Do Changes in Predicted Isotonic 1RM and Isometric Peak Torque Demonstrate Cross Education?


1,2LoRusso, S, 1Brownyard N, 1Hay S, 1Hiester R, 1Pion J, 1Schlanger S. 1Department of Physical Therapy and 2Exercise Physiology, Saint Francis University, Loretto PA

Purpose: To determine the cross education effects of bilateral and unilateral isotonic strength training on isometric ext. and flex. Peak Torque (PkTq) in the lower limbs at 30o, 60o & 90o of knee flexion. Introduction: Unilateral strength training effects changes in strength in an untrained, contralateral limb. This phenomenon, crossed education (CE), can prevent strength loss in a contralateral untrained limb. This study examined this phenomenon using isometric peak torque and changes in 1RM as measures of CE. Methods: In a randomized pre/post-test design, 10 college aged male and female subjects, not formally strength trained for 3 months, were assigned to isotonic unilateral strength training (U), or control no training (C) groups. All subjects underwent 9 sessions of bilateral leg ext. strength training, followed by 9 sessions of no training (C) or right limb training only (U). Initial pre-training, post bilateral training, and final bilateral and unilateral 1 RM for knee extension, and isometric PkTq ext., flex. values at 30, 60 & 90o of knee flexion with “0o” full extension were determined. Data analysis: One way ANOVA with Pos-Hoc Tukey for pair wise differences. Results: Bilateral training increased 1 RM, NS, (F=2.46,p=0.127), while right limb unilateral training increased significantly (F=7.87,p=0.007), with no change in left limb 1RM (F=2.16,p=0.158). Post hoc analysis indicated significant increase in right limb ext PkTq at 30o & 60o, and NS at 90o. Left limb PkTq at 30o & 60o decreased significantly, and slightly increased at 90o. Right limb Flex. PkTq increased NS at 30o & 60o and decreased at 90o. There were no changes in left limb PkTq flexion. Conclusion: Unilateral training produced significant increases in 1RM of the right limb, and prevented strength loss in the left limb, demonstrating CE. Right Limb Ext. PkTq values increased, but demonstrated no CE effect to the left limb, as these values decreased significantly, with no significant change at 90o. However, the NS increases in right limb flexion PkTq at 30o & 60o suggests unilateral exercise influenced the right hamstrings. These results indicate that PkTq did not demonstrate CE, but there was support for the concept of specificity with effects mainly occurring in the trained limb.

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