Reliability of isokinetic strength imbalance ratios measured using the Cybex NORM dynamometer

Abstract

The main aim of this study was to examine the absolute and relative reliability of some commonly used strength imbalance indices such as concentric hamstring-to-concentric quadriceps ratio, eccentric hamstring-to-concentric quadriceps ratio and bilateral concentric and eccentric strength ratios. An additional aim was to examine the reliability of the peak torque and work of the knee extensor and flexor muscles measured using the Cybex NORM dynamometer. Eighteen physically active healthy subjects (mean +/- standard deviation, age 23 +/- 3 years, height 176 +/- 5 cm, body mass 74 +/- 8 kg) were tested three times with 96 h between sessions. Peak torque, average work, unilateral and bilateral ratios were determined at 60, 120, 180 and -60 degrees s(-1). Low (0.34) to moderate (0.87) relative reliability (intraclass correlation coefficient, ICC) was found for strength imbalance ratios with eccentric hamstring-to-concentric quadriceps ratio showing the greater ICC (>0.80). High ICC values (0.90-0.98) were found for peak torque and average work. Absolute reliability (standard error of measurement) ranged from 3.2% to 8.7% for strength imbalance ratios and from 4.3% to 7.7% for peak torque and average work measurements. This study established the reliability of the most common strength imbalance ratios and of absolute isokinetic muscle strength assessed using the Cybex NORM.

The effects of strength training on isometric force production symmetry in recreationally trained males

“…3,6,19 However, there is still a lack of consensus on what a normal imbalance is and how much deviation is acceptable. 20 The current findings indicate that strength training can decrease lower body muscle imbalances, agreeing with the available previous research. Golik-Peric and colleagues found that 4 weeks of isoinertial and isokinetic training in athletes improved ipsilateral muscle symmetry by increasing the concentric hamstring to quadriceps torque ratio (conH/Q).…”

Asymmetries of Maximum Hand Grip-, Trunk Rotation and Extensor Strength of the Lower Extremities in Healthy Active Males

“…the data of our study were smaller than the results found with athletes from other sports (soccer, track and field, basket, fencing, and alpine skiing; N=41) where a percentage asymmetry ((stronger-weaker)/ stronger x 100%) of 108.6% was found for the stronger leg during testing of maximum isometric contractions in the closed chain (9). for elite soccer players tested in the leg-press (technogym, Italy), also a greater asymmetry of maximum strength (1 rM) between the legs was found.…”

“…from 41 sports athletes (soccer, track and field, basket, fencing, and alpine skiing) the peak force unfolded during the closed-chain maximum isometric contractions, measured using a load cell with a knee angle about 100°. the asymmetry index ((stronger -weaker)/stronger x 100%) was 108.6% for the stronger leg (9). In another study the lower-limb asymmetrical strength differences of soccer players (40 males, 26 females, national collegiate athletic association Division I) showed a significant greater peak force scaled for 2/3 body mass with the right leg versus left leg during isometric mid-thigh pulls (p < 0.05) (21).…”

“…tests of maximum strength ability for the documentation of the training progress are used in sport and therapy and serve in rehabilitation after injuries to examine the extent to which functional performance has been normalized (9,13). In case of unilateral injuries usually the performance of the uninjured side is taken as criteria for assessing the rehabilitation progress.…”

Laboratory-based tests for swimmers: methodology, reliability, considerations and relationship with front-crawl performance

“…However, when the objective is to measure strength asymmetries, the intraclass correlation coefficients reliability appears to be low to moderate (Impellizzeri et al, 2008).…”