My almost daily exercise is a 5K run without pause and without warm-up. Usually I decide after a few strokes whether I take it easy, i.e. in the 70-80% range, or challenge myself so that the second half of the 5K is in the 90-100% range. I like exercises in which I keep some reserve, so mostly as the HR increases, my 1K laps get faster.
The data in the graph are from this year. They show a fairly linear increase of average power vs average HR. As far as I know, there is no physiological reason why the trend should be linear, but the data do not suggest a more complex relationship.
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Of course, the data are very particular to my age, technique, fitness, prowess, etc., but my conjecture is that the percentual increase of 10% in power for 10% increase in heart rate will apply for many individuals.
My recommendation is that you increase your average intensity level to 60% of your vital range, in your case probably around 125, but do not take this as a fixed target. It is much more entertaining to increase the HR-target by 5 after each 1K lap or 5 mins, e.g. 115 - 120 - 125 - 130 - 135 bpm. From the power-HR data from each 1K lap you could check your personal slope.