[Carl Valle]

Carl Valle on March 8, 2012 at 1:23 am #18218

How much stretch is optimal? In a good discussion on the strength coach.com blog, Mike Boyle and Brendon Ziegler shared their personal perspective on stretch reflexes and overcoming inertia. The stretch reflex creates a great overall output, but the body is often required to go the opposite direction first, causing a time trade off that must be managed. When sprinters are in the starting blocks, s

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[tscm]

tscm on March 8, 2012 at 1:57 pm #115211

Carl, I will be frank and say that Boyle’s personal perspective often comes across as that of an uninformed and untelligent person. In some ways the stuff he writes is very funny but on another level sad as he is influencing athletes and coaches and it becomes very necessary for those like Mike Stone to point out the obvious. I have written notes on his blog below in a separate post. First, though, I will share my thoughts on key principles I look at from a postural perspective regarding transfer:

Background: Resistance Training is a powerful stimulus to induce many adaptations, and often overlooked in the search for Watts and Newtons are the implications of posture, length-tension relationships and intramuscular + intermuscular co-ordination which has big implications for transfer and performace of other activities (i.e. changes in posture generally –> changes in technique for sprinting/everything). Some of the below may seem negative, but I am all about refining and subtracting as much as adding, because resources for attention, focus and adaptation are ultimately finite.

1. Position of the centre of mass: With a load up to 2XBodyweight or more across the shoulders the COM of the system in a heavy squat is much different to an anatomical position with no external load. Effects are also clear for movements with the bar in the hands, and an anterior bar path has big effects.

Implication: Increased load on the bar has exponential effects on the location of the COM and increases torque on the spine and the pelvis greatly, interfering with Lumbo pelvic rhythm. The fact is the thoracic spine is not designed for large ROM in extension and the natural curve is slightly kyphotic (“arching” the upper back is not easy anatomically) , leaving the lumbar region to bear the brunt. With more and more weight added at shoulder level, the pelvis will eventually tilt anteriorly to gain stability, and a forward head will also likely result (see start position in video below). This is key to the debate of “how strong is strong enough?” as (especially for the lighter and less specific builds of non-strength sport athletes) lumbopelvic rhythm will deteriorate as loads get very high relative to bodyweight, regardless of leg strength, and transfer will be affected once these postural compensations occur.

Recommendations:

i) Keep the load to a level (often 60-80%) where lumbo pelvic posture is reasonably maintained and sticking points are minimised. If you have to yell “arch” at the athlete to maintain stability it’s probably too heavy.
ii) Be careful of shallow squats (and perhaps hang cleans with a countermovement 😉 ) as it is possible to overload the lumbopelvic region easily with artificially high loads.

2. Posture of the pelvis, tibiofemoral joints and ankle: I obviously have some criticism of Dan Pfaff but this response in an interview is an excellent sentiment https://www.down-right.co.uk/2008/08/dan-pfaff-training.html:

“So as a workout unfolds how do you know when the athlete is becoming prone to injury?

I look at postural integrity. If they start to change postures and sub-recruit muscles they shouldn’t be using I stop the workout. I look at the reflexivity of the joints and how fluid the motion is. If the fluidity goes away and it starts to look mechanical we stop.”

Strength sports have a great influence on strength and conditioning in many ways, but the background of maximal loads mean that advice centres around very conscious bracing and arching for stability, and overall very mechanical movements. At high loads we encounter sticking points, which almost inevitably result in lumbo-pelvic compensation (particularly in athletes not from strength sports who lack technical proficiency), often accompanied by compensation at the tibiofemoral joints (e.g. “knees coming in”) and ankle (not often recognized but loss of medial longitudinal arch is critical in squat position as functional anatomy and much research on ACL injuries attest). It is often suggested that Olympic lifting shoes allow depth by increasing anterior “dorsiflexion” ROM but the key is allowing less drop of the medial longitudinal arch, and dorsiflexion is the result.

