Arm Pump is a well known phenomena in the motocross. It causes pain in the arm due to a compression and is a common disorder among even skilled motocrossers. The etiology of this pain is not well understood although it may be related to excessive muscle tension and inappropriate posture. Most likely the pain is the result of dysponesis in which the motocross cyclist does not relax the muscles. This single case report demonstrates the use SEMG for diagnosis and development a successful clinical intervention. The subject was a 16 year old male who experienced severe pain after 10 min of riding. In the office, SEMG was recorded from the extensors of the underarm muscles while mentally rehearsing riding his motorbike. In the simulation, the EMG showed high activity (up to 40 pV) in the underarm muscles, as long as he was thinking of riding his motorbike. The SEMG training protocol consisted on teaching microbreaks (a 1 s epoch in which the SEMG decreased to 2-5 pV) while mentally riding. After 10 min of SEMG training he was able to make small microbreaks. The post SEMG recording with an imagery riding of the same circuit, showed a significant decrease in SEMG and numerous microbreaks. The second therapeutic session was at the actual motocross circuit where corrections of posture and arm position on the motorbike were given. Using appropriate language cues such as "feel the weight in your arms" facilitated relaxing of the muscles during the actual circuit riding. After these two interventions, he was able to drive for more than 2 h without any complaint. The rapid decrease in symptoms occurred most likely because of the dynamic relationship between the body posture and the motocross cycle. Combining mirror, photo and SEMG feedback demonstrated how to sit in an appropriate position on the bike as well as perform microbreaks. This case report suggests that changes in SEMG and body posture training should be used as a possible treatment and preventative approach for Arm Pump symptoms. Adapting this approach to sport specific symptoms may eliminate symptoms and improve performance. Keywords * SEMG * Arm Pump by Motocross * Peak performance