Working in a Coaching Zone gym that has been open for over a year now, you start to see trends and limitations of the program. Through the use of heart rate belts, people are motivated to get their heart rate sky high and get super out of breath in the 45 minute sessions.
While this is fantastic at improving aerobic fitness, people start to adapt to the sessions and progress is not quite as quick. People come in, do the session, lift the same weight and may add a couple reps here and there on some movements over time.
How could they improve their fitness much quicker?
Have a strength bias for a couple months.
Whether they do that outside of the actual session and drop the amount of sessions they do or add heavier weights during their session and not move through as quickly, getting stronger can improve their power output which they can then work on repeating over a period fo time during the normal sessions.
Consider the graph above. This shows two athletes power outputs over time. You can see that the weaker athlete can maintain a higher power output relative to their peak over time. Technically they are fitter at this stage. (Please note, the power output numbers are just that, numbers, to help contrast the difference between two athletes)
At the moment your strength athlete could be considered a powerlifter, who will not be able to maintain a high power output over a decent duration of time. This is athlete 1 or the stronger athlete in the graph.
And Athlete 2, the weaker athlete is your endurance athlete who can go the one pace all day.
It is quite obvious seeing from this, that the Strength athlete joining a gym like Coaching Zone will benefit greatly in overall fitness, as his aerobic fitness improves his repeated efforts will increase. His ceiling for repeated efforts is much greater, and if he can repeat efforts of power around the 45-70 mark, he has already exceeded the weaker athletes peak power output.
On the other hand the weaker athlete is already near their peak potential, and any increases in aerobic fitness will be minimal.
This is the stage most athletes find themselves. Most will need to increase their peak power output so they can significantly increase their fitness.
The athlete that can repeat the highest peak power output for the longest is your fittest athlete.