Intense exercise
How to do it and why you should

By Ryan Andrews, MS, MA, RD, RYT, CSCS

Research now shows that, on average, folks experience a 2-4% decline in their resting metabolic rate with each passing decade after the age of 25. But today we’re going to teach you that there’s hope. Here’s how to off-set the decline.

How’s that metabolism?

It’s bound to happen to your friends. It’s likely to happen to your family. In fact, if you take a look around, about 95 out of every 100 people will experience the dreaded age-associated metabolic decline.

Research now shows that, on average, folks experience a 2-4% decline in their resting metabolic rate with each passing decade after the age of 25. Add to this metabolic decline a 5lb loss of muscle mass with every decade and getting older is a depressing proposition.

Indeed, for most people these declines are all but definite. However, you’re not most people. You’ve got access to us. And in this week’s newsletter, we’re going to teach you how to off-set what some erroneously believe is inevitable.

Will work for oxygen

When it comes to metabolism and muscle preserving strategies, intense exercise is the king. With it, you get to keep that muscle mass and fuel that metabolism. Without it, you get to politely smile while you wave bye-bye to your youth, muscle strength, lean mass, and metabolic rate.

Now, the big question is this; what qualifies as “intense exercise.” Well, certainly resistance training (strength training) is one of the biggies. However, there are a host of other types. Here are a few, taken from the menu of activities that we’ve prescribed to our clients:

Interval Running, Climbing, Cycling, and Rowing
Resistance Circuits
Body Weight Circuits
Rope Jumping (Skipping)
Running Hills
Burpees, Jumping Jacks, and Other Plyometrics
Medicine Ball Tosses and Rotations
Kettlebell Exercises
Tire Flipping, Fireman Carries, Farmers Walking and Other Strongman Activities

Basically, any physically demanding task that a) incorporates many muscle groups and b) is done near your maximum heart rate qualifies. So feel free to invent your own form of intense exercise.

Now, when you do an intense bout of exercise, you overload your muscles. This overload helps stimulate protein turnover, protein building, and gains in lean mass (or at least lean mass preservation). But what about the cardiovascular system?

Well, with all those muscles doing so much work, the cardiovascular system MUST respond by pumping blood faster and delivering a lot of oxygen to your working muscles. So you definitely get a cardiovascular benefit from doing intense exercise.

In addition, your metabolic rate also benefits from the increased oxygen consumption.

You see, the more muscle you have and the more exercise you do, the more oxygen your body will need. As oxygen generates 5kcal per liter consumed, a high oxygen demand means that your body is burning a ton of calories.

After the storm

Now, it should be clear that DURING exercise, your oxygen demands are high. That’s why you’re breathing so heavy. You’re getting rid of the carbon dioxide your cells are producing at a high rate and you’re taking in additional liters of oxygen.

However, the real key to intense exercise is what happens AFTER your exercise session.

If your exercise is intense enough, your oxygen demand remains elevated for well after the exercise session. With low intensity cardio, you only benefit from a few minutes of additional oxygen demand (and metabolic activity).

However, with high intensity activity, the oxygen demand can remain high for anywhere from 6 hours to 48 hours, depending on the intensity and duration of the exercise session.

And remember, a bigger oxygen demand means more calories burned. So it’s only your high intensity activity that boosts your metabolism 24-7.

Now, the right question to ask would be this – why is oxygen consumption (and calorie burn) elevated after exercise?

Well, after an intense workout, it’s necessary for the body to metabolize additional fuel, replenish energy stores, and reload the depleted oxygen stores in the muscle and blood. Further, oxygen consumption (and metabolism) is boosted due to:

Higher body temperature
Increased activity of the heart and respiratory muscles
Elevated levels of hormones that increase metabolic activity
Energy absorbing pathways and the conversion of things like lactate into glucose or amino acids
Recovery of muscle damage

So, with intense exercise, more oxygen is being consumed (and energy being used) during the exercise, after the exercise, and pretty much all day long.

Interestingly, you burn a lot of fat too, during this post-exercise period.

