For the past few years, select members of the U.S. Marine Corps travel to the U.K. to participate in Royal Marines Commando training. True to the U.S. Marines’ institutional mentality to always adapt and improve, this provides them an opportunity to observe what works and how it can be implemented in the Corps’ physical regimen.

Some U.S. Marines (USMC) were also sent specifically to the Royal Marines’ Physical Training Instructor (PTI) program, a grueling 17-week process that produces combat-ready physical instructors that train the Royal Marines.

The assessment verdict: the British have a regimen far more sustainable and beneficial for the modern warfighter. USMC participants now recommend the Corps’ program focus on muscular endurance and functional fitness oriented toward combat.

In 2016, the USMC also launched the Force Fitness Instructor program, influenced by the PTI concept widespread in Commonwealth countries such as Canada, Australia, New Zealand, and the U.K.

Many experts argue that sheer strength and explosiveness are the ideal physical attributes for contemporary warfighters. Their points of view is informed from countless recent cases of urban warfare scenarios that require high levels of upper body strength–for example, to climb short walls; and explosiveness–for instance, in order to sprint from cover to cover.

On the other hand, there are other experts who argue muscular endurance and agility/mobility are far more important in the modern battlefield. Muscular endurance refers to the capacity of one’s muscles to perform a set task for long periods of time–such as bench-pressing lighter weights for more repetitions instead of doing fewer repetitions with heavier weights. And the saying “Agility/mobility is life” on the battlefield best describes its importance.

Considering the absurd amounts of equipment today’s warfighters have to carry, one can understand the need to opt for sheer strength over agility/mobility.

In the end, it’s far more important to tailor fitness regimens according to a unit’s or an individual’s mission–which often differs between deployments–rather than blindly commit to a specific program. For example, a unit deployed to the mountains of Afghanistan requires different levels of fitness than a unit deployed to the plains of Syria or the jungles of Venezuela. Perspective and situation must dictate preparation.