Matt Metzgar

Hormonal Exercise

Here's a new article that just came out on "hormonal exercise for fat loss".  It's nothing groundbreaking, but it points out how high-intensity exercise can boost the metabolism and burn more fat.

Interval Training is Key

I found this neat paper that looked further into the performances of middle distance runners.  The research looked at two different groups: recreational runners versus competitive sprint and middle distance runners (400m - 1500m races). 

The main difference in their training was the presence of interval training.  The competitive group had performed "intense short interval training" for years, while the recreational group had not.  This difference in training showed up dramatically when outcomes were compared:

• Body fat: competitive runners 9.2%, recreational 18.0%                     
• VO2 Max:  72.3 vs 57.8                                                                                                       
• 400m time:  49.4 seconds vs 64.8 seconds                                                                           
• 800m time:  115.2 seconds vs 158.8 seconds

What's also interesting is that the superior performance of the competitive group was related more to their high VO2 max than their anaerobic capacity.  Their VO2 max had most likely been raised due to the intense interval training.

This is a great study that shows how effective interval training is at reducing body fat and increasing performance.  It also shows that middle distance runners, who include some intensity in their training, maintain low body fat. 

The Case for Middle Distance Running

Many people have written about the physiques of sprinters versus marathoners.  Sprinters are generally muscular and lean, while marathoners are more frail though still lean.  Given the two, I'm sure most people would pick the physique of a sprinter.

However, these two cases represent the extremes.  Perhaps athletes that run distances in between a sprint and a marathon are in better shape than either of the two extremes.

I found this paper that shows that in masters athletes, middle/long distance runners are leaner than sprinters.  This held true for both men and women.  For men, the runners averaged 10.5% body fat, while the sprinters averaged 13.1%.  For women, the runners averaged 18.5% body fat, while the sprinters averaged 22.2%.

It seems likely that there is a "sweet spot", as far as the main competitive distance, that could maximize body composition.  I think 100m is probably too short.  It doesn't activate the aerobic system enough and hence, misses out on some fat-burning benefits. 

Distances like the half-marathon and up are probably too long.  That much running tends to diminish muscle mass and also may not provide enough overall intensity.

It's speculation on my part, but I would think that a primary distance between 400m and a mile might optimize body composition.

Does Aerobic Power Decrease With Age?

Here's a nice article that shows how intense training can limit or even stop the normal loss of aerobic power associated with aging.

Aerobic Power and Body Fat

I thought that this was a neat study, one that looked at aerobic power and body fat among children.  The study measured "maximal power output", a close correlate of VO2 max, and compared that against body fat levels determined via skinfolds.

The result was almost a direct straight-line correlation, with the sum of skinfolds decreasing as aerobic power increased.  The results held for both boys and girls, and across ages.  The obvious implication is that increasing aerobic power should lead to lower body fat levels.

Circuit Weight Training

Griff commented on something I was just thinking about: the ability of weight training to increase aerobic power.  One way to do this is circuit weight training, which, for example, LL Cool J has had great success with.

I do think that circuit weight training, or even regular weight training done with little rest, can improve cardiovascular fitness.  I don't however, think it can improve aerobic power (measured by VO2max, which isn't a perfect measure anyways) as good as intense cardiovascular work.

Also, it seems to confuse two somewhat separate objectives.  For me, weight training is about maintaining or increasing lean mass, while cardio is about building aerobic power.  By taking an adequate but not too long of a rest between sets, I can focus on lifting heavier weights.  With shorter rest periods between sets, I am able to generate less intensity on each set and not provide the best stimulus for building muscle mass.

If a person is in a time crunch, I think circuit weight training can do a good job at building some aerobic power and some muscle mass.  But if a person has more time, I think they would be better off splitting the two, utilizing longer rest periods during weightlifting for more lifting intensity, and performing high-intensity cardio like interval training for more gains in aerobic power.

Active Monkeys

Here's an article that points out many obvious truths, but it's still worth a read.  Scientists looked at monkeys and studied both their energy intake and energy expenditure.  Monekys that were the most active stayed lean - no matter how much they ate.  The sedentary monkeys, predictably, gained weight.

The scientists also put the sedentary monkeys on a diet, but it didn't cause them to lose weight.  This goes along with what I believe, that activity is the primary regulator of body weight and that dieting is ineffective for losing weight.

One curious part had to do with the monkeys' intrinsic desire for activity.  It was hypothesized that the active monkeys were that way due to their environment.  Yet when the active monkeys were moved inside with less room to move, they still stayed active.  The reverse was true for the sedentary monkeys: when they were given an environment more conducive for exercise, they didn't end up being more active. 

This points to a genetic disposition towards desired activity levels.  It wouldn't surprise me if the results were the same for active and sedentary humans.  Perhaps those with a sedentary disposition need to realize this genetic influence and push themselves to greater activity levels.

Intensity Threshold

If you increase exercise intensity, the body will adapt to it (given sufficient rest).  That's why many programs recommend an escalating level of intensity over time, so that the body is continually challenged.  However, there is a ceiling to this level of adaptation for both aerobic exercise and resistance exercise: a person can only achieve so much aerobic fitness and can only lift so much weight. 

Knowing that there is a ceiling to eventual progress puts exercise intensity in a different light.  If ever-increasing intensity is necesary, how do athletes who have hit the intensity ceiling (their maximum performance) continue to stay in shape?  It seems more likely to me that exercise must pass a certain intensity threshold to be effective, and it's not the case that exercise intensity must constantly be increased. 

Exercise Intensity II

As discussed in the last post, I'm becoming more convinced of the importance of exercise intensity in reducing body fat.  Yet one of the easiest things to overlook is the importance of rest days. 

If a person wants to lose fat, it would seem the more vigorous exercise they perform the better.  However, if you don't get enough rest in between sessions, you won't be able to generate as high of an intensity as usual, and hence the exercise will be less effective. 

For example, it would seem that three days of 85% intensity, with rest days in between, should be better for improving body composition than 5 days straight of 70% intensity.  Even though the latter program would burn more calories expended during exercise each day, the 85% intensity should raise metabolism more through post-exercise energy expenditure, and therefore burn more total calories all together.

For me, I've found it tough to take rest days lately because it feels like I'm doing nothing to accomplish my goals on those days.  Therefore, I'm trying to look at it from this newer perspective: more rest = higher-intensity exercise = increased metabolism = greater fat loss.

Exercise Intensity

I've been looking into different research on exercise intensity and fitness.  The study looks at which factors determine total energy expenditure among Japanese men.  The study cites high-intensity exercise and lean body mass as the two most signifcant factors, making up 51% of total energy expenditure. 

The second study shows that 40 minutes of high-intensity aerobics increases the resting metabolic rate(RMR), unlike resistance training which did not raise RMR in this study. 

A third study shows that high-intensity exercise raises metabolism over time, and gives a solid recommendation: "It is suggested that in the prescription of exercise to patients in weight reduction programmes, bouts of vigorous exercise interspersed by one or more days of relative inactivity, will be more effective than a constant level of exercise."