Similarities and Differences Between Children and Adults in the Physiological Responses to Exercise

For the last few years, schools, community park and recreation districts, agency and independent fitness centers have been trying to implement the recommendations from both the 1996 report of the U.S. Surgeon General and the 1997 Guidelines for School and Community Programs to Promote Lifelong Physical Activity among young people. Amongst these suggestions is the recommendation that schools, community programs and the fitness industry cooperate to provide safe environments, role models, competent leadership and developmentally appropriate activities for children and adolescents. In addition, parents are encouraged to plan and participate in physical activities with their children. However, if you were playing with your child, would you be concerned if you noticed that your child seemed to be breathing harder and had a higher heart rate but wasn’t sweating as much as you were?

Respiratory System

The primary role of the respiratory system is to provide oxygen and to eliminate carbon dioxide from the muscle cells. The amount of air exchanged per minute is called minute ventilation and is the product of the number of breaths (frequency) times the volume of each breath (tidal volume). Children and adolescents exhibit a higher frequency and lower tidal volume than adults at all intensities. (1,2) Because rapid breathing is readily noticed, it can be upsetting to a well-intentioned adult. The higher frequency and lower tidal volume is normal and no call for alarm. Actually, if you were to make adjustments for the body weight, children and adolescents breathe more air per minute per kilogram than adults do at the same sub-maximal intensity. These differences are offset by a smaller dead space. Dead space is the volume of air trapped in the conduction portion of the lungs that is not available for exchange at the alveoli. The alveoli provide the vital surface for gas exchange between lungs and the blood.. Alveolar tissue has the largest blood supply of any organ in the body.(3) This is similar to the portion of water in the pipes of your house. The smaller dead space results in a greater portion of the air inhaled by a child actually getting to the alveoli.(4)

A comparison is often made between the amount of air that is processed (minute ventilation) and the amount of oxygen used (VO2) to produce energy aerobically. This comparison is called ventilatory equivalent. Children and adolescents have higher ventilatory equivalents than adults do and the difference if inversely related to the age of the child. (1,2) Therefore, the younger the child, the more air they must breathe in. Because of the higher ventilatory equivalent seen in children and adolescent’s generally considered to be insufficient the youngster must expend additional energy to support respiration during exercise. (2) However, neither this insufficiency nor any of the other differences previously described for the respiratory system contraindicates physical activity for children or adolescents.

Cardiovascular System

The cardiovascular system is primarily a transport system composed of the heart, blood and blood vessels. Its job is to transport oxygen, nutrients in the form of carbohydrate, fat, protein and hormones such as insulin and epinephrine to reach the muscle cells. Carbon dioxide , heat and other by-products of energy metabolism are removed from the cellular level by the cardiovascular system. (5) The delivery of oxygen depends on the amount of blood pumped each minute from the heart which is called cardiac output (Cardiac output = stroke volume: the amount of blood pumped per ventricular contraction x heart beats per minute) and the amount of oxygen unloaded from the red blood cells, the arteriovenous oxygen difference. Children and adolescents exhibit a lower stoke volume and higher heart rate than adults do at all intensities of exercise. Because stroke volume is linked to ventricular size, the higher heart rate is probably an attempt to compensate for the smaller ventricular size of children and adolescents.

It’s normal for a child to have a higher heart rate than a parent if they performing the same exercises together. Maximal heart rate is higher in children and adolescents than adults, but does not significantly change during the growing years of 7 to 15. This makes estimation of maximal heart rate by set equations such as 220-age inaccurate for children and adolescents until the late teenage years. It also means unless there are signs of stress or duress, there is no cause for concern for heart rate values greater than 200 bpm. Healthy individuals should be able to exercise for several minutes at maximal heart rates. In fact, because VO2 max (the greatest amount of oxygen that can be inhaled during aerobic exercise) is relative to the individual’s body weight, VO2 max values are as high or higher than most adults. Heart rate will return to resting values quicker in children and adolescents than adults.(2) Temperature control of the cardiovascular system is critical for the exercising participant and is more of a challenge for children and adolescents. Their surface area-to-mass ratio is larger than adults which allows for a greater heat exchange by convection and radiation.

