Unilateral training

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A unilateral bicep curl with a dumbbell. First Lt. Jennifer Silvers does bicep curls at Air Station Fitness Center USMC-110816-F-2786W-001.jpg
A unilateral bicep curl with a dumbbell.

Unilateral training involves the performance of physical exercises using one limb instead of two. Such exercises should be considered as being distinct from bilateral, two limbed, exercises. For example, unilateral squats use one leg, and bilateral squats use two legs. A unilateral bench press uses one arm and a bilateral bench press two arms. Depending on the exercise, this may also entail using different equipment i.e. a dumbbell instead of a barbell. Unilateral exercise is commonly involved in comprehensive training regimes and especially those of professional sports people and athletes. Usually it is used in addition to bilateral training as opposed to instead of it. Unilateral training can yield numerous benefits including improving a person's muscle balance between the left and right sides of their body, improving their sense of balance, and helping to avoid or rehabilitate injury. [1]

Contents

Advantages

Sports specificity

Many sports require participants to perform actions with one limb instead of two. For example, a football player may kick the ball while standing on one leg, and a tennis player may hit the ball using a one-handed swing of their racket. The strengthening of the limbs in a unilateral fashion can help the players to perform these actions more effectively than if the limbs were trained in a bilateral fashion. This is because the unilateral action more closely resembles the sporting action, and, based upon the principle of specificity, benefits gained from it are more transferable to the performance of the sporting action. [2] Significantly, running is considered to be a unilateral action as it involves alternating between using the legs singly. Walking is also sometimes considered to be a unilateral action for this reason although it involves a bilateral element. Quick changes of direction during sport are also frequently performed in a unilateral manner. [3]

Muscle training focus

As unilateral exercises emphasise muscle use in a different way to bilateral exercises, and thereby alter the ratio in which different muscles are engaged, they can be selected in order to focus on training particular muscles. For example, a one-legged squat activates the gluteus medius more than a rear foot elevated split squat. [4]

Sense of balance

Unilateral exercises may require a person to try harder to maintain their sense of balance during the exercise. As a result, their sense of balance overall may improve. This is especially the case in regard to single leg exercises. On this basis, unilateral exercises are considered to be highly functional, in that the improved sense of balance that they help to develop, transfers well to most sports and athletics where the participants are more likely to need to balance on one leg and perform an action, or move through a range of movement using only one leg as a base of support. [5]

Muscle balance

Some people may have a problematic muscle imbalance between the different sides of their body, including the limbs, meaning one side is excessively stronger than the other. This generally means that performance is impeded and the risk of injury is increased. Such an imbalance may be the result of lifestyle factors, such as sitting at a computer using a mouse, or from training in an imbalanced way, or for other reasons. It may not be resolved by bilateral training as it may continue during the exercise. With unilateral training, however, the person definitely performs the same amount of work with either side of their body and this can therefore mean that the muscle imbalance is resolved. For example, if a person's right leg is stronger than their left leg, and it therefore performs 60% of the work in a bilateral squat, and the left leg 40%, then the bilateral squat will not fix the imbalance. Moreover, even if the percentage discrepancy remained the same, as their overall strength increased, the discrepancy in terms of how much force could be applied would increase. Unilateral squats performed alternately would, however, ensure that each leg was performing the same amount of work, meaning that the strength of each leg becomes more similar to the strength of the other leg, and the muscle imbalance is reduced. As it is reduced, performance improves and the risk of injury is reduced. [6]

Core strength

A unilateral overhead press. HIIT Workout.jpg
A unilateral overhead press.

