A combination of weights and aerobics has proven best for just about everything: heart disease, diabetes, brain function, obesity, aging, and more. A new study from Harvard pinpoints the specific role of each form of exercise in the war against fat gain. At the same time, UK searchers are urging that we downplay the difference between resistance and aerobic training and key in on effort. They don’t deny that there are differences between the two forms of exercise, but argue that the public would be better served by a wide range of exercise options “so long as the effort is high.”
The Harvard study was published online December 22, 2014 in Obesity. Let’s talk about it first and then consider the thought-provoking proposal from the UK.
Prior studies have focused on the effect of the two forms of exercise on specific populations (overweight, diabetics, elderly, etc.). Researcher led by Dr. Rania Mekary, Department of Nutrition (HSPH), studied changes in physical activity, waist circumference, and body weight in 10,500 healthy men over a 12 year period. They looked at which activity; weight training, aerobic activity, inactivity, had the most effect on body weight and waistlines.
They found that substituting 20 minutes of weight training for any other activity had the strongest association with less increase in waist circumference, while substituting 20 minutes of moderate to vigorous aerobic activity had the strongest association with less gain in body weight. Those who increased their sedentary behaviors (watched more TV and the like) had the largest increase in waistline circumference and body weight. (So what you don’t do, literally is killing you.)
They concluded that long-term weight training is associated with less increase in waist size, while aerobic activity is associated with less gain in body weight.
“Because aging is associated with sarcopenia, the loss of skeletal muscle mass, relying on body weight alone is insufficient for the study of healthy aging,” Dr. Mekary told Science Daily. “Measuring waist circumference is a better indicator of healthy body composition among older adults. Engaging in resistance training or, ideally, combining it with aerobic exercise could help older adults lessen abdominal fat while increasing or preserving muscle mass.”
The increase in metabolic rate and energy expenditure brought about by weight training, Mekary et al say, is “mostly reflected in less central adiposity (fat) or waist circumference gain.”
In simple language, weight training builds and preserves muscle mass, which increases metabolism, burns belly fat, and contributes to healthy aging.
Fine and good, I know you have all heard this before, from more people then me. So, why does weight training burn more belly fat? The researchers offer a logical explanation, which lends credence to the UK researcher’s stress on short term effort.
Time efficient, intense weight training causes more “Excess Post Exercise Oxygen Consumption” (EPEOC) than aerobic training. The difference in oxygen consumption can extend up to 48 hours after exercise. (Re-read that highlighted phrase 3 more times please!) Importantly, the after workout energy burn is mostly fat. (and this 3X as well!) The calories burned during a weight training session are mainly carbohydrate, but those burned afterward are mostly fat. (yes, re-read X 3!!!)
In the language of the Harvard researchers: “Another potential explanation is the shift in substrate utilization from carbohydrates (mostly used during weight training) to lipid oxidation (mostly used during aerobic training) due to an induced-training adaptation involving increased mitochondrial content in the muscle, so that short-term aerobic responses could result from long-term anaerobic [weight] training.” That’s profound. Please read it again.
In brief, short term effort in the weight room pays off (=) long term in a slimmer waistline. Is there an amen here please!
Before moving on to the UK proposal, let’s pause briefly to look at a new study showing that waist size is serious business. It’s about more than looking good at the beach.
Australian researchers led by Dr. Alla Lukich compared the effect of overall obesity (defined by BMI) and abdominal obesity (defined by waist circumference) on arterial stiffness in people with Type 2 diabetes. This is important because arterial stiffness is consistently observed in diabetics of all ages and can lead to cardiovascular disease and death. Currently, however, there is no consistent evidence regarding differences in cardiovascular disease and death in obese and nonobese diabetics, and even less regarding the impact of overall obesity and abdominal obesity. Lukich et al sought to clarify the issue. Why do some obese diabetic have arterial stiffness and others don’t? If you’re bored here, get interested quick, this is what’s destroying our health.
Their findings were reported in the journal Cardiovascular Diabetology, 2014; 13(141).
It’s complicated as usual, but for our purposes the key finding is simple and straight forward. Abdominal obesity was associated with significantly higher arterial stiffness in diabetic men and women of all ages, while overall obesity did not predict adverse vascular changes. Why not? What’s the difference? This is crucial.
