If you ever take time to pay attention, you'll notice something different about soccer players when you compare them to athletes who play other team sports.
For the most part, they all look the same.
Whereas a defensive back's body type can differ hugely from an offensive lineman's in football, soccer players more or less look the same.
Even when you compare bulky and scrawny players in soccer, say Neymar and Ronaldo, the discussion seems relative to the sport.
And the difference between those players never seems as drastic compared to athletes in other fields, like Kevin Durant and LeBron.
This is likely because at its highest level, soccer generally demands a distinct type of fitness for all of its players that other sports just don't.
The first indication of this fact is the sheer amount of ground soccer players have to cover during a standard match.
Companies like Stats Inc., which has the technology to track player movement throughout a match, concluded soccer players run between 6 and 7 miles per game.
Essentially, soccer players cover the distance of a 10k run each time they step onto the pitch. That amounts to so much more than the average distance covered by players involved in other major sports.
Wide receivers and cornerbacks in the NFL tend to run an average of 1.25 miles per game and NBA players usually top out at an average of under 3 miles per game, while tennis players can cover distances between 3 to 5 miles per during five-set matches.
All three of those statistics come courtesy of Gizmodo, with the help of Sport VU data. All three of them, furthermore, don't come close to soccer.
In fact, when CBS tried to answer the flat-out question of whether or not World Cup players are the fittest athletes, the only other athletes who could be mentioned as soccer players' peers were marathon runners, pro cyclists, Ironman triathletes and cross-country skiers.
In other words, the only other athletes mentioned in soccer players' class are those you'd expect to cover vast distances.
But soccer players have to master other intricate skills as well, like their first touch, heading, shielding and tackling, all while playing a team sport.
Joe English, who edits Running-Advice.com, put it plainly to CBS:
Soccer players need to be able to create intense but short bursts of speed, quickly change direction and conduct skillful actions while moving at high speeds
This is not to downplay other athletes' level of fitness. Football players are super strong, basketball players can jump through the roof, runners are super fast and baseball players master an insane level of hand-eye coordination.
From lacrosse players to gymnasts, the list can go on.
But soccer players master the most common aspects of fitness the average person can wrap his or her head around -- speed, endurance, dexterity and the like.
It's the reason you could stick Carli Lloyd and her US Soccer teammates in the middle of any of Nike Women's general fitness and workout ads and they'd fit right in.
And you're likely to have a couple of soccer players among your friends, certainly more likely than you are to know an Ironman.
So when you see those soccer players, the ones who burn between 800 and 1,000 calories per match, the ones who run around for two uninterrupted 45-minute halves, just know that they're probably the fittest athletes you know.