Category Archives: Sport Specific Training

Heavy Sled Towing Trumps Light Sled Towing for Acceleration

Every once in a while a study comes along and alters my understanding of biomechanics and sports science. Effects of weighted sled towing with heavy versus light load on sprint acceleration ability by Kawamori et al. was published ahead of print earlier this year in March. It’s an excellent study that supports what many strength coaches have been saying for quite some time (and refutes what many track & field coaches have been saying) – that heavier sled towing is effective in improving acceleration ability. In the past, many T&F coaches believed that using sled loads of greater than 10% of bodymass (or loads that reduced speed by greater than 10%) would alter sprint mechanics too much and negatively impact speed.

I’ve been a proponent of heavier sled towing for quite some time. However, prior to this study, I’d have told you that an progressive training cycle of heavy sled towing would increase speed production by increasing hip extensor strength which would produce larger horizontal ground reaction forces and therefore greater stride lengths. Now I attribute the increases to different mechanisms, which I’ll explain below.

sled training

The Study

The study examined 8 weeks of 2X/wk training of light sled (around 13% of bodymass) towing versus heavy sled (around 43% of bodymass) towing on 10m acceleration times. These loads reduced speed by approximately 10% and 30%, respectively.


The heavier sled towing group significantly increased 5m acceleration by 5.7% and 10m acceleration by 5%, whereas the lighter sled towing group only increased 5m acceleration by 2.8% (not significant) and 10m acceleration by 3%.


Here’s where it gets interesting. The heavier sled towing group significantly decreased resultant GRF impulse (impulse = force x time) by 4.3% and vertical GRF impulse by 11.5%, which wasn’t the case with the lighter sled towing group. The horizontal GRF impulses didn’t show any significant changes in either group. The heavier sled towing group also significantly increased step frequency by 8.1%, which wasn’t the case with the lighter sled towing group.

To reiterate, heavier sled towing created favorable sprint adaptations that led to sprinters producing less vertical impulse and less resultant impulse so that a greater percentage of the GRF impulse production was directed horizontally, which led increased stride frequency and acceleration.

To quote the authors:

“Based on such findings, it seems necessary to revise our understanding of potential mechanisms of weighted sled towing to improve sprint performance; that is, weighted sled towing especially with heavy loads improves sprint acceleration performance by teaching athletes to direct GRF impulse more horizontally, not necessarily by allowing athletes to produce larger horizontal or resultant GRF impulse.” 

I’d like to mention that this research jives perfectly with prior research I’ve mentioned on this blog two years ago HERE which examined the technique of ground reaction force application.  I also touched on this same line of reasoning three years ago HERE, and last year HERE and HERE.

Here’s another important quote from the authors:

“If this new hypothesis regarding the potential mechanism of weighted sled towing is correct, then weighted sled towing could be regarded as a skill practice exercise more than a strengthening exercise. That is, it does not necessarily strengthen the neuromuscular systems involved in sprinting in a specific manner, as many believe, but rather it teaches a more efficient/effective way to apply GRF impulse while sprinting, which has more to do with motor control than muscular strength improvement per se.”


Heavier and lighter sled towing both significantly improve 10m sprint ability, but only heavier sled towing improves 5m sprint ability. Coaches should abandon the “10% Rule” and start implementing heavier sled towing with their athletes.

Future research needs to continue along these lines and examine even greater towing loads on acceleration and maximum speed sprinting.

Shelly-Ann Fraser-Pryce lends support to Asafa Powell and and Sherone Simpson - video

Reverse Hyper Sprints: The Best Speed Exercise You’re Not Doing

I thought up this exercise several years ago and included it in my glute eBook, but I never showed a video of them. I feel that biomechanically, this is one of the most similar ways to load the sprint pattern for horizontal power. Sure there are a whole-lotta muscles that are highly activated in a sprint, but the hip extensors appear to be the “rate limiting step” in terms of maximal speed production.

Moreover, the more forward the orientation of forces, meaning the greater the ratio of horizontal forces to vertical forces, the faster the sprinter. Finally, the better developed the velocity-side of the horizontal power equation, the faster the sprinter.

Reverse hyper sprints likely help bridge the gap between weightroom strength and the track by increasing horizontal power via greater hip extension angular accelerations.

