Cross-education: effects of age on rapid and maximal voluntary contractile characteristics in males
The purpose of this study was to determine the effect of age on the cross-education of rapid and maximal contractile properties for the knee extensors.
Young (n = 10; age = 21.1 ± 1.7 years) and older (n = 10; age = 65.3 ± 8.3 years) males performed unilateral isokinetic resistance training (RT) of the knee extensors for 4 weeks. Maximal voluntary isokinetic (45° s−1 and 300° s−1) and isometric testing was conducted for the trained and untrained leg before and after RT. Peak torque (PT) and acceleration were obtained from isokinetic testing as well as torque at 30 ms (TQ30) and 100 ms (TQ100) from the 45° s−1 contraction. PT and rate of torque development were recorded from the isometric contractions.
Independent of age, isometric PT (10.1%; p = 0.006) as well as PT and acceleration at 300° s−1 (6.7%; p = 0.008 and 4.0%; p = 0.016, respectively) increased in the untrained leg. At 45° s−1, acceleration was increased (3.6%; p = 0.021), but PT remained unchanged (p = 0.227). TQ100 increased similarly between groups (4.5%; p = 0.014), but TQ30 increased only in the older group (9.5%; p = 0.022).
Cross-education of rapid and maximal contractile parameters can be achieved early during unilateral RT independent of age. These findings indicate the potential for particular unilateral RT protocols to be used for older adults in rehabilitative settings to offset disuse-related reductions in contractile function, which are most dramatic in this population.
KeywordsResistance training Aging Rate of torque development Acceleration Knee extensors
Acceleration at 45° s−1
Acceleration at 300° s−1
Coefficient of variation
Intraclass correlation coefficient
Maximal voluntary isometric contraction
Peak torque at 45° s−1
Peak torque at 300° s−1
Rate of force development
Rate of torque development
Standard error of the measurement
Torque at 30 ms
Torque at 100 ms
We would like to thank Mr. Pope for his assistance with some aspects of the data collection.
GH and JD conceived and designed the research. GH, MM, RC, AB-C, CE collected the data. AO, AB, PH processed the data and assisted with analysis. GH conducted statistical analysis and prepared the manuscript. JD reviewed and revised the manuscript. All authors read and approved the final version.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
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