I always encourage girls to compare their softball pitch speed only to their previous speed. It's important to encourage girls to continuously improve. Never want to put more pressure on pitchers than the position already carries.
I have created a chart below based on my former students to provide real information about softball pitch speed. I chose to use Age as a factor to separate physical development. I also chose stride length to reflect pitcher height and overall strength. Tall pitchers usually have longer arms that can create more leverage for the pitch. Pitchers with strong legs can also produce more push and create a longer stride. Height and strength are direct factors in pitching speed.
I'd like to retract this previous statement in light of new data. As a pitching coach, I teach my students to work on daily improvement in their skill set. I also practice what I teach. The former chart comparing pitching speed to stride length needs to be adjusted. If you have not been keeping up with my training, I have recently went back to audit a few courses at the University of Alabama in Huntsville's biology/kinesiology department. In the Biomechanics course, we studied stride length in depth. I learned that bigger is NOT better and ideal stride length should be within 2 inches (+/-) of the pitcher's height. Getting too big will actually decrease speed by getting "outside the pitcher's body" and now efforts are shifted to catch up to the over-stride and away from power production.
Now, to really get the best out of the stride length, three things need to happen.
1. Terminal knee extension on the drive leg
2. Stride leg height needs to be even with the hip
3. Land with knee over ankle
The chart below is the updated speed chart once I retaught the stride to my current students. There was a increase in speed overall with the updated mechanics. Included are a few frequently asked numbers.
Arm speed - is the pitch speed using only the windmill motion. This helps me check to see if girls are efficiently transitioning arm speed into their full motion mechanics. Looking for 15-20% increase from arm speed to pitch speed.
FB Velocity - Average fastball velocity for by age.
Spin Rate - Was measured with a RevFire. This has been a great addition to my training and has has yielded tremendous results this season with increased spin rates.
Change Up Range - I have included a minimum change up speed. There is such thing as being too slow and giving batters enough time to adjust. Minimums are calculated by pitching distance and travel time. Work to be above minimum speeds. "Diff" is for difference which is typically how change up speed is determined as the difference in speed between fastballs and changeups. For example, a 10 year old should have a change up above 25 mph at 35 feet or 8 mph slower than their fastball. A 16 year old pitcher should have a change up speed above 42 mph at 43 feet or 10 mph (or greater) than their fastball speed.