Mixed
Speed endurance training (SET), characterized by high lactate and hydrogen ion accumulation, specifically upregulates the Na+/H+ exchanger isoform 1 (NHE1) and Na+/K+-ATPase beta2-subunit, whereas sprint training (ST) does not, suggesting that intracellular acidosis is a key stimulus for these specific ion transport adaptations.
To improve your muscle's ability to handle fatigue during repeated high-intensity efforts, you need to train in a way that creates significant acidosis (low pH). Short sprints alone may not trigger the specific ion pump adaptations needed for this; longer high-intensity intervals (speed endurance) that push lactate and hydrogen ions higher are required to upregulate the specific transporters that manage fatigue.
Only in the SET group was the amount of the Na+/H+ exchanger isoform 1 (31%) and Na+-K+-ATPase isoform beta2 (68%) elevated (P < 0.05) after training... The observation that muscle pH was lowered to 6.98 in SET compared with 7.07 in ST during the training could lead to the proposal that a significant accumulation of H+ during training is important for the stimulation a net synthesis of NHE1.
Why this rating
Controlled human trial with invasive muscle biopsies and clear statistical significance, though small sample size (n=13).
Source
Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development
Magni Mohr et al. · American Journal of Physiology-Regulatory, Integrative and Comparative Physiology · 2006
DOI 10.1152/ajpregu.00251.2006
More from this paper
- Speed endurance training (SET) improves intermittent recovery performance (Yo-Yo IR-2) significantly more than sprint training (ST), primarily through enhanced lactate clearance and potassium handling rather than just increased muscle mass or fiber type changes.Good
- Sprint training (ST) specifically elevates creatine kinase (CK) activity, whereas speed endurance training (SET) does not, suggesting that the rate of creatine phosphate (CP) utilization, rather than total CP depletion, drives CK adaptation.Good
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