If you can’t squat, then you ain’t strong! This is a core belief among most serious strength athletes. However, sled training also provides a significant lower body load that is functionally similar to movements in many sports. Meaghan Maddigan and colleagues from Memorial University of Newfoundland in Canada found that muscle activation patterns were similar during squats and sled pushing. The load on the gastrocnemius (calf) was greater during sled pushing, but the load on the erector spinae was greater during squats. Both exercises are excellent for building powerful lower body and core muscles. The study used electromyography (EMG) to estimate muscle activation levels.
Source: Journal of Strength and Conditioning Research, 28: 3346-3353, 2014