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Success on the Court!

  |   Injury Prevention and Care, Performance Training, Photos, Video   |   No comment

Congrats, boys, on a tremendous win! Physically and mentally you outperformed an elite opponent.

 

Paris led all scorers with 21 points and a major spark in the second half while Ivan hit the game winner with 0.8 to play. See article below and gain some insight into the leading scorers training ingredients.

 

 

#repostmonday @chefboyparis #athlete #basketball #oakland #soldiers #dreamvision #ASPEED #ASPnation

A video posted by AccelerateSP (@acceleratesp) on

 

In this resistance based power protocol we take between 40% and 60% of Paris’s max resisted sprint capability and apply for short/moderate bouts for long durations. The key is that the athlete can maintain that pace throughout the entire session with the HR in the appropriate ranges during the work/rest portions of the session. In this case Paris was running with 25lbs of resistance at a speed of 9+mph for bouts of 10 seconds with 50 seconds of rest. His hard work and perseverance has served him well!

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Drew “probably felt a little too good”

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Always good to see our friends doing well! Looking forward to the season! Scroll through the article below and gain some insight into a small piece of his off-season training at ASP.

 

 

thumbnail-1
Drew setting up for some core elasticity work with our Split Stance Side High Throw

 

START
– Split stance with feet hip width apart side facing wall
– Head, shoulders, hips, feet all facing perpendicular to rebound wall.
– Shift arms laterally toward outside shoulder
– Outside arm level with shoulders

EXECUTE
– Lead hand is supporting underneath Medball and throw hand is behind Medball.
– Drive with full extension of throwing arm, maintaining elbow at shoulder height.
– Hips stay stable and side facing while rotation comes thoracically
– Repeat for prescribed repetitions.

FOCUS
– Rotate thoracically to throw Medball
– Drive off outside leg
– Maintain throwing elbow level with shoulders
– Thoracic rotation
– Hips and shoulders remain side facing rebound wall at end of motion

GOAL
– Upper body elasticity
– Upper body power

 

Keep up the good work!

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Shear Knee Forces in Weightlifting Exercises

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Introduction

 

All athletes are subject to various amounts of momentum, force, and overall impact on the knee. It is paramount that athletes build stable, synergistic, and efficient levers up and down the kinematic chain when engaging in their preferred sport.   Throughout the course of this article we will look at five different exercises; the dynamic squat, the barbell squat, the power squat, the front squat, and the lunge. With each exercise, we will discover the differences in shear and compressive forces on the tibiofemoral joint and the patellofemoral joint, as well as take a look at knee kinetics that occur during the different phases of each exercise. From the studies presented below, we can present and rank the following exercises in order from most stressful knee forces to least stressful knee forces:

 

1. Lunge

2. Front squat

3. Power squat

4. Barbell squat (unrestricted)

5. Barbell squat (restricted)

6. Dynamic squat

 

The Dynamic Squat

 

There are several studies that look at diverse exercise movements that involve flexion and extension of the knee joint. One such study involves examining knee biomechanics during a dynamic squat exercise, as illustrated in the picture below:

convexMoment Arm

 

In this study, the researchers examined tibiofemoral shear and compressiveforces, patellofemoral compressive forces, knee muscle activity, and knee stability relative to athletic performance, injury potential, and rehabilitation (Escamilla, 2001). Their results showed several things; first, that there were low to moderate posterior shear forces restrained primarily by the posterior cruciate ligament (PCL), that were generated throughout the squat for all knee flexion angles. Second, there were low anterior shear forces restrained primarily by the anterior cruciate ligament (ACL), that were generated between 0 and 60° of knee flexion. And third, patellofemoral compressive forces and tibiofemoral compressive and shear forces progressively increased as the knees flexed and decreased as the knees extended, reaching peak values near maximum knee flexion (Escamilla, 2001). Hence, training the squat in the functional range between 0 and 50° knee flexion may be appropriate for many knee rehabilitation patients, because knee forces were minimum in the functional range. The Barbell Squat (Back)   As mentioned above, the previous study only looked at the knee biomechanics during a bodyweight dynamic squat. However, even with just a normal bodyweight squat we can see that there are still compressive and shear forces acting on the knee joint. Here we will take a look at another research study that observed the effect of knee position on hip and knee torques during a barbell squat. ABTo be more specific, this study examined joint kinetics that occurs when forward displacement of the knees are restricted, versus when such movement is not restricted. The methods included seven weight-trained men who averaged about 27.9 years, being videotaped while performing two variations of parallel barbell squats (Fry, Schilling & Smith, 2003). The first variation performed was permitting the knees to move anteriorly past the toes (unrestricted), and the second variation performed was providing a wooden barrier to prevent the knees from moving anteriorly past the toes (restricted), as shown in the picture below: The results of the unrestricted squat showed that knee torque for all participants averaged about 150.1 N·m with a mean standard deviation of 50.8 N·m. Hip torque for the unrestricted squat was 28.2 N·m with a mean standard deviation of 65.0 N·m. The results of the restricted squat showed that knee torque was 117.3 N·m with a mean standard deviation of 34.2 N·m. Hip torque for restricted squat was 302.7 N·m with a mean standard deviation of 71.2 N·m. The restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knee and ankles. The illustration below provides a more detailed description of the torque produced at the knee and hip during both variations of barbell squats:   This study’s experimental studies demonstrate that although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this barbell exercise may require the knees to move slightly past the toes while the center of gravity remain directly above the midfoot.UnvsRES

