Issurin, V. (2008). Block periodization versus traditional training theory: a review. Journal of Sports Medicine and Physical Fitness, 48, 65-75.

The bases of contemporary training theory were founded several decades ago when knowledge was far from complete and workload levels, athletic results, and demands were much lower than today. Traditional training periodization, that is, the division of the seasonal program into smaller periods and training cycles, was proposed and became a universal and monopolistic approach to training planning and analysis. Further progress in sport emphasized the limitations and drawbacks of traditional periodization with regard to the training and preparation of contemporary top-level athletes and their demands. Major contradictions between traditional theory and practice needs appeared as 1) an inability to provide multi-peak performances during the season/[year]; 2) the drawbacks of long-lasting mixed-training programs; 3) negative interactions of non-compatible workloads that induce conflicting training responses; and 4) insufficient training stimuli to help highly qualified athletes to progress, because of the restrictions and inefficiencies of mixed-training. The successful experiences of prominent coaches and researchers led to alternative training concepts and, ultimately, to a reformed training approach that was called "block periodization" (BP). Its general idea suggests the use and sequencing of specialized mesocycle-blocks (several weeks), where highly concentrated training workloads are focused on a minimal number of motor and technical abilities [highly specialized training]. Unlike traditional periodization, which usually tries to develop many abilities simultaneously, the block concept suggests consecutive training stimulation of carefully selected fitness [and hopefully skill] components. The rational sequencing of specialized mesocycle-blocks presupposes the exploitation and superimposition of residual training effects, an idea that has recently been conceptualized and studied. It is hypothesized that different types of mesocycle-blocks are suitable to various modes of biological adaptation.

Implications. Issurin (2008) described a need to change from "old" training theory to accept a new realization of modern demands on competitive swimmers. The still-dominant belief that governs many training programs is that extended periods of training followed by a taper result in the best conditioned and prepared athletes usually for a two-peak competitive year. That model has been dressed up as long-term "periodization" but is largely irrelevant for today's 12-month trained swimmers. Issurin highlighted four weaknesses of the traditional training/planning model that contradict the demands of modern competitive programs.

• An inability to provide multi-peak performances during the season/year;
• the drawbacks of long-lasting mixed-training programs;
• negative interactions of non-compatible workloads that induce conflicting training responses; and
• insufficient training stimuli to help highly qualified athletes to progress (as a result of mixed training).

Contemporary training theory now accommodates:

• Frequent peaks within a year of competitions,
• a focus on very specialized training effects (largely specific velocity training with a marked reduction in irrelevant or "basic" training experiences) attained through a block of training over a relatively short period, and
• the recognition that swimmers have a continual state of general fitness upon which a block of specialized work superimposes specialized training effects.

Short-term blocks of increased intensity/specialized training while undergoing traditional training produces marked performance improvements in a number of sports. The effectiveness of blocks of specific training will be governed by the adjustment of training demands to individual and event differences within a training group. This change in training theory will require most coaches to reform completely their training beliefs and plans. As well, the analysis and interpretation of physiological factors will need to be reformed. In one sense, existing physiological research conducted on traditional periodized training no longer is relevant.

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