Knuckle conditioning has been around for a long time in various martial arts and has been used for a plethora of purposes. In styles of Kung Fu, knuckle conditioning was known as Iron Palm or Iron Fist. According to its page on Wikipedia, it allows fighters to use their techniques with extreme power, their hardened knuckles and hands being able to take extreme amounts of punishments compared to that of the average person, as if they were made from iron.
This type of bone conditioning has been seen in many fighting styles, namely Muay Thai, Karate and traditional bare-knuckle boxing. Knuckle conditioning specifically aims to harden the bones of the hand to allow the utilization of techniques that couldn’t be properly applied otherwise, whilst minimizing the damage a fighter might suffer from punching with incorrect technique or striking harder areas of their opponent’s body. Common injuries include the Boxer’s Fracture (which I suffered myself). This is a fracture of the outside of your hand caused by striking with pinky and ring finger knuckles.
Knuckle conditioning comes in two forms: conditioning the knuckles themselves by causing miniscule bone fractures which are healed and make the bone stronger, and the callousing of the skin around the knuckles themselves which prevents skin being torn. Training methods for this vary depending on the martial art, as different cultures had different ideas and equipment available to them. The process of conditioning the bones usually takes years, so it’s important to be patient with this training. Some martial arts also focus on conditioning other areas of the body with similar exercises.
The most commonly known method is using a piece of equipment called a Makiwara, thought to originate from Okinawa. It was developed for the practitioners of styles of Okinawan Tote (an ancient Okinawan martial art) and Okinawan Karate. The Makiwara is a striking post, which is secured to the ground, and is usually wrapped with thick rope to outline the striking area. Although it is primarily used for other purposes (such as the development of focus and technique) it can also serve to cause callousing of the knuckles. The repetitive striking (not at full power) of the post builds up knuckle damage over time, which when healed, will make the knuckles stronger.
In contrast, Muay Thai fighters usually focus on the conditioning of the shins, to ensure the surface that they kick with is rigid and can take the punishment of bone-on-bone contact, which tends to be extremely painful. These fighters are notorious for their incredible kicking power. Much of their conditioning comes from numerous exercises – the most impressive of which consists of repeatedly kicking their local banana trees due to their soft and rubber-like wood. But don’t get the wrong idea, kicking these is still a pain for the inexperienced. Another common, but not as well-known exercise, is the repeated light striking of the shins with sticks; the striking is more of a tapping, but the repeated abuse builds up quickly. Rolling the sticks on the shins while applying pressure is done too.
Furthermore, this article at livestrong.com states that rope-skipping and jogging can be used for conditioning the shin bones too. Though it is worth noting that the repeated stress of bouncing on your legs can cause pains on the shins known as ‘shin splints’ , which can be agonizing. On the other hand, these aren’t very good exercises for conditioning if they are not paired with some of the other exercises above – you are more likely to wear down your knees and ankles from repeating these movements too much as they put a lot of strain on the leg joints.
Bare knuckle boxers from back in the day also used to condition their bodies to avoid injuries. However, their conditioning differed from that of the styles above. They mainly focused on the hardening of their skin and prioritised protecting their face from cuts rather than their hands from injuries. They hardened the skin on their hands, and also hardened their skin on their faces and bodies to avoid gashes. Instead of conditioning their knuckles to be able to punch the skulls of their opponents, they adapted by mainly targeting the body of the opponent. This is why their memorable fighting stance wasn’t focused on protecting their head, and only covered up their body. In fact, many boxers used their head as a weapon to take advantage of the fact that punches to the face caused damage to the hands – they would purposefully aim to get their forehead in the way of their opponent’s fist in an attempt to break it upon impact.
The conditioning of the skin was done mainly through two means: the first was menial work which resulted in the callousing of your hands. The second method was done through the smearing of different liquids and concoctions. A summary of some bare knuckle boxing history at Boxing.com, claims that this was done through either the use of brine, or a solution of water and rock salt.
“The use of brine was prevalent. Fighters such as Terry McGovern would bathe their face with brine before and after every workout. Their skin got to be real leathery. It had to be or those fellows never would have been able to fight 25 and 30 rounds.” - Charley Goldman, trainer of the great Rocky Marciano
In more traditional martial arts, conditioning was used for the employment of techniques that could not be used otherwise without breaking fingers, knuckles, wrists, or hands. Jesse Enkamp, a passionate martial artist and karate champion, who founded the Karate Nerds community, gives perfect examples of such techniques (which are present in Karate but also other arts such as Taekwondo) in his video below.
Although bone conditioning was quite normal for martial artists in the past, it’s relatively uncommon these days and it’s considered as a hardcore method of training, as well as borderline insane. There are numerous reasons for this. One of these reasons is due to the evolution of equipment and gear in competitions and combat sports. It is very rare to find successful and legal combat sports that do not require the use of gloves or other protective gear in this day and age. In fact, the BKFC (Bare Knuckle Fighting Championship) is the first promotion allowed to hold a sanctioned bare-knuckle event in the United States since 1889, and even BKFC fighters use mouthguards.
Another of these reasons is that many martial arts practitioners live double lives, in which they work and take care of their families throughout a large portion of their day – it was much more common to see martial artists dedicate themselves to their training completely in previous eras. Due to having less time to train, a smaller amount of people opt to incorporate these diehard training exercises. They are much more common amongst Muay Thai fighters in Thailand, as many of the fighters there train and compete as a job, to provide money and opportunity to their families.