Last week, we took a deep dive into the topic of, based on this recent article and study reported on in the Wall Street Journal, whether cardio is really going to kill you. You learned all about the study, and you also learned about the glaring fact that diet was completely ignored in the study. This week, we're jumping straight back into the topic.
Let's begin where we left off...
2) Intensity Matters
While the study acknowledges that intensity for longer periods of time can cause damage to the arteries, it fails to point out the fact that intensity for shorter periods of time can actually allow you to become just as fit without subjecting the body to voluminous stress.
For example, according to an one study on the effect of HIIT on oxidative enzymes responsible for increasing endurance, there were enormous increases in skeletal muscle oxidative enzymes in seven weeks in subjects who did four to ten thirty-second maximal cycling sprints followed by four minutes of recovery just three days a week. Another six-week training study compared the increase in oxidative enzymes that resulted from either:
Four to six 30-second maximal-effort cycling sprints, each followed by 4.5 minutes of recovery, performed three days a week (classic HIIT training) or 40 to 60 minutes of steady cycling at 65 percent VO2 max (an easy aerobic intensity) five days a week. The levels of oxidative enzymes in the mitochondria in subjects who performed the HIIT program were significantly higher -- even though they were training at a fraction of the volume of the aerobic group.
So how could this favorable endurance adaptation happen with such short periods of exercise? It turns out that the increased mitochondrial density and oxidative-enzyme activity (both significantly increase endurance) from HIIT are caused by completely different message-signaling pathways than those created by traditional endurance training. In the HIIT pathway, a "master switch" is activated that promotes the favorable endurance adaptation. This master switch is known as PGC-1-alpha, which stands for peroxisome proliferator-activated receptor gamma coactivator 1-alpha. PGC-1-alpha causes that favorable increase in mitochondrial density and oxidative-enzyme activity but can be activated by two completely separate signaling pathways -- the calcium/calmodulin-dependent kinase (CaMK) pathway or the adenosine monophosphate-activated protein kinase (AMPK) pathway... Continuous, voluminous endurance training seems to activate the master PGC-1-alpha switch via the CaMK pathway, while intense interval training activates it via a completely different pathway: the AMPK pathway.
So ultimately, it turns out there are two different ways to train for a marathon or any other endurance activity: One method uses short, intense efforts, while the other uses the long, voluminous and often intense exercise the recent study found to be harmful to the heart.
3. Stress Matters
Let's face it: Many people who do intense endurance events such as marathons and Ironman triathlons are also hard-charging, successful business-people (just check out this study to see what I mean) who aren't just subjecting themselves to stress from exercise, but also stress from everything else: career, relationships, managing a home or business, hobbies, paying the bills, and everything else that goes along with wanting to be good at endurance sports but not necessarily at the same time being a professional athlete who can dedicated time to adequate sleep, recovery and de-stressing.
My friend Mark Sisson provides some valuable insight into this matter in his book The Primal Connection, in which he says that a major factor in the success of a pro endurance athlete is the absence of significant work stress -- deadlines, office obligations, etc.
Here's how Mark puts it when describing his experiences coaching a team of world-ranked professional triathletes and comparing their lives to the life of an amateur triathlete:
The typical amateur triathlete was a type-A overachiever with a demanding career and a busy family life. Fitting in the requisite workouts was a constant juggling act between work and family obligations. The word "squeeze" was used repeatedly to describe scheduling efforts, starting with the morning alarm and an abrupt commencement of the day's first workout. Pacing seemed to be an obsession, not just for tracking workout speed, but minding the clock at all times in order to remain "on time" for every item on the packed daily agenda. The popular "quick lunchtime swim workout" referred more to the peripherals than the lap times -- rushing out of the office, a presto change-o in the locker room, a one-minute postworkout shower, and then bursting back into the office an hour later with water beads still dripping from hair onto collar.
In contrast, the professional athletes -- whose job was to simply race fast -- lived lives centered around their workouts with minimal interference from real-life distractions or social obligations. While the pros conducted their workouts aggressively, the pace of their lives was leisurely. Lunchtime swim? Sure, but instead of toweling off, jerking the tie back into place, and rushing out to the parking lot, the postswim routine of the pros consisted of lingering in the poolside spa for nearly as long as the workout, shooting the breeze, stretching tight muscles, and generally decompressing from the intense effort in the water. Eventually, the pack moved from the spa into an easy lunch involving more shooting of the breeze. Eventually, they remounted their bikes for a couple more hours of pedaling, then took an afternoon nap, followed by a late-day run, followed by a stretching/icing session, followed by a quiet evening of television, reading, or lingering over a huge meal. As I spent more time in their world, I learned that the competitive advantage enjoyed by these professionals went beyond their impressive workouts. Embracing life both with purpose and at a more leisurely pace produces extraordinary results.
Stress is stress -- no matter whether it's from exercise or from lifestyle -- and the more stress you're placing on yourself from your lifestyle, the less stress you may be able to place on yourself from exercise.
So the question begs to be answered: What's the issue -- the lifestyle that goes along with the folks drawn to doing things like fast marathons, or the fast marathons themselves? It would be interesting, and I think quite revealing, to see the coronary calcium scores of, say, a professional Kenyan marathoner vs. a fast CEO marathoner.
What do you think? I'd love to hear your thoughts on the matter of whether runners have "one shoe in the grave"! Leave your comments below!