The maximal strength training protocol used in the present study has previously been shown to enhance muscular strength and neural drive. Results suggested that these neuronal changes were located at the supraspinal level. This hypothesis was tested using blood oxygen level dependent functional MRI, fMRI, to identify possible neuronal correlates to increased strength. In addition, cross education of strength in the untrained leg was investigated. The experimental protocol was approved by the local ethics committee and all subjects gave written consent. The training protocol consisted of 16 sessions in 4 weeks whereby subjects performed 6 sets of 6 isometric plantar flexion repetitions, unilaterally on the dominant leg (determined using the Waterloo Footedness questionnaire). Young healthy volunteers who had not undertaken strength training in the last 6 months were assigned to training (n=15) or control (n=11) groups. Most subjects (n=12, n=9 respectively) consented to MRI investigation before and after the training intervention as well as tests for: neural recruitment at rest; maximum voluntary isometric contraction torque (MVIC) and electrically evoked spinal reflexes. MRI investigation was performed using a 3.0 T Siemens Trio system and included a T1-weighted anatomical scan and fMRI during a series of isometric soleus contractions in response to a visual stimulus. During the task the foot was held in place with an MR compatible device, to enable isometric contractions to be performed. Various measures were taken to reduce head motion including a vacuum pillow around the neck and shoulders and paradigm presentation (Eprime, PST, Pittsburgh, PA) using VisualSystem goggles (NordicNeuroLab, Bergen, Norway). The fMRI images were analysed using FSL (FMRIB, Oxford, UK). MVIC was analysed by two way analysis of variance with Bonferroni post hoc testing (SigmaStat) and did not differ significantly across the groups prior to training. MVIC in the training group significantly increased from 131.8 ± 6.8 to 182.6 ± 7.8 Nm (p=0.00019) following training, whilst the control group showed no change (pre 147.1 ± 11.5 Nm; post 145.5 ± 15.1). The training group also demonstrated a significant increase in MVIC in the untrained leg (p=0.0087). The fMRI data from two control subjects was excluded due to excessive head motion (>2 mm). Task-related brain activation in motor and pre-motor regions was observed. However, when contrasted using standard thresholding (p<0.05, corrected for multiple comparisons) at the whole brain level, a significant training effect was not detected. Maximal isometric plantar flexion training enhances strength in the trained leg and also in the untrained leg through cross education. However, significant changes at the whole brain level in response to the training intervention were not observed.