Corrigendum: Skeletal Muscle Fiber Size and Gene Expression in the Oldest-Old With Differing Degrees of Mobility - Naro, Fabio; Venturelli, Massimo; Monaco, Lucia; Toniolo, Luana; Muti, Ettore; Milanese, Chiara; Zhao, Jia; Richardson, Russell S.; Schena, Federico; Reggiani, Carlo (Frontiers in Physiology, 2020)