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. Author manuscript; available in PMC: 2023 Jul 1.
Published in final edited form as: J Physiol. 2022 Jun 2;600(13):3069–3081. doi: 10.1113/JP283036

Figure 4. Relationship between quadriceps twitch force (Qtw) and intramuscular [H+], [Pi], and [H2PO4−] during exercise.

Figure 4.

Qtw, H+, Pi, and H2PO4− were measured using electric femoral nerve stimulation and phosphorus magnetic resonance spectroscopy (31P-MRS) during 60 knee-extensor MVCs. Trial 1 and 2 were separated by 5 min of rest. Individual participant data are presented in panels A,C, & E (these data are fit with linear regressions for illustrative purposes only). The linear mixed effects model results on the standardized (Z-score) Qtw, H+, Pi, and H2PO4− are presented in panels B, D, & F. N = 10.