Dealing with “pulled” muscles and strains

At one point in our lives almost all of us have felt that odd pulling sensation in a muscle followed by an uncomfortable spasm when performing an exercise or movement. Often at the time it feels uncomfortable, tight, or even slightly painful but we figure we can continue on with what we were doing only to find later on that this decision may not have been the best. You probably have strained or “pulled” a muscle.

A muscle strain occurs when the muscle or parts of the muscle can not overcome the forces applied to it. In the process it has either over-stretched or overly contracted and caused some soft tissue damage to the muscle fibers and possibly to the connective tissue as well. Although there are built in sensors within the tendons that act like circuit breakers when it experiences too much force, occasionally they do not respond fast enough or accurately leading to the strain. This can be caused by trying to lift a weight that is too heavy, a muscle (or muscles) that don’t activate at the appropriate time, or a sudden change in biomechanics leading to a sudden overload on the muscle supporting the joint. The tightness can often by physically felt in the affected muscle as a knot or tension due to the fact the muscle has entered a protective mode of increasing tension to reduce further damage.

A muscle strain is different from a tear where the actual muscle tissue has torn either partially, or in severe cases completely, and resulted in partial to total dysfunction. These tears often are accompanied with bleeding, swelling, and intense pain within the muscle. This type of injury often requires more advanced medical care and diagnosis to assess for any further damage to the surrounding joint and to plan a course for rehabilitation. Luckily, muscle strains often get batter on their own through adequate rest and gentle movement.

What do I do if I think I have strained or pulled a muscle?

 If you think you may have pulled a muscle the first thing you should do is to stop doing the movement that you think caused the pull. Continuing to “work through” the pain and complete the workout or task will only cause the muscle strain to get worse and increase the risk of further damage. To be safe, you should consider stopping the workout or task all together to start the healing process and to guard against any further injury.

Depending on the extent of the damage, swelling can begin to set in over the next few hours resulting in more pain and discomfort. Applying ice immediately to the area can help decrease the swelling and anti-inflammatories that are approved for your situation can also help. It can sometimes be difficult to tell the severity of the strain so it is generally a good idea to assume the injury is worse than you think and act appropriately. A strain is also different than a muscle cramp. Although the true cause of muscle cramps is not clear, a muscle cramp often occurs when the muscle overly and persistently contracts either as a form of protection, a neurological phenomenon, or a biochemical reaction within the muscle. To immediately reduce the intensity of the muscle cramp, continue to move the affected joint as it increases the energy production within the muscle which is essential to allowing the muscle to relax. This movement combined with gentle stretching and massage to deactivate the nerves can also be helpful. To help prevent further muscle cramps ensure good nutrition by eating a well-balanced diet, adequate hydration by consuming approximately 3-4 liters of fluids a day, and a good level of overall fitness through exercising at least 150 minutes a week at a moderate to high intensity.

Use caution when stretching a strained muscle. Although your instinct might be to try and reduce the spasm, it may not be a good idea to initially stretch a strained muscle aggressively during the first 24 hours as this could cause further damage. Massage, rolling, and percussion massage should also be used with care for the same reasons. However, these techniques can be useful later on to reduce the uncomfortable tension or spasms that can continue to occur as the muscle heals.

How do I work back into my workouts.

It is usually best to let pain be your guide. Often mild strains can resolve themselves in a few days and you can start back gently for the first workout with a reduced amount of weight and or volume. A more serious strain can take up to 7 to 10 days to recover and it is important to let it rest and recover enough before you head back to your workouts or former activity level. On your first day back, reduce the intensity by about 25% and the total volume by 50% in order to test how the muscles will respond.  Although it might feel like a step backwards, remember that the faster you get back to normal the quicker you will progress. If you rush it you may find yourself back in the same situation, delaying your progress even further.

How can I reduce the chance of a pulled muscle?

There are a number of things you can do to help reduce your risk of pulled muscles.

  • Perform a proper warm-up to help increase muscle temperature, blood flow, and prime the nervous system to help improve your muscle response time and readiness to work. Light cardiovascular exercise combined with specific movements that reflect the activity such as warm-up sets or dynamic stretching are all part of a good warm-up
  • Make sure your training routine and overall fitness is well balanced and focuses on symmetrical strength, muscle development and flexibility and addresses any weak points that may predispose you to injury.
  • Gradually adjust intensity slowly to allow the muscles to adapt and respond. The general rule of thumb is that a change in volume and or intensity of about 10% per week is a common amount that most people can handle.
  • Focus on proper technique in order to not over stress the joints and muscles. Common mistakes include rounding the upper back, twisting while bending forward, lifting a weight that is too heavy causing early technical failure, or performing the movement too fast which affects control and may not be necessary.

