The effects of pre-exercise vibration stimulation on the exercise-induced muscle damage.

[Purpose] To investigate the effects of pre-induced muscle damage vibration stimulation on the pressure-pain threshold and muscle-fatigue-related metabolites of exercise-induced muscle damage. [Subjects and Methods] Thirty healthy, adult male subjects were randomly assigned to the pre-induced muscle damage vibration stimulation group, post-induced muscle damage vibration stimulation group, or control group (n=10 per group). To investigate the effects of pre-induced muscle damage vibration stimulation, changes in the pressure-pain threshold (lb), creatine kinase level (U/L), and lactate dehydrogenase level (U/L) were measured and analyzed at baseline and at 24 hours, 48 hours, and 72 hours after exercise. [Results] The pressure-pain thresholds and concentrations of creatine kinase and lactate dehydrogenase varied significantly in each group and during each measurement period. There were interactions between the measurement periods and groups, and results of the post-hoc test showed that the pre-induced muscle damage vibration stimulation group had the highest efficacy among the groups. [Conclusion] Pre-induced muscle damage vibration stimulation is more effective than post-induced muscle damage vibration stimulation for preventing muscle damage.

The effects of shoe heel height and gait velocity on position sense of the knee joint and balance.

[Purpose] The aim of this study was to examine the effects of increased heel height and gait velocity on balance control and knee joint position sense. [Subjects and Methods] Forty healthy adults were randomly allocated to 4 groups: low-heel, low-speed group (3 cm, 2 km/h), low-heel, high-speed group (3 cm, 4 km/h), high-heel, low-speed group (9 cm, 2 km/h), high-heel, and high-speed group (9 cm, 4 km/h), with 10 subjects per group. Static and dynamic balance was evaluated using the I-Balance system and knee joint position sense using a goniometer. Measurements were compared using a pre- and posttest design. [Results] Increasing heel height and gait velocity decreased knee joint position sense and significantly increased the amplitude of body sway under conditions of static and dynamic balance, with highest sway amplitude induced by the high-heel, high-speed condition. [Conclusion] Increased walking speed in high heels produced significant negative effects on knee joint sense and balance control.

Effects of low-frequency electrical stimulation on cumulative fatigue and muscle tone of the erector spinae.

[Purpose] The aim of this study was to determine the effect of low-frequency electrical stimulation on fatigue recovery of the erector spinae with cumulative fatigue induced by repeated lifting and lowering work. [Subjects] Thirty-two healthy men volunteered to participate in this study and they were randomly divided into three groups: a MC group of 12 persons who underwent microcurrent, a TENS group of 10 persons who underwent Transcutaneous electrical nerve stimulation, and a control group of 10 persons who only rested. [Methods] Cumulative fatigue was induced and then, EMG, muscle tone, CK and LDH serum levels of the erector spinae were measured. Each group then underwent the assigned intervention and was re-measured. To analyze the differences in fatigue between before and after the intervention, the paired t-test was conducted, while groups were compared using analysis of covariance with a control group. [Results] The MC groups showed a significant reduction in muscle fatigue and decreased muscle tone when compared to the control group. However, no significant differences were found between the TENS and control groups. [Conclusion] These results suggest that microcurrent stimulation was effective for recovery from cumulative muscle fatigue while TENS had no effect.

Effects of high voltage pulsed current stimulation with a visible contraction intensity on expression of TGF-ß1 and synthesis of type I collagen in wound-induced white rats.

[Purpose] This study aimed to examine the expression of transforming growth factor ß1 (TGF-ß1) and type I collagen by applying high voltage pulsed current stimulation (HVPCS) with a visible contraction intensity to white rats with induced wounds. [Subjects] Thirty-six white rats were used for this study. HVPCS with a non-visible contraction intensity was applied to experimental group I, and HVPCS with a visible contraction intensity was applied to experimental group II. Placebo stimulation was applied to the control group. [Methods] After wounds were triggered, the intervention appropriate for each group was applied. Changes in the size of their wounds and expression of TGF- ß1 and type I collagen were measured on the third, fifth, and seventh days. [Results] Comparison of the sizes of the wounds among the groups showed that the most significant decreases were found in experimental group II on the fifth and seventh days. TGF-ß1 expression comparison revealed that experimental group II had the most expression on the fifth day. [Conclusion] HVPCS with a visible contraction intensity was effective in promoting wound healing by increasing expression of TGF-ß1 and synthesis of type I collagen.