Swanson, who is recovering from a mid-back strain, threw a 25-pitch bullpen session without issue Tuesday, Greg Johns of MLB.com reports.
The right-hander began experiencing discomfort back in mid-January while working out at home in North Dakota, and the issue currently has him a few days behind the rest of his fellow pitchers. However, given the positive results of Tuesday's bullpen, Swanson is now set throw another bullpen and a live batting practice before jumping into Cactus League action.