You can perform reverse hyper sprints with just bodyweight, with 5 lb ankle weights, or with 10 lb ankle weights. I haven’t experimented with anything greater than that.

It is VERY important that you use proper form when performing these. Notice that I do NOT hyperextend my lumbar spine or move into excessive anterior pelvic tilt? The trick is to NOT treat these like a hip thrust where you actively seek end-range hip extension and squeeze the glutes. Focus on the hamstrings and the glutes but slightly limit end-range hip extension so that the pelvis and spine are spared.

Rapidly reposition the limbs as quickly as possible while holding good position. Grip the handles hard so you can transfer some force from the arms through the lats through the thoracolumbar fascia and into the hips (serape effect). Envision sprinting on the track when performing these.

Reverse Hyper Sprints

How I Broke a Stubborn Record

Today’s article is a guest post from Will Vatcher. I found it quite interesting as I’d never seen anyone train specifically for a broad jump record. If you recall, Will interviewed Natalia Verkhoshansky HERE several weeks ago. 

For the 1st time in 3 years, I recently broke my broad jump record. For the 1st time since last year I also smashed my weighted broad jump record too. These had both stalled previously. I would like to share with you how I did this.

I have always played a lot of football (I’m English but I mean soccer) so I’ve always been used to a lot of sprinting and jumping on the pitch. I started doing broad jumps on a weekly basis in 2010. After several weeks I managed a 242cm jump. I would also do other jumps such as jumping while holding dumbbells in my hands. For a while I kept increasing my jumps. Then not only did I hit a plateau with them, I could only ever seem to achieve 237cm from then on. I tried breaking down the jumps by using percentages. No use.

Now, I love the Westside system. I love the way it is designed to build balance and eliminate weaknesses. After reading a number of Louie’s articles on their jump training, I started to use either a max jump or use percentages of a max for the desired reps. When it came to the loading parameters, I took his advice and looked to Prilepin’s table.


Prilepin’s Table

I love Prilepin’s table. It is remarkably accurate. For example, for exercises that are performed in the 90-100% intensity range he recommended the following:

No less than 4 reps in total

1-2 reps per set

No more than 10 reps in total

The optimal number of reps is 7

I had tinkered round with percentages ranging from 60-100% and kept rest periods to 45 second per set. Regardless, my broad jump didn’t increase.

After the jump training, I would do some assistance exercises such as hip thrusts. I would also have a max effort lower body day and upper body day followed by exercises such as glute ham raises, low box squats, heavy abs/oblique’s, rows, triceps extensions and presses.

Some time ago, I started to do much research on the works of Yuri Verkhoshansky and his daughter Natalia. Up till then I never paid too much attention to the type of jump I did, just as long as it’s done with maximal effort at the particular percentage of a max I chose and the jump is rotated regularly.

What I discovered was that there is a massive difference in outcome from using different types of jumps (just as in all exercises). Firstly, what we commonly call a depth jump is not a depth jump at all. It is a drop jump. It was actually largely introduced by a man named Carmelo Bosco. Bosco was influenced by the research of Paavo Komi.

Yuri Verkoshansky devised the depth jump to have a longer (but not excessively long) and more elastic amortization phase. In other words, you would land from a height of either 0.75m or 1.1m (Verkoshansky’s recommended heights), fully absorb the landing with knee flexion and jump as far as possible.

A drop jump on the other hand is what most people would define as a depth jump. It is characterised by an extremely short amortization phase followed by an instantaneous effort to jump as far as possible with the shortest ground contact time possible. The recommended dropping height is 20-60cm.

While it might seem subtle, that’s a big difference.


Now back to the broad jumps. With this information I did an experiment. Up until recently, I had been doing broad jumps based on my max jump but with a very short amortization phase (balls of feet touching ground for a fraction of a second). I noticed that I did not seem to be getting much out of them. I have always been naturally quick so this was not my weak spot. But quick amortization was what I was training repeatedly. No wonder I hit a brick wall. So I tried landing with my entire foot to fully absorb the force before resetting for another rep. I noticed that I went into greater knee flexion using this method. Now, up until this time I had been using this method for my max broad jump only. When using percentages, I would use the ultra-short ground contact. I tried it with the following based on a broad jump max of 242cm:

Week one: 75% of 242 for 8 sets of 3

Week two: 80% of 242 for 10 sets of 2

Week 3: 85% of 242 for 10 sets of 2

Week four test max… 246cm. 4 cm PR. Coincidence? Maybe.

