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.