 

The Power Squat, Front Squat, and Lunge

 

A final study done on knee forces looked to analyze intersegmental forces at the tibiofemoral joint and muscle activity during the power squat, the front squat, and the lunge, as illustrated in the picture below. The results for this study showed that maximal posterior shear of 495 N (±72) occurred with the lunge at 103° of knee flexion. During the power squat and the front squat, the posterior shear forces were the same, with a maximum of 295N (±32) at 93° and 295N (±33) at 97° of knee flexion (Growney, Lutz, Meglan & Stewart, 1996). Joint compression forces of 500-600 N remained relatively constant throughout the descent and ascent phases of the power squat and the front squat. The lunge produced the highest joint compression, reaching a maximum of 716 N (±70) at 76° (±25°) of knee flexion. A rapid increase in joint compression during the lunge occurred with the foot strike when stepping forward with the right leg, but the force remained relatively constant during the descent and ascent phases of the exercise (Growney, Lutz, Meglan & Stewart, 1996). The means of maximal extension moments were similar for all exercises, measuring 113 N-m (±23) for the lunge, 89 N-m (±12) for the front squat, and 86 N-m(±13)for the power squat at terminal flexion. Significant differences between the exercises were most notable when the knee flexion angle approached its peak.

 

In particular, the lunge exercise was found to have significantly higher posterior shear forces (tibia force on femur) than both the power squat and front squat at several exercise events (Growney, Lutz, Meglan & Stewart, 1996). These differences appeared when the knee was flexed at 60° in the descent phase, 90° in both the ascent and descent phases, and in the maximal magnitude of the shear force. Similarly, higher maximal net extension moments about the knee were observed in the lunge than in either the power squat or front squat. Significantly higher net extension moments in the lunge compared with the other two exercises were observed when the knee was flexed at 90° while in the descent phase (Growney, Lutz, Meglan & Stewart, 1996). The lunge net extension moments were significantly higher than the front squat moments at 60° of knee flexion during descent.   To summarize, the mean tibiofemoral shear force was posterior throughout the cycle of all three exercises. The magnitude of the posterior shear forces increased with knee flexion during the descent phase of each exercise. Joint compression forces remained constant throughout the descent and ascent phases of the power squat and the front squat. A posterior tibiofemoral shear force throughout the entire cycle of all three exercises in these subjects with anterior cruciate ligament-intact knees indicates that the potential loading on the injured or reconstructed anterior cruciate ligament is not significant. The magnitude of the posterior tibiofemoral shear force is not likely to be detrimental to the injured or reconstructed posterior cruciate ligament. These conclusions assume that the resultant anteroposterior shear force corresponds to the anterior and posterior cruciate ligament forces.  

 

Conclusion  

 

Throughout the course of this paper we have looked at five different exercises; the dynamic squat, the barbell squat, the power squat, the front squat, and the lunge. With each exercise, we have discovered the differences in shear and compressive forces on the tibiofemoral joint and the patellofemoral joint, as well as taken a look at knee kinetics that occur during the different phases of each exercise. From the studies presented above, we can present and rank the above exercises in order from most stressful knee forces to least stressful knee forces:

 

1. The lunge

2. The front squat

3. The power squat

4. The (unrestricted) barbell squat

5. The (restricted) barbell squat

6. The dynamic squat

 

It is important to take into account the stresses you are loading the knee with and incorporating exercises that may be more conducive to athletes’ longevity and injury prevention in regards to tibiofemoral or patellofemoral dysfuntion or related symptoms. That said be creative, empirically driven, and subjective in your approach to practicing or prescribing core and lower body strength exercises:

 

 

 

References

 

An, K.N., Growney, E.S., Lutz, G.E., Meglan, D.A. & Stuart, M.J. (1996). Comparison of intersegmental tibiofemoral joint forces and muscle activity during various closed kinetic chain exercises. The American Journal of Sports Medicine. 24, (6). 792-799.

