Why Are Professional Fighters Not That Muscular?

If you’ve watched any professional fighters in MMA or boxing, you’ve probably noticed that the fighters are not all enormous muscular people. It’s natural to want to correlate big muscles with toughness, but if that’s the case then why don’t professional fighters muscular like bodybuilders?

Professional fighters are not overly muscular because too much muscle mass requires more oxygen to use and can tire them out faster. Fighters also get diminishing returns on power output once they get past a certain threshold. Between that and the lowered endurance, too much muscle is not ideal.

In this article, we will look at how having muscle mass affects fighting in many different ways as well as look at some of the ways fighters optimize their bodies for fighting.

Why Fighters Do Not Have Bulky Muscles

At first glance, it seems like more muscles mean greater toughness and power, so a fighter might want to put on as much muscle as possible. However, most top-level fighters are lean muscular and not bulky muscular.

Professional fighters want to get the best performance out of their body by balancing many factors such as strength, flexibility and mobility, endurance, and power output.

If a fighter has too much in the way of bulky muscles it can negatively affect other important performance too much. This can outweigh the incremental benefits of additional strength

Unless a fighter takes great care to maintain their mobility at all times, they will lose out on flexibility and mobility when they go past a certain level of muscularity.

They will also have issues with a drop off in endurance due to the biology of having more muscles requiring more oxygen and blood flow to those muscles.

With those factors taken against the generally modest strength gains from adding more muscle than strictly necessary, it makes sense that professional fighters don’t focus on putting as much muscle mass on their frames as possible since it will throw off the performance of their bodies overall in terms of what is requires in fight conditions.

Lower Flexibility and Mobility

In combat sports having reasonable flexibility and well-developed mobility are essential factors for a fighter. Having good mobility allows for better-quality movement and plays a role in determining reaction time as well as having maximally efficient technical movements in a fighting situation.

When a fighter builds too much muscle they will lose out on some flexibility. Fighters have a generally optimal amount of muscle mass for their frame, and when they go past that they’ll have some issues with maintaining their flexibility.

In terms of mobility, being overly muscular can also reduce overall mobility. This mobility is essential, especially when you start to look at comprehensive combat forms like MMA as well as grappling combat forms like judo, BJJ, and wrestling. Mobility helps a fighter navigate a combat situation much more effectively and opens up options that a less mobile fighter will not have.

Lower Endurance

Combat sports and fighting in general saps a fighter’s endurance quickly. If a fighter can’t perform at near-peak levels for the entire fight, it is a major disadvantage for that fighter. Therefore, keeping endurance up for long enough to get through their rounds is mandatory for them.

If a fighter puts on too much muscle that gives them diminishing strength returns, they are going to have more issues with maintaining endurance throughout a fight. This is due to the biology of fighting off more lactic acid and being unable to deliver enough oxygen to muscles for an extended period of time.

Lower Power Output

Surprisingly, building muscle volume does not necessarily translate to maximal force output beyond a certain point. If you get beyond a certain point, power output stops increasing. This happens mostly because your movement quality in terms of mobility goes down and it’s harder to recruit your entire body to snappy movements like strikes.

The power of strikes and most combat movements comes from recruiting your legs, hips, and rotation of your entire body. Having muscularity at an optimal level for a fighter actually results in more power output per pound of body weight.

Why Are Professional Fighters So Lean?

For a casual observer watching professional fights, it might be surprising to see so many fighters being so lean. Some fighters do pack more muscle into their frame, but oftentimes you will see the skinnier fighter winning fights.

Fighters are so lean in order to best balance strength, flexibility, mobility, stamina, and power within a set weight class. Having a good strength-to-weight ratio is essential to perform at the highest level in combat sports with weight classes.

Strength-to-Weight Ratio

Strength is vitally important in combat sports since strength combined with technique creates the power to execute techniques that can finish a fight.

In some combat sports, like boxing this means striking your opponent to get knockdowns or knockouts. In others, it means being able to effectively off-balance, lift or otherwise take down an opponent like in wrestling, BJJ, or Judo.

Strength can also allow you to force your techniques through your opponent’s defensive techniques. A technique applied by somebody who is stronger and equally skilled will be far more likely to work than one applied by a weaker fighter.

So it makes sense that a fighter will try to pack as much strength onto their body as possible within a weight class to have this very notable advantage.

How Do Professional Fighters Get So Lean?

Professional fighters always seem to be very lean. I personally train at an MMA gym so I get to see my teammates going through different weight and body fat ranges all the time and can offer personal observations.

Professional fighters get lean from manipulating their diets alongside technique, sparring, and performance training. They do not usually walk around at extremely low body fat levels and cut weight before their fights. They use diet and normal training to maintain a healthy body fat level.

HIIT Exercises

Much of the types of training that professional fighters do to condition themselves for fighting have great carryover into getting lean.

A major example of this is doing fighting-specific High-Intensity Interval Training (HIIT) workouts where intense exercise is followed by short periods of rest. Studies show that HIIT workouts are great for weight loss and controlling abdominal visceral and subcutaneous fat.

Doing these high-intensity exercises are very efficient for fighters because it provides necessary conditioning for fighting alongside keeping their weight managed properly.

Compound Exercises and Full Body Workouts

Compound exercises are those that activate more than one muscle group. These include traditional weightlifting exercises like bench presses, squats, deadlifts, pullups, and push-ups.

These compound lifting exercises are both time efficient because they exercise several body muscles simultaneously, and more effective than a bodybuilding style workout because it builds better full-body power output instead of only building isolated strength.

For fighters, compound exercises are twice as important because they increase the kinetic link in the body. They train different body muscles to work together.


Much of the reason that fighters are so lean is that they are diligent with their diets. They often eat nutrient-dense foods and have a balanced approach to junk foods. Most fighters will keep an eye on total macronutrient intake as well as monitor their performance and make adjustments in close to real-time. This can be done in many different ways and the approach will vary based on the individual fighter.

They also drink lots of water, especially after training to recover the hydration lost while sweating. In fact, it’s recommended that a 140-pound (63.5 kg)  fighter consume 1.5 gallons (5.68 l) of water every day.

In the gym that I go to, I see fighters drinking about a gallon of liquid each while hanging out after class. Depending on the time of year they will often be taking in extra salts as well to maximize their ability to rehydrate.

What Body Fat Percentage Range is Ideal for a Fighter?

Most fighters maintain a reasonably low body fat percentage between 8 to 13 percent. Different individuals will vary in performance based on how their body reacts at different percentages.

The specific body fat percentage can vary in how much it influences speed, explosiveness, and strength in each individual fighter. However, it is important for weight classes; therefore, you’ll want to have a low body fat percentage as a fighter. That being said, heavyweights are a special case and can often get away with having higher body fat percentages.

Final Thoughts

Most professional fighters maintain a lean muscular body with a reasonably low body fat percentage. They don’t carry excessive muscle or much body fat because it makes them more inefficient in terms of performance-to-weight ratio for their combat sport.

Many factors need to be balanced in order to be an effective fighter and that is the reason that most fighters look relatively similar in terms of body composition as well as muscularity.

If you want to start training in a combat sport yourself and want to know if you need to be fit to start check out this article I wrote on the topic: Do You Need to Be Fit to Start Combat Sports?


Hi, I'm Andre and I am the author of this website. I currently train primarily in Brazilian Jiu-Jitsu but supplement with other grappling martial arts as well as help to coach my kid's blended grappling program.

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