THE ACUTE EFFECTS OF TWO DIFFERENT TRAINING MODELS ON MARKERS OF INFLAMMATORY ACTIVATION AND SKELETAL MUSCLE INJURY IN PATIENTS WITH CHRONIC HEART FAILURE

Background: Patients with heart failure (HF) are characterized by exercise intolerance, breathlessness, fatigue and excessive neurohormonal activation associated with premature mortality. Recently, inflammatory activation has been described as an important factor in the progression of HF. Increased levels of certain pro-inflammatory cytokines (e.g., TNF-ɑ, IL-6) have been related to increased severity of left ventricular dysfunction, the activation of the sympathetic and renin-angiotensin systems and the catabolism of skeletal muscle. Although exercise training is important in the management of HF, acute bouts of exercise may lead to increases in proinflammatory cytokines. It is believed that the skeletal muscle abnormalities associated with HF may increase the risk of damage to skeletal muscle, (i.e., exercise-induced muscle injury (EIMI) with associated inflammatory activation) especially following unaccustomed exercise training. Recently, several training methods have been proposed for patients with HF that challenge the traditional “steady-state” (SS) training model, including interval training (IT). Interval training methods employ greater muscular loading than SS and therefore may increase the risk of inflammatory system activation EIMI, and/or reduced muscle function. There is no study that has examined the effects of IT on EIMI, muscle function and/or inflammatory markers. Material and Methods: Fourteen male participants with HF (mean age: 59 +/- 7.8 yrs; mean VO2 peak: 13.64 +/- 4.5 ml/kg/m-1; EF < 45%) were matched (for body mass and aerobic fitness) and randomized into SS or IT for 20 minutes. The IT involved 2 minute work:recovery phases of 90% and 40% of heart rate reserve, respectively. The SS involved continuous exercise at 65% of heart rate reserve. Biochemical markers of muscle damage and acute inflammation, concentric and eccentric isokinetic muscle torque, and subjective indicators of delayed onset muscle soreness (DOMS) and lower extremity function were evaluated at baseline, and then immediately following the training bout, and at 6, 24, and 48 hours post. Results: There were no significant differences between the IT and the SS training group for markers of skeletal muscle injury or inflammatory activation. Conclusions: The findings from the present study suggest that IT or SS do not result in excessive inflammatory system activation or skeletal muscle injury. These results have important implications for clinicians prescribing exercise regimes for HF patients who may be starting back into activity after a prolonged sedentary period. Additionally, results from this study indicate that there is a need for future research looking at the actual and perceived effect of even a single about of exercise on lower extremity function.

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