Although muscle strains and pulls can sometimes be an inevitable part of moving, there are definitely successful techniques to help reduce the risk, speed healing, and guard against future injury.

Using EMG Analysis to Improve Performance

Surface eMG analysis or surface slectromyography records how the muscles activate when the nervous system sends a signal to the muscle to contract in order to move, stabilize or decelerate a joint.  The small electrodes that are similar to ECG electrodes are placed on the skin directly above the targeted muscle in order to measure the electrical signal caused by the movement of ions across the muscle cell membranes. This voltage, which is often measured in millivolts, indicates the recruitment of motor units as a result of the contraction process. A motor unit is a grouping of muscle fibers that is connected with a common nerve. These very low voltage signals are detected by the electrodes, amplified and filtered down to a computer where they are converted into a readable signal.

These signals are then used to identify what and when muscles are active, how much they are active, and can provide information on whether they may be fatiguing. Knowing this, it is then useful in determining what muscles are used in performing a movement as well as hinting at how the muscle may be responding to forces at the joint itself or adapting to an injury or impairment. For example, an athlete may have suffered an injury such as an ACL (anterior cruciate ligament) tear and may be completing her rehab to return to play. Coming back from an injury can be daunting as not knowing if the muscles are ready to be subjected to the forces of intense movements could increase the risk of reinjury. Strength, flexibility, and reaction training all play a key role in preparing for the return but will the muscles respond properly when the time comes? By examining the muscle activity pattern through EMG, we can learn more about how quickly the thigh muscles can set the knee joint, or pre-activate, to protect the ACL from too much strain from excessive movement or muscle delay and weakness. This gives more information to the coach and the athlete if she is ready to return. If the muscles are too slow to react to the movement, the forces on the ACL can increase too quickly leading to injury. However, if the muscles are properly trained to respond quickly and anticipate before the forces become too great, the knee is protected and the risk of injury is decreased.

Efficiency of movement is another aspect that can be examined by looking at the recorded EMG signal. The muscles around the joints often function in pairs with one muscle or muscle group providing the force to create movement (agonist) while the opposing muscle group applies force to stabilize the joint and help in controlling execution (antagonist). Too much activity from an opposing muscle group or antagonist will cause the agonist or movement muscle to work harder against the added resistance, thus decreasing efficiency in movement. Monitoring technique and muscle activation thus becomes important to increase efficiency and with the help of EMG analysis you can easily see if a muscle is activating at the appropriate time. Interpretation can then be determined if the activation is necessary for joint stabilization or if it is an unnecessary motor pattern that needs more attention. Comparing the left side to right side gives more information on symmetry and the rhythm of muscle contraction as well.

Targeting certain muscles for a specific training effect for strength, stamina, or growth can all benefit from real time analysis.  Often an individual’s recruitment pattern may be different from someone else due to learned habits or genetic factors such as muscle attachment and bone length. Are squats the best exercise to strengthen the quadriceps or is a lunge better? Are crunches on an exercise ball better for upper abdominal activation or does a decline crunch target that area better? Should I move faster or slower? These are questions that an EMG assessment excels at when looking at the individual instead of relying on group averages from a research study.

More advanced analysis can also be helpful in finding the point or threshold when muscles start to fatigue in order to develop training zones around these shifts in activation or to help decide if a training technique fatigued the muscle enough for a training effect. Rate of EMG development gives more information on power production and if the training routine is causing the necessary neurological changes as well as its role in recovery. Combining fatigue measurements (in regard to frequency shifts in the EMG spectrum) with amplitude could also give a window into helping decide if the muscle is fully recovered from a training bout or competition.

There are some limitations to EMG readings and interpretation that are also important to remember. The readings are not representative of the whole muscle, just the muscle fibers immediately under the electrodes and a certain depth into the muscle. Making definitive conclusions of recruitment of muscle fiber types as well as muscle force production is generally elusive and often the results are subject to general interpretation for specific situations. For example, although we may see that the EMG signal is stronger we can’t say for certain if it is producing proportionally more force as individual muscles can vary and often the strength to EMG signal is not always linear and can vary from muscle to muscle. However, quantifying muscle activation and timing is quite precise and reliable and is the basis of thousands of research studies examining muscle use during movement.  EMG analysis helps take the guesswork out of movement and provides an accurate measurement of muscle activity that a visual, interpretive, or touch assessment just can’t do.

