Blood Ammonia - Heart Rate Relationship During Graded Exercise is not Influenced by Glycogen Depletion

The blood lactate (La) - heart rate (HR) relationship assessed during a graded maximal exercise test (GXT) is often used to provide training guidelines to athletes. Glycogen depletion is a condition that is known to influence the La response during a GXT and therefore can bias the interpretation of La curves. The purpose of our study was to determine an influence of glycogen depletion through long-term exercise (GDE) on blood La and ammonia (NH₃) accumulation during a GXT. Eleven persons (5 males, 6 females; 26.3 · 4 yrs) performed a cycle ergometer GXT (3 min protocol) on two separate occasions with a 1-week interval. Using a randomized cross-over design, one of the two GXTs was preceded by a GDE. After GDE, blood NH₃ increased more rapidly in the depleted versus control state whereas La increased less rapidly in the depleted state. The NH₃ to HR relationship was not altered by glycogen depletion. We conclude, therefore, that determination of NH₃ during a GXT may provide helpful additional information for training recommendations which is not available through La determination only.

Key words

Ammonia - lactate - graded exercise test - training - La-paradox