Progressive resistance versus relaxation training for breast cancer patients during adjuvant chemotherapy: design and rationale of a randomized controlled trial (BEATE study).

BACKGROUND AND RATIONALE: Cancer-related fatigue is a common severe symptom in breast cancer patients, especially during chemotherapy. Exercise appears to be promising in prevention or treatment of fatigue. Resistance training as an accompanying treatment to chemotherapy has been minimally investigated, yet might counteract muscle degradation and inflammation caused by many chemotherapeutics, and thus forestall or reduce fatigue. Previous exercise trials mostly compared the intervention with 'usual care'. Therefore, it is unclear to what extent the observed effects on fatigue are based on physical adaptations by exercise itself, or rather on psycho-social factors linked to the group support or attention by the trainer. METHODS AND DESIGN: The BEATE study is a randomized, controlled intervention trial comparing a 12-week supervised progressive resistance training program with a supervised group-based progressive muscle relaxation training in 100 patients with breast cancer under adjuvant chemotherapy. The primary endpoint is cancer-related fatigue; secondary endpoints include quality of life, depression, and cognitive capacity. In addition, isokinetic and isometric muscle strength, cardiorespiratory fitness, and body composition are measured, and biomarkers, such as inflammatory parameters, cortisol, and oxidative stress are analyzed in blood, saliva and urine. Safety of the resistance training during chemotherapy is monitored. DISCUSSION: Strengths of the BEATE study include the investigation of progressive resistance training parallel with chemotherapy, the choice of a control group that enables an evaluation of the physiological effects of exercise beyond potential psycho-social effects, and the comprehensive and high-quality assessment of physiological factors and biomarkers potentially related to fatigue.

Effect of thiol antioxidant on body fat and insulin reactivity.

Insulin signaling is enhanced by moderate concentrations of reactive oxygen species (ROS) and suppressed by persistent exposure to ROS. Diabetic patients show abnormally high ROS levels and a decrease in insulin reactivity which is ameliorated by antioxidants, such as N-acetylcysteine (NAC). A similar effect of NAC has not been reported for non-diabetic subjects. We now show that the insulin receptor (IR) kinase is inhibited in cell culture by physiologic concentrations of cysteine. In two double-blind trials involving a total of 140 non-diabetic subjects we found furthermore that NAC increased the HOMA-R index (derived from the fasting insulin and glucose concentrations) in smokers and obese patients, but not in nonobese non-smokers. In obese patients NAC also caused a decrease in glucose tolerance and body fat mass. Simultaneous treatment with creatine, a metabolite utilized by skeletal muscle and brain for the interconversion of ADP and ATP, reversed the NAC-mediated increase in HOMA-R index and the decrease in glucose tolerance without preventing the decrease in body fat. As the obese and hyperlipidemic patients had lower plasma thiol concentrations than the normolipidemic subjects, our results suggest that low thiol levels facilitate the development of obesity. Supplementation of thiols plus creatine may reduce body fat without compromising glucose tolerance.