Convection is related to conduction which is the ability to gain or lose heat by the exchange of a solid, liquid or gas from one molecule. Because our bodies are usually warmer than the environment, the net exchange of radiant heat energy is through the air to solid, cooler objects in the environment. This does not require molecular contact with the warmer object. Radiation is how the sun warms the earth or in other words a person can remain warm by absorbing radiant heat from the sun or indirect sunlight reflected from snow, sand or water. Children do not sweat as much during exercise as adults. The number of sweat glands is the same but the activation of the sweat glands happens at a higher temperature; less sweat is produced from each gland and the sweat rate per unit of surface area is lower. Children and adolescents also have a smaller plasma volume than adults from which to draw fluids for sweating.(6) In neutral climates the temperature-regulating capacity of children and adolescents is equal to that of adults. However, children and adolescents have a shorter tolerance time for exercise in extreme temperatures. (6) They can acclimate to the heat, but it takes them longer than adults. The tendency is to try to do too much too soon. It is recommended to postpone or recommend strenuous activity when heat and humidity are high and making sure plenty of fluids are ingested before, during and after exercise. Thirst is not an accurate guide for fluid need.

Well, now you know the answer to the question in paragraph one. It’s perfectly normal for a child or adolescent to breath harder and have a higher heart rate than an adult, however, if the heat or humidity is excessive it may be prudent to postpone the exercise are lower the intensify. Don’t forget to hydrate before during and after. Good luck!

1. Bar-Or. Pediatric Sports Medicine for the Practitioner: From Physiological Principles to Clinical Applications. New York: Springer-Verlag, 1983; pp 1-65

2. Rowland, T. W Development Exercise Physiology. Champaign, IL: Human Kinetics, 1996

3. McArdle, William D., Katch, Frank, I., Katch, Victor, L., Exercise Physiology, 2nd edition, pg. 192.

4. Bar-Or. Pediatric Sports Medicine for the Practitioner: From Physiological Principles to Clinical Applications. New York: Springer-Verlag, 1983; pp 1-65

5. Plowman, S.A. and D. L. Smith. Exercise Physiology for Health , fitness and Performance, Boston: Allyn

6. Bar-Or, O. children and physical performance in warm and cold environments In Advances in Pediatric Sport Sciences. Vol I: Biological Issues. R.A. Boileau (Editor), Champaign, Il: Human Kinetics Publishers, 1984; pp. 117-0130

How To Test If You Have A Good Heart Rate Recovery

To begin with I must clarify I am not a health care provider. You should check with your own doctor before performing this method. A solid pulse rate recovery has been proven to be the number one indicator of overall individual fitness. The reasoning is the more beats a minute your heart rate (HR) drops after peak exercise the more fit a person is. When you run hell for leather for a couple minutes, reaching near maximum HR, a good quality recovery will be for your beats to fall at least 15 during that first minute after maximal physical effort. Here I would like to give the breakdown of the simplest way to perform the test and then get your number.

Firstly, you will want to have an estimate of your respective max. It is a benefit to know this number because the goal of the test is to get your heart beating near this number. Should you get nowhere near it, then you’ve not exercised quite hard enough. You need to take the number 220 and minus how old you are. What that equals is your estimated maximum number. Remember the number for reference in a while.

Second, you need to have a heartrate watch. You might take your pulse the old fashioned way: fingers on neck or wrist counting your pulse for ten seconds then multiply by six (to find the beats for each minute). But utilizing a heart watch is less work and probably more accurate. A strapless or chest strap empowered monitor will suffice. Here I will assume you have got one.

Third, for perfect results you’ll have to do some sprinting. Sprinting is basically really fast running. Visit an open area similar to a park or track. Take your heart rate prior to starting sprinting to check your watch is functioning. This readout may vary one person to another but will be from 50 to 90 beats every minute in healthy adults. Ok, now what you’ll have to do is sprint as fast as you can for as long as you can. Once you have achieved maximum exertion: stop and take your HR. The number should really be a minimum of 85% of the max HR estimate from the first part. If it is not, then you must do sprints up until you have a readout that’s more than 85% of your number from above. Do not forget that “max HR” you just got after your sprints and wait one minute.