Due to the fact that unilateral exercises are usually performed more to one side than the other, relative to a person's centre of mass, their performance necessitates different, and generally increased, core activity in order to provide the appropriate stability during the exercise. For example, a one-handed lift of a weight over a person's head, requires them to stabilise their core in a different way than if they were lifting a barbell over their head with two-hands. Generally, this means that they have to work harder to stabilise the weight and themselves during the lift, meaning greater levels of core activation. [7]

Injury prevention

As unilateral exercises can improve a person's sense of balance, correct muscle imbalances and improve the harmonious functioning of the muscular system, and transfer effectively to the performance of sports specific movements, they can also help to prevent injury as the practitioner becomes more capable and stronger in general, than if they only performed bilateral exercises. [8]

Rehabilitation

Unilateral exercises may be used in rehabilitation programmes. For example, single leg balances may be used to strengthen someone's ankle after they recover from an injury and thereby help to restore their ability to balance. [9]

Disadvantages

If unilateral exercises are used instead of bilateral exercises, or vice versa, then this can yield negative training outcomes overall. This is because even though unilateral and bilateral exercises may yield similar results, there can also be significant differences and the use of one and not the other may mean potentially advantageous outcomes are lost. For example, the incorporation of a unilateral barbell squat into a training regime, but not a bilateral barbell squat, may mean that only half the weight can be lifted. And so while the legs may be exercised to a similar amount in both types of squat, in the bilateral squat the core is forced to work significantly harder which can lead to the achievement of greater levels of core strength. The most common solution is to incorporate both bilateral and unilateral exercises in a training regime in order to gain the advantages of both types of exercise. The ratio of unilateral to bilateral exercises can be adjusted based upon the specific requirements of the training regime. [10]

Unilateral training and the cross education effect

When a person moves a limb they will naturally move the other paired limb in tandem, in order to improve their overall sense of balance. As well as balancing the spatial positioning of the limbs, this involves balancing the agonist and antagonist forces of the limbs. These co-activating forces relate to a person’s centre of mass where the forces towards and away from the centre are approximately even and the person is in a state of postural equilibrium. This can be meant in regard to either static postures or dynamic movements. [11] When a person moves, their centre of mass moves also in a unified process. [12] The ongoing stabilisation and reinforcement of the centre of mass, has a reciprocal benefit in that it enables the limbs to move from a more stable platform and thereby improves the efficiency of their movement. [13] Unilateral exercises can be particularly effective in improving a person’s ability to balance. [14]

In contrast to whole body balance, the cross education effect is considered primarily in regard to situations where one limb is moving, and the other limb concurrently activates but with limited, if any, perceptible movement. For example, a person is standing and they lift up their left arm while not moving their right. Even though the right arm does not perceptibly move, it is still activated by the movement of the left arm. The same phenomena applies for any form of limb movement, in that the other limb will also be activated. [15]

A form of unilateral training can be utilised which involves only the movement of one limb, with the other limb being non-moving. However, the non-trained limb also becomes stronger due to the cross education effect. [16] Research conducted by Munn and colleagues, assessed that the untrained limb strengthened on average by 7.8% over a period of training, which is 35.1% of the strength gain experienced by the limb actually being trained. [17] How the nervous system activates in conjunction with the moving limb is considered to be of particular importance in understanding the underlying causes of the effect, which are not as of yet fully understood. [18] In situations whereby one limb cannot be moved for some reason, the cross education effect can be used to strengthen it, improve agility, and prevent muscle atrophy etc. This can make it useful for the rehabilitation of sports injury, training people with a lateral imbalance of motor skills, or mobility impairments such as that suffered by stroke victims who may not be able to use one side of their body. [19] [20]

See also

Related Research Articles

<span class="mw-page-title-main">Calisthenics</span> Form of strength training exercises

Calisthenics or callisthenics (/ˌkælɪsˈθɛnɪk/) is a form of strength training that utilizes an individual's body weight as resistance to perform multi-joint, compound movements with little or no equipment.

<span class="mw-page-title-main">Clean and jerk</span> Composite of two weightlifting movements

The clean and jerk is a composite of two weightlifting movements, most often performed with a barbell: the clean and the jerk. During the clean, the lifter moves the barbell from the floor to a racked position across the deltoids, without resting fully on the clavicles. During the jerk, the lifter raises the barbell to a stationary position above the head, finishing with straight arms and legs, and the feet in the same plane as the torso and barbell.

