Vissing, K, Brink, M, Lønbro, S, Sørensen, H, Overgaard, K, Danborg, K, Mortensen, J, Elstrøm, O, Rosenhøj, N, Ringgaard, S, Andersen, JL, and Aagaard, P.

Journal of Strength and Conditioning Research: November 2008 - Volume 22 - Issue 6 - p 1799-1810 doi: 10.1519/JSC.0b013e318185f673

PURPOSE:

Compared changes in muscle strength, power, and morphology from equal time and effort strength training vs. plyometric training.

8 young, untrained men performed 12 weeks of progressive conventional resistance training (CRT).

7 young, untrained men performed 12 weeks of plyometric training (PT).

Pre- and post-tests were:

o 1-RM leg press.

o 3-RM leg extension.

o 1-RM leg curl.

o Countermovement jump (CMJ).

o Ballistic leg press.

o Magnetic resonance imaging scanning was performed for the thigh.

o A muscle biopsy was taken from the vastus lateralis (a quadricep) muscle.

RESULTS:

o Muscle strength increased by approximately 20-30% in the 1- and 3-RM tests.

o CRT showed a 50% greater improvement in leg curl (hamstring) strength compared to PT.

o PT increased maximum CMJ height x 10% and maximal power x 9% during both the CMJ and ballistic leg press.

o CRT only increased maximal power during the ballistic leg press x 4%.

o Quadriceps, hamstring, and adductor whole-muscle cross-sectional area (CSA) increased equally x 7-10% with CRT and PT.

o Type I and IIa fiber CSA increased in CRT x 32 and 49%, respectively.

o There were no significant changes for PT regarding CSA.

o Myosin heavy-chain IIX content decreased from 11 to 6% with no difference between CRT and PT.

IN PLAIN ENGLISH:

Specificity of training elicits relevant adaptations when training at fast and slow speeds of movement. Whatever one’s goal or whatever muscle adaptations are required for sport, use training modes that fit those.