High-intensity exercise decreases muscle buffer capacity via a decrease in protein buffering in human skeletal muscle

Abstract

We have previously reported an acute decrease in muscle buffer capacity (βmin vitro) following high-intensity exercise. The aim of this study was to identify which muscle buffers are affected by acute exercise and the effects of exercise type and a training intervention on these changes. Whole muscle and non-protein βmin vitro were measured in male endurance athletes (VO2max∈=∈59.8∈±∈5.8 mL kg-1 min-1), and before and after training in male, team-sport athletes (VO2max∈=∈55.6∈±∈5.5 mL kg-1 min-1). Biopsies were obtained at rest and immediately after either time-to-fatigue at 120% VO2max (endurance athletes) or repeated sprints (team-sport athletes). High-intensity exercise was associated with a significant decrease in βmin vitro in endurance-trained males (146∈±∈9 to 138∈±∈7 mmol H+•kg d.w.-1•pH-1), and in male team-sport athletes both before (139∈±∈9 to 131∈±∈7 mmol H+•kg d.w. -1•pH-1) and after training (152∈±∈ 11 to 142∈±∈9 mmol H+•kg d.w. -1•pH-1). There were no acute changes in non-protein buffering capacity. There was a significant increase in βm in vitro following training, but this did not alter the post-exercise decrease in βmin vitro. In conclusion, high-intensity exercise decreased βmin vitro independent of exercise type or an interval-training intervention; this was largely explained by a decrease in protein buffering. These findings have important implications when examining training-induced changes in βmin vitro. Resting and post-exercise muscle samples cannot be used interchangeably to determine βmin vitro, and researchers must ensure that post-training measurements of βmin vitro are not influenced by an acute decrease caused by the final training bout. © 2009 Springer-Verlag.