strength & Conditioning at the University of Michigan for 30 years and was a part of 15 Football Championships in that time. He explains, if you want to get faster… get in shape.

I received my Masters from Michigan. Our Exercise Physiology Department had one of the first isokinetic devices ever made. One of our assignments for post graduate work was to establish normative data for the utilization of the device.

As young adventurous students, we set off to establish power curves, strength curves, muscular endurance standards, and  quadriceps/hamstring ratios as normative data. After accomplishing much of this, the data was published or utilized by companies, trainers, students and coaches.

Out of curiosity we decided to see if we could predict 40 yard dash times from anthropometry and the results from a variety of power curves from leg strength tests. Understand at the time there were no collegiate strength and conditioning coaches in the mid-western United States. Thus the measurements were taken on athletes who did very little weight training and ran about 4 weeks, twice per week, prior to spring football. It was an interesting project with surprising results.

This is what we did:

1.    We timed every football player in the 40 yard dash at the beginning of their winter program. We timed them again at the end of their winter conditioning, just before spring football. All this was done with Coach Schembechler’s blessing.

Circumferences – neck, chest, waist, hips, thigh, knee, calf, ankle, upper arm, forearm, wrist

3. We took measurements of the length of the bones as well as total limb lengths

Size of hands and feet

Arm Length

Leg Length

Trunk length

Head and neck length

4. We also took the breadth of various bones and body breadth (skeletal frame size).

After we had good solid measurements

5. We began body composition


Hydrostatic weighing

4. Isokinetic dynamometer testing

Strength Curve

Power Curve

Explosive Muscular Contraction

Explosive Muscular Contraction Endurance…..the number of Explosive Muscular Contractions you could make until you reached 50% of your best explosive contractions…..

Ratios Quadriceps to Hamstrings

5. Of course Height and Weight and Age




Finished and weary, we took the data of 120 athletes to the Statistics Department.  Our goal was to find what measurements correlated significantly with the 40 yard dash time.

The statistics department handled all the data and ran computations comparing the results of each independent variable, as well as the possible combination’s of variables. Example: leg length was compared to 40 yard dash and then leg length and leg girth and leg power to the 40, and then leg length, leg girth, arm length, power, explosive strength to the 40, and on and on and on. The stats department compared everything every which way. The computer on North Campus was humming through combination’s and permutations of measurements.

We literally had box upon box of print outs that we got stronger just loading them back into the lab to analyze.

We assumed because of the reams of paper that it was going to take another semester of school to find the results and maybe some more statistic classes.

Looking at the data carefully, one thing was glaring, it didn’t matter how the variables were combined, none correlated significantly with the 40 yard dash with the exception of one.

The only variable that correlated with speed, that is the 40 yard dash time, was the number of explosive muscular contractions (endurance) an athlete could make without fatiguing below 50% of his maximum explosive leg strength.

The variable, the total number of explosive muscular contractions before fatigue, had to be by itself, independent of all the anthropometric measurements that were taken. This was the only way we had a significant correlate with the 40 yard dash time!

The athlete had to be in great muscular shape relative to himself to run fast or faster.

I became a strong believer in the following sprint test based on the above work we did as grad students. I knew if you trained to pass this test, you would run your best time. And without question if you could pass it, you would be in great shape.

I also knew if you didn’t pass it ——you could get faster.


Field set up: 

Start your sprint from the 20 yard line and sprint 40 yards. Once finished walk to the opposite 20 yard line and sprint back.

  Football Field




The athletes goal is to run 10 sprints within 5/10ths of their lifetime best forty. The rest interval is 20 seconds between each sprint.

How a timer counts the rest interval between sprints: As soon as the athlete crosses the forty yard line the rest interval begins. Immediately the timer records the time and begins counting 20-19-18-17-16-15-14-13-12-11-10-9-8-7-6-5-4-hand-on -the- line-2-1- go.

The athlete must achieve all ten sprints to be considered fit, anything less than ten is failure.

Soooo don’t fail to Get Strong.

2.  We then took the following measurements on each athlete two days after the results of the 40 yard dash


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