movements can be on muscles, joints, bone s, ligaments, and tendons. At first glance, moderate intensity endurance exercise may seem like it’s easier on the body than weight training or interval training, but it’s not. The same consistent impact for hours at a time causes hip pain, knee pain, or ankle pain, and overall inflammation. Even worse is that individuals doing this as a weight loss strategy are generally putting higher loads on their ligaments and joints.
Exercising at a slow pace for a long time is extremely unnatural. Our hunter-gatherer ancestors would probably laugh watching us run, bike, or swim for hours to burn calories. Back then, energy was conserved, and you either walked to get somewhere, or you ran really fast to get away from something. Even when hunter-gatherers developed organized hunting, they relied on their brains and other resources to track and trap animals, not chase them around for 3hrs! One could imagine what a huge waste of energy it would be if a 3hr persistence hunt was unsuccessful. Furthermore, recent findings provide evidence that the earliest form of human was not designed to run because the conical shape of the ribcage made it difficult for them to swing their arms.
“They probably couldn’t run over longer distances, especially as they were unable to swing their arms, which saves energy.”
We can even forget the hunter-gatherers for a minute, and take a look at children playing to determine what’s ‘natural.’ When kids are playing outside at the park, they unknowingly move in short bursts followed by ample recovery. Oddly, there was a study done on this exact scenario. Researchers determined that children naturally exercise in intervals, as opposed to moving at a consistent speed. Either way, running for distance as a consistent form of exercise is extremely unnatural. Looking at the medical records of most Cardio Kings and Queens, it’s not surprising that they’re frequently injured. The irony in the term ‘stress fracture’ is almost laughable when you think of the cortisol and oxidative stress one can expect from chronic and prolonged aerobic training.
Cardio Oxidizes Muscle
When the original free radical theory was revisited it evolved into what we now know as the mitochondrial theory of aging. Scientists realized that mitochondria were producing a fair amount of the free radicals during exercise. The higher the oxygen requirement during exercise, as is the case with cardio and other consistent movements longer than 45-60sec (aerobic), the larger the production of free radicals within mitochondria.
With exercise that is predominantly aerobic, oxidation takes place inside the mitochondria, while with anaerobic exercise oxidation takes place outside the mitochondria (as oxygen is not needed to produce energy/ATP).
The increased oxidative stress produced from muscle contractions during aerobic exercise produces consistent damage to the mitochondria, leading to eventual cell death. Muscle cells are essentially ‘oxidized’ from frequent and extended endurance exercise. Unfortunately, once these muscle cells are destroyed they CANNOT be replaced through cell division.
A model developed in 1992 by M.B. Reid suggests that free radical production is necessary at low levels to preserve normal muscle performance, but higher concentrations produce negative effects. During strenuous exercise free radicals are generated faster than any buffering agent can handle which impairs performance and force output.
His model implies avoiding full fatigue, favoring moderate free radical accumulation that favors increased performance and promotes a natural antioxidant response in balance with the free radical concentrations. Above the optimal threshold, oxidation outnumbers antioxidants, and thus harmful oxidative stress will prevail within muscle leading to muscle dysfunction and loss, damage to protein, lipids and even
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