Muscle anaerobic response to a maximal treadmill exercise test in Standardbred trotters.

This research aimed to establish a standardized maximal treadmill test in order to understand markers for anaerobic metabolism, particularly adenine nucleotide breakdown, in Standardbred trotters. Through the study, it showed that intense exercise like their treadmill test triggers anaerobic metabolism, with post-exercise uric acid concentration apparently marking the adenine nucleotide degradation happening during these activities.

Research Methodology

• The researchers designed a standardized maximal treadmill exercise test, which was performed until fatigue. This test was done to identify reproducible markers that indicate anaerobic metabolism.
• The test subjects were six Standardbred trotters. These horses had to perform an incremental maximal treadmill exercise that increased intensity every minute, starting from a speed of 7 m/s, and continued until they could no longer keep up with the treadmill’s pace.
• Two sessions of the test were done for each subject, with at least one week in between to ensure adequate recovery time.

Data Collection and Analysis

• Throughout the test, heart rates of the subjects were recorded while blood samples were taken during the exercise and in the period of recovery. These samples were then analyzed for concentrations of several compounds, including plasma lactate, hypoxanthine, xanthine, uric acid.
• Moreover, muscle biopsy samples from the m. gluteus of the horses were collected at rest, immediately after exercise, and after 15 minutes of recovery. These samples were analyzed for glycogen, creatine phosphate (CP), adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), inosine monophosphate (IMP), and muscle lactate (MLa).
• Data analysis involved statistical comparisons of the levels of these compounds pre- and post-exercise, and during recovery periods.

Research Findings

• Results of the tests showed significant decreases in glycogen, CP, and ATP levels, and notable increases in IMP and MLa right after the exercise. None of these metabolites had returned to resting levels even after 15 minutes of recovery.
• There was also a marked increase in plasma lactate during exercise, and its peak concentration was reached within 5 minutes of recovery.
• Interestingly, the uric acid concentration in the blood did not increase during the exercise but rose dramatically right after it. The highest level was achieved after 20 to 30 minutes of recovery.
• The study also found a correlation in the duration of the maximal test with the peak plasma lactate and the uric acid concentration after 30 minutes of recovery. Likewise, there was a connection seen between the ATP and IMP concentrations immediately after the exercise with the plasma uric acid concentration during recovery.

Study Conclusion

• The researchers concluded that the standardized treadmill test triggered anaerobic metabolism in the horses and suggested that uric acid concentration post exercise could be used as a marker for the degradation of adenine nucleotides during intense physical activities.
• Furthermore, the team also did not identify any significant differences in the horses’ metabolic responses between the two instances of the test, suggesting the results might be reproducible.