Video

Shoulder Health in the Plane of the Scapula

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What is the plane of the scapula?

 

The plane of the scapula can be defined as the normal resting position of the scapula as it lies on the posterior rib cage at an angle of 30-45˚ (Johnson 2005). It can also be defined as the angle assumed by the face of the glenoid fossa (Starkey & Ryan, 2010). In simple terms, this arm position is the angle in which the scapula is laterally facing outwards from an individual’s upper back. The picture below gives an illustration of where exactly the plane of the scapula lies:

 
Screen Shot 2015-05-18 at 9.25.35 AM

Why move within the plane of the scapula?

 

There are several reasons that explain why it is beneficial to move within this plane. The first, and probably the most important reason, has to do with simple physics. When one is in the plane of the scapula, the mechanical axis of the humerus approximates with the mechanical axis of the scapula (Johnson, 2005). This optimally aligns the deltoid muscles and the supraspinatus muscle for elevation of the arm, thereby avoiding subacromial impingement during shoulder abduction (Paine & Voight, 2013).

Screen Shot 2015-05-18 at 9.25.25 AM

 

Another reason for moving within the scapular plane is that it puts less stress on the shoulder capsule. When the arm is raised overhead in the sagittal or frontal plane, the shoulder capsule is stressed from obligatory humeral rotation. For example in the frontal plane, the anterior capsule structures are tensioned, which may complicate soft tissue healing in patients who have glenohumeral injuries/instability. Whereas within the scapular plane, the inferior part of the capsule is relaxed, since no humeral rotation is required (Paine & Voight, 2013).

 

A final reason for moving within the plane of the scapula can be explained by the rule of the length-tension relationship. Since the rotator cuff muscles originate from the scapula, the position of the humerus in the scapular plane increases the length-tension relationship of the deltoid and rotator cuff muscles, therefore helping to facilitate optimal muscle force (Paine & Voight, 2013).

 

Overall, research has suggested that exercises completed in this specific plane can provide great benefits for improving shoulder function. Improvements in function and shoulder biomechanics include relief of the anterior capsular structures of the shoulder, decreased chance of rotator cuff compression, and an overall improvement of the shoulder complex neuromuscular performance. As well as improving the overall function of the shoulder, the improvements also reduce the chance of pain and injury for the shoulder complex, particularly in overhead throwing sports/ movements. (Paine & Voight, 2013)

 

Pressing exercises in the plane of the scapula vs the frontal plane

 

An example of a strength exercise being performed in the scapular plane is the 2DB bench press. A study done on the avoidance of shoulder injuries during resistance training showed that performing this exercise, or any overhead press within the scapular plane will help minimize anterior capsular distension (Davies, Durall, & Manske 2001).

 

Several studies have shown the importance of exercising in the scapular plane versus exercising in the sagittal or frontal planes. For example, a study conducted on the assessment of internal and external rotation in the frontal plane versus the plane of the scapula found that isokinetic strength testing of the shoulder’s internal and external rotators within the scapular plane had several advantages to testing in the frontal plane. Abducting the arm within the frontal plane tends to place the glenohumeral joint into more of a closed packed position. This position may place undesirable stress on the soft tissues of an injured joint, and may even be uncomfortable for healthy subjects (Hellwig & Perrin, 1991). Movement within the scapular plane minimizes tension/rotation of the inferior portion of the capsule and enhances stability of the glenohumeral joint by allowing a maximal amount of congruity between the head of the humerus and the glenoid fossa (Hellwig & Perrin, 1991). Because greater stability and increased comfort are important factors to consider when strength-testing or rehabilitating the shoulder, the scapular plane should be the preferred position.

 

 

External rotation in the plane of the scapula

 
Studies have also shown that external rotation within the plane of the scapula is more beneficial in terms of the amount of torque produced during concentric and eccentric contractions. The study done by Hellwig and Perrin demonstrated that assessing isokinetic strength of the shoulder internal and external rotators in the scapular plane changes the peak torque to body weight ratios for concentric external rotation. They found external rotation peak torque to body weight ratio values to be significantly higher in the plane of the scapula than in the frontal plane (Hellwig & Perrin, 1991). This correlates with the previous finding of increasing the length-tension relationship when one is within the scapular plane, thus increasing the amount of torque and muscle force produced. The table below illustrates the degree of muscle activation during external rotation in several different positions:

 

Screen Shot 2015-05-18 at 9.25.02 AM

The table above demonstrates 3 of the 4 rotator cuff muscles and deltoid muscles that are activated during external rotation and abduction. Here we can see that performing external rotation while standing and in the scapular plane at 45˚ abduction shows the infraspinatus and teres minor being the most active, when compared to the supraspinatus, middle deltoid, and posterior deltoid (Andrews, Escamilla, & Yamashiro, 2009).

 

This is due to the role that the infraspinatus performs during glenohumeral abduction. At about 70˚, the humeral head becomes depressed by the infraspinatus, teres minor, and subscapularis to allow the humeral head to clear the acromion process. At 115˚, the humeral head is externally rotated by the infraspinatus and teres minor in order to clear the greater tuberosity of the humerus under the acromial arch.

 

Rhythmic stabilization in the plane of the scapula vs outside of the plane of the scapula: Is it still beneficial?

