Effect of creatine supplementation on oxygen uptake kinetics during submaximal cycle exercise

Area of Science:

• Exercise Physiology
• Nutritional Biochemistry

Background:

• Creatine supplementation is widely used to enhance athletic performance.
• Its effects on physiological responses during exercise, particularly oxygen uptake kinetics, require further investigation.

Purpose of the Study:

• To investigate the impact of oral creatine supplementation on pulmonary oxygen uptake (VO(2)) kinetics during moderate and heavy-intensity submaximal cycling exercise.

Main Methods:

• Nine healthy males underwent a crossover study involving oral creatine loading (20g/day for 5 days, then 5g/day).
• Subjects performed moderate (below ventilatory threshold) and heavy (above ventilatory threshold) intensity cycle exercise transitions.
• Pulmonary oxygen uptake (VO(2)) was measured breath-by-breath and analyzed using exponential modeling.

Main Results:

• Creatine supplementation did not alter VO(2) kinetics during moderate-intensity exercise.
• During heavy exercise, creatine loading significantly reduced the amplitude of the primary VO(2) component and end-exercise VO(2).
• The reduction in submaximal VO(2) correlated with the percentage of type II muscle fibers, suggesting a role for motor unit recruitment.

Conclusions:

• Oral creatine supplementation may influence oxygen uptake kinetics during heavy exercise, potentially by altering muscle activation patterns.
• The observed effects appear to be dependent on exercise intensity and individual muscle fiber composition.