Heart Rate During Aerobics

Q: Why is an elevated heart rate alone not always a valid indicator of an effective aerobic-training stimulus?

A: During aerobic exercise, an individual’s heart rate is a reliable indicator of how hard that individual is working. As the energy demands of the exercise increase, heart rate increases proportionately. Because the exercising muscles need more oxygen and fuel, an individual’s heart rate and stroke volume (i.e., the amount of blood pumped per beat) must increase to deliver more blood to the tissues to meet the increased metabolic needs of the active muscles. It is this increased metabolic demand that overloads the cardiorespiratory system and provides the necessary stimulus to improve aerobic exercise capacity.

With resistance training, heart rate is disproportionately elevated relative to oxygen uptake. At any given level of oxygen uptake, heart rates are much higher for resistance training than for aerobic conditioning. The disproportionate rise in heart rate during resistance training is due to a phenomenon known as the pressor response, which is governed by the autonomic nervous system and occurs reflexively from the contraction of the skeletal muscles. It causes an increase in heart rate with a corresponding reduction in stroke volume. As a result, even though heart rates are increased during resistance training, the oxygen uptake is not increased to the same degree as it is during aerobic conditioning. This factor minimizes the metabolic overload to the muscles and, therefore, limits the aerobic training benefit that can occur as the result of resistance training. The pressor response helps to explain, from a physiological standpoint, why the heart rate is disproportionately elevated, relative to oxygen uptake, during resistance training.

The misperception that resistance training can increase aerobic exercise capacity is not new. In fact, it was popularized in late 1970s and early 1980s in a form of exercise known as circuit weight training (CWT), which involves performing 10 to 15 repetitions of eight to 12 exercises, using 40 percent to 60 percent of one-repetition-maximum. During CWT, individuals rapidly move from machine to machine, with very brief (less than 30 seconds) rest periods between exercises. A review of studies involving CWT indicates that such training programs are effective at increasing muscular fitness, but only modestly improve aerobic capacity (i.e., approximately 5 percent to 7 percent). Conventional aerobic exercise training programs (e.g., running, cycling, swimming) conducted over a similar period of time, on the other hand, typically result in greater improvements in aerobic exercise training (i.e., 15 percent to 25 percent).

Despite marketing claims to the contrary, exercise products and programs that focus predominantly on resistance training do not provide a sufficient stimulus to produce meaningful aerobic training benefits even though exercisers’ hear rates are elevated during such training. It is important to understand that although a regular, sustained increase in heart rate is widely recognized as critical to achieving increased aerobic fitness, the heart rate merely serves as a monitor for the real training stimulus (i.e., increased energy expenditure or oxygen uptake). The best training approach for optimally improving both aerobic and muscular fitness is to separately participate in aerobic- and resistance-type activities. Circuit weight training can, however, serve as a time-efficient and relatively effective way for beginners and deconditioned individuals to achieve modest-to-moderate increases in both aerobic and muscular fitness.

Source: Bryant, Cedric X. ACE FitnessMatters, March/April 2004

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• Tip of the Month

  January 2012

  Smart Starbucks and Steakhouse Choices

  Starbucks Choices
  • Peppermint Choc Mocha- 520cals, 20g fat
  • Pumpkin Frappuccino- 420cals, 13g fat
  • Flavored Latte- 360clas, 16g fat
  • Latte- 220cals, 15g fat
  • Coffee w/cream and sugar 180 calories
  • Cappuccino- 120cals, 4g fat
  • Coffee w/sugar 90 calories
  • Coffee w/cream 90 calories
  • Coffee w/whole milk 60 calories
  • Coffee w/skim milk 30-50 calories

  Order a coffee with cream and sugar every work day?  Add 900 calories per week to your diet.  That is over 13 pounds in one year.

  Enjoy a cappuccino every day instead, and you save 300 calories per week, and cut 4 pounds per year from the above diet.

  Go to coffee with skim milk and Splenda?  Now you are only adding 250 calories per week, and under 4 pounds per year in coffee weight.

  Enjoy a flavored frappucino or latte once per week?  That could add up to 26,000 calories, and another 7.5 pounds per year.

  Just your coffee could account for 20 pounds of caloric intake annually!

  Steakhouse Choices
  • Caesars Salad- 800cals
  • Chopped Salad, 320cals
  • Spinach Salad, 170cals click here for more »

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• Recipe of the Month

  January 2012

  Drink alcohol a little more wisely!

  Drink Choices
  • Eggnog, 350cals
  • White Russian, 260cals
  • Riesling, 160-200cals
  • Shot of liquor, 70-125cals
  • Tonic or Soda, 100cals
  • Winter Beer, 150-200cals
  • Beer, 150cals
  • Bloody Mary, 130cals
  • Wine, 120cals
  • Light Beer, 55-85cals
  • Champagne, 85cals
  Enjoy a small glass of eggnog and two gin and tonics, and you have drank 750 worthless calories.
  Or, start with some champagne, and enjoy two glasses of wine and you only have drank 330 calories, less than half of your first choices.