Recommendations:

i) Avoid loads (and combination of load and reps/sets/overall session) that induce sticking points at any point during the set/s.

ii) Approaching failure, technical or otherwise, comes with big risks for maintenance of posture. You might not get injured, but transfer is unlikely to be optimal with loss of posture.

iii) Slow down the eccentric and make sure of posture. There are many benefits to eccentric emphasis, but in this case the point is that fast eccentrics under load are not friendly to posture, and the common “drop- bounce – grind through sticking point” technique of lifting is not desirable.

3. Range of Motion: Basically range of motion should be limited by the “postural integrity” and “sub-recruitment” of muscles Pfaff mentions. The lower we get in a squat the more closely we have to watch the position of the pelvis, tibiofemoral (often keeping an eye on alignment of the patella tendon is a good measure) and ankle joints in particular. If we force range of motion down/back to a fixed point as with a box squat or in chasing a deep squat without regard for posture this is where these substitutions are likely and we will see the drop-bounce-grind in play. There are also some exercises where lumbo pelvic rhythm is likely to compromised, and heavy loading should be applied cautiously to avoid undesirable effects on intermuscular co-ordination. Examples include:

The Bulgarian Squat: Forcing depth to a pad on the ground is exceptionally foolish in my opinion. If an athlete has a pelvis stabilized Thomas test showing hip position 20 or so degrees beyond neutral and 70 degrees knee angle with no frontal or transverse plane deviation, perhaps they can at least get into the start position with a loaded bar on their back and maintain a neutral pelvis, and potentially even get some of the way down. At the very least the load should be DB’s in the hands to reduce torque on the lumbar spine and realistically most athletes should stick to lunge positions where the rear foot is on the ground, and control depth with slow eccentrics based on individual lumbopelvic rhythm and avoid the dop-bounce-wobble/grind as per this video.

Note the subtle rotation of Boyle’s foot in the picture below, indicating that just frontal and transverse plane compensation for lack of sagittal range of motion is important. This foot rotation is very common in those with the notorious lateral myofascial tightness.

The Hip Thrust: Loading up the lower abdomen means force is applied through the region of the lower lumbar spine and results in a tendency for pelvic tilt. The elevation of the shoulders helps somewhat but the fixed anchor point of the scapulae means lumbar and cervical extension is very likely (watch head/neck below, also note lack of hip/knee/ankle co-ordination as per athletic movement).

[tscm]

tscm on March 8, 2012 at 2:13 pm #115212

Hang Cleans (with “rocking” etc): The effects of anterior bar path and using the back and legs on lumbo-pelvic rhythm is clear (more below) and has been well discussed. The catch portion of Olympic lifts can also be problematic for athletes who combine poor thoracic mobility and scapulo-humeral rhythm with a lack of hip extension.

Pistol squats: Not good for loading as the free leg flexion causes lumbopelvic disturbance, the thoracic and lumbar spine is flexed (especially with dumbbells held in front).

Recommendations:

i) Keep ROM individualized to a point where postural integrity and fluidity is maintained, do not force to set external depths, individualise ROM based on mobility level.

ii) Slow down the eccentric- individualizing ROM is nigh on impossible when the “drop-bounce-grind” technique is employed
iii) Be careful which exercises you load very heavily and how you load them (both weight and placement e.g. Bulgarian squats with weight in hands vs on back). Let manual testing and flexibility testing (with pelvic stabilization) guide you as to what are realistic exercises and depths where alignment (especially see frontal/transverse plane deviation on Thomas test, and Ober’s test for abduction with hip extension as lateral myofascial system around TFL, ITB, VL, lateral RF is often a mess) and postural integrity are maintained.

iv) Watch for lumbopelvic disturbance in split stance lifts as the combination of tilt plus rotation is very strong and not apparent in bilateral work with a symmetry focus.

v) A “hip-hinge” emphasis often results in lumbar extension (see box squats and hip thrust). The co-ordination of the hip, knee and ankle movement is an essential component of sport tasks and intramuscular + intermuscular co-ordination adaptations in the weight room can affect transfer.

