Training by competitive swimmers typically consists of repeated bouts of shorter or longer intervals in a short-course or long-course pool. Intervals span a continuum from longer slower intervals (50-1600 m for developing aerobic or endurance fitness) to shorter faster intervals (15-200 m for developing anaerobic or race pace qualities). The basic prescription of interval training can be simplified to four primary variables: (i) the number of intervals or repeat efforts, (ii) the length/distance of the interval (15 m to continuous swimming), (iii) the intensity (i.e., pace or velocity) of the interval, and (iv) the rest period between intervals (variously formulated as the cycle time or rest period).
Preseason training commences from the low base of fitness maintained during the off-season. Swimmers typically start the preseason phase with a single session per day and gradually increase the number of sessions over the first few weeks. A graded increase sees the frequency of training increasing from one session per day, to three sessions over 2 days, and eventually to the traditional two sessions per day format followed by the majority of high-level swimmers.
The main features of the early-season phase are a modest training volume to start, small 5-10 km increases in volume per week, low initial training intensity, and dry-land conditioning including flexibility, circuits, weight training, and other games and activities, to improve the overall sport abilities of the swimmer. After several weeks there are further increases in training volume, a graduai introduction of higher intensity aerobic work to the level of the lactate threshold, and emphasis on skill and technique development before moving to the faster training speeds.
In simple terms, training volume elicits improvements in general endurance fitness while training intensity develops the specific fitness required for racing and competitive success. The later weeks of the early-season phase focus on continuing development of the lactate threshold (endurance fitness), maximal oxygen uptake (maximal aerobic) and race pace training capacities, ongoing manipulation of training volume and intensity to maintain improvement, an individualized approach to volume, intensity and recovery, and refinement of skills particularly at race speeds.
The tapering strategy used by many swimmers to optimize competition performance has been defined as "a progressive non-linear reduction of the training load during a variable period of time, in an attempt to reduce the physiological and psychological stress of daily training and optimize sports performance" (Mujika & Padilla 2000). The aim of the taper before the main competitions of the season is to elicit substantial improvements in performance. These performance gains have been variously attributed to increased levels of muscular force and power (Trappe et al. 2000), and improvements in neuromuscular, hematological, and hormonal function, and/or the psychological status of the swimmer (Mujika & Padilla 2000).