The "Overshoot Phenomenon" (Part 2)

Carrying on from the previous post, both Andersen et al. (2000 & 2005) showed decreases in Type IIX and increases in Type IIA muscle fibres post training compared to baseline. Once these measures were taken, a 3 month detraining period was implemented. Detraining meaning no resistance training was performed and the subjects returned to their normal daily lives (subjects in both studies were sedentary, no previous regular resistance training and no regular exercise within the last year).

So what happens after a detraining period?

The proportion of Type IIX muscle fibres increased past baseline PRE training values while the proportion of Type IIA muscle fibres significantly decreased below PRE training values.  This is known as the “overshoot.” (Type IIX surpassing pre training values).

What about performance post detraining period?

Andersen et al. (2005) used isokinetic, maximal unloaded knee extension and evoked muscle twitch to measure performance.

Isokinetic testing if anyone didn't know what this machine was

Isokinetic muscle strength and power at 30˚ and 240˚ decreased back to pre training levels. However, angular velocity, angular acceleration, total moment of force, and power during the maximal unloaded knee extension all significantly increased past PRE and POST training values. Furthermore, peak twitch rate of force development (RFD) significantly increased post detraining compared to pre and post training.

An interesting point to note is that the subjects produced greater force post detraining at greater velocities compared to both pre and post training. Also, subjects produced more power compared to pre and post training at greater angular velocities. From these data, we could speculate that the overshoot may only relate to high velocity unloaded movements (E.g. punching, sprint cycling). However, I have also heard this method being used in bobsled with the starting push with great success so even some loaded velocity movements may benefit.

Part 3 will add a study looking at the overshoot with more of a performance based view in professional athletes to see whether or not this phenomenon can be seen in a sporting context. 

The “Overshoot Phenomenon” (Part 1)

There are only a few papers to date showing the “overshoot phenomenon” (Andersen et al. 2000 & 2005) and only one paper done using professional athletes within a season (de Lacey et al. 2014). Explained very simply, an “overshoot” occurs when a taper or detraining from resistance training takes place. Or in other words, time off is taken from resistance (weight) training. Anecdotally I have heard the Great Britain cycling team used this leading into the 2008 Beijing Olympics for the track cycling and cleaned up the gold medals. For now, let’s go into a little more detail.

There are 3 types of pure muscle fibres (to keep it very simple). Type I, Type IIA and Type IIX. Muscle fibres can also posses more than one type, e.g. Type IIA/IIX, but for now, we’ll stick to just 3 fibre types. Type I are your slow twitch fibres contributing more to the endurance aspect of muscle contraction. Type IIA and IIX are your fast twitch fibres and contract much more rapidly than Type I. Type IIX contract approximately twice as fast as Type IIA and about 5-10 times faster than Type I but fatigue very quickly.

As resistance training is undertaken for an extended period of time, (e.g. in Andersen et al. 2000 & 2005 it was 3 months for a total of 38 sessions) an adaptation occurs where the number of Type IIA muscle fibres increase while the number of Type IIX decrease compared to pre training. As shown in Andersen et al. (2000), a significant increase in Type IIA and a significant decrease in Type IIX were found post training. So we have a decrease in the bodies most powerful muscle fibres and an increase in more efficient fast twitch fibres.

So how do we increase Type IIX muscle fibres and potentially muscular power? Could this be useful for your sport you compete in? These will be explained in upcoming parts!

References:
http://www.ncbi.nlm.nih.gov/pubmed/10883005
http://www.ncbi.nlm.nih.gov/pubmed/15731398

Contrast Training to Develop Horizontal Capabilities

As promised, here are a few examples of complexes to develop horizontal capabilities.

A1. Hip Thrust 3-5x5-10             

A2. Broad Jump 3-5x1-4

A1. Heavy Sled Push or Drag 3-5x10-40m

A2. 10m Sprint 3-5x1

A1. Heavy 45˚ Back Extension 3-5x5-12

A2. Med Ball Scoop Toss 3-5x1-5

A1. Kettlebell Swing 3-5x5-10

A2. Light Sled Sprint 3-5x10-40m

A1. Glute Bridge 3-5x5-10

A2. Bounding 3-5x10-20m

These are just some examples of pairing a force based exercise with a velocity based exercise to help improve power output in the horizontal direction. Doing the complexes in this order enhances the explosive capability of the muscle, otherwise known as post activation potentiation. You can get creative with these and pair all sorts together.

The Strength Speed Continuum Specifically for Horizontal Capabilities

Here’s my post on the strength speed continuum for horizontal capabilities to potentially improve short sprint speed performance. Again to quickly recap, you have exercises ranging from absolute strength to absolute speed which are all used in order to improve power output (force x velocity) and athletic performance. Improving either side of the power equation will potentially increase the outcome of power.

Strength:

Hip Thrust, Glute Bridge, 45 degree back extension, Heavy Sled Push and Drag

Strength Speed:

Kettlebell Swing

Speed Strength:

Weighted Broad Jump, Medicine Ball Scoop Toss, Light Sled Sprint

Speed:

Sprinting, Bounding, Broad Jump

These exercises will help improve the horizontal force and velocity capabilities and potentially influence short sprint speed. These exercises can also be used as complexes to improve power output which I’ll cover on a later post.

Just Squat More To Get Faster? The Importance of Horizontal Force & Power for Short Sprint Speed

I know I said I'd post about the strength speed continuum for horizontal force and power development but I thought I'd explain the importance of horizontal force first :) We've all been told that in order to get faster, we just have to get stronger and squat and power clean more. But is this really the case? Here is a nice and short overview of why horizontal force and power is so important to improve short sprint speed.