During high intensity exercise, the rate of fat breakdown is high. However, fatty acid entry into the bloodstream is blocked. The good news – upon termination of exercise, this block on fatty acid release subsides and the fats overflow into circulation for eventual oxidation during the recovery period.

How cool – we’re burning tons of fat even after we leave the gym!

Beyond fat burning, when you do high intensity activity regularly, additional muscle will be developed. This creates an even further metabolic demand for the body and more energy is utilized for normal daily activities, even at rest.

Heck, only when you train with high intensity on a regular basis do you benefit from an increased thermic effect of feeding.

So, make no mistake, if you want to avoid becoming another metabolic slowdown or obesity statistic, the bulk of your exercise should be of the high intensity kind.

But easy isn’t all that bad

With all the talk about high intensity training and conditioning – one may be led to believe that lower intensity exercise and normal activities of daily living are worthless.

Not so fast.

With low intensity exercise, or any easy physical activity, more oxygen is consumed (and energy is being used) during the exercise itself.

However you don’t get that post-exercise, all-day metabolic boost. Nor do you build much muscle. So, from the “metabolic therapy” aspect of things, low intensity activity doesn’t deliver the most bang for your buck.

Another drawback of low intensity exercise as your primary exercise mode is that there’s an increased energy demand without any real muscle overload.

Therefore muscle can become just another fuel source that is gobbled up to sustain your low intensity exercise energy needs.

The best visual example of this scenario is the comparison between different types of athletes. Athletes involved with long, low intensity activities tend to be very thin and have minimal amounts of muscle mass.

Athletes doing high intensity (thus shorter) activities tend to be bigger with more muscle mass.

However, again, don’t take this to mean that low intensity exercise should be avoided. When combined with a high intensity exercise protocol, each of the drawbacks above is eliminated.

The high intensity bouts boost muscle mass. And they also create 24-hour metabolism magic.

However, the low intensity exercise does offer some additional calorie burning as well as improvements in the muscle gain to fat loss ratio when added to an intense exercise plan.

Indeed, muscular sensitivity to insulin is increased for about 48 hours after a single bout of prolonged low intensity exercise.

This probably explains some of the benefits associated with regular “non-exercise physical activity” during the day (e.g., stairs, walking to the bus, playing with kids, etc.)

Another bonus for long bouts of low intensity exercise is that the synthesis of new fat is temporarily inhibited, probably due to the low insulin levels and increased counter regulatory hormones.

Exercise + nutrition

Unfortunately, many people think that eating an unhealthy diet can be reversed with more treadmill or, in general, gym-time.

As you probably understand by now, sticking with the “I’ll burn the Big Mac off on the treadmill” mentality could actually be doubly disastrous.

More unhealthy food and more low intensity exercise can deteriorate overall health while promoting disease and deplete muscle mass in the long run!

But even with high intensity exercise, you still need to watch your food intake.

Indeed, in a recent study we did, we were shocked to find that research participants training with an Olympic weight lifting coach and a group exercise instructor for over 5 hours a week saw little benefit from this training.

In our study, everyone was shocked to find that even with 3 hours of training per week with an Olympic weight lifting coach and 2 hours of training per week with a body-weight circuit instructor, if participants didn’t control their dietary intake, their results were not much better than if they had not doing anything at all.

That’s right, in the 30 sedentary participants (35-45% body fat on average), without dietary control, 12 weeks of high intensity training produced a fairly disappointing 1% loss of body fat.

Further, the participants lost only 1 pound of fat and gained 2 pounds of lean vs. the placebo group.

Are you surprised? Don’t be. Even the best exercise plan, in the absence of a good nutritional plan, will disappoint.

By point of contrast, in our recent Precision Nutrition Body Transformation Challenge, the average fat loss was 1/2% (or 1lb) lost per week. Further, our finalists saw the following results:

Finalist #1 lost about 30lbs in 16 weeks – losing 23lbs of fat and only 4lbs of lean mass.
Finalist #2 – lost about 16lbs in 16 weeks – losing 23lbs of fat while gaining 7lbs of lean mass.
Finalist #3 – lost 37lbs in 16 weeks – losing 27lbs of fat and 10lbs of lean mass.
Finalist #4 – lost 25lbs during 16 weeks – losing 35lbs of fat and gaining 10lbs of lean mass.
Finalist #5 – lost 37lbs during 16 weeks – losing 31lbs of fat and 6lbs of lean mass.
Finalist #6 – lost 4lbs during 16 weeks – losing 14lbs of fat and gaining 11lbs of lean mass.