 

Escamilla, R.F. (2001). Knee biomechanics of the dynamic squat exercise. Med. Sci. Sports Exerc., 33, (1). 127–141. Fry, A.C., Smith, J.C. & Schilling, B.K. (2003).

 

Effect of knee position on hip and knee torques during the barbell squat. J. Strength Cond. Res. 17, (4). 629–633.

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Improving Sprint Mechanics

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Speed advantage is a sought-over quality for nearly all athletes, often the final determiner between a win or a loss. Today, we’re going to a deeper, science-driven look at how to gain speed advantage by analyzing the kinematics (joint angles) of sprinting.

 

Speed can be calculated as stride length times stride frequency. Oftentimes, athletes try to increase their stride length by extending at the knee and having their foot land in front of their center of gravity (their hips). Not only does the athlete put themselves at risk for hamstring injuries, but he or she also increases braking forces and robs him or herself of momentum that could be used to carry forward. The athlete should strive to maintain a neutral pelvis so that they can drive the knee up to 90 degrees and forcefully plant the foot directly under or slightly behind their center of gravity.

 

Grant, a rugby player for SF Golden Gate Rugby Team of the Pacific Rugby Premiership, demonstrates a great job of keeping a neutral spine and having his plantar foot land directly under his hips. However, the foot should be dorsiflexed (toes pointed up) as it makes contact with the ground in order to further minimize braking forces and elicit a stretch reflex. Grant lands plantar flexed (toes down) on the third, fourth, and fifth stride.

 

A few things that need to change in order enhance sprint form are:

 

(1) increasing his forward lean

(2) improving arm swing mechanics

(3) increasing stride length without compromising foot position

 

The max velocity phase of the sprint should still feel like a “controlled fall.” There should be between a 2-4 degree lean at the torso. For Grant’s last four strides, he should look to decrease the angle between his torso and thigh from 108-106 degrees to around 100 degrees by both leaning forward at the hip and lifting the knees higher. Grant is limiting forward momentum by being too upright during the max velocity phase of the sprint.

 

There is slight elbow extension during the arm swing during flight phase of every stride. The arms should keep bent at 90 degrees. Powerfully moving the arms about the shoulder while keeping the elbows bent should help contribute to increased stride frequency.

 

Grant is transitioning from playing in ruby 15s to rugby 7s and is currently in his pre-season phase of training. Rugby 7s is a much faster paced league and will require a strong speed and endurance foundation. In order to prepare him for the season, we are going to primarily focus on improving his sprint form and technique to increase efficiency.

 

As training progresses, Grant will look to increase stride length by increasing range of motion and flexibility of the hamstring group. Considering his body type, Grant should try to increase his stride length from 80 to at least 90 degrees.

 

Ultimately, the little details are what make for profound success.  In a world where one tenth of a second is the difference between getting tackled and scoring, we’re here to fine-tune the details.

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Repeat Sprint Ability

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Repeated-sprint ability (RSA) is the ability to perform repeated sprints with brief recovery intervals (Haugen et al., 2014) and is prevalent in most sports including basketball, football, and soccer.

 

Improving an athlete’s RSA requires an understanding of energy systems and how to stress those energy systems in a way that optimizes performance in sport.

 

In today’s blog, we will discuss:

 

(1) the history of studying energy system contribution

 

(2) some common misconceptions

 

(3) what we do here at Accelerate to develop RSA in our athletes.

 

Energy System Contribution: History of Study

 

During the 1960s and 1970s researchers began studying energy system contribution and interaction during maximal intensity bouts of exercise. Eventually, they came up with an energy system continuum in which one system was dominant within a particular range of time (see figure 1). Also, the power and capacity of each system was calculated so that the system likely to be dominating during a particular activity was given (see figure 2).

 

energy systems

Figure 1

energy systems by sport

Figure 2

 

 

 

Common Misconceptions

 

While insightful at the time, literal interpretation of energy system contribution has led to the misconception that they operate in an orderly and sequential fashion. Although certain energy systems are more suited to a particular exercise, this does not imply exclusivity (Gastin, 1993).

