What is fitness? – A measurable definition!
Physical fitness is how you look, feel and perform. It comprises two related concepts: Health-related fitness (a state of health and well-being) and Functional fitness (a task-oriented definition based on the ability to perform specific aspects of sports or occupations). Physical fitness is generally achieved through exercise, correct nutrition and enough rest. It is a vitally important part of life.
Fitness is relative. Just as your fitness will affect your goals, your goals will affect your fitness.
This is a depiction of the the sickness-wellness-fitness curve in the 2002 Crossfit Journal Article defining fitness. (I’d look at body composition rather than just body fat; our understanding of cholesterol has developed since 2002; Systemic inflammation (through C-Reactive Protein and other markers) is also something I’d want to measure as a ‘wellness’ marker. This diagram IS a good starting point for understanding Health-related Fitness.)
One way of looking at health is as our ability to survive and thrive RIGHT NOW. What’s your blood pressure? Blood sugar? Mental outlook? Stress level? Immune response? Ability to survive falling off a 12’ ladder? This is perhaps a simplistic view of health but I think it works quite well.
The indicators of sickness and wellness are measurable. The relative health of a person can be estimated using a range of biomarkers. Please keep in mind that across a population there are large variations in “normal”.
Using the scale, “Sickness” implies something may be amiss e.g Blood Pressure is above 140/90. This doesn’t necessarily mean there’s a problem or illness, but can spark further investigation and preventative measures if required. “Wellness” indicates normal or average health e.g BP of 120/80. A lower (but not too low) reading would suggest greater cardiovascular efficiency and greater “fitness”. Health and fitness do overlap, but the ‘ultra-fit’ do tend to be more prone to illness than ‘fit’. (Probably due to compromised immunity through chronic stress or inflammation)
What if we considered health (the moment to moment ability to survive) over time? We would have longevity. Longevity is health over the long haul.
Longevity CAN simply mean surviving for a very long time. Quality of life does matter. One’s health may be such that any stressor, a cold, a fall, will be more than the individual can deal with. Conversely, perfect health, as measured on the day-to-day level, may curtail longevity. People who have a cold here and there tend to have lower rates of cancer. An occasional drop off in health may translate into improved longevity.
Capability: Put simply, are you physically able to do the task?
Capacity: What volume of work/task are you able to accomplish?
The Crossfit model of fitness would include the concept that “He or she who does best at the widest variety of tasks is on average the “fittest”.” I would say that would make you the best generalist, or best at Crossfit. Ultimately, your ‘fitness’ is highly dependent on the tasks you wish to do.
The ability to recover after a physical challenge or illness is in itself an indicator of fitness. Consider two people. Both perform a gruelling task e.g shovelling a large load. At the end of the day, both are shattered. The following day, one is able to continue the task, the other can barely move. They have different levels of fitness / capacity (at least for that task).
Having a performance bias may be at odds with health and longevity. Loads of endurance training may lead to oxidative stress, immune compromise and suboptimal dietary requirements necessary to fuel such efforts. If endurance sports are your thing, that’s fine. It’s perhaps good to know some of the down sides so one might make smart alterations to nutrition and training plans. Similarly if you aspire to be a Super Heavy Olympic Lifter you may need to consume an amount of food and carry a body mass that is absolutely at odds with health and longevity.
Another model is the notion that to be fit one should have a good balance in the development of all the engines that drive human activity: the ATP/CP pathway, glycolytic, and aerobic paths. The specifics of these energy pathways, ways to train them and implications for everyday life will feature in future articles.
What all this boils down to is for general fitness you need capability in various modalities, physical adaptations and metabolic engines, and capacity across a wide variety of tasks and time-frames. This offers a quantifiable way of measuring fitness. Do more work in less time and you are fitter!
Once again – Fitness is relative. Just as your fitness will affect your goals, your goals will affect your fitness.