This article will help you create and instruct well-designed resistance training workouts that address muscular strength and/or endurance. Muscle strengthening classes continue to be a very popular i tern on today’s group exercise schedules. They go by many names from the traditional “body sculpt” or “muscle conditioning” to more creative titles like “power pump,” “reps and sets,” ‘iron yoga,” and more. In the group exercise setting, workouts may combine multiple fitness components in one “mixed” format, such as a step and sculpt class or cardio/strength circuit, or dedicate the entire class to strength training. These classes will typically use free weights, resistance tubes, and body weight exercises. They can last anywhere from 30-90 minutes.
Muscular strength and endurance, also known as muscular fitness, are components of fitness (along with cardio-respiratory fitness, flexibility, and appropriate body composition) that are important for overall health and well-being. As we go about our daily activities, muscular strength and endurance play a crucial role in how well our physical bodies meet a variety of demands and resist injury. There are a number of documented benefits that can result from resistance training, such as the following:
- Increased physical capacity to perform the activities of daily living.
- Increased bone density and the strength of connective tissue.
- Increased fat free mass resulting in decreased sarcopenia (gradual loss of lean tissue with age).
- Improved motor performance.
- Decreased risk of injury.
- Enhanced feeling of well-being and self-confidence.
- Overall improvement in quality of life.
Understanding the training effects related to a strength program will help you develop effective resistance training classes. There are five basic training effects. Muscular:
Muscular strength is defined as the maximum force a muscle or muscle group can generate at one time.
Muscular endurance is the capacity to sustain repeated muscle actions, as in push-ups or sit-ups, or to sustain fixed, static muscle actions for an extended period of time.
Muscle power is the explosive aspect of strength, and is the product of strength and speed of movement. Power = (force x distance/time, Power is especially important for improved athletic performance.
Muscle stability refers to the ability of a muscle or muscle group to stabilize a joint and maintain its position without movement, in other words, to be able to perform a sustained isometric, or held, contraction.
Muscle hypertrophy refers to an increase in the muscle fiber size, specifically in an increased cross-sectional area resulting from increased fibrils.
Amount of Resistance vs. Repetition
In the early days of group exercise smaller 2-3 pound weights and tubing were the primary tools used. Many reps were performed limiting the results to greater muscular endurance. Today, we see more programs including heavier bars and dumbbells in the group exercise classes to adequately challenge participants’ interest in greater strength gains.
Guidelines for Muscular Strength and Endurance Programming
To accomplish these training effects you will perform your classes using a sequence of exercise reps and sets. A rep refers to the completion of a single exercise movement from start to finish. A set is a series of reps performed together prior to a rest or break. The amount of resistance used is often referred to as the load. Volume is a weight training concept defined as the total number of repetitions performed multiplied by the total amount of resistance used during a single training session. In other words reps x load = volume. Volume can be varied by changing the number of repetitions, the number of sets, the number of exercises performed, or the amount of weight used. The amount of resistance used and the number of repetitions completed dictate the type of results that can be expected from a resistance training program. Light resistance with a high amount of repetitions will primarily lead to gains in muscular endurance. To obtain a larger muscle mass and muscular strength gains, heavier weights with fewer repetitions must be included (e.g., 6-8 reps).
This presents several challenges to consider when instructing in the group exercise environment. It is not always possible to have enough equipment to offer adequate resistance for all participants (in particular if working towards muscular strength gains). Additionally each participant may be limited to one or two different resistance loads making it difficult to properly challenge each muscle group. The load they choose may be perfect of a stronger muscle group like the latisimus dorsi, but too heavy for a smaller group such as the deltoids. It will be important for the instructor to sequence exercises in a way that allows the students to reach fatigue in a reasonable amount of repetitions and readily switch loads and/or make adjustments for larger (stronger) verses smaller (weaker) muscle groups. This will be further discussed in the sections on training intensity, exercise sequencing, and exercise order.
The American College of Sports Medicine recommends the following guidelines for resistance training for the average healthy adult. Perform one set of each exercise to the point of fatigue, while maintaining good form. Most people should complete 8-12 repetitions for each exercise, although a range of repetitions within 3-20 (e.g., 6-8, 8-10, 12-15) may also be appropriate. (For group exercise, AFAA recommends a range between 8- 25 repetitions depending on whether the focus is muscular strength or endurance.)