Best bets for Heavy Loading:

I favour bilateral squatting and Olympic lifts (eccentric concerns above less relevant for O-lifts) with an emphasis on fluidity and integration/co-ordination of the hip, knee and ankle, as well as the postural integrity concerns noted above.

Key Points:

1. Modify the load to reflect technical proficiency and ensure posture is adequate, the relationship between load and torque on lumbo-pelvic rhythm is not linear as more weight at the shoulders relative to bodyweight induces a change in the centre of mass of the system. Even highly experienced lifters in strength sports need to arch hard and brace to achieve stability at heavy loads.

2. Slow down the eccentric and look closely, take responsibility for posture and respect the limits of postural integrity.

3. Respect integration/co-ordination of the hip, knee and ankle in athletic movements.

[tscm]

tscm on March 8, 2012 at 2:29 pm #115213

Mboyle1959 Blog Post https://strengthcoachblog.com/2012/03/03/why-the-rock/

1. My athletes have been performing the hang clean in this manner for over twenty years. To be honest, initially I never taught it. It just happened. Our better lifters soon realized that trying to hang clean a heavy weight from a dead stop was difficult. Many began to rock or weight shift. They also began to hang clean a lot of weight. For a few years I simply let the lift evolve and at numerous points in the eighties and nineties had 30 football players hang cleaning over 300 lbs. Not bad for 1AA football.

Boyle’s biographical history is not my concern, as particularly in a pure strength and conditioning environment a lack of training history and objective measures means we are not in a meritocracy. A countermovement will increase power output and possible loads, as is seen by endless research on vertical jump movements with and without a countermovement, and bouncing bench presses every week night in the local gym. Obviously greater weights can often be lifted with poor form in a hang clean but the issue is transfer, and being drawn to loads going up is quite myopic. “realized trying to hang clean a heavy weight from a dead stop was difficult” – more difficult than with the countermovement? no shit 😉

2. A few years later I made the foolish mistake of listening to my critics. They said that rocking was wrong and that we needed to stop. Like a good coach I agreed and vigorously coached my athletes. I forbade them from rocking. The results were simple and obvious. Our numbers dropped and dropped a lot. One of my athletes actually came up to me and said “nice job you’ve managed to make us all weaker”. His hang clean max had dropped from 370 to 340. ( Please note- this players vertical increased 12″ in 4 years from 20 to 32″).

Clean numbers dropping is, again, not a revelation to anyone who is aware of the existence of the stretch shortening cycle (I may missed the memo that regarding a “death to the SSC” campaign 😉 ), to think that a coach with such experience (in training athletes to improve their vertical jump no less!), can’t recognize this is puzzling (perhaps Paavo Komi needs to present at the next Perform Better Summit LOL as fascial trains may be a bit advanced it seems 😉 ). For the athlete whose vertical had gone from 20-32″, what was the effect on his vertical of his clean going from 370 to 340 with the new technique? Why I have to ask this question or point out the advantage of a countermovement in this day and age is beyond me.

3. In order for the bar to clear the knees the hips and knees extend. After the bar clears the knees, the knees actually flex or rebend to move the hips into position. In the jump portion of the lift the knees extend again. The cycle is extend-flex-extend. The rock you see in our Olympic lifts is this same action. Weight shifts back to the heels, knees extend. Weight shifts forward, knees flex. Hips explode and hips and knees extend. What we are doing is what every athlete does to create maximal explosive power. Watch the vertical jumps at the NFL Combine. What do you see? Rocking, pre-stretch, weight shift.

Again it’s a little painful to have to point this out but there are obvious differences as Brendon Ziegler alluded. In the Boyle clean, the “flex/extend” is a countermovement that is then reversed, the bar goes down and comes back up, the COM of the system goes down and comes back up. In an Olympic lift, the bar continues to move up as does the COM of the system, and slight knee flexion in transition is a fluid part of the movement of a clean from the floor with the function of keeping the bar close to the body. The claim that “hips explode and hips and knees extend” in Boyle’s athletes’ cleans is false. The video below demonstrates a butt kick type jump and a lack of knee and hip extension, accompanied by a forefoot emphasis and anterior displacement of the barbell and COM.

