Changes of mental stress biomarkers in ultramarathon - Agawa, H; Yamada, N; Enomoto, Y; Suzuki, H; Hosono, A; Arakawa, K; Ghadimi, R; Miyata, M; Maeda, K; Shibata, K; Tokudome, M; Goto, C; Tokudome, Y; Hoshino, H; Imaeda, N; Marumoto, M; Suzuki, S; Kobayashi, M; Tokudome, S (Int J Sports Med, 2008)