Strength is an important component of success in most athletics events, and therefore should be an essential part of most training programs. The time spent in training for strength should be proportional to the requirement for these components in your event, and your deficiencies in this area.
Strength is the maximal force you can apply against a load, and power is proportional to the speed at which you can apply this maximal force. Training to improve in this area can include lifting weights, throwing heavier implements, running against a resistance, and plyometrics (depth jumping and bounding).
Improvements in strength follow the overload principle. That is, to increase muscle strength the muscles need to be stressed with a load greater than normal. The muscles are thus stimulated to adapt to the increased load.
The exercises chosen should be specific to the muscle groups used and the actions performed in your event. Variation is also important to maximize the gains in strength. Varying intensity (amount of rest, weight lifted) and volume (repetitions, sets, sessions per week), provides greater stimulus for strength gains than simply following a set program and progressively increasing the amount of weight lifted. Weight training three times a week, with at least one day between sessions is generally adequate. Rest days between sessions are necessary for recovery and the adaptation to take place.
Not everyone wants to be like Arnold Schwarzenegger, and nor do they have to be. Strength training is suitable for most events, males and females. With the help of an expert, a program specific for your needs can be designed by varying such things as the exercises, repetitions, sets, weight lifted and number of sessions per week.