To properly train any athlete, a well-structured training program will consist of both sport-specific training as well as strength and conditioning training. The emphasis placed on either training modality is entirely based on where the individual stands in not only their sport season, but also in their physical conditioning. Periodization involves shifting from non-sport specific training (strength and conditioning), that is of high volume and low intensity to low volume, high intensity sport-specific activities. This shift will occur over a period of many weeks to prevent overtraining and optimize performance.
The following image will detail the periodization periods
The preparatory period is the longest period and usually occurs at the time of year furthest from time of competition. This is the time for the athlete to establish a base level of fitness in order to build and grow from there. Slow, long distance running, light plyometrics, low resistance, high-repetition resistance training is all needed and utilized to begin conditioning.
When the preparatory period first begins and the training loads are high (long distance running/swimming, high repetition resistance training), the strength and conditioning sessions take a longer period of time, which leads to fatigued athletes that have little time for sport-specific training. As the preparatory period nears the end, the microcycles begin to change to lower the work volume, increase intensity (resistance loads), and increase sport-specific training.
The goals early on in the preparatory period should be to improve muscular endurance and hypertrophy. This goal is in place to increase the efficiency and size of the muscles so that they can then be honed and trained later. To train your muscles for endurance and hypertrophy, the individual should aim for 50-75% of their 1 rep maximum (1RM) which should result in a 10-20 repetition range. The hypertrophy/endurance phase should last anywhere between 1-6 weeks and then a low-intensity recovery week before transitioning into a basic strength phase.
Now that the individual has increased their muscular size and efficiency, the basic strength phase is designed to do just what it says and improve the overall strength of said muscles. The basic strength phase involves high intensity (80-90% 1RM) and moderate volume of 3-5 sets of 4-8 repetitions.
After the basic strength phase, the athlete can then transition into the strength/power phase. This is where high loads and low volumes are introduced to maximize the explosiveness and power in the muscles. The strength/power phase involves high intensity (75-95% 1RM) and low volume of 3-5 sets of 2-5 repetitions.
First Transition Period
A very short period, the transition period is designed to allow the body to heal and recover with one week of lower intensity, lower volume, or a combination of the two to prepare the athlete for the competition period.
Competition periods can last for a week to several weeks, although most athletes have a sport or competition season that can last for many months. During this time, the goal of the individual is to maintain their current strength and conditioning levels by continuing to train with high intensities, but greatly reduced volumes. Especially important during this time is that the sport-specific skills are honed and trained in order to "cash-in" on the training that has been completed in the preparatory period.
Another main goal of the athlete is to ensure that their strength and conditioning peaks during competition so that they maximize the return from the efforts they have put into their training up until this point.
Second Transition Period (Active Rest)
During this period, the goal of the athlete is to allow their bodies to rest and recover from a lengthy "peak" period during their competition season. Various light to moderate activities can be practiced as long as the body is not stressed or strained too hard. It is entirely possible for the individual to not have any resistance training at all.