I also set a broad jump record of 220cm with ankle weights last year. So I did a cycle the same way the following week:

Week 1: 75% of 220 for 8 sets of 3(wearing ankle weights)

Week 2: 80% of 220 for 10 sets of 2(wearing ankle weights)

Week 3: 85% of 220 for 10 sets of 2(wearing ankle weights)

Week four test max… 238cm, with ankle weights. 18cm PR.  Another coincidence?

I also broke all my good morning and squat maxes during this period. I do set records most weeks in these exercises, but I broke them by big margins AND set jump records that I hadn’t done for ages.


That’s a pretty good deal better than before. Don’t forget, I  was also using special exercises such a glute hams raises and squats and I max out once a week on a good morning or squat variation. I believe that absolute strength builds the foundation of force that is displayed during explosive efforts. I would also like to give credit to Bret Contreras for introducing specialized vector specific glute movements which I now do every week. In my opinion, they greatly help with horizontal force production (sprinting or broad jumps).

I am confident I can keep pushing it up further.

I hope this info can help you as much as it has helped me and several of the people I have the pleasure of training.

About the Author

Will Vatcher is a strength & conditioning coach based in Cambridgeshire, England. He has written several articles on training and published interviews with Louie Simmons & Fred Hatfield (Dr. Squat) on He can be contacted via email for information on articles and training.

Machines vs. Free Weights: More Research is Needed

The machines versus free weights debate has literally been going on for decades. Certain key figures that spearheaded this controversy, such as Arthur Jones, didn’t do a good job of representing this debate as his knowledge of sports science was insufficient. He was biased as the inventor of Nautilus and his arguments were rife with biomechanical error. I still believe that Arthur was great for the progression of our field (click HERE to read about his methods and beliefs) in many ways. Nevertheless, this debate is a legitimate debate, and the field of sports science has NEVER conducted a proper study to examine this question.

And to me, this is one of the most important studies that we as an industry should be focused on right now as the ramifications are huge. For years, I’ve listen to my colleagues blast machines, stating that they’re far inferior to free weights for purposes of inducing hypertrophic, strength, functional, and sport performance adaptations. I personally call bullshit on this entire premise (as I discussed from 10:30 – 15:55 in our recent podcast).

leg press

As I discussed in my Leg Press vs. Squat: The Final Chapter article, squats appear superior to leg presses, but both could be utilized for optimal results. However, this is besides the point. Squats utilize more musculature, stress more joints, and represent a more functional movement pattern compared to leg presses. So if you compare squats to leg presses, leg extensions, or leg curls, of course squats come out ahead for most purposes. However, if you compare squats to a lever machine squat, such as Tuff Stuff’s, then that’s a different story. They’re very similar in muscle activation and joint moments, but the machine is a bit more stable than the free-weight version (which could be an advantage of a disadvantage depending on how you look at it).

lever squat

Here are the pros and cons of free weight and machine training:

Free Weight Advantages

  1. Less stable (less degrees of freedom) = more stability function (proprioception, balance, sensorimotor coordination, etc.)
  2. Way more affordable
  3. Portable and takes up less space
  4. Have natural bar paths
  5. Represent more natural movement patterns compared to many machines (ex: leg press, leg extension, leg curl) – they better replicate real life movement
  6. More specific to powerlifting and Olympic weightlifting
  7. Work well in concordance with bands and chains (accommodating resistance)
  8. More versatile, provide for plenty of variation
  9. Well suited for maximizing spinal strength and stability
  10. Better suited for lower body ballistics (ex: jump squats)
  11. Better suited for complex, highly integrated lifts
  12. Barbell exercises can be more metabolically demanding
  13. Seem to transfer better to machines compared to how machines transfer to free weight strength

