Roig M, O’Brien K, Kirk G, Murray R, McKinnon P, Shadgan B, Reid WD. The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. Br J Sports Med. 2009 Aug;43(8):556-68.
This study is interesting, because it looks at the results of eccentric training on muscle mass and muscle cross-sectional area. Both parameters heavily define how your body looks and how tight it feels.
This study include 20 randomized controlled trial studies.
First, the results of this meta-analysis show that eccentric exercise at higher intensities increases total and eccentric strength more significantly than standard concentric training.
Second, eccentric training at high intensities is more growing muscles (measured in muscle girth) more effectively.
Third, eccentric training at high intensities show a notably trends towards increasing muscle cross-sectional area (measured with magnetic resonance imaging or computerised tomography), which effect how tight your muscles feels.