<span class="mw-page-title-main">Bench press</span> Exercise of the upper body

The bench press, or chest press, is a weight training exercise where a person presses a weight upwards while lying horizontally on a weight training bench. The bench press is a compound movement, with the primary muscles involved being the pectoralis major, the anterior deltoids, and the triceps brachii. Other muscles located in the back, legs and core are involved for stabilization. A barbell is generally used to hold the weight, but a pair of dumbbells can also be used.

<span class="mw-page-title-main">Leg press</span> Weight training exercise

The leg press is a compound weight training exercise in which the individual pushes a weight or resistance away from them using their legs. The term leg press machine refers to the apparatus used to perform this exercise. The leg press can be used to evaluate an athlete's overall lower body strength. It can help to build squat strength. If performed correctly, the inclined leg press can help build knees that can handle heavier free weights, on the other hand, it also carries a risk of serious damage since locked knees can bend the wrong direction throughout the exercise.

<span class="mw-page-title-main">Strength training</span> Performance of physical exercises designed to improve strength

Strength training, also known as weight training or resistance training, involves the performance of physical exercises that are designed to improve strength and endurance. It is often associated with the lifting of weights. It can also incorporate a variety of training techniques such as bodyweight exercises, isometrics, and plyometrics.

<span class="mw-page-title-main">Squat (exercise)</span> Workout that targets the legs

A squat is a strength exercise in which the trainee lowers their hips from a standing position and then stands back up. During the descent, the hip and knee joints flex while the ankle joint dorsiflexes; conversely the hip and knee joints extend and the ankle joint plantarflexes when standing up. Squats also help the hip muscles.

<span class="mw-page-title-main">Deadlift</span> Weight training exercise

The deadlift is a weight training and strength training exercise in which a loaded barbell or bar is lifted off the ground to the level of the hips, torso perpendicular to the floor, before being placed back on the ground. It is one of the three powerlifting exercises, along with the squat and bench press, as well as a frequent lift in strongman. It is also occasionally used in armlifting.

<span class="mw-page-title-main">Isometric exercise</span> Static contraction exercises

An isometric exercise is an exercise involving the static contraction of a muscle without any visible movement in the angle of the joint. The term "isometric" combines the Greek words isos (equal) and -metria (measuring), meaning that in these exercises the length of the muscle and the angle of the joint do not change, though contraction strength may be varied. This is in contrast to isotonic contractions, in which the contraction strength does not change, though the muscle length and joint angle do.

<span class="mw-page-title-main">Plyometrics</span> Maximum-intensity explosive exercises

Plyometrics, also known as jump training or plyos, are exercises in which muscles exert maximum force in short intervals of time, with the goal of increasing power (speed-strength). This training focuses on learning to move from a muscle extension to a contraction in a rapid or "explosive" manner, such as in specialized repeated jumping. Plyometrics are primarily used by athletes, especially martial artists, sprinters and high jumpers, to improve performance, and are used in the fitness field to a much lesser degree.

The snatch is the first of two lifts contested in the sport of weightlifting followed by the clean and jerk. The objective of the snatch is to lift the barbell from the ground to overhead in one continuous motion. There are four main styles of snatch used: snatch, split snatch, power snatch, and muscle snatch. The full lift is the most common style used in competition, while power snatches and muscle snatches are mostly used for training purposes, and split snatches are rarely used. Any of these lifts can be performed from the floor, from the hang position, or from blocks. In competition, only lifts from the floor are allowed.

Closed kinetic chain exercises or closed chain exercises (CKC) are physical exercises performed where the hand or foot is fixed in space and cannot move. The extremity remains in constant contact with the immobile surface, usually the ground or the base of a machine.

