Validation of the AC[La]+EPOCfast Method in Sprinters and Middle-distance Runners.

The anaerobic capacity (AC[La]+EPOCfast) method is of interest as it can differentiate between the contributions of phosphocreatine (PCr) and glycolytic energy, assess the anaerobic metabolism during a single effort, and evaluate various exercise modalities. However, no previous studies have investigated whether the superiority of the PCr and glycolytic systems can be assessed in athletes with high anaerobic capacity. This study aimed to compare the AC[La]+EPOCfast method in seven sprinters (SP) and seven middle-distance runners (MD). The participants underwent a graded exercise test and constant-load exercise at 115% ˙VO2max until exhaustion using a bicycle ergometer. AC[La]+EPOCfast was calculated as the sum of oxygen equivalents from the phosphagen (EPCr) and glycolytic (ELa) pathways. This study reveals that there was no significant difference in AC[La]+EPOCfast or maximal accumulated oxygen deficit (MAOD) between the two groups. Although EPCr was not significantly different between groups, ELa was significantly higher in the SP group than in the MD group. In conclusion, the AC[La]+EPOCfast method can be used to evaluate high and low anaerobic capacities. However, further studies on athletes with high aerobic capacity are required.

The effect of a decrease in stretch-shortening cycle function after cycling on subsequent running.

OBJECTIVES: Increased cardiorespiratory responses and changes in muscle activity and running kinematics occur in running after cycling compared with isolated running. Nevertheless, little is known about the causes of these changes. Cycling exercise decreases the stretch-shortening cycle (SSC) function, which can influence subsequent running. This study aimed to clarify whether the decrease in SSC function after cycling causes cardiorespiratory and biomechanical changes in subsequent running. DESIGN: Cross-sectional laboratory study. Participants were divided into two groups based on SSC function: an SSC dec group (those with decreased SSC function after cycling) and an SSC non-dec group (those without decreased SSC function after cycling). METHODS: Eighteen participants (10 triathletes and 8 runners) completed maximal aerobic tests for running and cycling. After these sessions, a submaximal run-cycle-run test was performed to compare between control run (no preceding cycle) and transition run (preceded by cycling). A jump test was administered before and after the submaximal cycling. SSC function was calculated as the ratio of the jump height to the time spent in contact with the ground (reactive strength index). Gas exchange measures, heart rate, and gait parameters were collected throughout the test. RESULTS: Oxygen uptake and ventilation were increased by cycling in the SSC dec group but not in the SSC non-dec group. In both groups, there were no significant differences in the gait parameters between control and transition runs. CONCLUSIONS: The decrease in SSC function after cycling would increase cardiorespiratory responses in subsequent running.