who can train
Men and women can train together as equals
Aikido relies on sensitivity, timing, balance and intent and generates large effects through blending energy and the principle of levers. It does not require superior strength so it is suitable for both sexes.
Young and old can train together as equals
The more you train the better you become. Some of the best aikidoka may be some of the oldest. So it can be practiced by all ages.
Learning how to roll and fall safely can be more challenging the older you start - but nevertheless can be achieved even by people starting after the age of 60.