Tag Archives: aerobic exercise

September 23, 2013 · 1:33 AM

Book Review: The Heart Healthy Lifestyle – The Prevention and Treatment of Type 2 Diabetes

I just finished an ebook, The Heart Healthy Lifestyle: The Prevention and Treatment of Type 2 Diabetes by Sean Preuss, published in 2013. Per Amazon.com’s rating system, I give it five stars (I love it).

♦   ♦   ♦

This is an invaluable resource for 1) anyone recently diagnosed with type 2 diabetes or prediabetes, 2) those who aren’t responding well to their current therapeutic regimen, and 3) type 2 diabetics who want to reduce their drug use.

Strength Training Helps Get Excess Blood Sugar Out of Circulation

Strength Training Helps Get Excess Blood Sugar Out of Circulation

Mr. Preuss is a fitness trainer who has worked with many type 2 diabetics. He demonstrates great familiarity with the issues diabetics face on a daily basis. His science-based recommendations are familiar to me since I reviewed many of his references at my blog, Diabetic Mediterranean Diet.

Like me, Mr. Preuss recognizes the primacy of lifestyle modification over drug therapy for type 2 diabetes, as long as drugs can safely be avoided or postponed. The main lifestyle factors are diet and exercise. Too many physicians don’t spend enough time on these, preferring instead to whip out the prescription pad and say, “Here ya go. I’ll see you in three months.”

I have gradually come to realize that most of my sedentary type 2 diabetes patients need to start a work-out program in a gym where they can get some personal attention. That’s Mr. Preuss’s opinion, too. The clearly explained strength training program he recommends utilizes machines most commonly found in a gym, although some home gyms will have them also. His regimen is easily done in 15-20 minute sessions two or three times a week.

He also recommends aerobic activity, such as walking at least several days a week. He recommends a minimum of 113 minutes a week of low intensity aerobic work, citing evidence that it’s more effective than higher intensity effort for improving insulin sensitivity.

I don’t recall specific mention of High Intensity Interval Training. HIIT holds great promise for delivering the benefits of aerobic exercise in only a quarter of the time devoted to lower intensity aerobics. It may be that it just hasn’t been studied in type 2 diabetics yet.

I was glad to see all of Mr. Preuss’s scientific references involved humans, particularly those with type 2 diabetes. No mouse studies here!

Another strength of the book is that Sean tells you how to use psychological tricks to make the necessary lifestyle changes.

The author notes that vinegar can help control blood sugars. He suggests, if you can tolerate it, drinking straight (undiluted) red wine vinegar or apple cider vinegar – 2 tbsp at bedtime or before carbohydrate consumption. I’ve heard rumors that this could be harmful to teeth, so I’d do some research or ask my dentist before drinking straight vinegar regularly. For all I know, it could be perfectly harmless. If you have a definitive answer, please share in the comments section below.

I read a pertinent vinegar study out of the University of Arizona from 2010 and reviewed it at one of my blogs. The most effective dose of vinegar was 10 g (about two teaspoons or 10 ml) of 5% acetic acid vinegar (either Heinz apple cider vinegar or Star Fine Foods raspberry vinegar).  This equates to two tablespoons of vinaigrette dressing (two parts oil/1 part vinegar) as might be used on a salad.  The study authors also say that “…two teaspoons of vinegar could be consumed palatably in hot tea with lemon at mealtime.”

The diet advice herein focuses on replacement of a portion of carbohydrates with proteins, healthy oils, and vegetables.

I highly recommend this book. And sign up for Mr. Preuss’s related tweets at @HeartHealthyTw.

Steve Parker, M.D.

Disclosure: Mr. Preuss gave me a free copy of the book, otherwise I have received no monetary compensation for this review.

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January 27, 2013 · 2:00 AM

Could Resistance Training Replace Slow Steady Cardio?

I was planning to review for you an article, Resistance Training to Momentary Muscular Failure Improves Cardiovascular Fitness in Humans: A review of acute physiological responses and chronic physiological adaptations.  It’s by James Steele, et al, in the Journal of Exercise Physiology (Vol. 15, No. 3, June  2012).

Exercise to momentary muscular failure may be safer on a machine

But it’s too technical for most of my readers. Heck, it’s too technical for me!  Too much cell biology and cell metabolism.  You’re dismissed now.