Make it hurt so good

There is one major drawback to high intensity exercise. It’s extremely uncomfortable. Also, many folks seem to get wrapped up in one or two forms of intense activity and get burned out.

Remember, anything that physically challenges the body in an intense manner fits the bill. It doesn’t have to be sprints or burpees.

Find the intense form of exercise that you can handle. Maybe you like doing repeated cartwheels or shoveling snow really quickly. Fine with us.

Another thing, everyone is at a different fitness level. A hike outside might be pushing the anaerobic threshold for one person while it might be active recovery for someone else. Adjust accordingly.

Your body doesn’t know or care if you are:

On a cardio machine or in a stairwell
Lifting cobblestones for Grandpa on the weekends or doing barbell deadlifts in the gym with 24 karat gold plates

It just knows it’s lifting something heavy and needs to recruit muscles and produce energy to meet the muscular demand.

Ramp it up

Another important thing to know is that the body is excellent at adaptation and efficiency. Repeated efforts at the same activity can result in stagnation.

Therefore, if you’ve been doing 3 – 20 minute interval sessions for the last 8 weeks, I guarantee that your body has already adapted. You’re going to have to bump up the interval time. Or the intensity.

Variety can also be a great way to increase intensity. Try jogging backwards outside or on the treadmill. Monitor your heart rate and compare it to your regular forward locomotion. It will be MUCH higher (well, unless you regularly jog backwards).

Doing activities fast and heavy can help too. Speed can increase muscular recruitment, along with additional loading. Keep that eccentric (negative) movement under control, but feel free and let loose on the concentric (positive) movement.

Exercise selection is another variable factor. Compare a one arm dumbbell preacher curl to a front squat/push press combination. Which is more intense? Which recruits more muscles? Which creates a higher oxygen (and energy) demand?

Preacher curls aren’t useless, heck, Arnold did them all the time. They are great for building better biceps. But, if you have 30 minutes of gym time, you may want to save the preacher curls for your summer vacation to Muscle Beach.

In the end, the goal is to challenge the body in new ways while incorporating many muscle groups. Definitely have fun with it. But remember, it’s supposed to hurt. And it’s supposed to get harder each week.

Research update on intense training

Some of the ideas we have discussed are now being illustrated in the research. Check out some of the more recent studies…

