Sims that go on adventures to Shang Simla, Champs Les Sims or Al Simhara will need to level up their martial arts skill if they ever hope to complete the more difficult tombs. In fact, there are a couple of quests in Shang Simla that flat out require specific skill levels before your sim can complete them. So, when you send your sim there, buy both a board breaker and a training dummy from the general store. These two items will be placed in your family (build mode) inventory; when your sim gets home, place them on your lot and practice with them.
You’ll have to start with the training dummy first, because the board breaker requires at least skill level 2 before your sim will be able to use it. When I train my sims, I have them switch to the board breaker as soon as possible because there are more wish opportunities for breaking specific numbers of boards, and these are generally quicker to achieve than the skill level wish opportunities. But, don’t discount the skill opportunities because there is nothing to prevent you from achieving both types of opportunities with the board breaker.
There are five types of boards your sims can use on the board breaker. In increasing order of difficulty, they are: foam board, balsa wood board, oak board, thin stone board and space rock block. One your sim is able to use the board breaker by reaching level 2 with the training dummy, your sim can break the foam board. For each of the first four board types, sims start with one board. As they become more skilled at breaking that type of board, they will add one more board to the stack on the board breaker for each attempt. The maximum number of boards to be broken at any one time is five. Although the number of boards broken may vary, a sim will always start with one until that level of board breaking is mastered. You cannot direct your sim to break any specific number of boards at a time, your sim will automatically place the maximum that his current skill level will allow.
When I have my sims use the board breaker, I will usually direct them to increase the difficulty by changing board types as they level up the Martial Arts skill itself. Usually your sim will be able to break a space rock block at martial arts level 9. Once your sim can do so, switch to the space rock. Your sim will often break a gem out of the space rock that can be collected like any other gem in the world.
The gems that appear from this interaction can be any gem type that is available, from the most basic quartz to the extremely rare tiberium.
Increasing Martial Arts skill will also increase the Athletic skill at the same time. Although your sim doesn’t need any specific athletic level to begin training, building athletic skill first can help speed up the martial arts skill building.