Viser hvordan muskler utmattes med opphopning av K+ kationer i den ekstracellulære væske, mens når CO2 økes fra 4% til 25% holder musklene lenger før utmattelse. Så for musklene er virker det som at de tåler mer i et mer surt miljø enn et basisk. Dette kan spille inn i Metabolsk pust hvor CO2 holdes igjen så godt som mulig istedet for å pustes ut.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2217490/

Effects of elevated extracellular K+ and muscle acidification on steady tetanic force in split muscles from adult rats. The figure shows summarized results from experiments performed essentially like the experiments illustrated in Fig. 1 except that muscles were stimulated by field stimulation. When force at elevated [K+]o had reached a steady level at normal pH (•), muscles were acidified by increasing the percentage of CO2 in the gas from 5 to 24% (○). Data were fitted to a Boltzmann sigmoidal curve. Data show means ± SEM from four muscles with 100% corresponding to 0.60 ± 0.03 N.