Muscular Oxygen Uptake Kinetics in Aged Adults

Area of Science:

• Exercise Physiology
• Aging Research

Background:

• Pulmonary oxygen uptake (V˙O2) and heart rate kinetics are affected by age and fitness.
• Muscular V˙O2 kinetics can be estimated using heart rate and pulmonary V˙O2 data.

Purpose of the Study:

• To evaluate a novel test for estimating muscular V˙O2 kinetics using pseudo-random binary sequences and a model.
• To determine if muscular V˙O2 kinetics are faster than pulmonary V˙O2 kinetics in elderly subjects.
• To investigate the relationship between muscular V˙O2 kinetics, pulmonary V˙O2 kinetics, heart rate kinetics, and maximum V˙O2 in older adults.

Main Methods:

• Assessed cardiorespiratory kinetics in 27 elderly subjects (73±3 years) using maximum cross-correlation functions.
• Applied a model with pseudo-random binary sequences to estimate muscular V˙O2 kinetics.
• Compared muscular V˙O2 kinetics with pulmonary V˙O2 kinetics and heart rate kinetics.

Main Results:

• Muscular V˙O2 kinetics were significantly faster than pulmonary V˙O2 kinetics (0.31±0.1 vs. 0.29±0.1 s; p=0.004).
• Heart rate kinetics showed no correlation with muscular or pulmonary V˙O2 kinetics or maximum V˙O2.
• Muscular V˙O2 kinetics demonstrated a positive correlation with maximum V˙O2 (r=0.35; p=0.033).

Conclusions:

• Muscular V˙O2 kinetics are faster than pulmonary estimates in elderly individuals.
• Muscular V˙O2 kinetics are related to maximum V˙O2 in this population.
• This approach may offer a way to assess muscular V˙O2 alterations independent of motivation and maximal effort.