Is transient increase in pulmonary artery pressure one reason why older runners take a while to "warm up"

Most  older folks who jog,run or cycle probably experience a sluggish,hard to get going period when they first start out on their exercise session.

Dr.SP Wright and colleagues have published data demonstrating that in the group they studied (men and women age 55+-6 years ) there was transient increase in pulmonary artery  wedge pressure (PAWP) pressure as determined by right side heart characterization.

PAWP increased  from baseline at 11+-3 to 22+- 5 with light exercise.and then declined back to 17+-5.

This information needed to be considered in light of what was already known about pulmonary artery and pulmonary artery wedge pressure at rest and on exercise.Kovacs et al reviewed data from 1187 subjects who underwent right heart catherterization  at rest and with exercise.( ref 1 below). ( I continue to be amazed at the number of people who agree to let doctors put  catheter  is the veins and snake them through the heart chambers and into the pulmonary artery)

 Current guidelines state that pulmonary artery hypertension (PAH) can be diagnosed when PAP exceeds 25 mm hg at rest or 30 with exercise. However  exercise levels of pulmonary artery pressure increase with age while pressure levels at rest do not and as is discussed below the 30 cutoff may be misleading in older patients..

During low levels of exercise in subjects less than fifty years of age the PAP was 19.4 +-4.8 while in those greater than fifty pressure were 29.4 +-8. So in older apparently normal subjects the PAP may exceed 30 .( In one review 20/97 normal subject over 50 years of age exceeded the  pulmonary artery hypertension diagnostic threshold of 30 . There will be a number of false positive diagnosis of pulmonary artery hypertension if the  exercise30 mm hg criterion  is used.

So in older humans the exercise pulmonary artery pressure is higher and then increases further with the onset of exercise but then returns to lower levels after about 5-10 minutes of exercise.

This transient increase in the wedge pressure could explain how some of us breath a little heavier when we first start to run. Further this  transient increase should be considered when doing clinical  research work regarding pulmonary artery pressures. So why is this transient increase occurring?

Although Wright's subjects were considered normal it is possible that they had some degree of exercise  induced diastolic dysfunction ( their resting echocardiograms were said to be normal). Impaired ventricular relaxation and decrease in left ventricular compliance seem part of the aging process.But if the transient increase in pulmonary artery related pressure is an indirect manifestation of diastolic dysfunction , why is it transient?



references:

1) Kovacs, et al "Pulmonary arterial pressure during rest and exercise in healthy subjects: a systematic review"European respiratory Journal , vol 34, issue 4 ,Oct 2009

2)Wright,SP et al. "The pulmonary artery wedge pressure response to sustained exercise  is time-variant in healthy adults"Heart 2016, Mar 102(6) 438