Changes in agonist-antagonist EMG, muscle CSA, and force during strength training in middle-aged and older people. - Hakkinen,K.; Kallinen,M.; Izquierdo,M.; Jokelainen,K.; Lassila,H.; Malkia,E.; Kraemer,WJ.; Newton,RU.; Alen,M. (J Appl Physiol, 1998)