Interval aerobic/resistance exercise training depresses adrenergic-induced apoptosis of lymphocytes in sedentary males

Purpose Adrenergic stimulation affects lymphocyte autophagy and apoptosis by activating β1-adrenergic receptor (β1-AR) and G protein-coupled receptor kinase 2 (GRK-2) downstream signaling. This study investigated how combined aerobic and resistance exercise training on the interval or continuous pattern influences aerobic/muscular fitness and β1-AR/GRK-2 signaling, and corresponding apoptosis/autophagy of lymphocytes in sedentary males. Methods Thirty-four sedentary males were randomized into interval training (IT, age = 22.5 ± 0.6 years, fitness level = 47.5 ± 0.9 mL/min/kg, body mass index (BMI) = 22.4 ± 0.4 kg/m 2 , n = 17) and continuous training (CT, age = 21.6 ± 0.4 years, fitness level = 45.2 ± 1.0 mL/min/kg, BMI = 22.2 ± 0.3 kg/m 2 , n = 17) groups. These subjects performed IT (bicycle exercise at alternating 40% and 80%VO 2 reserve (VO 2 R) and isokinetic exercise at alternating 60°/s and 180°/s) or CT (bicycle exercise at continuously 60%VO 2 R and isokinetic exercise at continuously 120°/s) for 30 min/day, 5 days/week for 6 weeks. Aerobic capacity and muscular strength/endurance were determined by the graded exercise test (GXT) and isokinetic strength test, respectively. Blood lymphocyte autophagy/apoptosis and β1-AR/GRK-2 signaling were analyzed using flow cytometry. Results Both IT and CT groups increased isokinetic strengths at various angular velocities, whereas only IT significantly enhanced muscle endurance, indicated by lowered fatigue index from 47.0 ± 1.3% to 41.8 ± 1.6% ( P < 0.05). Moreover, the IT group (143 ± 7%) revealed a higher improvement in VO 2peak than CT group (132 ± 6%) ( P < 0.05). Acute GXT augmented (i) GRK-2 and protein kinase A expressions, (ii) LAMP-2 upregulation and acridine orange staining, (iii) mitochondrial transmembrane potential diminishing, caspase-3 activation, and phosphatidylserine (PS) exposure caused by epinephrine in blood lymphocytes. However, the degree of epinephrine-induced lymphocyte PS exposure potentiated by GXT was suppressed from 65.2 ± 5.2% to 47.4 ± 6.5% following 6 weeks of the IT ( P < 0.05). Conclusion The IT may be considered more beneficial than CT in terms of improving aerobic/muscular fitness and simultaneously ameliorating apoptosis of blood lymphocyte evoked by intense exercise or adrenergic stimulation in sedentary males.