 

Research suggests that ATP (energy) is derived from each of the energy producing pathways during all exercise activities.

 

Because the aerobic energy system is slow to activate during exercise, it was thought that its contribution to sprinting was insignificant and that only the ATP-PCr and fast glycolysis energy systems were relevant. On the contrary, the aerobic energy system has been shown to play a role in even the shortest sprints and that all 3 energy systems make a contribution (Gastin et al, 1995).

 

The processes involved in supplying the working muscles during exercise are distinct yet closely integrated during maximal exercise. Although certain energy systems are indeed best suited for particular sports and exercises in terms of power output and duration, this does not promote exclusivity.

 

Energy System Contribution in a Single Sprint

 

A single, max effort sprint, is mostly (but not exclusively) influenced by the more powerful anaerobic energy pathways. The longer the duration of the sprint, there will be a greater utilization of the aerobic energy system. For example, it has been found that there is between a 28-40% contribution from the aerobic energy system for a sprint lasting 30 seconds. The aerobic energy system contribution is also considerable during shorter bouts of exercise, and has been reported to be around 30% during sprints over 12-22 seconds (Spencer et al., 2005).

 

It has been suggested that elite sprinters utilize PCr degradation and deplete their stores more than slower sprinters (Hirvonen et al., 1987). However, due to ATP production via glycolysis and the oxidative systems, PCr stores are not totally depleted within 5-10 seconds of sprinting. By studying blood lactate concentrations, literature suggests that anaerobic glycolysis will be activated during 2- to 3-second sprints, which are commonly performed during field-based team sports (Spencer et al., 2005). The idea that glycolysis during maximal exercise activates only after the PCr stores are depleted is no longer supported.

 

Energy System Contribution in Repeated Sprints

 

Energy system contribution in repeated sprints is slightly different than that of a single sprint. While the first sprint’s energy system contribution is described above, the following sprints’ energy contribution will be influenced by the number of bouts, duration of the exercise, and recovery between sets.

 

As the number of repeated sprints increases and as the duration of exercise is prolonged, there is a greater accumulation of blood lactate compared to a single sprint despite increased reliance on aerobic metabolism, and a reduced rate of glycolysis which will contribute to fatigue and diminished speed (Spencer et al., 2005).

 

A by-product of anaerobic glycolysis is lactic acid and a decrease of intracellular pH, which has been linked as a cause of muscular fatigue (Fox, 2008). Although extreme muscle lactate concentrations are evident after repeated sprint bouts of long duration, high concentrations are still apparent following shorter sprints as well.

 

As previously mentioned, PCr degradation is imperative to the first 5 seconds of a powerful sprint. In repeated sprints, the resynthesis of PCr will depend on the duration of recovery. It takes between 3 to 7 minutes in order for complete resynthesis of PCr (Fox, 2008). If recovery time is insufficient, power output will be decreased. As power is decreased, there is more aerobic contribution.

 

Developing RSA in our athletes: An ASP Case Study

 

 

Speed and speed endurance are essential physical characteristics for successful match-play in soccer (Bangsbo et al., 2007; Amonette et al., 2014). Elite soccer players have 150 to 250 brief intense actions during a game, indicating that the rates of PC utilization and glycolysis are frequently high during a game (Bangsbo et al., 2007). In order to sustain high the levels of activity an efficient reliance on oxidative pathways is required.

 

Our case study athlete is Marianna, a soccer player. In Marianna’s Woodway energy system development protocol, she is performing a series of 10 second sprints between 5-6 mph with a 30 second rest interval. The first repetition will be completed with 5 lbs. of resistance with each subsequent repetition increasing by 5 lbs. The set will be completed when the athlete can no longer achieve the target speed at a given resistance. The athlete will be given a 2 minute break and then will begin the next set back at 5lbs. resistance. The athlete’s goal is to complete up to 6 sets without a decline in power from set to set.

 

This force progression power protocol allows us to train several energy systems at once with the beginning of each set occurring well below maximal exertion, using Phosphocreatine and ATP stores. Each sprint repetition builds closer and closer to maximal exertion with the increase in resistance, thus tapping into the anaerobic glycolysis system. As the athlete completes the fifth and sixth sets, it is possible that they might be using some energy from the aerobic system as well due to the total duration of the workout (Spencer, 2005).

