Sundstrup, E., Jakobsen, M. D., Krustrup, P., & Aagaard, P. (2009). Effects of progressive heavy-resistance strength training on maximal eccentric and concentric muscle strength. ACSM 56th Annual Meeting, Seattle, Washington, Presentation Number 725.

"The torque/velocity-relationship obtained for human muscle in vivo demonstrates greater torque production for eccentric than concentric contractions. Consequently, strength training using the repetition maximum load principle does not provide a uniform relative loading for all contraction phases, that is, relative loading (%1 RM) is greatest in the concentric contraction phase. Hence, greater relative strength gains may be expected to occur in the concentric contraction phase."

This study evaluated the effect of low-frequency progressive heavy-resistance strength training on maximal voluntary concentric and eccentric quadriceps contraction strength in untrained men (N = 8). Ss performed progressive heavy-resistance strength training two times per week for 11 weeks. Training loads ranged from 6-10 RM with the first four weeks ranging 12-16 RM. Training exercises were squat, hack squat, incline leg pres, isolated knee extension, hamstring curls and calf raises. Maximal voluntary concentric and eccentric quadriceps knee extension torque were obtained by isokinetic dynamometry during slow (30°/s) and fast (240°/s) knee joint movements.

Slow concentric quadriceps peak torque increased by 16.7% following progressive heavy-resistance strength training whereas fast concentric peak torque remained unaltered. Slow and fast eccentric quadriceps peak moment increased 29.3%.

Implication. Gains in maximal quadriceps torque production are greater for eccentric than concentric muscle actions despite that relative loading being greatest in concentric contractions. Low frequency progressive heavy-resistance strength training leads to substantial gains in eccentric strength at both slow and fast joint movement speeds, while concentric strength only increases at the specific velocity of training, suggesting that the adaptations in maximal muscle strength differ between eccentric and concentric contraction conditions. Concentric muscle training is specific.

[This study used untrained men so one must be wary of generalizing its results to trained men and women.]

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