Physical work or exercise capacity has been widely reported as being impaired by iron deficiency. Previous, separate, studies using diet-induced iron deficient rats have shown decreased work rate capacity, diminished contractile force generation and an impairment of energetics during exercise, when compared to rats on normal chow. The aim of this project is to develop a technique that allows for the simultaneous assessment of force production, fatigue resistance and metabolic function of murine gastrocnemius muscle during exercise. To address this, a method of in vivo gastrocnemius muscle stimulation was established. A bespoke Perspex cradle was designed and manufactured for the hindlimb preparation. In this technique, mice are anaesthetised using 2 % isoflurane in oxygen (2 l/min), the ischiatic nerve is isolated surgically and electrodes are placed distal to the tibial nerve branch. The knee and ankle joints are immobilised, the calcaneal tendon is attached to a force transducer, via a suture thread, before a 31P saddle-shaped coil is placed over the muscle. The cradle is then placed into the 7 Tesla magnet and images of cross-sectional area (CSA) of the gastrocnemius muscle are obtained using the 1H volume coil. The measurement of CSA of the muscle allows the comparison of force produced between muscles of different sizes. A stimulation protocol consisting of a train of eight pulses of 100 μs at 30 Hz, followed by a rest period of 1.25 seconds, is repeated over a 10 minute period. During this exercise period, and the subsequent 20 minute recovery period, a 31P spectrum is acquired every 100 seconds. Reductions of contractile force in excess of 50 % are exhibited over the 10 minute exercise period, and increases in inorganic phosphate (Pi) and decreases in phosphocreatine (PCr) are acquired by 31P NMR spectroscopy (Figure 1). This technique will facilitate the simultaneous assessment of skeletal muscle function and metabolism, including fatigue resistance, in both diet-induced and genetic mouse models of iron deficiency, in the presence or absence of ferric carboxymaltose.