INDIANAPOLIS — Mike Zimmer is seeking answers to the Vikings' hamstring issues from last season, even though he said they had an average amount. Dalvin Cook, Anthony Barr and Eric Kendricks were the most prominent players to miss snaps because of injured hamstrings.

"We had 14 hamstring [injuries] last year and the average in the NFL was 14 and 1/2," Zimmer said. "We are going to have to look at those things. Is it shoes? Is it field condition? Is it not warmed up? Is it not hydrated enough? There are so many things. And actually the NFL is doing a big study on it right now as far as those kinds of things."

One solution could be getting more players to use a device placed in every NFL equipment room a year ago. The league and HP partnered to give each team 3D scanners that map feet and provide players with personalized cleat recommendations. Another answer could be injury management. Cook was on the injury report for seven weeks, during the middle of which he returned and reaggravated his leg.

"The second most time lost from any injury is the hamstring," Zimmer said. "For some reason that injury takes five or six weeks. Obviously ACL is the No. 1. … These track guys, which Dalvin basically is, for them to get right just takes a long time typically. I think he was better in the second half of the year."

Players also say hamstring injuries are among the trickiest to fully recover. Cook's injured hamstring made him wary of doing "something stupid" in practice, he said, because he said his leg felt fine walking around the facility but could tighten up after a warmup and sprint on the practice field.

Cornerback Xavier Rhodes injured his hamstring in the summer and was hampered throughout the year, listed questionable to play in Week 1 and Week 13 due to his bad wheel. He suited up to play both games, but couldn't do much in the December loss at New England. Four weeks later, Rhodes missed the season finale because of an injured groin.

"One injury happened, I was trying to get back on the field as fast as possible and it caused another one," Rhodes said in December. "So, maybe that was a lesson learned for me to not do too much when I have an injury lingering."