If you have a lower-body injury, be it acute or chronic, training for cross-country skiing can be frustrating: there are so many activities which must be cut back if you are trying to protect a knee, ankle, or foot. Luckily, there are good training options available, especially if you have access to a double-pole machine like an Ercolina or a Concept2 SkiErg. “I use the SkiErg a lot because I fight with feet injuries, and...