Problem Mid-section?

 

“Mirror, Mirror, on the wall….” It is usually after a holiday season has passed that people notice with some dismay that certain changes have taken place in their bodies. The numerous parties, hectic schedules, and an abundance of food all to often result in a bigger bulge here and a softer touch there. Fortunately, your body has a truly amazing ability to change its appearance so that you can shape up those problem areas and look the way you want! It all comes down to identifying the problem and formulating a plan to achieve success.

Desires to ‘tone up’ the midsection, ‘harden’ and ‘shape’ certain muscles, or lose fat from a particular area are quite common. However, what do they really mean? Essentially, ‘toning’, ‘hardening’, and ‘shaping’ involves causing the specific muscles to grow bigger and will often entail losing some body fat as well. Unfortunately, when it comes to losing fat, your body will not allow you to take fat exclusively from one area without taking fat from everywhere else on your body. In other words, ‘spot reducing’ is not possible.

Muscle definition is determined primarily by muscle size and the amount of fat that lies between the muscle and the skin. The most efficient way to increase the size of the muscles is to use weight lifting exercises that use those muscles. Often 3 to 5 sets of 8 to 12 repetitions per set (where the last repetition of each set is hard to finish) is sufficient to cause the muscle to grow in most people. For those unfamiliar with weight training, pick a weight which you can lift consecutively for 8 to 12 times. This is called a ‘set’ of 8-12 ‘repetitions’. Perform this 2 more times with a 3 minute rest between ‘sets’. Good results should occur when this routine is performed every 3 to 5 days.

In order to lose the fat that covers the muscles you want to see, aerobic-type exercise (such as walking, jogging, cycling or cross-country skiing) that you can perform for a long period of time is the most efficient exercise to choose. This will not only result in losing fat from those problem areas but also results in an overall loss of body fat.

The type of exercise that you choose is not nearly as important as the length of time and proper intensity with which you perform it at. After doing a good warm-up for 10-15 minutes, exercise at a little higher intensity for an additional 20-30 minutes longer. You should be exercising at a brisk pace while still being able to comfortably carry-on a conversation. Doing this 2 to 4 times a week is often enough to start to notice changes after a few weeks.

The most important aspect to any fitness program or routine is consistency and progression. After a time your body adapts to the exercise demands and consequently ceases to make progress. Therefore it is important to re-evaluate your program every 4 to 6 weeks in order to make it continuously effective. However, the time and labour will pay off when you can turn to your mirror with confidence that you will like what you see.

Please note that before performing this, or any exercise routine, it is advisable that you consult your physician in order to make sure that you are in good physical health and able to pursue an exercise program.

Personal Training FAQ

What is a personal trainer?

A personal trainer is a coach that works one-on-one with their clients to help them achieve a certain fitness goal by teaching proper exercise technique, intensity, and creating training program tailored to their needs. For example, some are interested in losing body fat, increasing strength, firming up certain body parts, building muscle, improving general health or training for sport to name a few goals.

How can a personal trainer help me?

A personal trainer can help you set attainable goals and design an exercise routine to make sure you reach those goals by working out with weights, doing cardiovascular exercise, stretching or a combination of all three. A trainer ensures you are working at the proper intensity and that your exercise technique is safe and effective to maximize your time spent on your workouts. The routine is designed around your schedule and goals and takes into consideration experience as well as any injuries or limitations you may have.

By meeting on a regular basis, the trainer can then make sure you are progressing properly with your weights and cardiovascular exercise and ultimately towards your goal. A consistent schedule of sessions can also help in improving motivation level, monitor exercise intensity, correct any problems with exercise technique before it becomes a problem and help prevent the risk of injury from inappropriate exercise intensity or technique. If you are advanced, getting a new direction for your exercise schedule or learning new exercises will help you to progress to the next level that much faster.

When should I meet with a trainer?

How often you meet with a trainer is an individual decision incorporating experience level, financial budget, fitness level, time schedule and fitness goals. Generally, those who are new to exercise or are unsure the proper way to exercise should meet with a trainer first to make sure they start properly. This usually incorporates at least 2 – 4 sessions working on strength training, 1 – 2 on cardiovascular exercise, and occasionally 1 session to discuss proper nutrition habits and strategies to complement the exercise routine.

