Research supporting the methods of Volt Athletics to develop the soccer athlete.
Soccer is a dynamic game that challenges an athlete’s physical and tactical abilities. From a metabolic standpoint, athletes must be conditioned to sustain short, intermediate, and long sprints with a high degree of change in direction. Players must utilize accelerative bursts of speed and rapid deceleration (5). Athletes are required to perform these short bursts repeatedly, which necessitates quick recovery. During the periods of intense bursts the athlete must be able to physically to possess the ball while holding off the opponent, challenge opponents for possession, and strike the ball from multiple angles and distances (1). The objectives for developing the soccer athlete demand training towards improving power, power-endurance (stamina), takeoff power, and maximum strength (2). From these listed objectives, Volt has prioritized three primary performance factors as the main sources of athletic development via implementation of a strength and conditioning program. Direct development of strength, lateral acceleration and deceleration abilities, and anaerobic and aerobic capacities set the foundation for peak soccer performance.
Soccer is a contact sport, in which players use their bodies to battle for possession of the ball as well as position on the field. Strength is a paramount factor in contests for possession. Evaluation of low versus high-level soccer players highlights a significant difference in leg strength and the positive correlation with short distance sprint speed (5). This difference is also highlighted in youth athletes (9). Implementing a progressive strength and conditioning program has been shown to increase the velocity of the leg when striking a ball (14). Strength is the ability to overcome or counteract external resistance by muscular effort (19). The primary mode of increasing muscular force production in Volt programming is the inclusion of multi-joint, barbell-based, open & closed-kinetic-chain resistance movements. These movements include all variations of squatting, deadlifting, pressing, and other movements where athletes are tasked with producing force into the ground while maintaining structural alignment. These movements are the most effective means of developing strength for athletes because they allow an athlete to move the largest amount of weight with their body as the base of support (11). Closed-kinetic chain movements, specifically, have a higher transfer of training effect to specific sporting movements (7). Developing strength is a key performance factor within the Volt program, emphasizing the development of total body strength through functional resistance training movements and progressions. The more force an athlete can apply into the ground, the faster they can run, jump, and change direction (10).
Explosive strength is fundamental for a soccer player to obtain the jump height necessary to head the ball or, in other words, the maximal ability of a muscle to exert force or torque at a specific velocity. The ability to win balls in the air has a huge impact over the course of the game. In addition to goal scoring, players challenge for headers in both offensive and defensive situations. An athlete’s vertical jump in conjunction with their technique and positioning determines their success in heading the ball over the opponent. Vertical jump performance depends not only on lower limb level of strength but also on the rate at which they are able to generate force, on the contraction velocity, on the ability of stretch-shortening cycle utilization, and on the degree of intermuscular and intramuscular coordination. The most effective way to develop force at a high rate is through periodized training programs using both Olympic lifts as well as plyometric training (17). Volt utilizes these science-based principles to provide a training program specifically designed to maximize the soccer athlete’s strength to set a foundation in power and speed based movements.
Development of Lateral Quickness
The intermittent nature of the sport places a high demand on change of direction ability. Volt focuses on the development of quicker and more powerful eccentric and concentric contractions, which translate to superior lateral quickness. Athletes can develop high levels of lateral quickness or change of direction (COD) ability with progressive training of eccentric and concentric control of single limb movements. This strength allows players to move more efficiently, safer and faster in all planes. A focused long-term strength-training plan has positive correlations with improved COD ability. (9). Volt Soccer progressively trains the development of unilateral control of the lower body, while slowly introducing different loading methods to develop both eccentric and concentric strength of those movement patterns. Developing the proprioceptive properties of proper unilateral knee and hip mechanics helps to increase efficient force production, absorption, and safer joint angles. An athlete who is able to change directions quickly is able to do so because of their ability to slow the momentum (deceleration) of their body with eccentric loading of the lower-extremity. In order to improve deceleration, muscles of the lower extremities need to be stressed to eccentrically contract in multiple planes. Deceleration training will overload the body through momentum in all planes, which will lead to improved explosiveness (6). Single limb training also focuses on the development of proper core muscle activation by stressing the dynamic stability of the athlete. Dynamic stability is stated to be an essential component of change-of-direction ability and multidirectional speed (13). Volt implements various unilateral progressions that place the lower-extremities through increasingly complex levels of both concentric and eccentric stress. Athletes will comfortably and safely develop the necessary strength for efficient and effective unilateral control for sprint deceleration and COD abilities.
