What exactly changes when you improve? (Read 93 times)


    I've just startet running (log is public) and just from a few low intensity runs I can already feel a huge improvement. Not in speed, but in how I feel during the runs.


    What I'm wondering, just out of curiosity, is what's happening to my body? What makes me able to run longer and feel better in just two weeks?

    an amazing likeness

      Your body is responding to this new workload by increasing abilities for oxygen uptake and delivery; more red blood cell, increasing lung capacity, heart muscle strengthens, etc -- its overall capability in taking in oxygen and moving to your muscles.

      Acceptable at a dance, invaluable in a shipwreck.

        Yeah, milktruck's got it. Specifically my understanding from the little I've read on the subject is that the *first* things to change are blood volume and capillarization. But I've never worried too much about it beyond understanding that training works!

        Runners run


        rebuilding r2th v2.0

          The OP mentions changes in 2 weeks of training with no improvement in speed but just overall comfort. It's unlikely that any major cardiovascular changes have occurred within that time frame. The physiological adaptations that milktruck and mike mentioned take weeks if not months to take place. My guess is that the adaptations that make Stki feel more comfortable are more neuromuscular  in nature - activating neural circuits that wire running. These make running feel easier because the entire nervous system has now more  or better 'connections' to coordinate legs and arms motions during running. These physiological adaptations typically happen much faster than cardiovascular changes and are likely to explain the fact that the OP feels better. This is why people add strides to easy running - there is no real increase of training load in terms or cardio, but these wire the body for leg turnover/faster running and make you run faster without any major cardiovascular changes.



            SMART Approach

              Yes, early on at 2 weeks it is more neuromuscular vs physiological changes. It is running skill. Your body is learning to run. Think of learning to walk or riding a bike as a kid. The skill improves week to week.

              Run Coach. Recovery Coach. Founder of SMART Approach Training, Coaching & Recovery

              Structured Marathon Adaptive Recovery Training

              Safe Muscle Activation Recovery Technique



                Here's another vote for neuromuscular. You quickly become more coordinated, then over the next few weeks / months you should start to notice the improvements in your cardio efficiency, and finally (and more slowly) your muscular skeletal system adapts to best handle the impacts and stress.


                As a beginner, its important to remember this order to help prevent common early overuse injuries. You might begin to feel like a beast before your muscles and bones become beast.


                Stay disciplined, be patient, read and study running physiology, and you're in for a rewarding lifestyle. Best wishes.



                  You might begin to feel like a beast before your muscles and bones become beast.

                  Thanks and I know...and I still struggle to hold back.

                    This is a complex question and I think the answers given here may not fully describe what happens. I suspect cellular changes, such as more efficient mitochondria, may be a big factor in early improvement. Mitochondria, as you may already know, are organelles that produce energy for the cells. Another possible source of early improvement is the nervous system learning to utilize a greater percentage of the muscle fibers. We don't really use 100% of the strength of our muscles, most is held in reserve in case of a dire emergency. Running may train the body to use more of that reserve. There are also two types of muscle fibers, fast twitch for explosive power and slow twitch for endurance. For slower running some of the fast twitch fibers may learn to function to help with endurance. Actual physical changes to the circulation, blood supply, structural strength and better muscles will take time to develop.

                    Slow and steady win the race

                      Yes to all the above - oxygen efficiency, neuromuscular: etc etc


                      do not under estimate the mental changes; from your ability to endure longer periods of discomfort to how you start to, nearly unconsciously, make different decisions regarding nutrition, rest, even the subjects of conversation,


                      looks like you have started a wonderful journey of change….enjoy it…..it’s going to really suck sometimes but a few years from now you may not even recognize the person you were.


                        This is a complicated subject, and I believe the responses provided here might not fully capture what transpires. I believe biological modifications, such more effective mitochondria, may have played a significant role in the first improvement. You may already be aware that mitochondria are organelles that give cells their energy. The nervous system becoming more adept at using more muscle fibers is another potential source of early improvement. The majority of our muscle strength is kept in reserve in case of a serious emergency; we hardly ever use it. Running may teach the body to tap into that resource more frequently. Muscle fibers come in two varieties as well: fast twitch for power and speed, and slow twitch for endurance. Some of the quick twitch fibers may adapt to work in slower running to aid in endurance. It will take time to generate actual physical changes to the circulation, blood supply, structural strength, and better muscles.  drift boss