Those who have been exercising consistently for 6 months (or inconsistently for a year) can benefit by adding to their current knowledge and to improve on existing or learn new exercise techniques. Similar to intermediate level individuals, advanced exercisers may wish to strive to a new level where the expertise and experience of a personal trainer will make that journey all the faster through new training techniques, keeping motivation level high and by providing a different, more efficient approach. Overall, it is best to discuss your goals with the trainer and to formulate a schedule that fits all the variables. In the end, the more you can meet with someone to help you, the better and quicker your results will come.

Training for Aerobic Performance

Although coaches, instructors, fitness trainers, and physiologists often differ on the terminology of the different aerobic training methods, generally one can divide the training into the following sections. Training zone determination can be performed by measuring lactic acid levels, heart rate in relation to power production, and/or changes in EMG amplitude and muscle fatigue at various points through a progressive stage test. From this information, critical fatigue thresholds can be determined and much more detailed training prescription that focuses on what the athlete needs to work on the most is the result.

Long Slow Distance (LSD) Aerobic Training or Base Training or Zone 1 Training

This type of aerobic exercise is performed as an entry-level type of conditioning to lead to higher intensity exercise. Another purpose for this long duration, lower intensity cardiovascular exercise is to gradually train the muscles to use the oxygen delivered in the blood for energy and, performance wise, to help create the necessary changes to metabolise lactic acid. Since this type of training mainly recruits slow twitch (type I) muscle fibers, there tends to be little direct effect on anaerobic energy production. The slow twitch muscle fibers’ energy systems are primarily aerobic as dictated largely by the concentration of the aerobic enzymes contained within the fiber. These aerobic and anaerobic enzymes (the latter being in higher concentrations in type IIa and Iib fibers) are ultimately linked to the myosin heavy chain proteins of that particular fiber. Subjecting these muscle fibers to this type of training is believed to help boost these enzymes as well as the number of mitochondria within these fibres which helps in producing more energy (ATP) from oxidation of fat and carbohydrate metabolism. As one becomes more trained, the less carbohydrates they use for energy and the greater fat metabolism of free fatty acids contributes to the process. The energy is then used to help power muscle contraction and aid in the breakdown of lactic acid molecules. Past research and practical appliaction suggest that the stimulus is primarily duration and not intensity based. Other physiological changes would be increases in myoglobin content and increased capillarization. To help deal with the increased demand for oxygen to the muscles there is an increase in stroke volume both at rest and during exercise, partially contributing to the changes in heart rate (although the autonomic nervous system has a role in this as well). Interestingly, actual muscle blood flow is often reduced due to the increased efficiency of the muscles at using the oxygen in the blood

Therefore in order to develop a good aerobic base an individual would need to run at a lower intensity for as long as possible. A good aerobic base would be defined as creating a good concentration of enzymes to help in the oxidation of fatty acids and lactic acid in combination with good capillarization to reduce any rate limiting steps in the energy production cycle that occurs at higher intensities. In addition, a good aerobic base would also help deal with the excess production of lactic acid and to keep it from climbing to critical levels from gylcolysis. Determination of this training zone is based on staying under the aerobic threshold. The aerobic threshold is determined by a slight deflection in ventilation rate when moving from one stage to the next in a progressive aerobic power test. Other methods include surpassing a given level of 2.0 mmol/L of lactic acid blood concentration (this is the method that the Peak Centre uses most often), or changes in the amount of CO2 expired as well as examining the respiratory exchange ratio. A combination of all those factors would be taken into account to find the aerobic threshold. For a more targeted approach towards indiviudal muscle response, recruitment patterns and conduction velocity can change with increasing workload and changing lactate levels in the muscle fibers, monitoring the EMG amplitude combined with frequency spectral changes will also allow you to help find individual thresholds that are muscle specific.

To mark the training zones in order to make it applicable to all types of training, heart rates are generally used. Since heart rates are fairly individualised (fitness level, size of heart, hydration level, stress level, etc.), the heart rate is recorded or extrapolated at the time the deflection occurred or when the individual surpassed the 2.0 mmol/L mark. There is also a margin of error worked into the heart rate zone to allow for measurement error and environmental factors. Generally, as the individual spends more time training in the proper zone, the heart rate for that particular zone will change (increase).

