Activities Sports & Athletics Are Cavity Back Irons for High-Handicappers and Musclebacks for Low? Share PINTEREST Email Print This collection of Titleist irons includes one muscleback (far right) and three cavitybacks of varying style. Acushnet Golf Sports & Athletics Golf Basics History Gear Golf Courses Famous Golfers Golf Tournaments Baseball Basketball Bicycling Billiards Bodybuilding Bowling Boxing Car Racing Cheerleading Cricket Extreme Sports Football Gymnastics Ice Hockey Martial Arts Professional Wrestling Skateboarding Skating Paintball Soccer Swimming & Diving Table Tennis Tennis Track & Field Volleyball Other Activities Learn More By Brent Kelley our editorial process Brent Kelley Updated March 02, 2019 Up until the 1970s, nearly all golf irons on the market were blade irons, a k a muscleback irons. But when cavity back irons arrived on the scene, they made hitting golf shots easier for golfers who needed that help most: amateurs and recreational golfers. Today, cavity back irons dominate the market, with muscleback irons making up a much smaller percentage of irons sold in pro shops. Over time, cavity backs became associated with mid- and high-handicappers to the point that many golfers came to believe that better golfers should not play cavity backs. Is that true? Is the thought that cavity back irons are for weaker golfers while muscleback irons are for the best golfers accurate? We spoke to a golf equipment expert to find out: Tom Wishon, a veteran golf club designer and founder of Tom Wishon Golf Technology, Key Takeaways "Cavity back" and "muscleback" are terms applied to the designs of the back part of a golf iron clubhead. If the back of the iron head is full, it is a muscleback. If metal has been removed, leaving a "cavity," it is a cavity back.Cavity-back irons once had the reputation of being only for mid- and high-handicap golfers. However, all golfers, regardless of skill level, benefit from the technology in cavity backs. Let's start by defining our terms. "A cavity back iron is any iron in which a small to large amount of the metal across the back of the head is removed, allowing that weight to be re-positioned on the perimeter of the head, farther away from the head's center of gravity," Wishon explained. "A muscleback iron is the term given to any iron in which there is no cavity on the back of the head, i.e., the weight is more evenly distributed across the back of the clubhead." And what about that old bromide that mid- and high-handicappers should always play cavity back irons, while only the best golfers should play musclebacks? Wishon affirms that bromide, but perhaps not for the reason you might expect. "Cavity back irons are better for higher-handicap golfers," Wishon says, "but this is true because no golfer is better off playing a muscleback iron over a cavity back iron unless the golfer is skilled enough to never miss the center of the clubface. "All deep-cavity back iron designs will deliver more distance from an off-center hit than will any muscleback iron, because the cavity back iron has a higher moment of inertia about the vertical axis of its center of gravity." The Formula to Use When it comes to golf clubs, a simple formula holds true, even for the best golfers in the world: Higher MOI = Less Twisting of the Head from an Off-Center Hit = More Distance from Off-Center Hits. By around 2007 on the PGA Tour, Wishon explained, cavity back irons had crossed the 50-percent threshold in terms of usage. By that time, in other words, more than half the players on the PGA Tour were playing cavity back irons. That was a long time ago; the percentage has only gone up since. But many pros, and some low-handicap amateurs, do continue using muscleback blades. "The reason many players use muscleback iron designs is because they are convinced that, one, they can intentionally fade or draw the ball more easily with a muscleback than a cavity back iron; and, two, they are convinced that the 'feel' of impact when hitting a muscleback iron is 'softer' or simply more pleasing compared to a cavity back, which increases their confidence," Wishon said. Which leads us to the next question: Is that true? For more on that topic, see "How do cast irons and forged irons compare?" for the answer.