 

At ASP, we identify the physiological needs of the athlete in order to improve athletic performance. Although certain sports rely more heavily on a particular energy system, it is important to train multiple energy systems because most team sports require an athlete to perform repetitive bouts of low, medium, and high intensity sprinting with varying amounts of time, distance, rest, and recovery. By creating sound protocols and training methodologies, ASP stresses all of the athlete’s energy systems in a way that is most beneficial to each individual athlete.

 

Reference

 

Amonett, W., Brown, D., Dupler, T., Xu, J., Tufano, J., & Witt, J. Physical determinants of interval sprint times in youth soccer players. Journal of Human Kinetics. 2014; 40: 113-120.

 

Bangsbo, J., Iaia, F., & Krustrup, P. Metabolic response and fatigue in soccer. International Journal of Sports Physiology and Performance. 2007; 2:111-127.

 

Hirvonen J, Rehunen S, Rusk H. Breakdown of high-energy phosphate compounds and lactate accumulation during short supra-maximal exercise. European Journal of Applied Physiology. 1987; 56:253-9

 

Spencer M., Bishop, D., Dawson, B. & Goodman, C. Physiological and metabolic responses of repeated-sprint activities specific to field-based team sports. Journal of Sports Medicine. 2005; 35 (12) 1025-1044.

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Hypoxia and Tempo Training

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Training under hypoxic conditions will promote fatigue of type I fibers and enhance activation/overload of type II fibers, which are critical for powerful athletic movements. In the preceding video, we demonstrate tempo training for various exercises – split squat, pushup, pullup, row.

 

 

To increase muscle mass and strength, traditionally it is recommended to perform high-intensity resistance training with loads of 70-85% of 1RM (American College of Sports Medicine, 2009). However, new research indicates that comparable gains in muscle hypertrophy and strength can be achieved with lower-intensity resistance training of 20-30% of 1RM under hypoxic conditions (Manimmanakorn, 2013). At Accelerate, we take advantage of hypoxic training by modifying time under tension or tempo for eccentric, isometric, concentric actions.

 

Training Effects under Hypoxic Conditions

 

Hypoxia is a condition in which the body or a region of the body does not receive adequate oxygen supply. Hypoxia occurs at ~80% arterial blood oxygen saturation, whereas normal blood oxygen levels are >95% (Manimmanakorn, 2013). Training with inadequate oxygen supply will force the body to:

-Increase reliance on anaerobic metabolism for energy production
-Increase recruitment of type II muscle fibers for force production

 

Increased use of anaerobic metabolism will result in elevated blood lactate and decreased intracellular pH, which can inhibit muscle contraction and lead to muscular fatigue (SEE Energy System Contribution to Sport and Muscle Fiber Type POST ). However, by consistently training the anaerobic energy system, the body will improve its ability to clear lactate from the blood and raise its anaerobic threshold. As a result, a properly trained athlete will be able to recover faster and perform at a higher intensity without lactic acid buildup.

 

Without sufficient oxygen supply, type I muscle fibers will fatigue as they rely on aerobic metabolism for energy production. Consequently, this will require recruitment of additional type II glycolytic muscle fibers to maintain a given force (Manimmanakorn, 2013). Without the contribution of type I fibers, increased mechanical loading will be placed on the available type II fibers. As a result, type II fiber adaptation will be enhanced via increased muscle activation and hypertrophy due to overload.

 

Muscle Fiber Types and Sport Requirements

 

 

The major characteristics of the different muscle fiber types are summarized in the table above. Type I fibers are slow-twitch, low force, high endurance, utilizing the oxidative energy system. Type II fibers are fast-twitch, high force, low endurance, utilizing the glycolytic energy system. Type I fibers are employed in low-intensity, long duration activities, whereas type II fibers are emphasized in high-intensity, short duration movements.

 

 

The recruitment of type I vs. type II fibers depends on the sport requirements for intensity and duration. Various events and their muscle fiber recruitment are summarized in the table above. Endurance athletes (ex. long distance runners) primarily employ type I fibers, whereas power athletes (ex. sprinters) mainly use type II fibers. Sports such as soccer, lacrosse, and hockey require high recruitment of both fiber types, as they involve short bouts of high intensity along with longer periods of moderate activity.

 

For most field sports, type II fibers are especially important for powerful movements such as jumping, cutting, accelerating, and decelerating. These actions require quick and high applications of force, which are only produced by type II fibers. Therefore, the development of type II fibers in terms of strength, size, and endurance is essential for athletic performance. At Accelerate, we modify time under tension to take advantage of hypoxic training and type II fiber stimulation.

