EDEN PRAIRIE, Minn. The Minnesota Vikings went on the road last week and won a game against the Detroit Lions, ending their NFC North losing streak without scoring an offensive touchdown.Improved special teams units, exemplified last week with two return touchdowns and five touchbacks, have played a big role in Minnesota's surprising 3-1 start. With a rookie kicker who has met all expectations and the consistent availability of returner Percy Harvin, the Vikings have featured one of the most complete special teams groups in the entire league, quite a change from last season's often-maligned unit."It starts with the head coach, and it starts with our general manager and the guys we bring in," special teams coordinator Mike Priefer said. "Our head coach preaches it, talks about it. Our assistant coaches back me on all that stuff with the individual guys in their respective rooms. We have high-character young men that understand the importance of special teams."Really, if you don't want to play it, I tell them right off the bat, If you don't want to play it, you don't want to be involved, then come find me and I'll take you off. But you better start on offense or defense because we're going to try to find a replacement for you.' And I think we've drawn that line in the sand and said, You're either with us or not with us,' and we've got the majority, if not all, our guys are with us."The addition of kicker Blair Walsh was the biggest shakeup on the Vikings' special teams; he replaced veteran Ryan Longwell after being chosen in the sixth round of April's draft. Walsh is proving it was a wise decision with a big leg that has affected both the scoreboard and field position.Walsh, a nominee for NFL offensive rookie of the month in September, is nine of 10 on field-goal attempts his first miss came last week and set a team record by hitting field goals of 50-plus yards in each of the first three games. He's eighth in the league in scoring with 36 points and is 3 of 3 from beyond 50 yards. Last season, Longwell slipped to 22 of 38 (78.6 percent) on his field-goal tries. Walsh also had 12 touchbacks on his 20 kickoffs; the 60 percent touchback rate is 11th in the league, and teams have had an average start of the 24.3-yard-line. Last season, Longwell managed a touchback on just 19 of his 78 kickoffs (24.3 percent).Priefer has been able to use the explosive Harvin regularly on kickoff returns after Harvin had been used sparingly for the past few seasons. Harvin, named the NFC special teams player of the month, leads the league with a 38.3-yard average on returns and became one of two players to return a kick for a touchdown when he went 105 yards last week for a score."Please," Priefer said when asked what he said to coach Leslie Frazier to use Harvin more. "Obviously, when Percy's back there, it's a whole different dynamic. It's a dynamic for our football team. Now we've got guys believing he can score every time he touches the ball."Punt returner Marcus Sherels entered training camp without any assurances of keeping his job, with the team bringing in several options to replace him, including fourth-round pick Jarius Wright. But Sherels earned the job in large part by taking care of the ball, and now he's doing much more than that. He ranks third in the league with an 18.8-yard average on eight returns, thanks in large part to his 77-yard return for a touchdown last week."He broke two big tackles, and he made a couple of people miss and then he sidestepped the last guy," Priefer said. "In fact, against Indianapolis we had two 15-yard punt returns that could have been big plays if guys finished the block, and that's been our emphasis ever since Week 2: You have to finish your blocks downfield, high and in front, legal blocks, and good things will happen."Punter Chris Kluwe has been inconsistent, but his averages of 46.0 gross yards and 40.2 net are above his career averages."He didn't hurt us, but you want him to be more consistent," Priefer said. "He wants to be more consistent, and he knows we need to get there for him to play at a high level every week."Meanwhile, the coverage units that caused Priefer so much consternation last year have had their moments as well. Aside from the San Francisco game in Week 3, in which the 49ers' Kyle Williams had returns of 94 and 50 yards, the coverage units have held up well. Minnesota has allowed 9.0 yards per punt return and 34.3 yards per kick return.Henderson returns to full participation: Frazier said linebacker Erin Henderson had been cleared and the Vikings' starting weakside linebacker went through a full practice on Thursday for the first time since suffering a concussion two weeks ago.Frazier said Henderson could be ready to play Sunday when Minnesota hosts the Tennessee Titans."The time he's missed and the fact he was able to go through the entire practice, that's a good sign," Frazier said. "We'll see how he does tomorrow. When he wakes up, make sure everything is still fine, but he had a good day."Frazier said Jasper Brinkley will retain the role as a nickel linebacker with Henderson returning.Defensive end Jared Allen didn't practice for the second straight day while he recovers from a groin injury, but he didn't seem concerned, and Frazier said he should be ready for Sunday's game."I haven't been in the training room this much in my entire career, so it's new to me," Allen said. "Just trying to get my body ready for Sunday, little tweaks and pulls here. Our training staff's doing a good job, our coaching staff's doing a good job allowing me to get a little rest and get this thing right for Sunday."Safety Andrew Sendejo was still out with an ankle injury, but receiver Michael Jenkins (rib) practiced in a limited capacity.Frazier said quarterback Christian Ponder had no problems from a knee injury that had developed in the game. Frazier said Ponder wasn't bothered by the pain on Monday but had more soreness during the week."Much better today," Frazier said. "He didn't have any inhibitions today."Sherels (quadriceps), guard Charlie Johnson (low back), cornerback Antoine Winfield (knee), and linebacker Marvin Mitchell (calf) were listed as limited participants. Frazier said Mitchell stretched his calf during Thursday's practice and was headed for an MRI.Follow Brian Hall on Twitter.