Date of Award

2013

Degree Type

Thesis

Degree Name

Master of Science (Sports Science)

School

School of Exercise and Health Sciences

Faculty

Health, Engineering and Science

First Advisor

Professor Ken Nosaka

Second Advisor

Associate Professor Michael Newton

Abstract

Unaccustomed exercise consisting of eccentric contractions induces muscle damage that is characterised by muscle weakness, soreness, swelling and increased muscle stiffness. These symptoms affect daily activities and athletic performance; therefore, interventions to attenuate the symptoms and enhance recovery from muscle damage are necessary. Pulsed electromagnetic field therapy (PEMFT) is anecdotally reported to increase muscle blood flow and oxygenation to enhance tissue healing. One previous study showed that PEMFT was effective for alleviating muscle soreness and losses in range of motion after exercise. However, studies investigating the effect of PEMFT on recovery of muscle strength following eccentric exercise are lacking. The purposes of this study were to investigate the effects of PEMFT treatment on muscle temperature, blood flow and oxygenation (Study 1), and on the symptoms associated with eccentric exerciseinduced muscle damage (Study 2).

In Study 1, the effects of 30 min PEMFT on muscle temperature, blood flow and oxygenation were examined using nine healthy men (23.6 ± 3.7 years). A device called e-cell™was used for PEMFT in this study, which is the size and shape of a computer mouse weighing approximately 140 g, and sham treatment used a visually identical device without pulsed electromagnetic field production. PEMFT was applied over the bicep brachii of one arm for 30 min, and the other arm received sham treatment, while each subject was lying supine on a massage table. The device was marked A or B; thus, both the investigator and subjects were blinded as to which device was active e-cell™ or sham, and the use of dominant or non-dominant arm for device A or B was randomised and counterbalanced among subjects. Pre-treatment muscle temperature was measured by a thermistor needle (22 gauge, 70 mm) inserted to a depth of 20 mm at 10 mm laterally adjacent to a near infrared spectroscopy (NIRS) probe unit that was attached to the skin at the mid-belly of the biceps brachii, and the post-treatment measurement was taken at 5 mm proximal to the first site. The NIRS was used to measure tissue oxygenation index (TOI), a measure of muscle oxygenation, and total haemoglobin content (tHb), an indirect measure of blood flow, which were recorded throughout the treatment period. Changes in muscle temperature from before to immediately posttreatment were compared between e-cell™ and sham conditions using a paired t-test, and changes in TOI and tHb from baseline to 30 min of treatment (0, 10, 20 and 30 min) were compared between conditions by a two-way repeated measures analysis of variance (ANOVA). Muscle temperature significantly (p

In Study 2, eight men and eight women (24.8 ± 6.2 years) performed two bouts of 60 maximal isokinetic (30°⋅s-1) eccentric contractions of the elbow flexors on each arm separated by 4 weeks. In each eccentric contraction, the elbow joint was forcibly extended from a flexed (90°) to a fully extended position (0°). At immediately after, and 1-4 days following the exercise, the exercised arm received 30 min of either e-cell™ or sham treatment described above. The arm dominance and the order of treatment conditions were randomised and counterbalanced among the subjects, and the study was conducted in a double-blinded manner. Dependant variables included maximal voluntary contraction (MVC) strength, range of motion (ROM), upper arm circumference (CIR), muscle soreness by a visual analogue scale, muscle tenderness measured by pressure pain threshold (PPT) and plasma CK activity. Changes in these variables for 7 days following the exercise were compared between e-cell™ and sham treatment conditions, men and women, and the first and second bouts of exercise by a two-way repeated measures ANOVA. The changes in the variables from pre- to post-treatment were also analysed by a two-way repeated measures ANOVA. All variables changed significantly (p

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