I’m just going to pull out a few pearls from the article that are important to me.  I ran across this in my quest for efficient exercise.  By efficient, I mean minimal time involved yet still effective.

The authors question the widespread assumption that aerobic and endurance training are both necessary for development of cardiovascular fitness.  Like Dr. Doug McGuff, they wonder if resistance training alone is adequate for the development of cardiovascular fitness.  Their paper is a review of the scientific literature.  The authors say the literature is hampered by an inappropriate definition and control of resistance training intensity.  The only accurate measure of intensity, in their view, is when the exerciser reaches maximal effort or momentary muscular failure.

The authors, by the way, define cardiovascular fitness in terms of maximum oxygen consumption, economy of movement, and lactate threshold.

“It would appear that the most important variable with regards to producing improvement in cardiovascular fitness via resistance training is intensity [i.e., to muscle failure].”

The key to improving cardiovascular fitness with resistance training is high intensity.  These workouts are not what you’d call fun.

From a molecular viewpoint, “the adenosine monophosphate–activated protein kinase pathway (AMPK) is held as the key instigator of endurance adaptations in skeletal muscle.  Contrastingly, the mammalian target of rapamycin pathway (mTOR) induces a cascade of events leading to increased muscle protein synthesis (i.e.,[muscle] hypertrophy).”  Some studies suggest AMPK is an acute inhibitor of mTOR activation.  Others indicate that “resistance training to  failure should result in activation of AMPK through these processes, as well as the subsequent delayed activation of mTOR, which presents a molecular mechanism by which resistance training can produce improvement in cardiovascular fitness, strength, and hypertrophy.”

You’re not still with me, are you?

“… the acute metabolic and molecular responses to resistance training performed to failure appear not to differ from traditional endurance or aerobic training when intensity is appropriately controlled.”

Chronic resistance training to failure induces a reduction in type IIx muscle fiber phenotype and an increase in type I and IIa fibers.  (Click for Wikipedia article on skeletal muscle fiber types.)

“It is very likely that people who are either untrained or not involved in organized sporting competition, but have the desire to improve their cardiovascular fitness may find value in resistance training performed to failure.  In fact, this review suggests that resistance training to failure can produce cardiovascular fitness effects while simultaneously producing improvements in strength, power, and other health and fitness variables. This would present an efficient investment of time as the person would not have to perform several independent training programs for differing aspects of fitness.”  [These statements may not apply to trained athletes.]

Before listing their 157 references, the authors note:

“It is beyond the scope of this review to suggest optimal means of employing resistance training (i.e., load, set volume, and/or frequency) in order to improve cardiovascular fitness since there are no published studies on this topic.”

In conclusion, if you’re going to do resistance training but not traditional aerobic/cardio exercise, you may not be missing out on any health benefits if you train with high  intensity.  And you’ll be done sooner.

Steve Parker, M.D.

PS: See Evidence-based resistance training recommendations by Fisher, Steele, et al.

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February 24, 2012 · 2:00 AM

Aerobic Versus Strength Training for People With Diabetes

“Resistance training, similarly to aerobic training, improves metabolic features and insulin sensitivity and reduces abdominal fat in type 2 diabetic patients,” according to a report in the current issue of Diabetes Care.

Italian researchers randomized 40 type 2 diabetics to follow either an aerobic or strength training program for four months.  The increase in peak oxygen consumption (VO2 peak) was greater in the aerobic group, whereas the strength training group gained more strength.  Hemoglobin A1c was similarly reduced in both groups, about 0.37%.  Body fat content was reduced in both groups, and insulin sensitivity and lean limb mass were similarly increased.  Pancreas beta-cell function didn’t change.

Per this one study, neither type of training seems superior overall.  If you’re just going to do one type of exercise program, choose your goal.  Do you want more strength, or more sustainable “windpower”? 

The Pennington Biomedical Research Center found somewhat different results in their larger and more complex study published in 2010.  However, they were primarily testing for diabetes control (as judged by hemoglobin A1c improvement), rather the improvements in strength or aerobic power.  The found the combination of aerobic and strength training is needed to improve diabetic blood sugar levels.  Both types of exercise—when considered alone—did not improve diabetes control. 

As for me, I do both strength and aerobic training.

By the way, I only read the abstract of the current research, not the full report. High-intensity intervals on a treadmill help me git’r done quicker.