Machine Advantages

  1. More stable = more prime mover activation
  2. Easier to learn (easier to stabilize) and more comfortable for certain lifters
  3. Can use to groove unique motor patterns (ex: smith machine for more upright squat)
  4. Fixed bar paths can prevent acute injury subsequent to lack of stabilization
  5. Certain machines maintain more constant tension on the muscles by utilizing variable resistance (ex: CAMs, plate-loaded, etc.)
  6. Can take spinal stability out of the equation to focus on the legs (ex: leg press, lying squat)
  7. Can be performed after heavy barbell lifts when stabilizers are fatigued to further tax the prime movers
  8. Better suited for targeted, more isolative lifts
  9. Well suited for initial stage rehabiliation
  10. Well suited for training the elderly
  11. Well suited for training beginners who lack confidence in free weights
  12. No spotters required
  13. Are self-contained (no additional equipment required)
  14. Isokinetic dynamometers are well suited for data collection and eccentric or isometric training
  15. The smith machine can be used for ballistics (ex: bench throws)
  16. Better suited for circuit training

Free Weight Disadvantages

  1. Certain lifts are awkward for certain body types
  2. Higher rates of acute injury
  3. Some lifters learn to rely on excessive momentum
  4. More correlated with sloppy form and contorting the body to accomplish a lift
  5. Many lifts have torque-angle curves and strength curves that stress a particular ROM but lighten up at the opposite ROM (ex: squats, good mornings)
  6. Certain lifts require spotters or rack supports
  7. Not always well suited for rotary and lateral vector movements
  8. Loading and unloading plates is cumbersome for strong lifters

Machine Disadvantages

  1. Certain machines don’t feel comfortable for certain body types
  2. Can have unnatural paths which can lead to pattern overload
  3. Higher rates of chronic injury
  4. Costlier to purchase and for maintenance
  5. Not always portable and takes up more space
  6. Less variety and versatility
  7. Aren’t always well-suited for particularly tall or short lifters
  8. Can lend themselves more to left/right imbalances
  9. Often weight stacks don’t accommodate advanced individuals

But it All Depends on the Machine…

As I mentioned previously, it all depends on the machine. A lever squat and hammer strength squat-lunge machine are very similar to the barbell counterparts. I’ve tested the muscle activation in both and the lever variations actually produced higher activation in certain primary muscles.

Hammer strength deadlift

Power squat

Lever lunge

Pendulum quadruped hip extension

Reverse hyper

With These Five Lifts, I Could Produce Better Lower Body Results than 98% of Trainers

Using just these five machine exercises, I bet that I could produce superior lower body hypertrophic and explosive power results to those of the vast majority of trainers just by teaching solid form and relying on optimal program design skills. Kinda blows the whole machines are inferior mantra out of the water, right (assuming I’m correct about my statement)?

Calling All Sports Science Students

I get emails all the time from students in sports science who are seeking a topic of study for their thesis. Well, here you go! This would be a landmark study that would be referenced many times over for years to come. It would go a long way in helping to settle the debate between free weights and machines. But you need to do the study justice. Hopefully some student out there has a great laboratory for testing and a great gym facility for training, which offers free weights along with the hammer strength squat lunge and a power squat (and more).

Sample Study Design

This could actually be an entire PhD thesis that could involve cross-sectional studies involving analysis such as EMG, joint moment, or perhaps force plates if you got creative, with a longitudinal training study to culminate the project. However, it could also just be a standalone study. Here are my thoughts:


  • 2 groups of ten male lifters with at least 3 years of training experience. 
  • Group one performs barbell exercises
  • Group two performs machine exercises

Study Duration:

  • 12 weeks

Prestesting and Posttesting:

Could involve any of the following:

  • countermovement jump height,
  • countermovement jump peak power (would require force plate),
  • broad jump distance,
  • 20 meter sprint time,
  • body mass,
  • body composition,
  • muscle size (would need MRI),
  • strength (perhaps on exercises not involved in the study so neither group has an advantage, perhaps isometric measures using a force plate)

Training Intervention: 