The Olympic lifters below demonstrate fluid extension and the velocity of the bar in the vertical direction is always positive during the “double knee bend, and it is not an active knee bend but a result of co-ordination between the knee and hip, with their respective extension velocities being different at various points in the lift. Again, there is no countermovement in high level Olympic lifters with slight double knee bend, the bar and moreover the COM of the system DOES NOT deviate from a positive vertical velocity (the bar is also kept close to the body).

Boyle’s athletes

Liao Hui World Record

Pyrros Dimas Power Clean

Further Examples

https://www.youtube.com/watch?v=uHBtG0xaLUY

4. What we are doing is what every athlete does to create maximal explosive power. Watch the vertical jumps at the NFL Combine. What do you see? Rocking, pre-stretch, weight shift.

What I see:

i) The COM of the system in a vertical jump with bodyweight load is relatively close to its anatomical position, rather than “somewhere out and down there” due to a heavily loaded bar in the hands which has deviated anteriorly from the body by a large margin as we see with the rocking hang clean.

ii) The hips, knees and ankles extend fully in a co-ordinated manner. I have yet to see a butt kick technique recommended for a maximum vertical jump at the combine or anywhere else for that matter.

iii) “Rocking” is a beautiful description of a not so beautiful movement as it perfectly described the lack of fluidity displayed by Boyle’s lifters with their jerky, lumbar extension dominant form (compare to the smooth, truly aesthetically and biomechanically beautiful kinematics of some of the Olympic lifters above). As per the above, the weight shift from flat foot to toe at take off is the result of co-ordinated movement in a vertical jump and acceleration of the COM is much lower as we move into plantarflexion, rather than an aggressive “weight shift” at the start of a clean.

5. I have lots of females cleaning 135 lbs for reps and the majority of my male hockey players hang clean between 250 and 320? Am I wrong? You be the judge. Healthy athletes, great clean numbers, great speed improvement, great vertical jump. Where do I go wrong?

RE “am I wrong?” see above. Boyle went wrong in completely forgetting about (ignoring?) biomechanics, physiology, and motor control as well as logic and context. A systematic review of the literature will tend to show that in pubescent neophytes weight training induces strength, acceleration and vertical jump improvements, and we need to get more precise to evolve training.

While Boyle seems keen to stop listening to critics, potentially he needs to stop listening to himself, as he appears to be unbelievably uninformed on the basics of the exercise sciences and greatly challenged when it comes to rational thought on the basis of blog posts like the above.

[tscm]

tscm on March 9, 2012 at 12:13 am #115218

RE points from the original blog:

What is the value of the prestretch in sport?

As you say this is matter of return on investment given how much can be gained in time to the ball by positioning and skill vs speed, the importance of speed to team sport performance, and also how much can be gained and how readily from improving gross power output compared to prestretch. In the context of team sports, acceleration is very often in the context of a cutting movement rather than continuing straight ahead as per a “false/split step”, and cutting requires deceleration first (i.e. velocity will approach a static start first) in the sagittal, frontal and transverse planes before acceleration can occur. Cutting will also involve a lowering of the COM, and give more quad/glute emphasis in the subsequent acceleration.

As such the prestretch requirements are less related to the triceps surae and much more related to slower eccentrics from the quads, glutes, hip abductors and hip rotators, and power output to overcome inertia is critical. While relevant “prestretch” qualities of the quads and glutes will likely be addressed through many conventional training methods, the related function of the hip abductors and extensors is due to many mechanisms covered in detail in ACL injury research.

