Visit your local neighborhood gym or club and you will undoubtedly see people engaging in downhill running or walking, depth jumps, abdominal rollouts, etc. which are all exercises focused on the eccentric rather than the concentric contraction.   Eccentrics are the downward portion of the exercise, such as lowering yourself in a squat or lowering the bar to your chest in a bench press.   More focus in being paid to eccentric exercises for good reason. Studies have shown that your body can tolerate up to 1.75 times more weight eccentrically than it can concentrically. Skeletal muscle generates force by either shortening (concentrically) or lengthening (eccentrically). Eccentric exercise is characterized by a lower metabolic demand and requires less muscle activity than concentric exercise at the same level of exerted force.   

Eccentric exercise induces a significantly greater increase in lipid oxidation in overweight and obese patients than in lean subjects. This is particularly relevant because of the following three reasons. First, patients with obesity usually exhibit a lower rate of lipolysis.  Second, body fat content significantly positively correlates with type IIx fibers. Third, oxidative enzyme activities negatively correlate with insulin resistance. This greater increase in lipid oxidation may arise from the increase in the hydrolysis of fatty acid phospholipids of the damaged muscle membranes and the alteration of the glucose transport system and insulin resistance following eccentric exercise

Exercise induced muscle damage after eccentric exercise leads to local inflammation and regeneration, which enhances protein degradation and synthesis via activation of well-known intracellular hypertrophy signaling pathways. Both acute and chronic eccentric exercises induce larger increases in post-exercise Resting Energy Expenditure, than acute and chronic concentric exercises performed at the same power output, partially because of the increase in muscle protein turnover and gain in lean mass. Both acute and chronic eccentric exercises can also modify metabolic substrate use by increasing post-exercise fat oxidation and reducing glucose oxidation, leading to a switch to a more oxidative metabolism. In line with the increased demand of the working muscle for fatty acid substrates to regenerate injured muscles, both acute and chronic eccentric exercises improve blood lipid profile to a greater extent than concentric exercises.

By increasing post-exercise resting energy expenditure, modifying metabolic substrate, and improving both blood lipid profile and insulin resistance, eccentric training is a potential exercise modality for individuals with chronic conditions such as those who are overweight and obese.

Scand J Med Sci Sports. 2019 Jan;29(1):4-15. doi: 10.1111/sms.13301.