Fourth, after one minute has passed since you maximally exerted yourself sprinting, take your heartbeat again and remember that number. Now take your measured “max HR” and subtract the number recorded after one minute and you should, hopefully, get yourself a number in excess of 15. The quantity you get, nonetheless, is the recovery heart rate number. The larger the number the more physically fit you are. If your HR decreases to your starting resting rate inside the first minute from peak then you are of exceptional fitness.

If your number is certainly less than 15 do not be alarmed. It just means that you will benefit from heart rate target zone training. Zone training is that act of keeping your HR elevated for prolonged time-span. The numerous zones are just looking at the different levels of maximum HR. Persist with the 55% to 70% of maximum HR zone if your number was lower than 15 above. In time your recovery heart beats will greatly improve.

Evaluating Your Current Fitness Level Through Heart Rate Monitoring

What is your current fitness level? Are you in shape or out of shape? Let your heart answer that question.

Simple measures like weight and BMI (body mass index) give little information about someone’s fitness level. A top athlete in a sport such as American football may have a very high weight and an abnormally high BMI, but be in excellent physical condition. Someone may have an ideal weight and BMI, but be in very poor shape.

To accurately evaluate fitness you need a set of measurable standards by which you can compare different individuals. Two popular, and easy to measure indicators of someone’s fitness level are “resting heart rate”, and “recovery heart rate”. People in good physical condition generally have a heart that beats slower at rest than more sedentary people. An athlete in top physical form’s heart may beat, at rest, only 40 to 60 beats per minute. A sedentary adult, in comparison, heart may beat 75 to 100 times per minute. A fit heart has to work less to maintain a body at rest.

Another general indicator of fitness is how fast the heart recovers from or returns to its resting heart rate, this is called the recovery heart rate. In out of shape individuals once the heart reaches a high BPM (beats per minute) it tends to stay their longer. An in shape or athletic persons heart recovers from exertion quickly, returning to the natural resting HR more quickly.

If you compare someone’s resting and recovery heart rate to patterns for the corresponding age group you can understand how their fitness level and heart health compare to established norms.

If you want to know your own resting and recovery heart rate there are many affordable and wearable heart rate monitors available today. Many have built in features that will help you evaluate your fitness level. These tools are useful, however, they are no substitute for the assistance of a trained professional who will be able to guide you safely through the process and best interpret the results.

Knowing where you are today heart-health wise will be of great benefit as you progress toward your individual fitness goals. Your heart will become more efficient working less while at rest and recovering more quickly from exertion. Seeing this progress represented in real numbers is a great motivator, allowing you to see the changes in your body. Also, it can shift you away from relying on less meaningful numbers like weight and BMI as an indicator of health.

Why Knowing Your Target Heart Rate Is Beneficial to a Successful Workout Program

What is a pulse or target hear rate?

Your heart rate is defined as your pulse. In one minute, your heart beats X number of times. Your target heart rate is important to know for a successful exercise program. Pulses can vary between certain people. When you’re resting, your pulse is much lower than when you’re active. Exercise requires oxygen-rich blood. If you know how to take your pulse, you’ll be able to better evaluate your exercising progress.

How do you determine your pulse?

Your pulse and how to check it:

1. With your index, second and third fingers, place your fingertips on the middle of your wrist, palm side, right below your hand. You can also place these same fingers on a side of your neck.

2. If you push down slowly with your fingers, you’ll feel your blood steadily pulsing.

3. Use a stopwatch, a clock with a second hand or the timer on you workout DVD.

4. If you count 6 seconds worth of pulses and multiply the number you get by ten, you’ll figure out your pulse (heart rate) for each minute.

The formula for this is:

Number of beats in a 6 second span x 10 = number of beats per minute.

Is your pulse normal?

Here is a list of normal pulse rates for those at rest:

For children under 15, the average rate is 70-100 pulses per minute.

For adults 18 and older, the average rate is 60-100 pulses per minute.