An example of a long slow distance exercise or Zone 1 would be an easy jog or bike for 30 – 60 minutes. Although considered an entry-level type of conditioning, it is a training method that is used 60% – 80% of the time independent of fitness levels. Even Olympic calibre athletes still spend much time in the off-season building a good “aerobic base” to excel at higher intensities. However, it is important to remember that this type of exercise does little to directly boost VO2 max.

 

To perform this type of exercise: This type of training is an easy paced type of exercise where your heart rate should be about 120 – 140 beats per minute (bpm) that can go on for as long as 60 minutes. If your heart rate is above 160, you are probably going a bit to fast. Slow down and check your heart rate again in about 5 minutes. You should be going at a pace where you are breathing heavier but you can speak in fluid sentences. In other words you do not have to take occasional big breaths in order to get enough air.

Medium Intensity Aerobic Training, Sub Threshold Training, Zone II Training –

This training method also continues to help to improve the delivery and metabolism of the oxygen in the blood as outlined in Zone 1/LSD type training, but also introduces higher levels of lactic acid to the blood. During Zone II training, your body is still relying on aerobic metabolism for the majority of the energy production, however anaerobic metabolism also begins to significanlty contribute as well in varying degrees. This is because the rate and amount of energy you are expending can no longer be provided by only aerobic metabolism, anerobic energy production needs to kick into help provide the extra energy. As anaerobic metabolism increases, lactic acid also increases proportionately when exercisisng below anaerobic threshold.

As you train at a Zone II pace, Type IIa fibers (or fast, oxidative glycolytic – FOG fibers) are recruited. As these muscle fibers have both aerobic and anerobic enzymes, the anaerobic system and lactate delivery and production cycle is now trained under the exercise stimulus as well. This training helps get the exercised muscles used to being exposed to moderate levels of lactic acid, trains the muscles to remove it from the blood, increase muscle capillarization, as well as help increase anaerobic enzymes within the muscle fiber responsible for its resepective energy production. More specifically, it begins to train the enzymes to help transfer the lactic acid molecules across the muscle fiber membrane wall. This leads to better recovery and an ability to do more work at a higher intensity as it speeds the clearing of lactic acid from the blood and makes anerobic metabolism that much more efficient.

In addition, the slow twitch fibers are also exposed to a higher lactate environment and therefore enables those fibers to help deal with higher lactic acid levels as well. Similar to LSD or Zone 1, this training technique is also a stepping stone to higher intensity work.

To perform this type of exercise: This type of exercise is a bit harder than LSD where your heart rate may bounce between 140 – 160. For example, exercise for 10 minutes at 140 bpm and then increase intensity to go about 10 minutes at 160 bpm. This cycle can continue for 35-40 minutes. A heart rate above 180 would indicate you are probably going to fast again, therefore slow down and re-check your heart rate. The light intervals should have you breathing at a fairly heavy rate where you could not speak in fluid sentences. This is usually at a pace where going a bit faster would feel considerably more uncomfortable.

Threshold Training or Zone III training

The name for this type of training comes from what is referred to as anaerobic threshold. Anaerobic threshold is the point your body switches from using mainly oxygen to generate energy (aerobic) to burning the body’s sugar (gycogen) stores. It is desirable performance wise to be able to do a high rate of work (run at a fast pace for example) before your body reaches this point. When working above anaerobic threshold, most individuals last anywhere from 15 seconds (in extremely high rates of work such as sprinting) to 5 – 15minutes (such as fast running) before fatigue sets in and they eventually have to slow down. The cause of this fatigue is a result of rapidly climbing lactic acid that ultimately affects affects muscle contraction, ventilation rate, blood pH, and neural functoning

At anaerobic threshold, the muscle fibres and circulatory system are just able to cope with the amount of lactic acid produced by Type IIa fibers and possibly some Type IIB (fast twitch) fibers. In this situation the body is metabolising lactic acid within the muscle fibers, liver, and respiratory system and is able to keep the level under homeostatic control. However, a slight increase in pace would tip this balance in favour of the anaerobic system and would result in lactate levels climbing rapidly (logarithmically actually!) as production would exceed the amount the body could handle.

