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4SPEED™ stands for the 4 key performance metrics of your running race fitness: general endurance, lactate threshold, VO2max capacity, and neuromuscular power.


“A weakness in any of the 4 key performance metrics limits your potential.”


General Endurance: Your general endurance is your ability to run for extended periods at an easy pace. It requires a well-developed fat metabolism, large glycogen stores, and the resilience of your bones, tendons, ligaments, and muscles to withstand the repeated pounding that is characteristic to running.

Lactate Threshold: Your lactate threshold (LT) is your ability to process and clear lactate from your system. This is of major importance for half marathon and marathon races. 5K and 10K races are run above your LT and therefore depend more on lactate tolerance. A high LT lets you access a higher percentage of your VO2max at all distances.

VO2max Capacity: Your maximal aerobic capacity is your ability to supply your muscles with oxygen at a fast rate. It has the largest effect on your running speed for long-distance events. In fact, it determines your race performance by a staggering 80%. Adaptations occur at the heart, blood, and within the muscles themselves.

Neuromuscular Power: Your neuromuscular power is your ability to generate force quickly. While you don’t have to clock the times of a sprinter to find success in long-distance running, your cadence (via ground contact time) and stride length (via plyometric ability) will improve significantly with more neuromuscular power.