You'd think it would be strength/resistance training, but think again
Exercise is a true elixir.
But it hasn’t been clear which type yields the most energy, or most potent anti-aging punch.
Now, exciting findings reveal which kind excels at boosting energy in muscle cells as we age.
The clinical study focused on microscopic “organelles” in our cells — the energy factories called mitochondria.
Decline in mitochondrial function is a feature of aging, and that decline has been seen as possibly unstoppable and irreversible.
The new findings suggest that certain exercise routines may deflect — or even reverse — that downward slide.
Background to the new findings
Different kinds of exercise bring distinct, overlapping benefits.
For example, aerobic exercise excels at boosting heart and lung health.
And — as described in Jump-Start Your Metabolism — strength (resistance) training builds muscle, which aids weight control by raising your metabolism.
Overall, exercise fosters cardio-respiratory fitness (CRF), raises metabolic rates, and reduces the risks for cardiovascular disease, diabetes, dementia, and certain cancers.
As the Japanese authors of an evidence review concluded seven years ago, “Better CRF [cardio-respiratory fitness] was associated with lower risk of all-cause mortality and CHD/CVD [coronary heart disease/cardiovascular disease].” (Kodama S et al. 2009)
Their conclusions were recently affirmed by the American Heart Association: “… CRF [cardio-respiratory fitness] is a potentially stronger predictor of mortality than established risk factors such as smoking, hypertension, high cholesterol, and type 2 diabetes mellitus ...”. (Ross R et al. 2016)
Likewise, U.S. researchers recently concluded that higher cardio-respiratory fitness in mid-life reduces the risk for lung and colorectal cancers (Lakoski SG et al. 2015).
And last year, the Danish authors of another evidence review concluded that moderate and high-intensity aerobic exercise alike improve a key aspect of cardiovascular health — the so-called “endothelial function” of people’s arteries (Kolmos M et al. 2016).
Mayo Clinic trial yields surprising results
Muscle tissue is unusual in that it’s cells rarely divide.
Likewise, brain and heart also wear out and can’t easily be replaced.
So, if exercise restores — or even just preserves — key mitochondria functions in muscle cells, that effect may explain its proven heart and brain health benefits.
One of the first signs that exercise may boost mitochondria functions came from a rodent study in which moderate, long-term physical activity brought that benefit to the animals’ heart cells (Ferreira R et al. 2014).
But it’s been unclear which kind of exercise excels at making the little energy factories in our muscles more efficient.
Now, the results of a U.S. clinical trial offer an answer ... one that’s a bit surprising.
A team from the Mayo Clinic recently tested the effects of two different exercise types — alone and combined — on the mitochondria in participants’ muscle cells, and the related capacity to make critical proteins.
They recruited 72 people — 36 men and 36 women — from two age groups: “young” volunteers (aged 18-30) and “older” volunteers (aged 65-80).
The volunteers were then randomly assigned to perform one of three different exercise programs for 12 weeks:
- Resistance (strength) training using weights
- High-intensity interval training (HIIT) on stationary bicycles
- Combined resistance and HIIT exercise
The researchers biopsied tissue from the volunteers' thigh muscles, and compared their muscle cells to samples from sedentary volunteers.
They also measured the volunteers' lean muscle mass and insulin sensitivity (more of either being better for overall health).
Their findings reveal that two basic exercise types deliver distinct but overlapping benefits:
- All three regimens improved cardio-respiratory fitness, muscle, and insulin sensitivity.
- All three regimens enhanced the mitochondria-based cellular process for making new proteins, thus reversing a major adverse effect of aging.
- HIIT yielded the biggest energy benefits in muscle cells, via better mitochondria function: a 49 percent rise among the younger volunteers, and a 69 percent rise in the older ones.
- HIIT did the most to improve insulin sensitivity, which typically reduces the risk for developing diabetes.
- Resistance training and combined exercise added more muscle and strength than HIIT.
- Combined HIIT and resistance exercise boosted the volunteers' aerobic capacity, and mitochondrial functions in their muscle cells.
As the study's lead author, Dr. Sreekumaran Nair, said, “… the take-home message for aging adults [is] that supervised high-intensity training is probably best, because, both metabolically and at the molecular level, it confers the most benefits.”
“There are substantial basic science data to support the idea that exercise is critically important to prevent or delay aging,” said Nair. “There's no substitute for that.”
Based on his team's findings, high-intensity interval training (HIIT) may be the best exercise to maintain or bolster muscle energy and overall health as we age.
But they also found that it’s even better to combine resistance training and HIIT, for a fuller range of benefits.
As an aside, Dr Nair noted that it usually takes two days of light-to-moderate resistance training per week to gain significant muscle mass and strength.
Simple guides to HIIT and strength exercise
What if you can’t exercise outdoors or go to a gym, and don’t want to lift weights?
You can get plenty of HIIT and "body-weight" resistance exercise at home, in less than 20 minutes a day.
We described a very rapid routine in 7-Minute Fitness HIIT — one that should dramatically boost your fitness and sense of well-being. That article links to a brochure with illustrated instructions for the included exercises.
And The New York Times recently published an excellent guide to at-home, equipment-free resistance training by sports physician Jordan D. Metzl, M.D., called “The 9-Minute Strength Workout”.
As Dr. Metzl said, “Alone, they work a set group of muscles, but strung together in one-minute intervals, these nine exercises become a complete, whole-body workout.”
His excellent article also provides links to other highly useful exercise guides published by the newspaper.
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