The other important point is that the attentional demands of technical and tactical execution detract greatly from the potential for conscious sprinting technique during a game or play. Changing inherent qualities to a large extent will result in the best carry over when focus on technique is difficult, and large changes are generally more achievable in gross active power output rather than prestretch mechanisms. Compared to sprint specific prestretch, gross power output from positions of lower COM is generalisable to many sporting actions from jumping to low COM lateral movement (defensive shuffle positions in basically all team sports), to stability when making a tackle (whether it involves a collision as in gridiron/rugby or not as in soccer) and others. The two big areas for gains in “game speed” will tend to be

i) Concentric power output from hip and knee extensors for propulsion in a linear, lateral, and vertical direction with a bias to slow contraction velocity as most sprints are very short.

ii) Eccentric power output from hip and knee extensors for braking in the complex context of specific postures related to hip abductors and external rotators with some contribution from trunk and foot as well. In terms of return on investment this area also has big injury prevention relevance.

The video posted on Rodriguez and Ronaldo is relevant here, note force absorption into a squatting position and subsequent acceleration from that position again for efficient slalom running, compared to the heightened impact of sagittal prestretch in sprinting.

Pre Stretch vs Pre Tension vs Pre “Jerk”

I’d make a very clear distinction between

Pre tension: Which will exist in a static block start or snatch from blocks or certain sport postures.

Pre Stretch: A significant, controlled and co-ordinated movement which contributes to efficient performance in the concentric phase, like a “repeat hang snatch with a prestretch” or a countermovement jump.

Pre-Jerk: Poorly controlled movement lacking co-ordination which subverts the essential components of the concentric and leads to alters muscle recruitment. E.g. the “rocking” hang clean with a jerk forward and a loss of the hip and knee c-ordination inherent to Olympic lifts, with lumbar extension substituted.

Hang snatches are one option, though the amplitude of hip extension vs knee extension in a hang snatch may be somewhat different to block starts. It should be noted there is nearly always some countermovement from the body when lifting from blocks although the bar may not move. Another option is a push jerk (either split or squat landing) from a pause squat. Alternating Bench/step (30-40cm) jumps and conventional vertical jumps with a weighted vest can also be useful.

[tscm]

tscm on March 9, 2012 at 12:17 am #115219

Plantar flexor prestretch in the block start

Hanging the heel over the block must be considered, along with block spacing and angles, in the context of power output and alterations to individual posture. I am not sure about hanging the heel over re joint stiffness, and particularly on the front leg it reducing the available surface upon which to apply force may be unhelpful re muscle activation. I would suggest that a greater length of the triceps surae in the blocks may allow higher velocity due to improved timing and co-ordination of the relatively sequential extension of hip-knee-ankle in the block start. Research of interest

Longer plantarflexors or increased pre tension on knee extensors?

https://www.tandfonline.com/doi/abs/10.1080/02640410500131753
Nine male sprinters performed maximal sprint starts from the blocks that were adjusted either to 40° or 65° to the horizontal… Muscle- tendon lengths of the medial gastrocnemius, soleus, vastus medialis, rectus femoris and biceps femoris were calculated from the set position to the end of the first single leg contact…block velocity was greater (P < 0.01) in the 40° than in the 65° block angle… the initial lengths of the gastrocnemius and soleus of the front leg in the block at the beginning of force production until half way through the block phase were longer (P < 0.001) in the 40° than in the 65°…initial length and the length in the middle of the block phase were also longer in the 40° than in the 65° block angle…for both the gastrocnemius (P < 0.01) and soleus (P < 0.01- 0.05) of the rear leg. In contrast, the initial lengths of the rectus femoris and vastus medialis of the front leg were longer (P < 0.05) in the 65° than in the 40° block angle condition. All differences gradually disappeared during the later block phase. The peak ankle joint moment (P < 0.01) and power (P < 0.05) during the block phase were greater in the 40° than in the 65° block angle condition for the rear leg. The peak ankle joint moment during the block phase was greater (P < 0.05) in the 40° block angle for the front leg, whereas the peak knee joint moment of the rear leg was greater (P < 0.01) in the 65° block angle condition. The results suggest that the longer initial muscle- tendon lengths of the gastrocnemius and soleus in the block phase at the beginning of force production contribute to the greater peak ankle joint moment and power and consequently the greater block velocity during the sprint start.

