Football players who compete at a collegiate level undergo rigorous training throughout their four-year careers to get bigger, leaner, stronger, and faster. Despite the National College Athletic Association (NCAA) rules that state coaches can only take 20 hours a week of their players’ time regardless of the sport, college football players spend an average of 43.3 hours on their sport, according to a NCAA survey. These long, excruciating hours of practice may help football players get bigger and stronger, but not improve their speed or how high they jump, says recent study.

Findings published in the September issue of the Journal of Strength and Conditioning and Conditioning Research revealed a college football player’s speed and power does not change. This result is said to be sound advice specifically geared towards wide receivers, running backs, corners and safeties from the researchers of the study. Scientists followed 156 NCAA Division I college football players for seven years, including their four-year careers, to record the players’ height and weight, strength, power and speed.

In the study, power is defined as the ability to jump vertically, according to Bert Jacobson, study author. Power is a useful skill for football players when they want to deflect a pass or when the ball was passed too high. Strength was measured by various weight-lifting tests, while speed was assessed with a 40-yard sprint, HealthDay News reports.

92 out of the 156 football players were offensive or defensive lineman, while the rest (64 players) were wide receivers or defensive backs. The 64 players were referred to as skill players in the study.

In football, the offensive lineman moves the players from the opposing team out of the way so their team could move the ball forward towards the opposing team’s side of the field. The defensive lineman is responsible for blocking players that try to move forward, says Skill players require a great deal of speed and power to tackle down their opponents.

The researchers recorded the average weight of a lineman to be 283 pounds at the start of the study. Throughout the course of the study, these players were found to gain an average of three percent of their original body weight — averaging 292 pounds by the end of the study. While the linemen got physically bigger, on average dropped from 23 to 21 percent in body fat. This result indicated that these players are gaining more muscle mass.

A vast improvement was witnessed in the endurance of the linemen throughout their four-year careers by the researchers. At the initial start of the study, they were reported to bench press 350 pounds and by the end of the study, they bended 410 pounds — an 18 percent increase. A loss of speed, and no change in power was recorded by the researchers.

The skill players in the study gained nine percent of their original body weight. These players were recorded to be 175 pounds at the start of the study and ended with an average of 191 pounds. There was as decrease in body fat from 8.4 percent to 8.1 percent in the skill players.

Wide receivers and defensive backs, like the linemen experienced a loss in speed from 40-yard sprint from year one to year four. It was only from year one to year two that the skill players gained an average of 1.5 inches in their vertical jump. This was also the same and only year that the researchers saw a great increase in power in these players.

Speed and power are contingent on the type of muscle fiber a person said Jacobson. “People have either fast-twitch or slow-twitch muscle fibers” and "that's not going to change.” “You're born with that speed," he continued.

Muscle fibers do seem to influence how the muscles respond to training and physical activity. The muscle fibers act differently in their ability to contract in a certain way, says Elizabeth Quinn, a Sports Medicine reporter. Human muscles are said to contain a genetic mix of slow and fast fiber types. Quinn says on average, humans have approximately 50 percent slow twitch and 50 percent fast twitch fibers in most of the muscles that are used for movement.

Speed and power are not just dependent on these variables according to Dr. Victor Khabie, chief of sports medicine and chief of surgery at Northern Westchester Hospital in Mt. Kisco, N.Y. Speed and power depend on how hip, knee and ankle joints are able to hold the muscles together and how they are coordinated, said Dr. Khabie to HealthDay News.

The findings of the study could alter the way coaches train their athletes.