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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 3. Relationship between quadriceps twitch force (Qtw) and intramuscular [Pi] during exercise.

Figure 3.

Qtw and Pi were measured using electric femoral nerve stimulation and phosphorus magnetic resonance spectroscopy (31P-MRS), respectively, during two 60 knee-extensor MVCs trials. The data were fit with a two-segment piecewise linear function to test for a break point between two linear segments (i.e., critical [Pi]). The Pi break point was 15.1 ± 3.3 mM, r2 = 0.72 ± 0.13. N = 10.