The relationship between voluntary and involuntary muscle contractile properties in young women
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This article is not in any list yet, why not save it to one of your lists.Abstract
Isokinetic dynamometry and neuromuscular electrical stimulation (NMES) are two commonly used approaches for quantifying muscle contractile properties. Few studies, however, have investigated the relationship between such testing procedures, particularly in women.
PURPOSE
To determine the relationship between voluntary isometric and isokinetic torque and torque during involuntary, electrically evoked contractions of the knee extensor muscles.
METHODS
Thirty young women (age 23 ± 5 y) performed maximal knee extensions on an isokinetic dynamometer at angular velocities of 0, 1.57, 3.14, 4.71, and 6.28 rad/s. Following this testing, NMES of the quadriceps (400 V, 200 µs) was used to determine unpotentiated and potentiated twitch contractile properties. The quadriceps were also stimulated with 1 s trains at 1, 5, 10, 15, 20, 25, 30, 35, 40, 60, 80, and 100 Hz to determine the torque-frequency relationship.
RESULTS
Voluntary torques at 1.57 and 3.14 rad/s were significantly correlated (i.e., multiplicity-adjusted P≤0.01) with the rate of torque development during potentiated twitches (r = 0.60 and 0.55, respectively). No other significant correlations were found between voluntary and involuntary muscle contractile properties, including various measures of the torque-frequency relationship.
CONCLUSION
Although there is some relationship between voluntary and NMES indices of muscle contractility, such results are only moderately well-correlated at best. The two techniques should therefore be considered complementary rather than interchangeable.