 

Rhythmic stabilization movements are short, rapid movements in an acute area performed for a short period of time, i.e., 10 seconds. These movements can be used to enhance shoulder function, as they improve neuromuscular control, proprioception, and dynamic stabilization. Physiologically speaking, these exercise drills facilitate agonist/antagonist muscle co-contractions, which allows for efficient coactivation to occur. This restores the balance in the force couples of the shoulder joint, and thus enhancing joint congruency and joint compression (Townsend et al, 1991). Research has shown that rhythmic stabilization movements performed in the plane of the scapula, and at the end-range external rotation positions can greatly benefit the shoulder complex, especially for the overhead throwing athlete who is either recovering from injury, or who is preventing injury in the first place. In saying this, rhythmic stabilization exercises performed in different planes can be beneficial for the injury prevention of any athlete, as different angles though the various possible ranges of motion can be targeted and improved on (Wilk et al, 2002).

 

 

References
 
Durall, Chris J., Robert C. Manske, and George J. Davies. “Avoiding Shoulder Injury From
Resistance Training.” Strength & Conditioning Journal 23.5 (2001): 10.
 
Escamilla, R. F., Yamashiro, K., Paulos, L., & Andrews, J. R. (2009). Shoulder muscle activity
and function in common shoulder rehabilitation exercises. Sports medicine, 39(8), 663-685.
 
Hellwig, E.V. & Perrin, D.H. (1991). A comparison of two positions for assessing shoulder
rotator peak torque: the traditional frontal plane versus the plane of the scapula. Isokinetics and Exercise Science, 1, 1-5.
 
Johnston, T. B. (1937). The movements of the shoulder joint: A plea for the use of the plane
of the scapula as the plane of reference for movements occurring at the
humero‐scapular joint. British Journal of Surgery, 25(98), 252-260.
 
Paine, R., & Voight, M. L. (2013). THE ROLE OF THE SCAPULA. International Journal of
Sports Physical Therapy, 8(5), 617–629.
 
Starkey, Chad, Sara D. Brown, Jeffrey L. Ryan, and Chad Starkey.Examination of Orthopedic
and Athletic Injuries. Philadelphia: F.A. Davis, 2010. Print.
 
Wilk, K. E., Meister, K., & Andrews, J. R. (2002). Current concepts in the rehabilitation of the
overhead throwing athlete. The American Journal of Sports Medicine, 30(1), 136-151.

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Success on the Court!

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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 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 2 of 3)

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Sports such as football and skiing involve high compressive forces via collision impact or ground reaction.  This excessive loading of the spine under high velocity combined with a forward bent posture can cause vertebral endplate lesions or anterior intravertebral disk herniation (Rachbauer, 2001).  Forward bending greatly increases intradiskal pressure, causing fracture of the normal vertebral endplate.  In baseball and golf, athletes perform forward bending and rotation while swinging, which applies shear stresses to the spine that can lead to annular tears of the intervertebral disks.  In gymnastics and dance, vigorous lumbar flexion and extension movements produce tensile stresses on the spine, which can strain the surrounding lumbodorsal fascia, muscles, or ligaments.  In addition, repetitive hyperextension of the low back, which is common in numerous sports (football, gymnastics, diving, figure skating) can lead to the development of spondylolysis – stress fractures of the pars interarticularis (Jagadish, 2013).  With the various movements (flexion, extension, rotation) involved in sports combined with external loading, the lumbar spine can be damaged due to a combination of compression, shear, and tensile stresses.  It is important to take all of this into account when providing exercise prescription for each athlete’s respective sport.

 

ASP athlete and founder, Jack Cooney, understands, implements and practices first hand, the programming necessary, across all sports, to strengthen the posterior chain and involved structures that support the spine.  

 

Interestingly, a study on surfers’ low back pain, reported CT scans that showed no fractures or disk herniation and MRI studies that showed no spinal cord compression, acute disk changes, or ligamentous injury (Chang et al., 2012). This non-traumatic spinal cord injury is known as surfer’s myelopathy. The hypothesis is that the low back pain is associated with lumbar hyperextension and ischemia (lack of blood flow) resulting in tissue death of the great anterior radicular artery which provides the blood supply to the lumbar and sacral cord.  Lying prone on a surfboard in a hyperextended position with simultaneous paddling and maneuvering requires well-developed back musculature (Shuster, 2011).  Therefore, novice surfers may exert considerable forces on the spine if insufficiently trained muscles cannot protect the back.

 

At ASP we make sure that every one of our athletes is fully aware of their required posture for each exercise and the implications on the spine through positioning, breathe, and their individual bony structure.

 

Similarly as in sport, daily life, prolonged sitting and slouched posture can increase compressive forces on the lumbar spine exposing it to injury.  Sitting has been shown to increase intradisk pressure by approximately 40% when compared to standing (Howell, 2012).  Slouching results in backward rotation of the sacrum, causing dorsal widening of the L5-S1 disk and strain on the iliolumbar ligaments.  Both activities produce extended loading of the spine, decreasing disk hydration and separation between vertebra.

 

Lastly, certain body types are predisposed to injury such as flat back or scoliosis (congenital or functional), where the lumbar spine is in an unfavorable postural position.  The lumbar lordosis curve is necessary to evenly distribute the center of body weight load.  Studies have shown correlation between decreased lumbar lordosis and increased spinal nerve compression.  Using thermographic imaging, reports show less lordosis resulting in higher temperatures in the lumbar region, as nerve muscle stimulation was transmitted to the skin (Gong, 2011).  Also, sitting with a straightened back shows increased intradisk pressure by approximately 10% (Howell, 2012).

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