Frequently, I am seeing suggestions that men over 50 should “stop doing cardio”. Those making such claims tend to also promote a keto diet (i.e., a very low carbohydrate diet that promotes ketosis to lose fat) and emphasize six-pack abs as the primary goal of training. They suggest that cardiorespiratory training has a negative effect on hormones and muscle mass. This may or not be the case, but…. I am often suspect of the cherry-picking of scientific literature that biases such fitness claims. Not that the individual studies lack validity. Rather, I am of the opinion that all fitness research is limited because the sample sizes tend to be small and the durations of the studies tend to be rather short to be broadly generalizable. People vary significantly. Genetic differences are immense. Adaptability and trainability vary.
Cardio training is essential for heart and vascular health. One need not, however, go to extremes with training. Twenty to 30 minutes a day (or even as infrequently as 2-3 days per week) is all that is needed. The “how” of cardio is quite individual. In my opinion, do what you like and what works—and what suits your goals.
Cardiorespiratory exercise has numerous benefits that at rather well known: improved heart function, improved blood chemistry (e.g., blood sugar and cholesterol levels), and increased caloric expenditure. There are, as well, additional “unintended” benefits of cardiorespiratory exercise of which few are aware. These include improved immune function, sleep, and metabolism.
“Neiman’s J” (seen below) suggests that regular moderate intensity can significantly reduce the incidence of upper respiratory infection (e.g., cold). In addition, regular cardiorespiratory exercise increases immune system cell function. For example, T-cell function and natural killer cell (NK cell—my favorite immune system cell) activity increase to fight pathogens and reduce the risk of cancers. As we see with Neiman’s J, too much is not a good thing. Research has actually shown that prolonged, intense exercise creates an “open window” for illness. With this in mind, care is needed to moderate training and exposure to pathogens to reduce the risk of getting sick. Proper planning and recovery are required. In general, regular exercise means better health.
Exercise also moderates brain chemistry. Serotonin, for example, affects mood. Serotonin is produced in the brain (indeed, the serotonin used by the brain must be made by the brain) during exercise. Thus, exercise acts as a natural antidepressant—along with the endorphins released during exercise. Accordingly, regular exercise can give one a short-term boost to mood, as well as long-term (via improved self-image and sense of accomplishment).
Cardiorespiratory exercise can also increase metabolic rate, allowing one to burn calories more effectively. Any exercise can boost metabolism. Some types, however, are better than others. Low intensity, steady-state exercise burns calories, but, for the most part, only during the exercise. High-intensity exercise burns calories at a higher rate and has a more prolonged post-exercise caloric expenditure. HIIT (and perhaps to a greater extent HIIRT) can extend energy expenditure for hours, post-exercise. Thus, proper exercise can allow one to even burn calories while one sleeps.
When it comes to a decision of “how much” cardio, one has to consider one’s goals and opportunity. The marathoner or ultra-endurance athlete much dedicate the greater portion of training time to endurance training, whereas the powerlifter/Olympic lifter has very limited time for cardio. Most of us fall somewhere along this spectrum. While many, who are focused on building muscle, might refrain from doing cardio, I would recommend at least a minimal amount. For such as these, some cardio, in addition to benefiting the cardiorespiratory system and overall health, can aid in recovery. While rest (i.e., sleep) is necessary for adaptation to occur, active recovery is performed as a means of cool-down and recovery of muscle damage. It can take on many forms, but modest cardio has all the aforementioned benefits.
In general, when goals are mixed, I recommend partitioning training accordingly—e.g., keeping cardio and weight training to separate sessions. If multiple daily sessions or an alternate-day schedule is not possible, the order of exercise should be structured according to goals. For example, if gains and strength and muscle mass are favored over cardiorespiratory endurance, lift first and end the workout with cardio. In such a case, fatigue might reduce the intensity of the cardio exercise but not the intensity of the resistance exercise. Keep in mind, we want to optimize the training volume (and recovery) according to the goals of the exerciser.
How much cardio? “As much as is necessary” is perhaps the best answer. I would not, however, recommend “none”. Be smart about the cardio you do.
Be your best today; be better tomorrow.
Carpe momento!
Neiman’s J: http://www.exercisemed.org/_Media/image-12_360.png