Strength & Power are Dependent for Athletic Performance
In the modern-day sport both sport coaches and performance coaches understand the importance for athletes to be able to perform with high amounts of power. Increases in power are related to faster speeds, higher verticals and bigger hits. To understand and quantify power we can calculate power by multiplying work by time or force by velocity (8). Regardless of the calculation high-level athletes must be able to produce power under loaded and unloaded conditions. This discussion is meant to shed light on how training should be organized to develop power and how strength levels play the most pivotal role on power / force production.
First, we must understand that maximal strength levels play the critical role in sport. When strength levels are high, power & force capabilities are high (9), as well as a decrease in likelihood to succumb to injury. Therefore, our training order can be translated to strength development (build cross-sectionals); maximal strength (back squat measured); the production of high force in short periods (power both loaded and unloaded); and finally, develop velocity (fast with force).
To understand strength we must understand movement, which is simple muscle activity to produce force. We know there are three types of muscle actions, which are eccentric, concentric and isometric. The eccentric action results in muscle lengthening. The concentric action results in muscle shortening. The isometric action results in no muscle length change and therefore produces zero mechanical work, by definition. The eccentric action is when external force is applied on to the body and the body has to slow down or absorb the force placed upon. The concentric action is the muscle producing the force on to an object. When we break down the back squat, which should be the fundamental movement for all performance programs, we know the eccentric load is on the way down, the isometric action is when you pause at the bottom, and the concentric action is when you stand up with the weight. Strength development, which is the key to building more cross-sectionals for greater force development, requires athletes put emphasis on the eccentric muscle action. The eccentric action elicits the most muscle breakdown and soreness but is necessary to produce growth and gains. Now, strength gains can be achieved but on topic will strength lead to power?
By definition, power is the rate at which mechanical work is done, which can be quantified by multiplying force by velocity (11). The higher level of mechanical work (i.e. more loads lifted or more force produced through contraction) requires higher levels of strength. On the contrary, the lower the load or mechanical work the higher velocity can be obtained. Therefore, we can deduct that in order to achieve high rates of power athletes must obtain high levels of force (i.e. strength). In fact, strength levels are the primary indicator for an athlete’s ability to produce high rates of force development (9).
Strength development and maximal strength is the corner stone to athletic performance because stronger athletes produce force faster. When maximal back strength was measured, from a variety of collegiate sports, there was a positive correlation with peak power and agility test times (7). Maximal strength and strength development therefore need to be emphasized first, in any strength and conditioning program in order to achieve adaptations of power and high force output.
When training young athletes or less developed athletes, developing strength should be the primary objective because as weak athletes they are not able to perform high power movements. Once strength has been increased to optimal levels younger athletes will then be able to perform movements for power. In fact, by simply enhancing young weak athlete’s strength levels you will enhance their power abilities by allowing their skeletal muscle to produce higher levels of force at faster rates thus drastically enhancing their athletic performance.
Athletes who are prepubescent and not able to hypertrophy muscle will still benefit from performance training. Strength, at this level, is created through neurological efficiency or better known as muscle activation. Our training focuses on teaching young kids how to use their muscles through proper movement patterns to better prepare themselves for strength development. One example is teaching young athletes how to do a single leg bridge, which will create activity through the hamstrings and glutes.
Strength to Power
In American football, particularly college football, strength and power levels differentiate higher and lower divisions. Higher division athletes primarily have higher maximal strength and power levels (6). This same statistic is constant through a wide array of sports across numerous regions, not just American Football.
Strength levels must be maximized in order to incorporate ballistic movements and sport specific movements. Using back squats as a measuring tool many have postulated that an athlete must be able to squat two times his or her body weight in order to benefit from power-specific movements (3, 10). Once an athlete has achieved this benchmark of two times his or her body-weight that athlete must continue to maintain and enhance their strength levels for two main reasons. One, athletes with even higher strength levels than two times their bodyweight are able to sprint faster and jump higher. Two, if an athlete considers this two time level as achieved and discontinues strength focus then not only will a rapid loss in strength occur but a loss of power output and a major increase in risk of injury. Therefore, strength and strength development must continually be emphasized and trained for in all athletic performance training programs. The success forms this focus is long-term, not short-term, so learn to be patient.
Explosive strength can be often referred to as a sport specific movement that is a fast muscle contraction, often under loaded conditions. For example, change-of-direction (COD) is a loaded power movement that requires explosive strength. The rate at which force is produced must be fast and forceful. Therefore, sports such as soccer that require hundreds, even thousands of COD per game require that their athletes have significantly high levels of explosive strength.
During training ballistic actions with loads around 45-65% might serve as greater training potentiation for enhancing velocity output. For more advanced athletes training ballistic actions with loads from 65-85% might serve well. The training levels of the athletes dictates the loads. However, we recommend differentiating between the two by referring to power movements of 45-65% as velocity training and 75-85% as explosive strength training. Our most common ballistic movements to stimulate velocity training are bounding, squat jumps, jump shrugs, etc… Our preferred method of training to work explosive strength is through barbell loaded movements such as Olympic pulls, barbell platform jumps, depth jumps with resistance, etc…
Understanding the focus of the training protocols is vital for enhancing athletic performance for athletes both trained and untrained. Training for velocity and/or explosive does not develop basic strength or maximal strength but it does enhance an athlete’s rate of force development, which is essential for power.
