Effects of isometric exercise versus electrical muscle stimulation on serum enzymes, plasma lactate and peak torque levels in males
Abstract
The purpose of the study was to examine the effects of
electrical muscle stimulation (EMS) and isometric exercise (IE)
on peak torque, plasma lactate and serum enzymes. The subjects
were 14 male volunteers aged 22-41. The subjects were randomly
assigned to either the EMS group (Stayodyn EMS/plus stimulator;
bipolar technique of the quadriceps; 50 pulse/sec; pulse width
of 200 /isec; 2 sec ramp and 8 sec maximum /lO sec rest for 45
trials) and the IE group (Kin-Com); 10 sec maximal voluntary
contraction /lO sec rest for 45 trials). The subjects performed
both tests on two alternate weekends. The peak torque value was
measured for each contraction for both tests. Blood samples
were taken from the antecubital vein prior to testing and at 5
minute, 1 hour and 24 hours post exercise to determine plasma
lactate concentrations (HLA), serum creatine kinase (CPK), serum
aspartate aminotransferase (AST), and serum lactate dehydrogenase
(LDH) activities. The enzymes and HLA were analyzed using an
Abbott VP Bichromatic Analyzer.
The results indicated that: (a) peak torque produced by IE
was significantly greater (P<0.05) than that produced by the
EMS/plus stimulator; (b) both exercise modes produced significant increases (P<0.05) in HLA concentrations 5 minutes post exercise,
with the increase in HLA concentration of the IE group being
significantly greater (P<0.05) than that of the EMS group; (c)
both exercise modes resulted in significant increases (P<0.05)
in serum CPK activity 24 hours post exercise, with the increase
in serum CPK activity of the IE group being significantly greater
(P^O.05) than that of the EMS group; (d) both exercise modes
resulted in significant increases (P<0.05)in serum AST activity
24 hours post exercise, with the increase in serum AST activity
of the IE group being significantly greater (P<0.05) than that
of the EMS group; (e) neither IE nor EMS resulted in a
significant increase (P>0.05) in serum LDH activity.
It was concluded that both IE and EMS can produce an acute
exercise response. The significant difference (P<0.05) in peak
torque, HLA, serum CPK and AST between the two groups would
suggest that the exercise stress of the IE group was greater and
therefore, the intensity of the exercise was greater than that
of the EMS. The significantly lower (P<0.05) torque values in
the EMS group may have been due to: (a) "failed force outputs",
due to the inability to activate all of the motor axons of a large
muscle group; (b) "accommodation" to the electrical stimulator
output; (c) motivational factors, which may include the inability
to tolerate the electrical current, by some subjects.
Whether the increased acute exercise response demonstrated
by the IE group would result in significant improvements in
strength or endurance over the EMS group, would require a
comparison over an extended training program.
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- Retrospective theses [1604]