<span class="mw-page-title-main">Pull-down (exercise)</span> Strength training exercise

The pull-down exercise is a strength training exercise designed to develop the latissimus dorsi muscle. It performs the functions of downward rotation and depression of the scapulae combined with adduction and extension of the shoulder joint.

<span class="mw-page-title-main">Overhead press</span> Weight training exercise

The overhead press, also known as the shoulder press, strict press or military press, is an upper-body weight training exercise in which the trainee presses a weight overhead while seated or standing. It is mainly used to develop the anterior deltoid muscles of the shoulder. The standing version was once a component of the sport of Olympic weightlifting as part of the clean and press movement, but was removed in 1972 due to difficulties in judging proper technique.

<span class="mw-page-title-main">Bodyweight exercise</span> Strength-training exercise to provide resistance against gravity

Bodyweight exercises are strength training exercises that use an individual's own weight to provide resistance against gravity. Bodyweight exercises can enhance a range of biomotor abilities including strength, power, endurance, speed, flexibility, coordination and balance. Such strength training has become more popular among recreational and professional athletes. Bodyweight training uses simple abilities like pushing, pulling, squatting, bending, twisting and balancing. Movements such as the push-up, the pull-up, and the sit-up are among the most common bodyweight exercises.

<span class="mw-page-title-main">Ballistic training</span> The maximal acceleration of weight for exercise.

Ballistic training, also known as compensatory acceleration training, uses exercises which accelerate a force through the entire range of motion. It is a form of power training which can involve throwing weights, jumping with weights, or swinging weights in order to increase explosive power. The intention in ballistic exercises is to maximise the acceleration phase of an object's movement and minimise the deceleration phase. For instance, throwing a medicine ball maximises the acceleration of the ball. This can be contrasted with a standard weight training exercise where there would be a pronounced deceleration phase at the end of the repetition i.e. at the end of a bench press exercise the barbell is decelerated and brought to a halt. Similarly, an athlete jumping whilst holding a trap bar maximises the acceleration of the weight through the process of holding it whilst they jump- where as they would decelerate it at the end of a standard trap bar deadlift.

The rear delt raise, also known as the rear deltoid raise, or rear shoulder raise is an exercise in weight training. This exercise is an isolation exercise that heavily works the posterior deltoid muscle. The movement is primarily limited to the two shoulder joints: the glenohumeral joint and the scapulothoracic joint. Scapular movement will also cause movement in the sternoclavicular joint and acromioclavicular joint. If the elbow bends during the extension exercises, it gravitates into a rowing motion.

Football strength is a training regime, considered the most complex physical quality to be developed by an athlete. The training regime, exercises used, how the exercises are performed, and the types of equipment all play important roles in achieving desired results.

<span class="mw-page-title-main">Power training</span> Common type of speed and strength training

Power training typically involves exercises which apply the maximum amount of force as fast as possible; on the basis that strength + speed = power. Jumping with weights or throwing weights are two examples of power training exercises. Regular weight training exercises such as the clean and jerk and power clean may also be considered as being power training exercises due to the explosive speed required to complete the lifts. Power training may also involve contrasting exercises such as heavy lifts and plyometrics, known as complex training, in an attempt to combine the maximal lifting exertions with dynamic movements. This combination of a high strength exercise with a high speed exercise may lead to an increased ability to apply power. Power training frequently specifically utilises two physiological processes which increase in conjunction with one another during exercise. These are deep breathing, which results in increased intra-abdominal pressure; and post-activation potentation, which is the enhanced activation of the nervous system and increased muscle fibre recruitment. Power training programmes may be shaped to increase the trainee's ability to apply power in general, to meet sports specific criteria, or both.

<span class="mw-page-title-main">Plyo box</span> Exercise equipment

A plyometric box, also simply known as a plyo box or jump box, is a piece of training equipment used for plyometric exercises. Plyometric exercises are a type of explosive power training that uses muscle elasticity to produce rapid, forceful movements. The plyometric box provides a stable platform for performing plyometric exercises such as box jumps, box squats, and box step-ups.

References

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