The short, high part of the intervals at this zone helps to gently exceed this balance and place the body in a state with excess lactic acid. The lower intervals help to train the system to get rid of the excess lactate in the body. By repeating these intervals, your anaerobic threshold should rise slightly as the body becomes more accustomed to dealing with lactic acid at higher levels. By following the threshold training method outlined in your exercise program, this helps your body deal with lactic acid better by stressing the appropriate enzymes and allows you to do a greater amount of higher intensity work before fatigue slows you down. In essence it helps to raise your anaerobic threshold which is somewhat determined by your lactate and ventilatory threshold depending on how you interpret anaerobic threshold. At the Peak Centre they believe anaerobic threshold occurs at 4.0 mmol/L of blood. In a large percentage of people this is generally true however it is not unusual to see a lactate threshold up around 5.0 mmol/L as well. A true anaerobic threshold is determined from several lactic acid measurements over a period of time and combined with ventilation readings to look at ventilatory threshold. This would obviously make for an impractical test, however looking at lactate threshold and ventilatory threshold combined would probably be accurate for a one time field test.

Physiological changes affected by training at anaerobic threshold or by training in zone III would include raising the anaerobic threshold, increases in anaerobic enzyme activity and efficiancy, and other changes similar to that for Zone II

To perform this type of exercise: This type of exercise is harder than MI or Zone II and where you will really start to breathe heavier and feel the lactic acid build up. For this exercise your heart rate should bounce between 160 – 180 where you go for about 5 minutes at 160 bpm and then increase intensity to go about 5 minutes at 180 bpm. Essentially, when you start to feel the muscles burn and starting to get tired you go back down to the easier intensity in order to recover. This cycle can continue on for up to 30-35 minutes. At the end of this type of cardio you should feel really tired and that you probably could not go on any more. Signs of fatigue you should be aware of are not being able to follow proper technique for longer than a couple of minutes and not being able to follow a certain pace without overshooting or undershooting your target heart rate.

Interval Training, Hill Training, Wind Sprints, Zone IV and Zone V Training

 

Zone IV and V helps to improve your body’s ability to use oxygen at higher intensities thereby improving your maximum aerobic fitness level or VO2 max. At VO2 max, your aerobic system is working at 100% maximum of energy production along with a certain percentage of your anaerobic system, so much so that any increase in pace will result in your body less able to produce energy from oxygen resulting in a drop of oxygen metabolism. The goal of Zone IV training is to help boost VO2 max by increasing the amount of time you are spending at VO2 max. The lower portion of the intervals allow your body to recover and lower lactic acid levels to allow you to increase your pace back up to max to help boost your VO2. Physiological changes from maximum exercise results in an increase in stroke volume from cardiac hypertrophy and increase in contraction efficiency; increases in lactic acid production combined with better tolerance of higher lactic acid levels; and increases in pulmonary function and lung volumes resulting in better gas diffusion capabilities (ability to move large amounts of oxygen and carbon dioxide across a larger surface area. Although Zone V can also increase VO2 max, the main goal of this type of training is to decrease the amount of time it takes for your body to reach VO2 max. This will allow an athlete to reach his/her maximum aerobic power in minimal time thereby maximizing his her speed (an 800m runner is a good example of someone who would benefit from this type of training). Similar to Zone IV, other benefits include increasing the concentration of enzymes that help transport lactic acid from the muscle cell into the blood stream. One indication that may illustrate that the lactate is being removed from the exercising muscle would be a maximum lactate for a distance runner of about 8 – 10 mmol/L lactic acid in the blood.

To perform this type of exercise: This will be the hardest exercise that you will have to perform and you will really feel the lactic acid fatigue and burning as well as your breathing will be fast and deep. Similar to the last 2 exercise methods your heart rate should bounce between 120 and 180-185 bpm with about 2 – 5 minutes at the high level and about 2 – 5 minutes at the low level. Similar to threshold training, you should only exercise at the higher intensity until you really start to feel the fatigue and burning sensation, then slow down to the lower intensity. This should be repeated for a total of about 30 minutes or as long as you can last. With this type of exercise you will experience a rise in heart rate with each interval at the lower intensities. This is fine and is to be expected.

Checking your heart rate

 

As your perform aerobic exercise heart rate increases with a corresponding increase in intensity. Taking a heart rate (HR) measurement every so often will insure you stay at the proper intensity. This type of monitoring helps to set a proper exercise pace for those who choose to exercise outdoors. It is also important to remember to allow at least 3 minutes for HR to stabilize after the beginning of exercise or after a change in pace or intensity and to measure it either while doing the exercise or immediately upon stopping. For longer duration exercise heart rate drift is common and is in part due to dehydration.