Assessment of agonist–antagonist shoulder torque ratios in individuals with paraplegia: a new interpretative approach

Abstract

Study Design: Cross-sectional study. Objective: To evaluate isokinetic shoulder flexor-extensor (F/E) and abductor-adductor (Ab/Ad) torque ratios in individuals with paraplegia using a new interpretative approach. We proposed to study torque ratios according to joint angle sections (151 angle subgroups) over a selected range of motion. Setting: Pathokinesiology Laboratory, Montreal, Canada. Method: Sixteen individuals with complete motor paraplegia, without shoulder pain or impairment, were included in this study. After a preloading period of 1 s, maximum isokinetic concentric contractions of all muscle groups were completed at 30, 60 and 1201 s À1 over the entire tested ranges of motion (70 to À351 for the flexion-extension and 15 to 601 for the abduction-adduction). After the continuous torque curves were rebuilt, the mean F/E and Ab/Ad torque ratios were calculated and analyzed every 151. Results: A significant modification of the F/E (F ¼ 66.3; Po0.001) and Ab/Ad (F ¼ 100.6; Po0.001) torque ratios was observed according to the 151 angle subgroup evaluated. More precisely, a progressive decline of both the F/E and Ab/Ad ratios was noted as the shoulder flexion or abduction progressed. Angular velocity did not have any influence on torque ratio values. Conclusion: Angle subgroup torque ratio analysis leads to a better estimation of the balance between the agonist and antagonist muscle groups than does traditional peak torque ratio analysis. In individuals with paraplegia, this precise estimation of torque ratios may lead to the development of specific shoulder strengthening programs to prevent muscle imbalance and its consequences.

The association between conventional and dynamic control knee strength ratios in elite soccer players

“…These results suggest that different sports [11] and surfaces where these sports are practiced [1] may result in different H/Q strength ratios, which may lead to specific imbalances necessary to the specific sports performance. Furthermore, the use of ratios based only on PT has been debated [38][39][40]. In a previous study from our laboratory [40], we demonstrated that there were differences in several angles when comparing shoulder rotators DCR calculated by PT and by a 10 • angle specific torque (AST) approach.…”

Angle Specific Analysis of Side-to-Side Asymmetry in the Shoulder Rotators

“…This has also been shown to affect the interpretation of shoulder rotators unilateral strength imbalance [1], and many studies have opted to use an AST approach in order to gain more specific information of joint strength imbalances [1,3,4,[6][7][8]. We have previously demonstrated that shoulder IPT dynamic control ratios are significantly different than AST at several angles when calculated by 10° intervals over a 150° total ROM [1].…”

“…In addition, a few studies have opted to use 5°, 10°, 15° or end of ROM angle specific torque (AST) intervals for a more accurate estimation of unilateral dynamic muscle balance of the knee or shoulder joints [1,3,4,[6][7][8][9]. Dehail et al [7] demonstrated there was a significant progressive decline of flexion/extension and abduction/adduction AST strength ratios as the shoulder progressed to flexion and abduction, respectively. Yildiz et al [4], found that although internal rotator eccentric strength of the preferred side was greater than the non-preferred side at the end of the ROM, only the internal rotator concentric strength was greater than the non-preferred side at the beginning of the ROM.…”

“…Yildiz et al [4], found that although internal rotator eccentric strength of the preferred side was greater than the non-preferred side at the end of the ROM, only the internal rotator concentric strength was greater than the non-preferred side at the beginning of the ROM. Although IPT evaluations may be more sensitive to assess muscle strength balance changes after strength rehabilitation programs [10], AST analysis has been shown to be a more appropriate tool to precisely locate potential muscle imbalances present at specific joint angles [1,6,7]. This information may be used for the prescription of strength exercises of the weak angles.…”

“…Typical shoulder strength asymmetry has been reported as an upper-limb dominance of 5%-10% measured by independent peak torque (IPT) in nonathletic and recreational-level athletes [5]. However, these IPT measurements fail to reproduce the functionality of muscles during sporting activities, because torque is not calculated through the entire range of motion (ROM), or at corresponding angles [1,6,7].…”