Adding 45 minutes of aerobic exercise 5 days per week, for 12 weeks, had no effect over nutrition modifications alone. (Utter AC, et al. Influence of diet and/or exercise on body composition and cardio respiratory fitness in obese women. Int J Sport Nutr 1998;8:213-222.)
4 hours of aerobic exercise each week had no effect on weight loss. (Van Dale D, et al. Does exercise give an additional effect in weight reduction regimens? Int J Obes 1987;11:367-375.)
This review concluded that aerobic exercise is not an effective weight loss modality in women. (Gleim GW. Exercise is not an effective weight loss modality in women. J Am Coll Nutr 1993;12:363-367.)
The addition of aerobic training did not affect overall energy expenditure in this study sample. (Buemann B, et al. Three months aerobic training fails to affect 24 hr energy expenditure in weight-stable, post-obese women. Int J Obes Relat Metab Disord 1992;16:809-816.)
Strength training groups seemed to lose more body fat than aerobically trained groups. And the aerobic groups seemed to lose more muscle mass. (Geliebter A, et al. Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects. Am J Clin Nutr 1997;66:557-563.)
No elevation in post exercise metabolism was found for the low to moderate intensity exercisers. (Poehlman ET, et al. The impact of exercise and diet restriction on daily energy expenditure. Sports Med 1991;11:78-101.)
Higher intensity exercise raised metabolism for 3 hours after the session. The lower intensity exercise group didn’t have the same elevation. (Phelain JF, et al. Postexercise energy expenditure and substrate oxidation in young women resulting from exercise bouts of different intensity. J Am Coll Nutr 1997;16:140-146.)
Intensity has the biggest impact on post exercise oxygen consumption (and energy use). (Sedlock DA, et al. Effect of exercise intensity and duration on postexercise energy expenditure. Med Sci Sports Exer 1989;21:662-666.)
High intensity resistance training will elicit a greater post exercise oxygen response than lower intensity resistance training. (Thornton MK, Potteiger JA. Effects of resistance exercise bouts of different intensities but equal work on EPOC. Med Sci Sports Exerc 2002;34:715-722.)
A 31 minute, high intensity weight training circuit elevated post exercise oxygen consumption for 38 hours. (Schuenke MD, et al. Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management. Eur J Appl Physiol 2002;86:411-417.)
Low intensity exercisers lost more muscle and the same amount of fat when compared to high intensity exercisers in this sample. (Mougios V, et al. Does the intensity of an exercise programme modulate body composition changes? Int J Sports Med 2006;27:178-181.)
Exclusive aerobic work may do little to prevent age related muscle loss and metabolic decline. (Williams PT, Wood PD. The effects of changing exercise levels on weight and age-related weight gain. Int J Obes (Lond). 2006;30:543-551.)
Plenty of intense exercise can offset age related metabolic declines. (Van Pelt RE, et al. Age-related decline in RMR in physically active men: relation to exercise volume and energy intake. Am J Physiol: Endo Metab 2001;281:E633-E639. and Lemmer JT, et al. Effect of strength training on resting metabolic rate and physical activity: age and gender comparisions. Med Sci Sports Exerc 2001;33:532-541.)
Maybe Dr. Berardi was onto something? Resting metabolism is influenced by exercise, energy intake, and their interaction. A higher G-flux may be more important than just “regular” exercise. (Bullough RC, et al. Interaction of acute changes in exercise energy expenditure and energy intake on resting metabolic rate. Am J Clin Nutr 1995;61:473-481 and Bell C, et al. High energy flux mediates the tonically augmented β-Adrenergic support of resting metabolic rate in habitually exercising older men. J of Clin Endo and Metab 2004;89:3573-3578.)
Despite a lower energy cost, the interval training group in this study had a more pronounced reduction in subcutaeneous fat (fat under the skin) when compared to the endurance training group. (Tremblay A, et al. Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism 1994;43:814-818.)
The higher intensity exercise group lost more fat than the lower intensity exercise group. (Bryner RW, et al. The effects of exercise intensity on body composition, weight loss, and dietary composition in women. J Am Coll Nutr 1997;16:68-73.)
Intense training can create a “fat burning” environment in the body outside of exercise time. (Talanian JL, et al. Two weeks of high intensity interval training increases the capacity for fat oxidation during exercise in women. J Appl Physiol 2007;102:1439-1447.)
Strength training can help to preserve muscle mass and lower body fat better than aerobics. (Geliebter A, et al. Effects of strength or aerobic training on body composition, resting metabolic rate, and peak oxygen consumption in obese dieting subjects. Am J Clin Nutr 1997;66:557-563.)
Resistance training helps to increase metabolism and fat oxidation, even hours after finishing. (Poehlman ET, Melby C. Resistance training and energy balance. Int J Sport Nutr 1998;8:43-59. and Hunter GR, et al. Resistance training increases total energy expenditure and free living physical activity in older adults. J Appl Physiol 2000;89:977-984 and Osterberg KL & Melby CL. Effect of acute resistance exercise on postexercise oxygen consumption and resting metabolic rate in young women. Int J Sports Nutr Exerc Metab 2000;10:71-81.)
Can you maintain muscle mass on an 800 calorie diet? With resistance training, I guess so. That doesn’t necessarily mean it’s a good idea…(Bryner RW, et al. Effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. J Am Coll Nutr 1999;18:115-121.)
What about building muscle on 800 calories per day? It’s possible only through the modern technology we call “resistance training.” (Donnelly JE, et al. Muscle hypertrophy with large-scale weight loss and resistance training. Am J Clin Nutr 1993;58:561-565.)
Check out this comparison. Nutrition modifications vs. Nutrition modifications + aerobics vs. Nutrition modifications + aerobics + resistance training…Adding resistance training helped the subjects lose more weight. And maintain metabolism. (Kraemer WJ, et al. Influence of exercise training on physiological and performance changes with weight loss in men. Med Sci Sports Exerc 1999;31:1320-1329. and Hunter, et al. Resistance Training Conserves Fat-free Mass and Resting Energy Expenditure Following Weight Loss. Obesity (Silver Spring). 2008 Mar 6.)
Wouldn’t low intensity aerobic work for 12 hours each week increase resting metabolism? I guess not. (Broeder CE, et al. The effects of aerobic fitness on resting metabolic rate. Am J Clin Nutr 1992;55:795-801.)
Weight training may be more metabolically demanding than originally thought. (Scott CB. Contribution of anaerobic energy expenditure to whole body thermogenesis. Nutr Metab (Lond) 2005;2:14.)
Have 20 minutes to hit the gym? It may serve you better (in terms of fat loss) to fit in a circuit workout instead of the treadmill. (Braun WA, et al. Acute EPOC response in women to circuit training and treadmill exercise of matched oxygen consumption. Eur J Appl Physiol 2005;94:500-504.)
Any good news for those long-term, regular exercisers? Yes indeed. The more you exercise – the better you are at burning fat. (Wong T, Harber V. Lower excess postexercise oxygen consumption and altered growth hormone and cortisol responses to exercise in obese men. J Clin Endocrinol Metab. 2006;91:678-686.)
A 2 hour increase in post exercise oxygen consumption was noticed with resistance training in young women. (Binzen CA, et al. Postexercise oxygen consumption and substrate use after resistance exercise in women. Med Sci Sports Exerc 2001;33:932-938.)
Before you get all “anti low intensity cardio”, data have shown that both walking AND vigorous exercise are associated with substantial reductions in the incidence of cardiovascular events. (Manson JE, et al. Walking compared with vigorous exercise for the prevention of cardiovascular events in women. 2002;347:716-725.)