Perform both the concentric and eccentric phases of the exercises in a controlled manner (-2 to 4 sec concentric, -2 to 4 sec eccentric). Exercise each muscle group 2 to 3 non-consecutive days per week, and, if possible, perform a different exercise for the muscle group every two to three sessions.Perform a minimum of 8-10 exercises that condition the major muscle groups, with a primary goal of developing total body strength and endurance in a relatively time-efficient manner.
Physiology of Muscular Strength and Endurance
Learning how a muscle works will help instructors receive a better understanding of how to sequence or progress a resistance training class.
Neuromuscular Facilitation and “Muscle Memory”
Performing a muscle contraction with correct form and maximal fiber recruitment is a learned process. Muscle contractions are actually controlled by the brain. Simply put, the brain sends a message to the biceps to contract. If the message does not reach the biceps, then the muscle does not contract. Neuromuscular facilitation is the act of training the brain and the muscle to work as a team.
Muscle memory is fashioned over time through repetition of a given set of fine or gross motor skills. As one reinforces skills through repetition, the neural system learns those movements or skills to the degree that one no longer needs to think about them, but merely to react and perform appropriately. In the context of strength training, muscle memory can also imply that muscle strength can be gained back rapidly after one consistently trains for a given period of time, takes a long break from weight training, and then returns to weight training. This occurs because the muscle maintains a “muscle memory” of its previous, trained conditioning.
It is extremely important for instructors to recognize that their class participants are at various stages of muscle memory. Thus, instructors need to offer plenty of options and modifications in particular for challenging or skill related exercises. They should always emphasize mastery of proper resistance training techniques prior to offering more advanced exercise variations.
In every joint action, there is a muscle that contracts and acts as the primary mover or agonist. To allow this joint action to occur, there is another muscle that acts in opposition to the agonist called the antagonist. There are also stabilizer muscles at work that prevent unwanted movement and allow the agonist and antagonist to perform the movement with full contraction. For example, in a biceps curl performed at shoulder level, the biceps is the agonist, the triceps is the an tag on ist, and the deltoid acts as the stabilizer of the movement.
Muscle balancing is a foundational concept for resistance training workouts. Think of the body as the center pole of a tent. There are ropes attached to the center pole (muscles) that will pull the tent one way or another depending on which rope is the tightest and strongest. To create a well-stabilized tent, all ropes must be equally strong and stable.
The same is true of the human body. All the muscles of the bodywork in pairs to create movement. If one part of the pair is stronger than another, a muscular imbalance is created, which leads to improper body alignment and movement mechanics. For example, if the pectoralis (chest) and abdominal muscles are very strong and tight while the back muscles are very weak and laxed, a postural condition is created called kyphosis or “hump back.” To reverse this condition, the pectoralis must be stretched and the back muscles strengthened. These imbalances can also increase the possibility of exercise related injury. In order to prevent muscular imbalance, your class format should include exercises for all of the major muscle groups. You will also need to stretch each major muscle group. Stretches can be integrated in between strength sets (at the completion of a particular muscle group).
Extra focus can be given to muscles that tend to be weaker or tighter than their opposing group due to life stresses or typical training habits. Muscles that are weaker should be given additional strength or stability exercises while muscles that tend to be tighter should be given extra stretch time.
In order to see the results from your strength exercises, it is important to work the targeted muscle group to fatigue, but not to a point of failure. This means the muscle feels tired, but you are able to complete the movement without the loss of proper exercise form and technique. Ideally, the resistance used (e.g., weights, bands, or body weight) is enough to achieve a strong level of fatigue within a reasonable amount of repetitions (e.g., 1-3 sets of 8-16 reps). Once fatigue is reached, it is time to rest prior to performing another set of the same exercise. Rest periods between sets of an exercise can range from a minimum of a few seconds to a few minutes. The greater the fatigue and heavier the resistance, the longer the rest period will need to be between sets. In the group setting, instructors will often alternate between muscle groups using super-sets, tri-sets, and giant sets (a combination of two, three, or more different exercises done back to back without a rest period) to avoid long rest periods and keep the flow of the workout going.
An additional technique often used in group classes to expedite the onset of muscle fatigue is a mid-range isometric hold or short-range pulse. These holds and small pulsing actions are typically added after the final set of full range repetitions, in particular, when the resistance available does not sufficiently fatigue the muscle in the recommended rep ranges.
