Western States 2012 Research Findings

I just got an email through about some research done at the 2012 Western States about stride length/rate and what type of foot strike individual runners had as well as the stats for the whole field.

Odd, considering I thought I was more of a mid-foot striker, but at 100-mile mountain speeds the whole running motion is shorter and slower, I suppose.

Here's the email:

Hi Ian,

As you may recall, we collected filming data at the 2012 Western States Endurance Run (WSER) to analyze foot strike pattern.  This email summarizes the overall as well as your individual results. 
Our interest in the study was four-fold.
1. We wanted to characterize foot strike patterns of ultramarathon runners during a 100 mile trail run.
2. We wanted to determine if foot strike pattern, stride rate, and stride length changed over the course of the run.
3. We wanted to determine if foot strike pattern was related to performance.
4. We wanted to determine if creatine kinase (CK, an indication of the extent of muscle damage) concentration was related to a runner's foot strike pattern.
There were 4 filming zones -  1 prior to the Lyon Ridge aid station (10.2 miles); 2 after the Michigan Bluff aid station - 1 on a level running surface (56.1 miles), 1 on a 9% downhill grade (56.4 miles); and 1 prior to the finish line (100.1 miles).
The overall results of the study are summarized as follows:
1. The rear-foot strike prevalence was approximately 80-90% at each of the 4 sites.  This is slightly less than previously observed in a marathon.  Rear-foot strike prevalence was approximately 80% at 10.2 miles.  It increased to 90% at 56.1 miles, then decreased to approximately 85% on the track near the finish line.
2. Stride length was longest at 10.2 miles, decreased at 56.1 miles, then increased at the finish, but was still shorter than the stride length observed at 10.2 miles. Stride rate was highest at 10.2 miles.  It decreased at 56.1 miles and remained similar at the finish.
3. Overall, a specific foot strike pattern was not related to better performance.
4. There was evidence of lower blood CK concentrations among those using a rear-foot strike pattern compared with runners using a mid-foot or fore-foot strike pattern.
Individually, your foot strike pattern, stride length, and stride rate at each site are included below. Foot strike patterns were classified as rear-foot strike (RFS), mid-foot strike (MFS), fore-foot strike (FFS), a combination of mid-foot and fore-foot strike (NON-RFS), a combination of rear-foot and non rear-foot strike (MIXED RFS/NON RFS), or undetermined (UNCLASSIFIED).  NOT DETERMINED will appear when stride length and stride rate could not be determined.  Averages for stride length and stride rate are included (in parentheses) at each site for your reference.
Site = 10.2 miles (Lyon Ridge)
Foot strike = RFS
Stride Length = 95.28 inches (79.12 inches)
Stride Rate = 1.75 strides/s (1.75 strides/s)
Site = 56.1 miles (Michigan Bluff - level)
Foot strike = RFS
Stride Length = 88.19 inches (74.45 inches)
Stride Rate = 1.46 strides/s (1.54 strides/s)
Site = 56.4 miles (Michigan Bluff - downhill)
Foot strike = RFS
Stride Length = 105.51 inches (82.88 inches)
Stride Rate = 1.54 strides/s (1.55 strides/s)
Site = 100.1 miles (Auburn)
Foot strike = RFS
Stride Length = 91.34 inches (78.94 inches)
Stride Rate = 1.58 strides/s (1.55 strides/s)
Thank you for your participation in the 2012 Western States Endurance Run and our research.  We will be presenting our findings at a national sports medicine conference and publishing the work in a sports medicine journal.  If you have any questions about the results please feel free to contact Dr. Marty Hoffman (martin.hoffman@va.gov).
We look forward to seeing you on the Western States trails again.
Sincerely,
Marty Hoffman, MD
Mark Kasmer, MD
Jeremy Wren, MD