As you learn and grow as an athlete, you realize there are as many different methods of training as there are coaches and athletes. However, there are a few general concepts that most endurance coaches agree are helpful for individual sports training.

Specificity - this is the idea that if you want to become skilled at something, you need to practice that exercise specifically. For example, if your goal is to run fast in a 5k, then doing a slow 10 mile run is not entirely specific - it aids in aerobic development and is "running" - but it is not running at your goal pace, which would be much more specific. As your training moves further away from your goal, it becomes less specific. This does not mean you should only train specifically; it means that you should plan your training so that your key workouts are specific.

Key workouts - these are workouts where you work hard for a reason, achieve a specific goal, or simulate a race or event. A week will usually contain 2 to 4 key workouts in the later stages of training. In the early stages there may be no or fewer key workouts (they increase as you progress into your training plan).

Training periods - These have different names but a few in common usage are:

Base / Early season - a period of time where the bulk of training is used for aerobic development and to lay the foundation for more challenging training later in the year. You may spend more time working on your training limiters during this period.

Late base / later season - a period of time where you may be training at a higher volume than early season with more challenging workouts, a mix of aerobic and lactate threshold training, typically still leaning towards the aerobic side.

Build / race season - a period of time where you will most likely be training at less volume than late base but higher than early base, and including a higher percentage of lactate threshold training and anaerobic training.

Taper / peak season - a period of time where your goal is to rest for a big race. You will do short workouts with a limited amount of time at or above your goal race pace.

Training limiters - your weaknesses or what is currently holding you back from achieving your goals. These involve some combination of endurance, speed, and power. To refer to the original example, if you can run 10 miles without a problem but are a few minutes off of your goal 5k time, then your current limiter is lactate threshold speed, not endurance.

Lactate threshold - this is the point during endurance exercise where your body produces more lactic acid then can be broken down. It is tied to a specific heart rate, which is your lactate threshold heart rate (LTHR). If you maintain efforts at heart rates above this point, you will only be able to continue at that effort for 5 minutes or so before fatigue and the accumulation of lactic acid force you to slow down.

A well trained athlete can maintain the LTHR for roughly one hour. The goal in most forms of endurance exercise lasting 4 hours or less is to raise your LTHR so that you are able to maintain faster speeds then before you took up a regimented training plan. Using the 5k as an example, a well-trained athlete may run the first 2 miles of the race ranging slightly above and below lactate threshold, then run most of the last mile above lactate threshold, finishing the race just before fatigue forces him to stop.

In general, a well trained Ironman or long-distance athlete will find that their steady pace (aerobic endurance threshold) is just about 20 beats per minute below their lactate threshold.

You should also know that muscle soreness the day after a hard workout is not caused by lactic acid - lactic acid is re-absorbed or removed from your system after an hour or so of stopping exercise. The soreness is a result of muscle breakdown (torn muscle fibers).

Skills training - most sports involve a combination of pure athletic ability and honing specific skills. If you want to excel at sports like swimming, running, and triathlon, you need to become competent in the technique and form best used to move yourself forward in the most efficient and quickest manner.

Marty Gaal is a NSCA certified strength and conditioning specialist (CSCS), USA Triathlon coach, and producer of the Powerstroke: Speed through force and form freestyle swimming instruction DVD.