Monitoring Training Intensity
It is the instructor’s responsibility to monitor the group throughout the class and help participants select the proper resistance in a non-intimidating way. It will also be important to teach participants to monitor their own form and level’ of fatigue: Some participants may have trouble initially gauging their resistance training intensity. Fatigue levels can be measured using the Borg RPE scale. A suggested range is 12-13 (on the 6-20/15-point scale) initially, then 15-16 near the end of the set for submaximal training, and up to 19-20 for high-intensity training.
Muscle soreness, which occurs during the workout, is known as acute muscle soreness. Stretching the muscle or switching to a different exercise can often relieve this soreness. Another type of muscle soreness is called delayed onset of muscle soreness (DOMS). This usually happens 1 to 2 days after a workout. There is still controversy over what causes this condition and how it can be relieved. Some theories state that there is an actual tearing and inflammation of the muscle during the workout, and that warming up properly and stretching the muscle after training along with using lighter loads will help to alleviate this soreness.
Safety and form are of major concern in any resistance training program. Therefore, all exercises should be performed in a slow, controlled manner. Fast, explosive movements can place excessive stress on the muscles, joint structures, and connective tissues. One common cause of injury in a resistance training class is movement that is executed too rapidly (e.g., trying to keep up with the beat of the music) and/or with incorrect body alignment. Movement speeds of 2-4 seconds on the lifting phase (concentric action), a pause at the most contracted position, and 2-4 seconds on the lowering phase (eccentric action) help to maintain good execution.
The most common types of injuries that occur in resistance classes are inflammation problems caused by overuse or “over- reps.” Excessive squats and lunges often used in combination work may cause some knee problems. Other commonly over-stressed joints include the shoulder, wrist, and spine. It will be important to keep overhead movement in a range that does not aggravate the shoulder and decrease the stress on areas like the wrist, neck, and low back by maintaining proper alignment during exercise execution. Less common injuries include muscle strains or ligament sprains.
A complete warm-up along with proper body alignment and the use of appropriate resistance are the most important factors in injury prevention. Training participants how to facilitate effective neuromuscular response also aids in decreasing injury.
If injury does occur, recommend they use the RICE method-rest, ice, compression, and elevation-for immediate relief. If pain persists after the provision of such first-aid, advise your participant to seek the advice of a physician.
Breathing Through Resistance
Breathing also plays an important safety role in resistance training. It is advisable to exhale on the exertion (lifting phase) and inhale on the lowering phase. Holding the breath will create muscle fatigue at a faster rate and may illicit the Valsalva maneuver. This is a condition causing the glottis to close and the abdominal muscles to contract, forming an unequal pressure in the chest cavity, reduced blood flow to the heart, and insufficient oxygen to the brain. Dizziness and temporary loss of consciousness may occur. Blood pressure will also increase which may be a concern for participants with a history of coronary artery disease.
The Value of Rest
Rest and repair are necessary for muscle growth and recuperation. Generally, 48 hours is sufficient for this process to occur. Two to 3 non-consecutive days of resistance training (e.g., Monday, Wednesday, and Friday) is an adequate schedule for the average person. If working with heavier resistance, a rest period of 30- 90 seconds between exercises is sufficient for immediate muscle recovery.
Types of Equipment
The equipment you choose for the muscle-sculpting segment of class can vary from day to day because the choices are always increasing. Hand-held weights, tubing, weighted poles, balls, balance boards, and benches are just a few of the products on the market. Adding different types of resistive equipment to your routines will enhance training effects as well as reduce the incidence of plateaus and boredom. Remember to instruct your students as to the appropriate use of any new piece of equipment introduced.
Constant vs. Variable Resistance
Constant resistance is a form of dynamic resistance where the resistance directed against the target muscle or muscle group does not vary through the range of motion. Constant resistance training uses free weights, such as dumbbells, barbells, medicine balls, or even your own body weight. Gravity and position play a major role in the effectiveness of this type of resistance. The main disadvantage of constant resistance is the inability to train effectively against gravity through a full range of motion for certain exercises.