Steve Parker, M.D.

PS: PWD = people or person with diabetes.  Do you like that term or would you prefer “diabetic”?

Reference:  Bacchi. Elizabeth, et al.  Metabolic Effects of Aerobic Training and Resistance Training in Type 2 Diabetic Subjects
A randomized controlled trial (the RAED2 study).  Diabetes Care.  Published online before print February 16, 2012, doi: 10.2337/dc11-1655

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April 8, 2011 · 2:00 AM

Exercise, Part 9: Realistic Goals If You’re New to Exercise

FITNESS

Sustained physical activity requires that your heart pump blood to the lungs and to the exercising muscles.  The muscles extract oxygen, sugar, and other nutrients for use in chemical reactions that enable the muscle to keep moving (contracting).  To say that someone is physically fit simply means that the heart easily pumps a large volume of blood and the muscles extract and use nutrients very efficiently.  The heart, after all, is just a hollow muscle that pumps blood.  If you stimulate your heart muscle through exercise, it will become more powerful and able to pump more blood.  Regular sessions of physical activity increase the metabolic efficiency and power of your other muscles, too.  There are various degrees of fitness, with professional and Olympic athletes at the extreme upper end.

GETTING STARTED

I’ve had otherwise healthy overweight patients so “out of shape” that walking 20 yards to the mailbox was a real chore.  They were tired and panting when they got to the mailbox and had to rest a bit before returning to the house.  These folks are habitually sedentary and dramatically overweight.  But you need not feel too sorry for them.  After starting and maintaining an exercise program, these unfit people achieve the greatest degree of improvement in fitness level.  They make more progress, and faster, than those who begin with a greater level of fitness.

The way to achieve aerobic fitness is to regularly challenge your large muscles to perform sustained physical activity.  “Regularly” means at least four days a week, if not daily.  Left alone, your muscles don’t want to do much other than just get you through your day comfortably, without effort or aching or cramps.  You must challenge them to do more, work a bit harder, tolerate a little aching.  You’ll know you’re challenging them during exercise when you perceive that mild to moderate effort is required to keep the activity going.  You should be mildly short of breath, perhaps even perspiring lightly, yet still able to converse.  “Sustained” physical activity means at least 30 minutes in a day.  Most people find it a better use of their time to exercise for 30 minutes continuously rather than break it up into five or 10 minutes here and there.

Discontinuous activity (e.g., 10 minutes thrice daily) probably is just as good. If you think about it, there are many easy ways to increase your discontinuous physical activity. Consider taking the stairs instead of the elevator, parking far from the supermarket or workplace doors, walking the golf course instead of riding a cart.

(The exercise model above is “old school,” which isn’t necessarily good or bad.  Some newer scientific studies suggest that you can achieve comparable levels of fitness with much less time exercising, if you do it intensely.  An example is high-intensity interval training (HIIT).  That’s worth a blog post or two by itself.  I also leave strength training—also an important aspect of fitness—for another day.)

If you’re starting out in poor shape, you won’t be able to do 30 minutes of any exercise without adverse effects.  Don’t even try.  The worst thing you could do at this point is injure yourself or have such a horrible experience that you give up entirely.  Thirty minutes of daily activity is your goal to achieve over the next four to 12 months.  Moderate to high levels of fitness will take you six to 24 months.  The most important thing when getting started is to exercise at least a little, five to 10 minutes, on most days of the week.  And don’t overdo it in terms of intensity. Start low, go slow.  After three months, exercise will be a habit.  Prolongation of your exercise sessions will be easy as your amazing body responds gradually to the workload through the process called physical conditioning.

If walking 30 minutes daily is too hard for you at first, try walking just an extra 10 or 20 minutes daily.  If you can do that but it’s a bit of a strain, gradually (every two weeks) increase your walking time by five minutes daily until you are up to 30 minutes.  Average walking pace is 2 mph (3.2 km/h).  Once you can comfortably handle 30 minutes daily, the next step is to increase your walking pace to 3 or 4 mph (4.8–6.4 km/h) for the entire 30 minutes.  Four mph (6.4 km/h) is definitely a brisk walk.  It’s difficult for many people to sustain over 30 minutes until they work up to it gradually.  This is often done by walking at two paces, normal and brisk, during an exercise session.  You might walk five minutes at normal pace, then five minutes briskly, alternating every five minutes until the session is over.  Every two to four weeks, you can increase the minutes of brisk pace and taper off the normal pace.  You’re able to do this easily because your level of fitness is increasing.