The mechanism that links abdominal obesity with arterial stiffness is not precisely known. What we do know is that visceral fat (brown fat) is metabolically active and plays an important role in insulin sensitivity, inflammation, lipid metabolism, and plaque formation in the lining of arteries.
We’ve seen that combining weights and aerobics helps to control fat accumulation all over the body, including visceral fat. That brings us to the UK researchers’ assertion that exercise prescriptions should focus on effort. (6 letter word, it’s OK)
Drs. James Fisher and James Steele, Centre for Health Exercise and Sport Science, Solent University, Southampton UK, maintain that optimal results in both resistance exercise (RE) and aerobic exercise (AE) are produced at “higher physiological effort.” They question the wisdom of the “Resistance/Aerobic Training Dichotomy.” They lay out their case in “A commentary on physiological adaptations determined by effort rather than exercise modality.” (Journal of Human Kinetics, volume 44/2014, 137-242)
Their proposal is based on a few revealing findings, some widely accepted and others newly reported. The overarching revelation is that resistance and aerobic exercise are of the same parents so to speak. You can’t have one without some of the other. Add effort to either modality and the benefits grow. “Effort appears to be the single most significant controllable variable to determine physiological adaptations to exercise,” Fisher and Steele asserted.
It’s a new way of thinking that opens up wide ranging, and exciting, new approaches to exercise. Let’s look at some of the details, starting with examples which are generally accepted.
Everyone agrees that sustained low effort (walking or jogging) is aerobic, and that as effort increases beyond the threshold (sprinting) the body transitions toward anaerobic energy production, which is typically associated with resistance exercise (RE). Likewise, RE performed at a low enough level of effort can become aerobic; up the effort and it becomes anaerobic. “As such AE and RE when performed at sufficiently high effort level will use the same metabolic pathways and thus catalyze the same fatigue responses,” the UK researchers wrote.
Taking it a step further, Fisher and Steele offer evidence that high effort AE can build muscle, and that high effort RE can build aerobic capacity. “The notion that both RE and AE at higher physiological effort levels produce greater aerobic/cardiovascular adaptations is becoming more widely accepted,” they reported. You should now begin to cheer loudly…
Carpinelli, Jungblut, and others have shown that resistance exercise performed to almost failure recruits as many muscle fibers as possible and stimulates the most significant gains in strength and size. Recent evidence suggests that cycling to near
muscular failure also results in significant muscular hypertrophy. Lundberg et al had subjects cycle at 70% of maximum for 40 minutes, and then increased workload until momentary failure. The prolonged cycling was predominantly aerobic, while cycling to failure at the end was anaerobic in nature. “The results of the study,” Fisher and Steele wrote, “showed that a group performing AE+RE attained significantly greater hypertrophy than a group performing RE only (14% vs. 8%, respectively).”
The muscular bodies of sprinters are probably the best known demonstration of what all-out aerobic exercise can produce. Resistance training, of course, makes them even more muscular and faster.
“Based on these findings…a muscle either contracts or relaxes,” they continued. “A muscle cannot identify the external resistance mode it is contracting against (whether it be free-weight, resistance machine, or cycle ergometer).” In fact, they added, external resistance are not even required. Body weight exercise (bodyweight Wednesday) or contracting muscle groups against one another, performed at high effort, can build significant strength and muscle size. No way….WAY!
Fisher and Steele also say that resistance and aerobic exercise produce similar health benefits. Tellingly, some of the most impressive health benefits come from low-volume, high-intensity interval training using 30 second all-out cycle sprints.
When effort is maximal or near maximal, the evidence suggests that similar adaptations-aerobic fitness, strength, hypertrophy, health, are likely “irrespective of exercise modality.” This should make everyone very happy right about now, options are not just encouraged but significant to creating overall health and fitness.
It should be understood that the UK researchers are not suggesting that a cyclist or runner can attain extreme cardiovascular fitness from resistance training or that a weight lifter can achieve world class strength and muscle mass from aerobic exercise. For that specialized training is necessary. They are suggesting that “the notion that exercise modality may be inconsequential [will open] up a [wide] range of possibilities for lay persons, (us) wishing to improve health, fitness and muscle size effectively.”
The multitude of options will allow many more people to find forms of exercise they enjoy, yes, enjoy, and actually want to continue exercising. The no-time-to-exercise excuse might even become a thing of the past. This is my 24/7 prayer.