  • Both groups train 3 days/week. 
  • Group one performs barbell back squats, barbell RDLs, barbell deadlifts, barbell reverse lunges, barbell hip thrusts, barbell bench press, barbell incline press, and barbell bent over rows
  • Group two performs lever squats, hammer strength RDLs, hammer strength deadlifts, lever reverse lunges, cable pull-throughs, hammer strength chest press, hammer strength incline press, hammer strength bent over rows
  • Daily undulating periodization is utilized so that 3 sets of 6-8 reps are performed on Monday, 3 sets of 8-10 reps are performed on Wednesday, and 3 sets of 4-6 reps are performed on Friday
  • Monday and Friday involves back squats (and lever squats), RDLs (and hammer strength RDLs), bench press (and hammer strength chest press), and bent over rows (and hammer strength bent over rows)
  • Wednesday involves reverse lunges (and lever reverse lunges), incline press (and hammer strength incline press), and hip thrusts (and cable-pull throughs)
  • Progressive overload is utilized

Be Sure to Measure Hypertrophic, Strength, and Performance Adaptations, along with Injuries

As you can see, I included a wide variety of data which will help answer a lot of questions. I suppose you could add in a power component if you wanted – power cleans versus the power trainer, jump squats versus the bear, etc. (see Powernetics as they have some cool looking power machines).

Power Trainer

I Will Help You!

I would love to be an author on the paper so I’d be happy to help out!


Yes, doing squats will produce better hypertrophic and vertical jump results compared to just doing leg extensions or leg presses. However, what if free weights were pitted against plate-loaded lever machines? Then what would happen? Machines represent an entire continuum, with more isolative movements on one end and more integrative movements on the other end. Which would be superior for hypertrophic gains? What about gains in jumping and sprinting? How big would the differences be – marginal or huge? Which is safer?

Regarding hypertrophy training, would adding leg extensions to a squat protocol add or detract from gains in quad mass, and would adding leg curls to a deadlift protocol add or detract from gains in hamstring mass? Are isolation movements not well-suited for inducing high levels of metabolic stress? Keep in mind that seated leg curls have been shown to increase hamstring flexibility to the same extent as static stretching of the hamstrings, but they likely did so via increasing muscle length rather than increasing stretch-tolerance, and leg extensions have been shown to occlude the distal quadriceps and produce significant hypoxia during sets taken to failure. Can these exercises then be utilized to impose specific adaptations depending on the goal?

Until proper studies are conducted, all we can do is speculate, and nobody really knows the answer. Please check out the research below to help you formulate your opinion.

Some Links to Existing Research

Here is some existing research on free weights versus machines:

Roundtable Discussion: Machines Versus Free Weights – linked to pdf – check out Carpinelli and Stone’s arguments – amazing discussion with lots of references to pull up

Training-specific muscle architecture adaptation after 5-wk training in athletes – this is the best training study IMO

A Comparison of Two Methods of raining on the Development of Muscular Strength and Endurance – this is the worst IMO – WTF is rhythmic isometric exercise haha?

The Effect of Variable Resistance and Free-Weight Training Programs on Strength and Vertical Jump

Hot Topics: Machine Versus Free Weights – pdf is linked

Comparison of muscle force production using the Smith machine and free weights for bench press and squat exercises

A kinetic and electromyographic comparison of the standing cable press and bench press

Specificity of training modalities on upper-body one repetition maximum performance: free weights vs. hammer strength equipment

A comparison of muscle activation between a Smith machine and free weight bench press

A comparison of muscle activity between a free weight and machine bench press – pdf linked

Kinetic comparison of free weight and machine power cleans

A comparison of free weight squat to Smith machine squat using electromyography

Strength outcomes in fixed versus free-form resistance equipment

Comparison of chain- and plate-loaded bench press training on strength, joint pain, and muscle soreness in Division II baseball players

A Comparison of the Effects of Three Strength Training Programs on Women

Strength Training Modes Free Weight-Part II: Considerations in Gaining A Strength-Power Training Effect (Machines vs. Free Weights)

A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance

A biomechanical evaluation of resistance: fundamental concepts for training and sports performance

The Effects of Training with Free Weights or Machines on Muscle Mass, Strength,
and Testosterone and Cortisol Levels – master’s thesis

Comparison of muscle force production for the smith machine and free weight modes using similar exercises – master’s thesis

A Comparison of Muscle Activity during Free Motion versus Fixed Resistance Exercises – Case study by manufacturers but good researcher (Rhea)

Glutes to the Max – not published by good researcher (Porcari)

Muscle activation during lower body resistance training

Hamstring activation during lower body resistance training exercises

Do single joint exercises enhance physical fitness?