Point well taken? Are you convinced that high intensity interval exercise is superior?

Now, before we go on – it would be foolish to say that lower intensity aerobic work is worthless. Don’t swear it off just yet.

We all know the healthy and lean endurance athlete. We know the physique athlete who did one hour of power walking per day to tighten up the waistline and glutes. Etc.

As many people know, body composition is determined by an interaction between many different factors. Exercise, consistency with exercise, body type, nutrition, sleep, nutrition consistency, supplementation, medications and so on.

The most important factor with exercise is finding the variety that you are likely to stick with for the long-haul.

What to do

Ok let’s take all this theory and make it really practical. Here’s how, based on your body type, you might split up your activity if your trying to improve your body composition.

Ectomorphs

3 hrs/wk of resistance training
30 minutes/wk of high intensity conditioning
30 minutes/wk of low intensity conditioning

Mesomorphs

4 hrs/wk of resistance training
30 minutes/wk of high intensity conditioning
60 minutes/wk of low intensity conditioning

Endomorphs

4 hrs/wk of resistance training
60 minutes/wk of high intensity conditioning
90 minutes/wk of low intensity conditioning

Notes

The forms of exercise listed above are described here:

Resistance Training = training with weights. Includes body weight training, some forms of yoga, dumbbells, barbells, kettlebells, machines, cables, med balls, etc.

Higher Intensity Conditioning = any physical activity that uses a lot of muscles and causes fatigue in a short period of time. You can tell if you are doing it correctly because you won’t be able to go very long and will be sucking wind. One could use cardio machines, body weight, free weights, med balls, jump rope, hills, stairs, etc.

Lower Intensity Conditioning = any physical activity that is easy and repetitive. One could do a brisk walk, hike, bike ride, sports, dance, rollerblade, flexibility work (static and dynamic), most pilates, most yoga, cleaning the house, walking the dog, etc.