California high school football participation is down 4 percent from 2007, according to an August 2012 survey by the California Interscholastic Federation. (danxoneil/Creative Commons)

Often competing against opponents that fielded more than 40 members on a squad, the Spartans wrapped up the season with a 3-7 record, finishing tied for last in the CIF Central Coast Section's De Anza League. But given the roster limitations he had to work with, Carter said it could have been worse.

"We probably had about 18 or 20 players that had the ability to go out there and play the game," said Carter, who has since resigned from Mountain View and was recently hired to coach defensive backs at West Valley College. "It was tough, man. It's hard to motivate the kids."

Carter, who played seven seasons in the Arena Football League as a wide receiver and defensive back, said an offseason training program that emphasized teaching players proper tackling techniques is one of the reasons why he was able to limit the injuries -- namely, concussions -- with such a thin roster.

Mountain View's challenges in getting more players to participate may perhaps reflect a wider trend among California high schools. An August survey conducted by the California Interscholastic Federation saw participation in 11-man football decline over the past five years. The number of high school football athletes in California dipped from 107,916 players in 2007 to 103,088 in 2012, a roughly 4 percent drop.

Carter said he believes publicity surrounding football-related concussion studies have contributed to this decline in participation at high school programs across the state, including the one he coached. The issue of brain injuries in football has received considerable attention thanks to a string of high-profile deaths, such as former NFL linebacker Junior Seau. A team of scientists analyzed Seau's brain tissue after he committed suicide last year and found that the one-time USC Trojans standout suffered from a brain disease likely caused by two decades of hits to the head.

"It's discouraged them a lot," Carter said. "Parents don't want their kids going out there getting injured. It gives [the game] a bad name right off the bat when you mention concussions. With what's going on in the NFL, it makes it extra tough."

The possibility of developing head injuries lingered constantly with parents of players on his Mountain View squad, Carter said. He remembered the first week of preseason during the start of two-a-days, when players trying to acclimate themselves to the high school game voiced concerns about headaches from wearing helmets and absorbing hits for the first time.

"When kids are playing in high school and he puts on the helmet for the first time ever, he has no idea what the feeling is," Carter said. "Yes, he's going to get a headache. It's like getting punched in the arm. If you get punched in the arm for the very first time, you're going to be sore."

Mountain View is not the only California school suffering from a depleted roster. Los Altos High School fielded just 32 players to start the 2012 season. Cerritos High suspended its varsity program and played the second half of the season at the junior varsity level due to safety concerns. Although Mountain View was spared of major setbacks to its shallow depth chart, players on teams with smaller roster sizes are still at higher risk of injury due to having to see action on the offensive and defensive side of the ball.

"More time on the field increases the risk for many injuries," Dr. Shawn Sorenson, a USC adjunct professor in the Division of Biokinesiology and Physical Therapy, said in a phone interview. "All other things being equal, I would expect that twice as much playing time, for example, results in twice as much risk of injury. This applies to anything from ankle sprains to contusions to head injury."

The hits eventually take their toll, said Dr. Eric Nauman, who helps coordinate the Purdue University Neurotrauma Group in West Lafayette, Ind. In a phone interview, Nauman said today's younger football players are at greater risk of suffering head injuries due to the increased level of athleticism in the high school game.

"Football players today have been playing since they were 6 or 7 (years old), so they accumulate a lot of hits over a lifetime," Nauman said. "Athletes are bigger now than they were in the 1970s and that's a big difference."

A study of 3,500 NFL players who played at least five seasons from 1959 to 1988 revealed that players were four times more likely to die from brain disease than the general population -- a finding that could be prompting parents to discourage their children from pursuing football as a sporting option.

"I'm a parent as well. If I let my kid play football, it needs to be done in a safe way," Nauman said. "If [parents] don't feel comfortable, then they should pull their kids out."

To address the growing concern for player safety among parents of high school athletes, Nauman has been working on a helmet design to help reduce the impact of concussions. The professor of mechanical engineering has been collaborating with colleagues Tom Talavage and Larry Leverenz on testing a helmet that can reduce G-force to a player's brain by 50 percent.

While helmets commonly used in today’s game are effective in preventing skull fractures, they often have minimal impact in reducing damage to a player's brain. The research group's objective is to develop a helmet that can spread out the force of a blow to a larger area of the protective gear and away from the skull.

The group conducted studies on players at Lafayette Jefferson and West Lafayette high schools, close to the Purdue campus. The research concluded that the average athlete absorbs at least 200 blows per week in between two practices and a full game. This can add up to as many as 3,000 hits over the course of a season.

It does not take a helmet-rattling hit for a player to develop concussion symptoms. Nauman said players "can still have neurological impairment" from multiple routine shots to the head in one season, but getting to the bottom of the concussion issue starts with better detection.

"Once you find a way to detect injuries earlier, football can be as safe as soccer," Nauman said. "Then people won't be as worried anymore."

Injuries are inevitable in a sport where bruising behemoths are coming full-speed at one another. But increasing awareness of concussions could be the most vital tool to help ease parents' fears of their children getting hurt, Sorenson said. He recommended that parents consult the Zurich Consensus Statement on Concussion in Sport, published in the British Journal of Sports Medicine, for information on evaluating and treating head injuries among competitive athletes.

"One has to be very careful about what they read in a newspaper or magazine, or hear on television and radio," Sorenson said. "They must be even more careful about what they hear anecdotally from friends or colleagues."

Mirroring California high school football participation trends, youth football at the national level experienced a nearly 20 percent drop in participation from 2008-2011, according to the Sports and Fitness Industry Association. But it may be farfetched to think that sagging participation numbers could force America's most popular sport to punt the ball away anytime soon.

Sorenson said scientific knowledge of head injuries is more developed than in years past, which can only lead to better identification and treatment in the future.

"Competitive sports, including high school football, can be a profoundly good thing for young people," Sorenson said. "We should do our best to promote them in a way that emphasizes fun, healthy competition, teamwork and the development of lifelong positive health behaviors."

Carter echoed Sorenson's sentiment on the sport's role in molding young lives.

"It's more than a game to me," he said. "It's more of a mentorship and providing an opportunity for these kids to get a free education. My reason for coaching the game is seeing players grow and becoming better young men."

Reach Senior Staff Reporter Danny Lee here or follow him on Twitter.