Mountain climbing is often said to be a challenging outdoor activity for only the most (1- determine) ........................... of sportsmen. But it has evolved into an exciting (2- athlete) ....................... activity called indoor climbing. At centres known as rock gyms, climbers make their way up artificial walls that are (3- construct) ....................... from wood or plastic. These walls vary in (4- high) ................. while the difficulty depends on which route up the wall you take. Indoor climbing requires upper body (5- strong) ..................... rather than a high level of fitness. Climbing centres employ fully qualified (6- instruct) ............................. to help you improve your technique. Indoor climbing has advantages over traditional mountain climbing. It is safer because you climb under controlled conditions, which means there is less risk of (7- injure) ......................... If you fall, the floor is soft enough to keep you from (8- hurt) .............................. yourself. It is also convenient - being indoors means you can go climbing whatever the weather. And though some would not consider indoor climbing a (9- compete) ................................. sport, organized events are held, where teams race their (10- oppose) ......................... to reach the top of the wall first. Lately, indoor climbing has become a popular way to celebrate a child's birthday and certainly offers a party with a difference.