Variable resistance exercise is designed to achieve maximum muscular involvement and is usually carried out through the use of specialized machines. When using variable resistance machines, the applied force changes throughout the range of motion due to the special arrangement of pulleys or cams. With variable resistance machines, the resistance design attempts to match the particular muscle’s strength curve, allowing for a fuller range of effective training. True variable resistance is hard to duplicate in a group exercise class. The closest thing to variable resistance that is used in a group class would be elastic tubing and bands. Unlike a fixed weight, elastic resistance is variable because the resistance continues to increase as the device is progressively stretched, compressed, bent, or twisted. With tubing, the load or the intensity of the exercise can also be varied by changing the anchor angle as well as the foot or grip positioning. For example, when holding a tube you can vary your grip allowing for less or more working tube length; the less the length, the greater the resistance. Also, by its nature a tube or band becomes less elastic at the end range of its extensibility, making it much harder to pull. This fact works well with muscle groups where the strength curve matches the end range of an exercise motion. Examples include the anterior deltoid during a front raise and the quadriceps during knee extension.
In these exercises, the muscle produces the most force at the end range of motion. However, flexors of the elbow (biceps) are relatively weak close to full extension and close to full flexion, and so a band or tubing does not match the capabilities of these muscles. Unfortunately, when the resistance produced by the band is greatest, a large component of the resistance puts stress on the elbow joint, rather than on the contracting muscles. Be aware when using tubing where you feel the exercise. Ideally, you should feel the fatigue in the targeted muscle group(s). If the stress is joint related, ease up on the tension by selecting a lighter resistance, limiting the range of motion or shifting the anchor point.
Action Steps for Designing a Resistance Tubing Class
- Prior to using, check all tubing for holes or tears.
- Avoid pulling the tubing toward the face.
- Select appropriate resistance to maintain proper form and alignment.
- Avoid gripping the handles too tightly as to not elevate blood pressure.
- Maintain wrist allurement so the hand is in line with the forearm.
- Maintain continuous tension in the lubing so that movement can be controlled.
- Maintain a smooth and controlled pace on the lifting and lowering phase.
The music you choose for your resistance training class or the muscle strengthening segment of a mixed format class can help motivate your students to work hard and stay engaged in the movement. A strong, driving beat between 120 and 130 beats per minute (bpm) will keep the energy high while allowing instructors to execute the movement with proper form and full range of motion. Participants may find it pleasing to move with the beat and complete the sets and reps with the musical phrase. This is not a must, but does add a level of polish to a body sculpting class. Thus, for example, a 4 beat lift (approximately 2 seconds) with a 4 beat hold (approximately 2 seconds) followed by an 8 beat lowering phase (approximately 4 seconds), would work perfectly with music created for exercise purposes. A verbal count down usually takes 2 beats of music (e.g., hold one and two and three and four) unless you are doing small-range pulsing type move, which can move on the beat. In order to have your sets match the phrasing of the music, it is best to perform 8 or 16 repetition sets.
This is just one example of many ways you can work with the beat of your music. Keep in mind that working with the beat takes practice and a higher level of musicality on the part of the instructor. Music linked classes are not for every class or instructor. There are certain classes and exercises that are better taught without adherence to the music. A circuit format where everyone may be doing different exercises at the same time is one such example. Another example would be a class where there is a wide variance in participant abilities. Those participants with heavier weights may not be able to move at the same tempo as the ones who have selected lighter resistance. In these cases, it will be the responsibility of the instructor to direct and remind participants to always work at their own pace and avoid moving at a speed that reduces their ability to maintain good form and alignment. So, whether you prefer moving with the beat or simply having the music in the background, be sure to keep your primary attention and focus on the needs of your class participants.
Effective cueing can be tricky in the group environment due to the wide variety of participant goals and abilities. It is a good idea to start with the least challlenging version of an exercise then progress appropriately for your group. Once an advanced exercise is introduced the instructor should re-visit the easier version or modification for those who are not ready to advance. It is even trickier to control what the participants think they should be doing. This is where you must utilize your greatest communication skills. You need to find ways of encouraging those who should advance without discouraging those who should not. A phrase such as, “if you are sensing fatigue you are working at the perfect level; if not try adding this variation” may help to encourage all class participants. Watch out for cues that are not inclusive, negative, or overly aggressive, like “come on, you can do it, no pain no gain” or “go for the burn.” Keep in mind that the group wants to follow what the instructor is doing, so be sure to demonstrate a variety of options to make everyone feel comfortable.