I’m asking you to walk briskly (3–4 mph or 4.8–6.4 km/h) for 30 minutes most days of the week.  This brisk pace burns roughly 200 calories per session, in case you’re wondering.  If you eat a 400-calorie muffin, it provides enough energy for a one-hour brisk walk.  If you don’t burn the muffin calories as exercise or basal metabolism, they’ll turn into body fat.  (But you’re not eating muffins anymore, are you?!)

If you prefer physical activity other than walking, the general rule is to start slowly and gradually increase your effort (intensity) until you’re up to about 30 minutes of moderate-intensity exercise most days of the week.  Start low, go slow.

Steve Parker, M.D.

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February 14, 2011 · 5:08 PM

Exercise, Part 5: Aerobic Exercise

What’s “aerobic activity”? Just about anything that mostly makes you huff and puff. In other words, get short of breath to some degree. Examples are brisk walking, swimming, golf (pulling a cart or carrying clubs), lawn work, painting, home repair, racket sports and table tennis, house cleaning, leisurely canoeing, jogging, bicycling, jumping rope, and skiing. The possibilities are endless. A leisurely stroll in the shopping mall doesn’t qualify, unless that makes you short of breath. Don’t laugh: that is a workout for many who are obese.

But which aerobic physical activity is best? Glad you asked!

The most important criterion is that it be pleasant for you. If not outright fun, it should be often enjoyable and always tolerable.

Your exercise of choice should also be available year-round, affordable, safe, and utilize large muscle groups. The greater mass and number of muscles used, the more calories you will burn, which is important if you’re trying to lose weight or prevent gain. Compare tennis playing with sitting in a chair squeezing a tennis ball repetitively. The tennis player burns calories much faster. Your largest muscles are in your legs, so consider walking, biking, many team sports, ski machines, jogging, treadmill, swimming, water aerobics, stationary cycling, stair-steppers, tennis, volleyball, roller-skating, rowing, jumping rope, and yard work.

Walking is “just what the doctor ordered” for many people. It’s readily available, affordable, usually safe, and requires little instruction. If it’s too hot, too cold, or rainy outside, you can do it in a mall, gymnasium, or health club.

Another option is instructional exercise DVDs, often featuring either a celebrity or prominent fitness trainer. Many of these programs require only a pair of sneakers and loose clothing. Others include the option of using inexpensive equipment, such as light hand-held weights.

If exercise videos sound appealing, consider one of these: Walk Away the Pounds—Walk Strong, by Leslie Sansone; Tighter Assets With Tamilee: Weight Loss & Cardio, by Tamilee Webb; Burn & Firm—Circuit Training, by Karen Voight; Minna Optimizer—Balanced Blend, by Minna Lessig; Personal Training System, by Denise Austin; Timesaver—Lift Weights to Lose Weight (volumes 1 & 2), Super Slimdown Circuit, and Functionally Fit—Peak Fat Burning, by Kathy Smith. Search for these titles at Amazon.com, where you can read reviews of them by actual users. Although many of these are designed for weight loss, you’ll get a good workout even if you’re at a healthy weight. Several of them also feature strength training.

Another fun option for indoor aerobic exercise is Dance Dance Revolution by Konami. Perhaps you’ve seen a version of this video game in an arcade. You must use a video game console, such as a PlayStation or Xbox, and the Dance Dance Revolution Controller along with your TV screen. The controller is a 32 inch by 36 inch (81 x 91 cm) floor pad partitioned into several large squares. The TV screen shows you which squares to step on in sequence as the music plays, and you rack up points for accurate timing and foot placement. If you enjoy moving to music, it’s more fun than I can describe

The latest indoor computerized exercise gadgets are the Kinect for Microsoft’s Xbox 360, the PlayStation Move, and Wii Fit. Check’em out.

Steve Parker, M.D.

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November 30, 2010 · 7:39 AM

Aerobic vs Strength Training: Which Improves Diabetes More?

Judging from improvement in hemoglobin A1c, the combination of aerobic and strength training is needed to improve diabetic blood sugar levels.  Both types of exercise—when considered alone—did not improve diabetes control, according to the latest research in the Journal of the American Medical Association.

