Strength of two‐ and one‐leg extension in man

Abstract

Two- and one-leg extension strengths were compared in 155 female and male, untrained and trained (eight bicyclists, 38 weight-lifters) subjects and in a polio patient with almost no strength in one leg. On average two-leg strength was 82 +/- 1.3% (SE) of the sum of the strength of the right and left legs (leg-strength ratio) with no significant difference between the untrained and trained subjects. In the polio patient two-leg strength was lower than the strength of the strongest leg. A similar leg-strength ratio was found when measurements were made with a knee angle of 150 degrees (n = 128) and 90 degrees (n = 25). The ratio did not change when re-determined after 1 year (n = 9). Moderate changes in the subjects' position during measurements did not affect one-leg strength (n = 13). However, familiarization with the experimental apparatus increased the leg-strength ratio from 80 +/- 2.5% to 97 +/- 2.9% (P less than 0.01) (n = 18). In contrast, two-arm extension strength was similar to the sum of the strength of the right and left arms (n = 15). The results demonstrate that two-leg strength in general is lower than the sum of the strength of the right and left legs, and that this phenomenon is found even after intensive endurance or strength training. However, familiarization with the experimental apparatus can increase the relative two-leg strength which suggests that muscle strength in man may be limited by the central nervous systems' ability to activate maximally all synergistic muscles and/or to control antagonistic muscles.

Expression of the bilateral deficit during reflexively evoked contractions

“…15, 17, 20-22, 24, 25, 27, 28, 30, 32, 33, 41) and has become known as the bilateral deficit (BLD). For example, a 7-25% reduction in bilateral force production compared with summed unilateral output has been reported for isometric knee extension and combined isometric hip and knee extension (17,22,33,34,37). Dynamic contractions also display this phenomenon (33,(39)(40)(41)(42)(43)(44)(45), and a similar effect has been found for the upper limbs, although the deficit is generally smaller compared with the lower limbs (for a review, see Ref.…”

Considerations for Single and Double Leg Drop Jumps: Bilateral Deficit, Standardizing Drop Height, and Equalizing Training Load

“…The decrease in bilateral force is not due to increased antagonist activity. 7,13 Bilateral deficit is influenced by training 14,15 but in order to reduce bilateral deficit the training must be bilateral training, and commensurate with the testing protocol. 16 The most often cited mechanism for bilateral deficit is a lesser activation of fast twitch motor units 2,13,17 but whether this originates due to inter-hemispheric inhibition, 18 or at other supraspinal levels, 16,19 or both, is not clear.…”

Déficit bilateral em exercício multiarticular para membros superiores

“…Secher et al 8 found bilateral deficit in multiarticular exercises as leg press (lower limb), but not for the bench press (upper limb/multiarticular) in a group of younger volunteers.…”

“…Such deficit has been studied through strength and electromyography, confirmed most of the times with the use of uniarticular exercises [3][4][5][6][7] being controversial concerning EMG and strength in multiarticular exercises for lower and upper extremities 3,8 .…”