The English dictionary helpfully defines the word Fitness as "the state of being fit". The word fit is defined as "being in good physical condition, in good health". The Medical dictionary is more specific;
The state or condition of being physically sound and healthy, especially as the result of exercise and proper nutrition.
A state of general mental and physical well-being.
The state of being suitably adapted to an environment.
So, why all these definitions? I've been wondering what it is that defines fitness. I've realises over the years that just focussing on cardio vascular fitness is a slightly one sided approach.
For me the medical definition resonates; in that it's a wider definition, including mental as well as physical health and being adapted to your environment (and training). Being physically sound and healthy; not being injured and not being in pain. This interests me particularly as many runners I know have a niggle on the go or pick up injuries, so being fully fit means you are capable of doing the training you have planned without getting injured. To master this is quite an art!
Diet is also an interesting one, as you can be running well, performing well whilst eating badly. I know people who, because they exercise, see they have a licence to eat what they want as they won't put on weight. But weight gain isn't the only downside of a bad diet; too many sugary drinks and gels can still cause damage regardless of your size or fitness and not getting all the nutrients you need will slow recovery and lead to problems longer term.
It's interesting to consider mental health as part of an overall definition of fitness. It makes sense; I know from experience how big an impact my state of mind and mindset has on my life as well as my running performance. Whilst, for me, running improves my mental health and lowers stress levels I know I need balance. Overtraining or overly controlling what you eat for example are areas where mental and physical health cannot be separated out; it's just "health".
The final point in the medical definition is being adapted to your environment. For training this means the right sessions, recovery, rest/sleep and food to allow your body to rebuilt and adapt to cope better with the next session. The flip side is that the more the body tries to adapt to the habits and positions is finds itself in ( being at a desk five days a week) the more running and overall health is impacted. Muscle imbalance, back pain, tightness and neck and shoulder issues are often linked to making your body do something it's not designed to all day; sitting down.
Thinking about fitness in more athletic terms; my sense is the definition is wider than just the cardio vascular training you do. For endurance sports like running it's tempting to just run and not pay attention to other areas of fitness like strength and flexibility. Strength in particular is a weakness for many, this and good range of motion and flexibility are key for a long and healthy, active, life.
So you could define fitness by resting heart rate, body fat percentage and heart rate recovery times. And as someone who loves stats, numbers and watching them improve that would be very fulfilling and easy to do! I have to work hard to keep reminding myself of the wider meaning of fitness; strength, flexibility, diet, recovery, mental health.
It's not easy and much of the time I don't focus on it enough, but when I do I notice the improvement in how I feel. So it's got to be worth it :)