 

Slow Tempo Resistance Training

 

In tempo training, we utilize a slow cadence for concentric, eccentric, and isometric actions.
At low contraction velocities, type I fibers have a higher efficiency than type II fibers in terms of continuous force production (Buitrago, 2012). Therefore, at low speeds and low intensity, type I fibers are predominantly recruited, which will result in increased aerobic metabolism and oxygen consumption. However, during resistance training, peripheral arterial vessels of working muscles are compressed which causes a reduction in muscle perfusion and impairment in gas exchange (Buitrago, 2012). In summary, slow tempo resistance training induces an increase in oxygen consumption and a decrease in oxygen delivery over an extended exercise duration, which will ultimately lead to local hypoxia in the working muscles. This in addition to effective buffering of lactic acid has proven to be very beneficial in athletic performance.

 

 

 

References

 

Abe T. Exercise intensity and muscle hypertrophy in blood flow-restricted limbs and non-restricted muscles: a brief review. Clinical Physiology & Functional Imaging Jul2012, Vol. 32 Issue 4, p247 6p.

 

Baechle T. Essentials of Strength Training and Conditioning, Third Edition, 2008.

 

Buitrago S. Effects of load and training modes on physiological and metabolic responses in resistance exercise. European Journal of Applied Physiology Jul2012, Vol. 112 Issue 7, p27-39 10p.

 

Manimmanakorn A. Effects of resistance training combined with vascular occlusion or hypoxia on neuromuscular function in athletes. European Journal of Applied Physiology Jul2013, Vol. 113 Issue 7, p1767 8p.

 

Nishimura A. Hypoxia Increases Muscle Hypertrophy Induced by Resistance Training. International Journal of Sports Physiology & Performance Dec2010, Vol. 5 Issue 4, p497 12p.

 

Sumide T. Effect of resistance exercise training combined with relatively low vascular occlusion. Journal of Science and Medicine in Sport (2009) 12, 107—112.

 

Tran QT. The effects of varying time under tension and volume load on acute neuromuscular responses. European Journal of Applied Physiology Oct2006, Vol. 98 Issue 4, p402 9p.

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Energy Systems (Part 2 of 2)

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DSC09405

Muscle Fiber Type: Fast Twitch vs Slow Twitch

 

Skeletal muscles are composed of fibers that have significant physiological and morphological characteristics. Classifying muscle fiber type is most commonly done so by referring to how fast they can twitch, or contract. The identified fibers are Type I (slow twitch), Type IIa (intermediate fast twitch), and Type IIx (fast twitch). The contrast in mechanical characteristics of Type I and Type II fibers is accompanied by a distinct difference in the ability of the fibers to demand and supply energy for contraction and thus to withstand fatigue. (Fox, 2008)

 

Slow Twitch

 

A main characteristic of the slow twitch, Type I muscle fiber is that it has a high capillary density and is greatly supplied by blood and oxygen. This muscle fiber type utilizes the oxidative energy system and is very resistant to fatigue. Due to the fiber’s small diameter, it is not able to contract with much speed or force. Postural muscles such as the soleus (in the calf) or sternocleidomastoid (in the neck), which are constantly being contracted in order to support our bodies, are classified as Type I muscle fibers.

 

Fast Twitch

 

The fast twitch, Type IIx muscle fiber type is essentially opposite to the Type I muscle fiber in every aspect. Type I muscle fiber is has a low capillary density, fatigues quickly, and relies on the anaerobic energy systems to generate fast, powerful muscle contractions. Because the muscle diameter is so large, it is able to have more actin-myosin binding sites for greater strength.

 

Intermediate

 

Finally, the intermediate, Type IIa muscle fiber type has characteristics that are similar to both fast and slow twitch muscle fiber types. This muscle fiber is not quite as powerful as Type IIx but is also less susceptible to fatigue because it has a decent amount of capillary density.

 

A muscle’s variability in percentage of muscle fiber type make up is primarily pre-determined genetically but is also subject to change through imposed demands.

 

Training and Converting Muscle Fiber Type

 

There is some evidence to show that muscle fiber type can convert in response to the type of exercise. For example, if an athlete that has more Type I, slow twitch muscle fibers and trains for speed under anaerobic conditions, the Type I will start to take on characteristics that of Type IIa. In contrast, if an elite sprinter started to train for a marathon, their IIx muscle fibers change characteristics and become progressively more oxidative. While still powerful, they are now more resistant to fatigue do to increase in capillary density and greater ability to utilize the oxidative energy system.

