Six patients, (four children aged 6 to 12, and two young men aged 17 and 23) affected by the mild form of SMA underwent bilateral isokinetic tests and isokinetic strengthening exercise on the weaker leg three times weekly for 1 month. Children obtained an average of 33% of increase in muscle strength for both extensors and flexors of the knee in the trained leg. Adults obtained a very high increase in peak torque values: 122% for quadriceps and 52% for hamstring muscles. The untrained leg also showed some improvement from 0 to 17%. >