Maximum heart rate:

The highest pulse that you achieve during cardio exercise is the maximum rate for your heart. Use this formula to find your max heart rate:

220 – your age = estimated maximum pulse rate

For example, a 20 year old’s estimated maximum pulse is around 200 beats a minute.

Some medications and health conditions are enough to affect one’s heart beat. Heart disease, diabetes, and high blood pressure can all affect your heart beat. Asking a doctor about your heart is advisable. Knowing what your doctor has to say about your pulse during exercise is beneficial to your health and safety. In fact, in order to get the most accurate heart rate, you can take a supervised medically graded test.

Target Heart Rate

When you exercise, it is beneficial for you to work out in your target heart rate zone. This is when your heart beat is between 60 to 80% of your maximum rate. When exercising in your target heart zone, you will reap the benefits of a cardiovascular workout. As your body gets accustomed to your workout, it will take you longer or more intensity to get into “Your Zone”. It may even require you to change or alter your workout program so that your body is doing something different. I have people say to me that they are walking or riding a bike everyday but lose no weight. The answer could as simple as getting into your target heart rate zone. Your healthcare provider might find it necessary to decrease your maximum rate to 50% in the beginning depending on your health.

Exercising above a level of 85% is not recommended for anyone. That sort of intensity has no health benefits; if anything, it increases your risks for orthopedic and cardiovascular damage.

When starting an exercise program, check with your medical provider. Your provider can determine a program that works for your needs.

You may determine that gradually building up to your target heart range works best for you, especially for those who do not tend to exercise regularly. Slow down if your target heart rate gets too high.

How to Control Your Heart Rate for a Performance

A fast heartbeat is defined as a heart rate that is faster than normal. The heart normally beats fewer than 100 times per minute in adults. In children, the heart can beat slightly faster than 100 times per minute and still be considered normal. At rest, a person’s heart rate usually stays within a standard range. This range is usually 50 to 100 times per minute in adults and slightly faster in children. With increased physical activity, stress, or other conditions, however, the rate may increase above the normal level.

Sometimes a high rate is due to excessive physical activity, while other times it can be due to panic, stress or anxiety. To truly measure your heart rate, one must analyze his or her results while at in a relaxed, resting state. Anything over 100 beats per minute consistently is considered as having a high heart rate (tachycardia).

Although moderately harmless sometimes, tachycardia can cause the heart rate in the upper or lower chambers to increase. When this happens, your heart is not able to efficiently pump blood to your body. Lack of oxygen to your body can cause dizziness, light headedness, chest pain or fainting. A person with a rapid heartbeat may have no symptoms at all. When symptoms do occur, they may include palpitations, or an unusual awareness of the heartbeat, excessive sweating, fatigue or weakness, shortness of breath, chest pain, lightheadedness or dizziness, and fainting.

Tachycardia can be caused by several factors:

• Heart conditions – heart related conditions such as high blood pressure and poor blood supply to the heart muscle due to coronary artery disease, heart valve disease, heart failure, heart muscle disease, tumors or infections.

• Health conditions – Overactive thyroid (hyperthyroidism) and emphysema and other lung diseases.

• Stimulants – drinking large amounts of alcoholic or caffeinated beverages, smoking cigarettes, and abuse of recreational drugs.

• Other – abnormal electrical pathways caused by a genetic defect at birth, electrolyte imbalances in the body (too little potassium, calcium, sodium and other minerals), and side effects of heart medications.

Prevention is related to the cause. Many cases cannot be prevented. In most people, regular exercise is advised even though it causes a rapid heartbeat. In this case, prevention is not an issue. Avoidance of cocaine or alcohol can prevent cases from these drugs. Getting enough fluids can prevent many cases due to dehydration. If you see a consistent high heart rate, it may be time to look into a professional analysis. Contact your doctor about your heart rate to find the best solution that works for you. The speed of the heartbeat usually can be measured by checking the pulse or listening to the heartbeat with a stethoscope. A test that measures the electrical activity of the heart, called an electrocardiogram or ECG, can also be used to measure the heart rate.