 

Energy System Development after Lifting

 

Is it more advantageous for a basketball player to move quickly and jump high or to stay in the game for a longer duration? Does a marathon runner want to sprint the first 400 meters or do they want to run the entire 26.2 miles?

 

The intensity and type of training the athlete trains under should reflect the sport for which they compete so that their energy systems and muscles can adapt in a way that is most beneficial for performance.

 

At ASP, the athlete may end their resistance training with an ESD session or have ESD specific days. Depending on what phase of the season the athlete is training, the ESD portion of the workout will vary in order to continue or improve the gains from the strength training. It is important that the ESD portion of the workout does not negate the muscular adaptations that we are looking to develop during resistance training.

 

For example, an athlete looking to gain power, speed, and explosiveness would have a heavy weight lifting session followed by an ESD program that would continue to recruit Type IIx and IIa muscle fibers by working at a high intensity with little rest in between bouts.

 

Similarly, we do not incorporate slow endurance training into an athlete’s program when their goal is develop power. Combining heavy lifting with endurance training has been associated with reduced vertical jump ability (Costill, 1967) and reduced or unchanged muscle strength (Costill 1967; Fitts et al. 1989; Kraemer et al. 1995; McCarthy et al. 2002). Possible explanations for this less than optimal power development include adverse neural changes and the alterations of muscle proteins in muscle fibers as Type IIx converts to Type IIa.

 

In the case of endurance athletes, incorporating heavy resistance lifting into an endurance athlete’s program has shown no adverse effects on aerobic power. Work economy and/or endurance performance has been reported to improve after a period with heavy strength training (Cantrell et al, 2014).

 

 

References

 

Cantrell, G.S., Schilling, B.K., Max, R.P, & Murlasits, Z. (2014). Maximal strength, power, and aerobic endurance adaptations to concurrent strength and sprint interval training. European Journal of Applied Physiology.

 

Costill, D.L. (1967). The relationship between selected physiological variables and distance running performance. The Journal of Sports Medicine and Physicl Fitness, 7(2), 61-66

 

Fox, Stuart. (2008). Human Physiology. New York: McGraw-Hill College.

 

Kraemer, W.J., Patton, J.F., Gordon, Se.E., Harman, E.A., Deschenes, M.R., Reynolds, K., Newton, R.U.,

 

Spencer MR, Gasin PB. (2001). Energy system contribution during 200 to 1500m running in high trained athletes. Medicine, Science, and Sports Exercise. 33 (1), 157-164.

 

Triplett, N.T., & Dziados, J.E. (1995). Compatibility of high-intensity strength and endurance training on hormonal and skeletal muscle adaptations. Journal of Applied Physiology, 78(3), 976-989.

 

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Energy Systems (Part 1 of 2)

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Energy System Contribution to Sport and Muscle Fiber Type: Fast Twitch vs Slow Twitch

 

When training athletes, it is important to appreciate the sport for which they compete in order to develop a sound training program that benefits the athlete. Understanding how to train the specific energy systems that are most dominant within the athlete’s sport and the distribution of muscle fiber type that are needed to support those energy systems is crucial to peak athletic performance. This blog will expand on ASP’s approach to energy system developmental training with an emphasis on recruitment and strengthening different muscle fiber types.

 

Overview of Energy Systems

 

The main source of energy that the body uses for all exercise is a coenzyme called adenosine triphosphate (ATP). There are three pathways, or energy systems, that produce ATP that can ultimately be used by the working muscle.

 

The Oxidative, Fast Glycolysis, and ATP-PCr can be classified as either aerobic (requires oxygen) or anaerobic (does not require oxygen).

 

Oxidative Energy System

 

 

In the presence of oxygen, stored glycogen, fat, and, to a certain extent, protein are utilized for the resynthesis of ATP in the oxidative energy system. Within the inner layer of the mitochondria, oxygen is the final electron acceptor by means of the electron transport chain. ATP is formed from ADP and an inorganic phosphate due to the energy release from this flow of electrons. While the supply for this energy system is great, its ability to provide energy to the working muscle is very slow because it relies on the cardiorespiratory system to take in oxygen to the lungs and then transport the oxygen via the heart. This energy system is most dominant in slower endurance sports such as long distance running and cross-country skiing.

 

Phosphocreatine System

 

 

Without oxygen, the body can produce ATP via the ATP-PCr system or the fast glycolysis system.

