spierpomp

Spierpomp is a Dutch term used in fitness and physiology to describe the temporary swelling and fullness of a muscle that occurs during and after resistance training as a result of increased blood flow and fluid accumulation within the muscle tissue. It is commonly described by athletes as “the pump,” and is especially noticeable after high-volume or high-intensity training.

The mechanism involves rapid vasodilation of blood vessels in working muscles, increased capillary recruitment, and a shift of fluid from the intravascular space into the interstitial space, leading to visible expansion and a feeling of tightness. Factors that influence the pump include exercise intensity and duration, hydration status, carbohydrate and sodium balance, and training adaptations. Nitric oxide and other vasodilatory signals contribute to the process.

The pump is typically most evident during or immediately after exercise and can last from several minutes to a few hours, depending on circulation and hydration. While it can improve the apparent size and fullness of a muscle and enhance the sensation of performance, it does not directly translate to long-term muscle growth. The magnitude of the pump is not a reliable predictor of hypertrophy, which depends on factors such as mechanical tension, metabolic stress, and adequate recovery.

In practical terms, some athletes seek to optimize the pump through training structure, hydration, and nutrition, but the effect varies between individuals and remains transient. Understanding the pump helps distinguish temporary fullness from genuine, lasting increases in muscle size.