Heart Rate

[mikesbytes]

While recovering from injury, I've been checking my heart beat and I've noticed that it goes up to a point and then rather than get faster the beats get stronger and stronger

Does this mean that my heart rate isn't going to give me an indication of effort?

[sogood]

Depends on what you were doing while recuperating in bed.

Seriously though. What activities were you engaged in? What was the HR range at the time? And were you able to elevate it to a higher range before? HR is but one aspect of one's CV response to work. SV is the other and I assume that's what you meant by stronger.

[mikesbytes]

Wot's CV and SV ?

[sogood]

Sorry.

CV- Cardiovascular
SV- Stroke volume (volume of blood ejected by each heart beat)
HR- Heart rate

Fundamentally, one key parameter of CV response to work is the Cardiac Output (CO). Higher the CO, greater the nutrients (eg. Oxygen) can be carried out to the muscles and other organs, hence performance. And,

CO = SV x HR

So given that we can't easily perform non-invasive measurements of CO and SV, HR is the only parameter we can use ie. HRM.

And if you look at the other often talked about performance parameter, VO2max. It's equation is linearly related to CO. The O2 content differential just quantifies the respiratory and blood gas carriage capacities.

VO2max = COmax x (Differential b/n arterial and venous O2 content)

So in your case, your "stronger beat" may be an indication of greater SV or awareness of your increased heart activities. Depending on the specific stimulus (drug, fluid load, hormones etc) or pathologic states, there can be preferential changes in either the SV or HR. However, they tend to be limited and not something most have to worry about.