A study by Morin et al. (2012) looked at the 100m sprint which involved 9 physical education students. 3 national level sprinters and 1 world class sprinter. Since this little review is focused on short sprint speed, only the 4sec distance will be talked about.

The authors found significant correlations between the index of force application, horizontal GRF (ground reaction force) and 4sec distance (r=0.683 & r=0.773 respectively). However, no significant correlations were found between vertical GRF and 4sec distance. Average and maximal power output were also significantly correlated with 4sec distance (r=0.903 & r=0.892 respectively). NOTE: correlation of 1 means a perfect correlation, e.g. if power was correlated with speed at r=1, whenever power goes up, speed would go up, if power went down, speed would go down.

    Just squatting more to get faster may not be the answer

This has been further backed up by a recent paper by de Lacey et al. (2014). 10m and 40m sprint performance were measured comparing backs and forwards in elite rugby league players. Backs were found to be significantly faster than forwards in both sprints, however there were no significant differences found in vertical force or sprint kinematics. Significant differences in relative horizontal force (effect size/ES=0.87) and relative power (ES=1.04) were found between forwards and backs. In contrast, no significant differences were found in relative isokinetic strength even though sprint times and kinetics were different.

What does this all mean?

These data suggests that the direction force and power is applied in (horizontal direction) is more important than the magnitude (how much) of force and power produced when it comes to short sprint performance. Furthermore, with relative force being equal between athletes, further improving horizontal force production may potentially improve short sprint performance.

References

http://www.ncbi.nlm.nih.gov/pubmed/22422028

http://www.ncbi.nlm.nih.gov/pubmed/24513623

Developing Power? The Strength Speed Continuum

Here's a very general overview of the strength speed continuum. Basically you have exercises ranging from absolute strength to absolute speed which are all used in order to improve power output (force x velocity) and athletic performance. Improving either side of the power equation will increase the outcome of power  It can be broken down like this...

Absolute Strength:

Squats, Deadlifts, Pressing, Rows, Chins etc. Any exercise that uses heavy loads.

Strength Speed:

Olympic Lifts. Exercises that require high velocity but are still lifted at high percentages of 1 rep max. Can also throw in dynamic day lifts as per Westside method.

Speed Strength:

Loaded jump squats, loaded broad jumps, medicine ball throws etc.

Absolute Speed:

Bodyweight jumps, sprints, bounding etc.

This is a very general overview and can be applied to pretty much any sport. My next post will have a strength speed continuum specifically for improving short sprint speed via horizontal force and power.

Should I Use a Weighted Vest to Improve Speed?

Weighted Vest to Improve Short Sprint Speed (Acceleration) or Long Sprint Speed (Maximum Velocity)?

A recent paper by Matt Cross has looked into the effects of a weighted vest on sprint kinetics (forces) and kinematics (motions).

Why the use of a Weighted Vest?

A weighted vest while sprinting is commonly used to overload the neuromuscular system which could potentially elicit positive effects on ground contact time, flight time, step length and step frequency. Therefore, this can increase the athlete’s ability to generate vertical and horizontal forces.  This can potentially translate into greater force production and better sprint performance (i.e. faster) when the vest is removed.

How heavy?

In this paper, a 9kg vest and an 18kg vest sprint was run as well as a baseline (no vest) sprint on a non-motorised treadmill. This translates to roughly 7% and 20% of body mass of the subjects which falls in line with previous literature. Thirteen sport active university athletes took part (rugby, hockey, track sprint, weightlifting)

How did loading affect motion (compared to baseline)?

       Step frequency remained similar between all conditions while step length significantly decreased in loading conditions.

       Peak velocity significantly decreased in both loaded conditions.

How did loading affect Acceleration (compared to baseline)?                                                            No significant effect on peak ground reaction force (vertical forces; GRF), horizontal force, power output  with either load.

       Ground contact time remained unchanged.

       18kg vest flight time significantly decreased.

What about Max Velocity (compared to baseline)                                                                         Only with 18kg vest did peak vertical force significantly increase.

       No significant effect on horizontal force.

      Significantly lower power output during 18kg vest sprint.

       Significant increase in ground contact time.

       Both loading conditions resulted in significant decreases in flight time.

Interesting Findings?

                At max velocity, only the 18kg vest showed moderate increases in GRF meaning heavier loads may be needed in order to promote greater GRF production. Peak GRF did not significantly increase during the acceleration phase at any loading protocol meaning it seems that additional mass to the athlete does not result in increased GRF. This could be explained by the additional load affecting the rise and fall of the centre of mass (COM) during the flight phase (i.e. decrease in flight time). If flight height during the acceleration phase decreases, this means there will be a resultant decrease in GRF.

Vest loading had no significant effects on horizontal force and power. It appears vest loading affected the athlete’s ability to produce force in the horizontal direction through not being able to effectively control the additional mass.

So Should I Use a Weighted Vest To Get Faster?

It seems a weighted vest is not an effective way to improve acceleration (short sprint speed) as GRF, horizontal force and power were not significantly affected. A greater load may be needed to overload GRF and power during maximum velocity but greater loads can potentially elicit negative changes to sprint kinematics.

Based on this paper, I would not recommend using a weighted vest to improve short sprint speed or long sprint speed due to the weighted conditions not overloading important factors to improving speed (i.e. horizontal force and power, GRF). Further posts will give my recommendations J

Reference: http://www.ncbi.nlm.nih.gov/pubmed/24378661

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