Optimal loads for Power
Power has a lot of cross over between explosive strength and velocity training, but it does not have cross over with maximal strength. Maximal strength movements and power movements have an inverse relationship in that as the load becomes closer to 100% 1RM strength becomes the primary training focus and power is reduced. On the other hand coupling the two training focuses within the same program or workout has proven successful. Take sprinting for example; top running speed is a combination of force and power with fast runners typically characterized with higher stride rates and lengths. This one movement, which is a staple in athletics, brings us back full circle to the beginning of our discussion that stronger athletes can express higher levels of power output. Taking it a step further we understand that in order to generate high levels of power an athlete must be able to produce high contraction velocities in combination with high levels of force.
Force and velocity are interdependent in that concentric force decreases as velocity increases (9). We analyze this by looking at contact loaded sport such as Rugby. A key between Rugby players level of play, elite vs. non-elite, is that they must have high force capabilities as well as high power capabilities under loaded conditions (6). Therefore, a Rugby player must not only train with loads at moderate percentages to enhance velocity but they must train for power under heavier loads to prepare for high power output under loaded conditions.
During power training the strength and conditioning or performance coach must understand the nature and physicality of the sport that they are training. For contact sports, such as Rugby, training for explosive strength with percentages around 70-80% might serve better then 60-70%. On the one hand this prepares the athletes to perform under loaded conditions while putting out high power levels (10). We also know that high contraction velocities are required for any power activity so training for velocity around 45-65%, moving as fast as possible, can be included in their training protocol. Both velocity and explosive strength training can serve to enhance power, however, for more physically loaded power sports training for explosive strength more frequently will have a greater effect.
Let’s look at soccer or futbol as another real example. This sport, at the surface, shows requirements for unloaded power training. This would mean spending time performing velocity training (45-65%) while spending the majority of the time training power (65-75%). At the same time the strength and conditioning professional will have their athletes perform unloaded ballistic movements, such as bounding or other repetitive plyometric, to enhance power and velocity capabilities. This style of training will influence the high-velocity area of the force-velocity relationship (10) but it will not influence the high-velocity portion, which requires more loaded power movements. The misconception in regards to this sport is that ‘on the surface’ loads and high velocity seem to solve it all. Not only is this notion completely contradictory, there is no evidence or research to support this idea.
Change of Direction (COD) requires high levels of unilateral strength and power. This high impact characteristic is best trained through slightly higher loads in order to enhance the high-force portion of the force-velocity relationship (10). Therefore, training for soccer (Futbol) requires athletes to spend extensive time training in the explosive strength percentages (70-80%) along with power percentages at the higher end of the spectrum (70%). Through training with more loaded conditions athletes will enhance their COD abilities along with decreasing their likelihood to succumb to injury because their lower musculature will be better prepared for high-impact activities in multiple planes.
Combined methods of training, for all athletes, are the best and most influential training methodology to enhance athletic performance and prowess. The strength and conditioning professional should engage in periodization with clear focuses throughout the seasons and combine training focuses across a given training day. Having one focus through out a period and/or training session is not successful nor is it realistic. Athletes are dynamic and each sport requires different training influences.
Initially, for the development of power, all strength and conditioning professionals should engage in strength training by building cross-sectionals within the muscles. This hypertrophy (building) phase will allow athletes to develop higher strength potentiation. This building phase will consist of traditional forms of trainings, such as front squats, utilizing sets from 3-5 and reps from 8-15. Typically, repetition speed should be controlled and much of the exercise selection during this period should be spent doing unilateral training. Olympic Weightlifting movements can be utilized during this phase with slightly higher rep schemes; for example, hang power cleans for 5x5 focusing on movement pattern, timing, positions and speed.
Following the building phase, the strength & conditioning professional transitions to the strength phase where time should be spent on maximal strength gains. There can be a significant level of crossover between the “building” phase and the “strength” phase. The amount of time spent in each phase is predicated on an athlete’s ability and their training level (age). Strength phases typically focus on squat strength development, particularly the back squat, and include sets at 4-6 and reps at 2-6. Maximal strength is testing an athletes one rep max (1RM) and can be done once or twice during a maximal strength phase. Regardless, this phase will allow the strength and conditioning professional insight into the athlete’s strength abilities, which will indicate if a power phase is best served or a shorter “building” phase is required.
The third phase, “power,” is where combination training is most essential. Within the “power” phase the strength and conditioning professional must integrate velocity, classic power, and explosive strength training. In addition, the integration of maximal strength and hypertrophy movements must be integrated in to the training protocols throughout the program. A discontinued focus on strength will cause athletes to reduce their muscles abilities to produce maximal levels of force. Coupling power with strength, sometimes in the same phase, can therefore be a highly successful training method to produce highly explosive athletes.
Enhancing an athletes athletic capabilities is highly dependent the strength and conditioning professional ability to enhance athletes’ power. In addition, we now know that without developing adequate strength levels beforehand, high power cannot be achieved. It is in the best interest of the athlete to develop training regimens that blend multiple movements and training focuses throughout the entirety of their post, off, pre and in-seasons.
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