What is the difference between the two-arm pull and one-arm pull?

The SkiErg is designed for both double poling - the two-armed pull common to all variations of Nordic skiing - and the alternating arm motion used in Classic Nordic ski technique. The double-pole involves more of the larger muscle groups, resulting in increased aerobic demand, calorie burn, and an overall higher quality workout. The classic alternating arm motion is also a good workout, while using a slightly different and smaller set of muscles.