Increased ankle stiffness allows more efficient transmission of forces from hip/knee?

https://www.ncbi.nlm.nih.gov/pubmed/22098532
One elite sprinter performed 10 maximal sprint starts…The lower-limb joints predominately extended and revealed a proximal-to-distal sequential pattern of maximal extensor angular velocity and positive power production. Pearson correlations revealed relationships (P < 0.05) between ankle stiffness (5.93 ± 0.75 N x m x deg(-1)) and selected performance variables. Relationships between negative power phase ankle stiffness and horizontal (r = -0.79) and vertical (r = 0.74) centre of mass velocities were opposite in direction to the positive power phase ankle stiffness (horizontal: r = 0.85; vertical: r = -0.54). Thus ankle stiffness may affect the goals of the sprint push-off in different ways, depending on the phase of stance considered.

Elongation = plantarflexion + better proximal to distal sequencing?

https://www.ncbi.nlm.nih.gov/pubmed/1585060
The sprint starts of 12 skilled collegiate sprinter/hurdlers were filmed for four different sprint start conditions. ..The subjects employed their preferred right-left leg placement in the blocks, while the anterior-posterior spacing of the front block with respect to the starting line and the amount of forward lean in the set position were varied. Four positions were constructed that accounted for anthropometric differences. The four positions consisted of combinations of two arm orientations (forward lean and perpendicular to ground) and two front block to starting line distances (bunched and elongated). … The results indicated that the elongated starting positions resulted in greater horizontal displacement, greater propelling impulse, increased first step toe-off velocity, and greater average velocity through a 2-m speed trap…Forward lean tended to result in greater vertical velocity at block clearance and horizontal velocity at first step toe-off, whereas perpendicular arm positioning resulted in greater 2-m speed trap velocity.

Stiffness but not tension?

https://www.ncbi.nlm.nih.gov/pubmed/17215551
Pre-tensed and conventional starts that exert, respectively, large and small forces against the starting blocks in the "set" position (0.186 vs. 0.113 N per newton of body weight) were analyzed. The starts were videotaped, and the horizontal forces exerted on feet and hands were obtained from separate force plates. In the pre-tensed start, the legs received larger forward impulses early in the acceleration (0.18 vs. 0.15 N x s per kilogram of mass in the first 0.05 s), but the hands received larger backward impulses (-0.08 vs. -0.04 N x s x kg(-1)). At the end of the acceleration phase, there was no significant difference in horizontal velocity between the two types of start and only trivial differences in the center of mass positions. The results did not show a clear performance change when the feet were pressed hard against the blocks while waiting for the gun.

Earlier EMG is possibly helpful

https://www.springerlink.com/content/h7pkxp283803k3w3/
Eight male sprinters were filmed running three maximal starts over 3 m on a long force platform. ..EMG activities of the gastrocnemius caput laterale muscle (GA), vastus lateralis muscle (VL), biceps femoris caput longum muscle (BF), rectus femoris muscle (RF) and gluteus maximus muscle (GM…Total reaction time (TRT) was defined as the time from the gun signal until a horizontal force was produced with a value 10% above the base line. Pre-motor time was defined as the time from the gun signal until the onset of EMG activity and motor time (MT) as the time between the onset of EMG activity and that of force production. ..Significant positive correlations were observed between MT and maximal horizontal force and the velocity of the centre of gravity during the last observable contact on the blocks (P<0.05-0.01). The EMG activities of the muscles analysed demonstrated large individual variations until the end of the first contact after the blocks. This resulted in non-observable MT in some individual cases. In general, however, despite the complex multijoint character of TRT, its fractions could be analysed during the early phases on the blocks. To optimize starting action it is desirable that all the important muscles should be activated before any force can be detected against the blocks.