One type of resistance training

One of the things that impressed me about Dr. Richard Bernstein’s book, Diabetes Solution, was his strong advocacy of weight training, also known as resistance training and strength training.  Weight lifting is a typical example.

Prior studies had shown exercise-induced  improvements (reductions)  in hemoglobin A1c, a great test for overall diabetes control, in the range of o.66% to 1.0% (absolute change, not relative).  That’s comparable to what we see with many drugs.  Much easier to pop a pill though, huh?

One earlier study showed hemoglobin A1c lowered by 0.4% with resistance training, 0.5% with aerobic training, and 1.0% with combined resistance/aerobic.  But folks doing both aerobic and resistance were exercising 270 minutes a week—39 minutes a day—which was significantly more than the people just doing one type of exercise. [This was the DARE study: Diabetes Aerobic and Resistance Exercise.] 

Investigators at the Pennington Biomedical Research Center in Louisiana wondered which type of exercise would be more effective, comparing the same minutes per week of activity.

Methodology

They randomized 262 sedentary type 2 diabetics to one of four groups: control, aerobic exercise, resistance training 3 days a week, or combined aerobic and resistance training (resistance twice weekly).  All three groups exercised for about 140 minutes a week—just 20 minutes a day, on average—for nine months.  Exercise intensity was 50 to 80% of maximum oxygen consumption (determined by a baseline treadmill stress test).  Nearly all participants were on diabetic drugs; 18% were on insulin.  I think the aerobic group exercised on treadmills.

Participant characteristics:  Women were 64% of the total.  Average age 56. Forty-seven percent were non-white (114 black, 10 Hispanic/other).  Average body mass index was 35.  Average hemoglobin A1c was 7.7%.  Not too many people dropped out of the study before it was over.

Results

No serious adverse event occurred during exercise.  The authors didn’t mention the occurence of hypoglycemia.

The combination training group dropped their hemoglobin A1c average by 0.34% (p = 0.03). The pure resistance and aerobic exercisers didn’t show any improvement over the control group.

The combination group lost 1.6 kg body weight on average compared to the control group.  Pure resistance and aerobic exercisers’ weights didn’t differ from the control group. [Remember, this was not a weight-loss study.]

Comments

The authors write:

The failure of the aerobic group to lose a substantial amount of weight (or fat) has been reported in numerous aerobic exercise trials, which may be due to aerobic training resulting in [higher] energy intake, expenditure compensation, or both.

If you’re trying to lose excess fat weight, resistance training appears to win over aerobic exercise.

Doing either aerobic execise or resistance exercise for an average of 20 minutes a day will not improve hemoglobin A1c levels in most type 2 diabetics.  We can assume blood sugars aren’t lower either.  It takes a combination of both types of exercise to lower hemoglobin A1c.

A hundred and forty minutes of exercise weekly—just 20 minutes a day—is not too much to ask for, if improved health and weight management are the goals.  More would be better.

Over nine months, the control group ended up needing more diabetic drugs.  The combination training group decreased its drug use.

Dr. Bernstein may still by right to stress resistance training over aerobic.  I bet he’d say these folks weren’t exercising enough.  The study at hand suggests that it’s important to do both types of exercise, especially if you’re not going to put much time into it.

The details of the resistance training program are probably important.  You can read the study yourself and decide if participants were on a good regimen.  I’ve little expertise in that area. 

ResearchBlogging.orgDiabetics taking insulin, sulfonylureas, and meglitinides are at risk for hypoglycemia during exercise. The study authors made little mention of this, so it may be safe to assume it wasn’t a problem. Certified diabetes educators saw participants monthly, which may have nipped the problem in the bud.

Steve Parker, M.D.

Reference: Church, T., Blair, S., Cocreham, S., Johannsen, N., Johnson, W., Kramer, K., Mikus, C., Myers, V., Nauta, M., Rodarte, R., Sparks, L., Thompson, A., & Earnest, C. (2010). Effects of Aerobic and Resistance Training on Hemoglobin A1c Levels in Patients With Type 2 Diabetes: A Randomized Controlled Trial JAMA: The Journal of the American Medical Association, 304 (20), 2253-2262 DOI: 10.1001/jama.2010.1710

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