 

Phosphocreatine (PCr) is a chemical compound that is stored within the muscle and combines with ADP to produce ATP very quickly. According to Paul Gastin (2001) the rate of PCr degradation is at its max immediately after the ignition of contraction and begins to decline after only .3 seconds. The ATP-PCr system allows the body to perform powerful bursts of maximum intensity exercise but is limited by the small amount of stored PCr. The ATP-PCr system is prevalent in a shot-put throw, a baseball pitch, a max jump and the first 1-5 seconds of a sprint. It has been found that it usually takes between 3-7 minutes for the muscle to replenish its stores of phosphocreatine and be prepared for the next explosive bout of exercise.

 

Fast Glycolysis

 

 

The other anaerobic energy system is fast glycolysis, which exclusively uses stored glycogen to produce ATP. During glycolysis, glucose is converted into two molecules of pyruvate. Under anaerobic conditions, pyruvate accepts a pair of hydrogen ions and produces lactic acid within the cytoplasm of the muscle cell in order to quickly provide energy. Although ATP is resynthesized quickly for a time, the accumulation of lactic acid reduces pH levels which interferes with the calcium binding site at the level of the muscle’s myosin head, thus limiting muscle contraction. Eventually, the low pH is also likely to reduce the activity of the glycolytic enzymes, particularly phosphorylase and phosphofructokinase, and results in a reduced rate of ATP resynthesis. ATP production from fast glycolysis does not reach its maximum rate until after 5 seconds and is maintained at this rate for up to 30 seconds after. Sports like basketball, football, soccer, boxing, and the 400m race mostly utilize fast glycolysis.

 

As training occurs, muscle fiber type will adapt in order to support the energy system that is utilized.

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Low Back Pain Introduction (Part 1 of 3)

  |   Injury Prevention and Care, Photos   |   No comment

At ASP we have clients who take part or compete in the super-G, extreme skiing, surfing, gymnastics, rugby and football among others.  What all of these sports have in common are highly compressive forces via impact or ground reaction, associated with forward flexion, rotation, and/or extension.

 

Sources of Injury

 

In the USA, low back pain is the 2nd most frequent reason for physician visits, the 5th ranking cause of hospital admissions, and 3rd most common cause of surgical procedures (Bakhtiary, 2005).  The majority of low back injuries are not caused by a single event, but rather a culminating injury event resulting from a history of excessive spinal loading (Liebenson, 2007).  Therefore, to understand the source of injury it is important to consider athletic activities as well as activities of daily life that repeatedly apply excessive stress to the spine.

 

Colored in blue are the intervertebral disks which act as shock absorbers between vertebra and colored in pink are ligamentous structures that help provide stability to the spinal column.

 

Regarding injury to the lumbar spine, there are three common mechanisms to consider:

-Compression or axial loading to the spine

-Shear resulting from torque or rotation in a horizontal plane

-Tensile stress produced from excessive motion on the spine

 

Structures & Symptoms

The first picture above displays a top view of a healthy intervertebral disk.  The annulus fibrosus is the sturdier outer portion of the disc, which houses the central aspect called the nucleus pulposus, a gelatinous mass in the center of the disc. Repeated flexion of the lumbar spine creates compression in the anterior region of the disk, as well as stretching or tension posteriorly.  With aging, the disks lose water content and become less flexible and also thinner.  The posterior aspect of the annulus fibrosus is the thinnest portion and if there has been any degeneration of that structure the nucleus pulposus may herniate and compress the spinal cord or the nerve roots (Moore and Dalley, 2005).  This is depicted in the second image with the nucleus pulposus migrating posteriorly through a weakened section in the annulus fibrosus and impinging on the spinal nerve.

 

Depending on the level of nerve-root irritation, symptoms such as pain, numbness, or weakness can radiate down into the posterior thigh, calf, heel, and foot (Kolar, 2005). L5-S1 and L4-L5 are the levels most commonly involved in disk herniation due to the fact that 75% of flexion occurs at L5-S1 and 15-70% at L4-L5 (Prentice, 2004).  Disk herniation at these levels can affect various lumbosacral nerves: superior and inferior gluteal (buttocks), sciatic (thigh), common fibular (foot), tibial nerve (foot) (Kolar, 2005).  In addition, a degenerative disk can cause surrounding musculature to tighten in order to support the low back.  These shortened muscles can also cause nerve compression of the lumbosacral plexus. For example, the piriformis muscle helps to stabilize the hip and when overly tight can compress on the sciatic nerve stemming from L4-S3.

 

A deep understanding of the associated anatomy is very important for proper preventative exercise prescription as well as diagnosis and rehabilitation.  Next week, we will discuss a few things we do at ASP to avoid or rehab the associated structures.

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