In conjunction with strength development, Volt implements a progressive speed, agility, and quickness (SAQ) program. Volt SAQ places a training demand on the ability of an athlete to execute change of direction tasks from simple to complex drills. Movement tasks designed to challenge frontal, lateral, and vertical movement abilities are designed progressively to teach an athlete increasing levels of movement complexity. Training movements with demands on jumping mechanics can help to improve change of direction ability (4). Using plyometric drills, cone and ladder drills, and other movement challenges, athletes will improve multi-directional quickness and jumping and landing mechanics.
Development of Stamina
Proper energy system training is essential to meet the metabolism demanded by soccer player’s bodies during the course of a competitive season. During the 90+ minutes of play, athletes are functioning largely aerobically but rely on highly intense bursts of speed, this means that soccer athletes must prepare both aerobic and anaerobic energy systems. Progressive plans to produce both aerobic and strength improvements in soccer athletes have worked with the proper timing in periodization (15). In conjunction with the periodized strength program, Volt has designed a 12-week conditioning program, focused on increasing the aerobic pathways as well as the ability to withstand repeated alactic and lactic efforts. Training with repeated sprint conditioning and explosive strength drills both showed independent improvements in short sprint ability (3). An aerobic base phase sets a foundation for the development and maintenance of the aerobic energy system. The anaerobic phase is the longest and most prolific phase, focusing on glycolytic energy pathway development and improving the repeat sprint ability of soccer athletes under fatiguing conditions. The program concludes with an alactic phase designed to maximize the ATP-CP energy pathway and improve maximal acceleration and sprint speed as well as improving repeat sprint abilities. The combination of combined speed-endurance training and high intensity training show strong correlations to improved soccer fitness (8).
Injury Prevention Methods
Typical injury sites occur on the lower limbs predominantly, of which most common are hamstring pulls/tears, injury to knee ligaments, groin/hip dysfunction, and lateral ankle rolls (12). The lower extremities, mainly the knee and ankle joints and accompanied muscles and ligaments of the thigh and calf, are the most injured body site (~80%) (18). To combat the injury risk of obtaining non-contact injuries in soccer, Volt institutes several methods of injury –prevention programming in the strength training plan. A multi-component injury prevention program is effective at reducing injuries in soccer players (16). Proper strength training alone is an effective measure of increasing joint stability and integrity. Following the addition of a strength-training program, injuries in soccer dropped markedly (12). Proper movement selection that focuses on hamstring strength, flexibility, and lower limb proprioception are programmed specifically to reduce the risk of potential injury. Most injuries can be prevented with corrections of poor flexibility, muscle imbalances, muscle weakness, neural tension, fatigue. Due to the constant stimulus of hip flexion occurring within the game, specific hip extension exercises are programmed to reduce muscular imbalance. Specific unilateral limb movements are also programmed for the cause of reducing the amount of bilateral asymmetry between limbs. Strength imbalance will increase the likelihood of injury in the weaker leg. It has been reported that players are 2.6 times more likely to suffer an injury in the weaker leg if this imbalance is >15% game. Although programmed as a performance piece, eccentric strengthening of the hamstrings is a popular choice for injury prevention training. The hamstring in particular is a key contributor during deceleration as it works eccentrically to slow the body down. One-third of all soccer-related injuries are muscle related, with the majority (92%) affecting the following major muscle groups of the lower extremity: hamstrings (37%), adductors (23%), quadriceps (19%), and calf muscles (13%), hamstrings to be the most commonly injured muscle, constituting 12% of all strains. Indeed, players are 2.5 times more likely to sustain a hamstring than a quadriceps strain during a game (16).
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