Aim
  The study aimed to develop an appropriate in vivo rat model of muscle strain to investigate whether electroacupuncture is useful for improving muscle strain.
Methods
  An in vivo muscle strain model was developed with Wistar rats by the eccentric contraction (EC) evoked by pulling their hind limb with a stainless-steel wire that was connected to a weight; the EC was given under anesthesia during tetanic contraction in their gastrocnemius evoking by electrical stimulation of the sciatic nerve. Development of muscle strain was evaluated by comparing the muscle tension induced by the twitch of the gastrocnemius, pain thresholds measured using the Randall-Selitto test, and the serum creatine kinase (CK) activity between the following three experimental groups : EC×1 group, EC was temporarily evoked to their hind limb only once (n=10); EC×5 group, EC was temporarily evoked to their hind limb five times consecutively (n=6); and control group, EC was not evoked to their hind limb (n=6). After confirming the absence of a significant difference in the parameters between the two EC conditions, the effect of electroacupuncture (EA) was evaluated using the model of one-time EC (EA group n=10). At 12 hours after EC, EA was carried out at a frequency of 50 Hz and an intensity of 0.5 mA for 15 min; this stimulation was given for six consecutive days.
Results
  Muscle tension, pain thresholds, and the CK activity showed no remarkable changes in the control group during the experimental period. A significant decrease in the muscle tension was observed after EC in the EC×1 and EC×5 groups, and the decrease sustained until 48 and 24 hours after EC, respectively. Pain thresholds in the EC×1 and EC×5 groups were significantly lower than those in the control group at each of the time periods studied after EC, and were sustained at least until 120 hours after EC. The CK activity increased in the EC×1 and the EC×5 groups at 30 minutes after EC. Recovery in muscle tension after EC was faster in the EA group than in the EC×1 group. Pain thresholds also showed faster recovery in the EA group than in the EC×1 group, indicating statistically significant differences at 72, 96, and 120 hours after EC.
Discussion
  The in vivo rat model, which was developed in the present study, was considered to be an appropriate model of muscle strain because it clearly showed a decrease in the muscle tension and pain thresholds, and an elevation in the CK activity. EA was considered to be capable of accelerating the recovery of muscle strain as it was found to improve muscle tension and pain thresholds in the model.

[Objective]Daily repetitive exercise is known to be necessary for players in sports. In this study, to further explore the potential functions of acupuncture, we studied whether electroacupuncture (EA) stimulation has efficacy for repetitive exercise-induced oxidative stress.
[Methods]Six healthy male volunteers participated in both the non-treatment control group and the EA group in a crossover design. EA stimulation was applied to both the medial vastus muscles at 2 Hz and optimum intensity for each subject during ten min just before each exercise period. The subject performed ergometer exercise for 20 min with 75%of maximal oxygen uptake each day. This exercise period was performed once a day for three consecutive days. Blood lactate level (BLL) and plasma lipid peroxide (LP) concentration were measured as the markers for metabolism and oxidative stress, respectively. Visual Analogue Scale (VAS) was used to evaluate the individual level of fatigue due to exercise.
[Results]During and just after the exercise period, each value of BLL in the EA group was lower than the same points in the control group. Whereas LP concentrations before the exercise period on the first day in the control group was higher than the values in the same points on the second and third days. LP concentrations before the exercise period in the EA group were almost the same levels for three days. Furthermore, after the exercise period for the three consecutive days, LP concentrations and VAS in the EA group were lower than each value of the same points in the control group, and especially, the alteration of VAS showed a significant difference.
[Conclusion]The increased tendency of LP concentrations before the exercise period for three days in the control group indicated that repetitive exercise induced the accumulation of excess lipid peroxide. It might be suggested that EA stimulation suppressed subjective fatigue by an enhanced energy metabolic rate and decreased production of lipid peroxide. Hence the evidence strongly supported that EA stimulation might be useful for sports conditioning.

No abstract available.
Dermatofibrosarcoma* ; Keloid* ; Thorax*