Take a look at the following video of me ‘practicing’ for the Yoke Walk;
Walking on the spot with 326 kg puts 406 kg through the floor through one leg
Something which I feel HIT is somewhat blinkered on, is its approach to training for athletic activities… in this case I am using the Yoke Walk as an example.
The typical advice from the HITer to train for the Yoke Walk might be something along the lines of;
“First one should train the muscles for strength via full range exercise on specially designed machines. If one has only free weights one should still use full range exercise and adhere to the principles of good form via slow controlled movements. One should then practice the specific activity of the Yoke Walk by using the Yoke Walk apparatus with the weights that one intends to use in a manner exactly like that in competition and so practice is specifically like that for which it is intended to be used!”
However if we look at the video and perform a few calculations for my walking on the spot with a 306 kg barbell (which lasts 21.2 seconds) we will see that a force of at least 386 kg goes through the floor (my bodymass being 80 kg) – this force being transmitted through each leg with each step.
At the ankle the force is 384.6 kg, at the knee the force is 378.9 kg and at the hip the force is 364.1 kg. There would also be accelerational forces to add to this.
Let’s assume that my full repetition squat for the same time (about 24.1-26 seconds) is here;
The calculations for this lift show that at the floor the force through each leg is 111.5 kg.
The forces for this exercise at the ankle is 110.1 kg, at the knee is 104.4 kg and at the hip is 89.6 kg.
The differences in forces between the Walk and the Squat being;
- Floor 3.5
- Ankle 3.5
- Knee 3.6
- Hip 4.1
This means that if I were to take the HITer’s advice and practice full squats for strength and then ‘practice’ an actual Yoke Walk that my bones, joints and muscles would be woefully unprepared for the stresses.
Ahh, but barbells are inefficient what about the Duo Squat and Duo Leg Press with their eccentric cams?
Fair point! But do they really match the forces in such an event such as the Yoke Walk?
The HIT specificity principle says that the actual machines should in no way mimic the Yoke Walk and having used the Duo Squat I can verify that this is so! When locking out the legs on the Duo Squat the legs feel entirely stable – indeed they are locked into a fixed path and as such there is no requirement for muscles such as the abductors and adductors to keep the leg from deviating laterally. Similarly there is no requirement for the muscles to stop the leg deviating ventrally or dorsally.
Furthermore intra-rep fatigue means that the resistance curve of the machine will never match the required forces of the Yoke Walk. I go into some detail on intra-rep fatigue here.
Intra-rep fatigue looks something like this;
This is a schematic of what my sumo style deadlift fatigue might look like, where I use 213 kg for 8 reps. The blue line is the resistance curve of weight and the red lines are the potential strength curves for each of the 8 reps I perform in the deadlift. The potential strength curves are obviously all above the blue line (I am stronger than the weight) until on the 8th rep it just grazes the blue line at the cross. If I were to perform another rep I would fail because the red line would drop, at some point, below the blue line.
It might seem that a machine would be better because one could make its resistance curve more like the potential strength curves… except that the potential strength curve is force at each point that could be generated at each point if the barbell was artificially stopped whilst the lifter then pushed as hard as possible.
This means that if a variable ‘barbell’ was used the potential strength curve would be flatter because fatigue during the rep would be greater. In effect the ‘better’ resistance curve at the beginning of the lift would weaken the lifter at the end of curve compared to that of the ‘inefficient’ barbell.
Thus one might well design an eccentric cam with a shape that ramps up the resistance by 4 times but this would mean that one would have to use a smaller weight at the beginning to be able to generate the required resistance at the end. Thus the force curve of a Duo Squat or a Duo Leg Press from the start of the move to lockout would have to look something like this for each leg (numbers in kilos);
| Floor | 111.5 | 386 |
| Ankle | 110.1 | 384.6 |
| Knee | 104.4 | 378.9 |
| Hip | 89.6 | 364.1 |
However in reality I could not take the equivalent of ~100 kg (per leg) at the bottom of such a machine because this would wear me out quicker than the 20-25 seconds of the walking squat and squat videos. I would in effect have to use 0 kg for the first 80-90% of the move to simulate the full ~386 kg at the end of the move… if I used anymore than 0 kg for the move then I would be weakened for the final part of the move such that I could not lift 386 kg.
Finally walking with the bar is much different than the fixed path machine in that alternately standing on one leg then the other also requires great strength in the torso to stop the spine and hips flopping about like spaghetti. This is not merely a matter of ’skill’ but of building strength in the waist and torso and upper back to stop the upper body collapsing like a deflated balloon – I haven’t come across any machine that matches these stresses.