Intramuscular Heating Through Fluidotherapy and Heat Shock Protein Response

Context: Therapeutic modalities that can increase intramuscular temperature commonly are used to treat injuries in the clinical setting. Researchers recently have suggested that the physiologic changes occurring during an increase in temperature also could provide a cytoprotective effect for exercise-induced muscle damage. Objective(s): To determine if the Fluidotherapy treatment increases the inducible expression of heat shock protein (HSP), to identify the rate of heating that occurs in the lower extremity with Fluidotherapy treatment, and to evaluate the relationship between the inducible expression of HSP and temperature. Design: Controlled laboratory study. Setting: Laboratory. Patients or Other Participants: Six male (age = 21.67 +/- 1.63 years, height = 180.09 +/- 4.83 cm, mass = 87.60 +/- 10.51 kg) and 6 female (age = 24.60 +/- 4.59 years, height = 151.05 +/- 35.76 cm, mass = 55.59 +/- 14.58 kg) college-aged students. Intervention(s): One lower extremity was randomly selected to receive the heat treatment, and the other extremity received no treatment. Main Outcome Measure(s): We measured intramuscular temperature every 10 minutes, determining peak intramuscular temperature by 2 identical sequential measurements, and we analyzed the time to peak temperature. We analyzed the amount of HSP70 expression and HSP27P:T (ratio of HSP27 to the total HSP27 expression) in the gastrocnemius and soleus muscles and measured baseline skinfold thickness and estradiol levels. Results: Fluidotherapy increased intramuscular temperature by 5.66 +/- 0.78 degrees C (t(11) - 25.67, P < .001) compared with baseline temperature, with a peak temperature of 39.08 degrees C +/- 0.39 degrees C occurring at 84.17 +/- 6.69 minutes. We did not find a heat treatment effect for HSP70 or HSP27P:T in the gastrocnemius or soleus muscles (P > .05). Peak temperature and the percentage change of HSP70 were positively correlated for the gastrocnemius and soleus muscles (P < .05). We found no other correlations for skinfold thickness, sex, or estradiol levels (P > .05). No effect of sex for skinfold thickness or estradiol levels at baseline was discovered (P > .05). Conclusions: This Fluidotherapy protocol increased the intramuscular temperature to a therapeutic level; however, it did not stimulate inducible HSP70 or HSP27P:T in the soleus and gastrocnemius muscles regardless of sex or skinfold thickness. These data confirmed that Fluidotherapy is an effective heating modality but suggested it is not an effective method for stimulating an HSP response in the lower limb.