Effects of resistance training on CO2 excess and swimming performance in competitive swimmers

The purpose of the present study was to determine the change in total excess volume of CO2 output (CO2 excess) due to bicarbonate buffering of lactic acid produced during exercise and change in swimming performance following resistance training for 8 weeks in competitive swimmers. Ten healthy university competitive swimmers were assigned to either a resistance training and swimming training group (COMBINE : N=5) or a swimming training only group (SWIM : N=5). Muscle mass was measured using magnetic resonance imaging (MRI). CO2 excess and blood lactate concentration were measured during incremental exercise on a cycle ergometer and swimming performance was measured during competition. COMBINE showed a significantly higher percentage change in muscle mass (11.1+/-4.5%) than SWIM (3.5+/-2.5%). The percentage change in CO2 excess, CO2 excess per body weight (CO2 excess/BW) and CO2 excess/BW per blood lactate accumulation (CO2 excess/BW/Delta La) during exercise was significantly higher in COMBINE (107.3+/-60.1, 102.6+/-56.8, 59.1+/-37.7%, respectively) than in SWIM (42.5+/-10.0, 42.9+/-10.4, 13.4+/-22.4%, respectively). The percentage change in swimming performance was significantly higher in COMBINE (2.2+/-1.8%) than in SWIM (-2.0+/-3.6%). A negative correlation between percentage change of muscle mass and percentage change of CO2 excess/BW/Delta La (SWIM : r = -0.993, P < 0.01, COMBINE : r = -0.744, P > 0.05) was found, It was suggested that combined swim and resistance training resulted in greater increases in the bicarbonate buffering system (CO2 excess/BW/Delta La). However, increases in muscle mass may have subsequently caused a relative decrease in the contribution of the bicarbonate buffering system.