text: A long-term study followed 1583 middle-aged men and women with no personal history of either dementia or heart disease for two decades. Before-and-after tests done 20 years apart showed that the ones who had kept in shape had larger brains. The poorly conditioned participants had lost gray matter.
  Maintaining gray matter prevents cognitive decline and decreases dementia risk.
  Besides helping us keep our gray matter, aerobic/endurance/cardio training results in adaptions that benefit the body in other ways. Here's how.
  Bigger Tidal Volume
  Aerobic conditioning moves more oxygen to the working muscles. The first adaptation is breathing capacity, aka tidal volume. The air volume the lungs can move with each breath increases with improved diaphragm strength and breathing technique. Higher tidal volume is also associated with longevity.
  Bigger Blood Volume
  Blood increases with cardio training. The body produces more red blood cells and blood to carry more oxygen to body tissues. Increased blood volume also improves metabolic waste removal and recovery.
  The volume of blood ejected by the heart per beat increases, indicating improved heart function. This adaptation tends to occur at heart rates below 160 beats per minute. When people talk about "strengthening" the heart, this comes closest to being the underlying mechanism.
  By pumping more blood per beat, the heart moves a greater workload. The strength-training equivalent would be lifting a heavier weight with slow repetitions, versus pumping light weights quickly.
  More Capillaries*
  Capillaries are blood vessels with walls one cell thick. They surround muscle cells and deliver oxygen and nutrients. The capillary network becomes denser with aerobic workouts. This provides greater oxygen transfer to the mitochondria in the muscle cell.
  Size Matters – Density, Too*
  Aerobic training increases the size and density of mitochondria. Mitochondria are structures in muscle cells that convert fuel to energy aerobically. They're the receptor sites for the molecular oxygen that powers the Krebs (or citric acid) cycle and produces ATP. Mitochondria are the only sites in the body that burn fat – except for the heart, which uses whatever it gets, including lactate.
  More Type 1 Muscle Fibers*
  Aerobic conditioning sensitizes working muscle to insulin, partly by promoting Type 1 fibers. Type 1 fibers are high-endurance and sensitive to insulin. (Type 2 are better for explosive power but less sensitive to insulin.)
  Everyone knows cardio training can reduce the risk of heart disease, hypertension, stroke, diabetes, cholesterol problems, and more. Because insulin resistance underlies those conditions, workouts that improve insulin sensitivity are significant.
  More Fat-Burning Enzymes
  The hormone HSL (hormone-sensitive lipase) moves fat from storage to bloodstream for use as fuel. HSL is activated by brain chemicals and hormones when the body needs to mobilize energy stores. It's inhibited by insulin.
  Adaptations marked * above are peripheral, specific to the working muscle. So upper-body cardio will increase mitochondria, capillaries and type-1 fibers in the upper body, while lower-body training affects the lower-body muscles.
  Adaptations without * are central. They impact the entire body and permit a transfer. So upper body aerobic training can improve lower-body aerobic performance. Yes! (Krankcycles®, anyone?)
  What About Weight Loss and Aerobic Training?
  Aerobic workouts improve the body's ability to move oxygen and burn fuel. They may have limited impact on weight loss, though, partly because of the low intensity and low calorie burn. That's why high-intensity training is also necessary.
  But training is obviously about much more than weight loss.
  A major benefit of aerobic conditioning is it supports recovery from intense training. Trainers who advocate only high-intensity work often miss this point.
  Finally, when it comes to the sheer pleasure of training – indoors or out – a well-developed aerobic system lets you feel fantastic. And grows your brain!?
  If you're working to improve your fitness, don't forget your food. They need to work together. Just visit www.LastResortNutrition.com and request your free Empowered Eating Consult. Discover how easy it can be to make small shifts that provide big results.