Velocity, Force, Power...What???

Of these, what makes us faster?? From what I understand the greater force we apply in each step or the faster we can apply the same magnitude of force in a step, the faster we move. Is this correct?
David W wrote:
“Power = Force x Velocity
Velocity is trained through sprinting itself therefore sprinters need only train to develop maximum force in the gym. This calls for limit strength lifts, e.g. squat. I prefer squatting over dead lifts for reasons we’ve discussed many times (high CNS stress, low range of movement, difficulty in determining a strict repetition maximum etc etc).”

Now by laws of physics Force=massxacceleration. So to develop max force via limit strength exercise, we must lift increasingly heavier weights. And the simple task of moving the weight at all shows that we are obviously accelerating it, otherwise there would be no movement at all. Thus F=Ma with an emphasis on the Mass.
Now obviously Force can be developed by keeping the mass constant while increasing acceleration. Is this why speed-strength methods are employed??

Now my question is are limit strength methods better for increasing Force than speed-strength?? Or is it just the fact that with Limit strength it is easier to quantify increases in Force??

So going back to the equation for power…Power = Force x velovity, and the velocity component being taken care of by speed work.
Why is:
Power = F(via limit) x speed work
advocated more than
Power = F(via SS) x speed work

I hope this post came out in a somewhat coherent manner.

Whether one needs to address speed strength over strength speed ultimately lies in which manifestation of muscular strength is the weaker.

There are force dominant exercises and strengths and rate dominant exercises and strengths.

However, if it has been identified that an athlete must develop their force dominant strength than that athlete must increase their limit strength, strength speed.

Reference the force:velocity curve and I believe you will have a clearer picture of the concept.

The greater the force (mass), which is expressed via an exercise, the lesser the velocity (speed), vice, the greater the velocity, which is experssed via an exercise, the lesser the force.

Athlete 1 has a a 300lb back squat and a 33in vertical leap at a body weight of 185lbs

Athlete 2 has a 400lb back squat and a 33in vertical leap at a body weight of 185lbs

From this information only, we may state that in order for athlete 1 to increase his vertical leap, he must increase his strength speed, whereas, in order for athlete 2 to increase his vertical leap he must increase his speed strength.



Now I see the relevance for developing these specific strengths for jumping and other athletic endeavors like throwing, but specifically for speed development for a sprinter…what are the benefits?? If an athlete has good strength and poor speed , hed do speed work. If he had good speed but lacked strength, hed heavy weights, right. So for a sprinter, is there a reason to do strength speed work since strength development is more of a general training element.

For a sprinter, the cessation of strength speed training would be athletic suicide.

Generally speaking, short sprints are largely affected by an athletes relative strengh. You will be hard pressed to find an elite level sprinter who does not possess great relative strength in the squat, bench, chin ups, etc.

So long as a reasonable nutrition plan is being followed, the development of strength speed will greatly aid in the development of relative strength.

The most common occurance of the power:weight ratio being negatively affected is by an increase in bodymass.

Generally, as bodymass increases-relative strength decreases.

Correspondingly, most athletes, whos sport relies heavily on the development of relative strength or power:weight ratio, would be best served by increasing strength, speed, power, and specifically targeted lean muscle mass until the point where any addition of lean muscle mass inhibits the expression of relative strength.


Limit strength also has a much bigger window for improvement then speed strength. Say you squat 200 lbs and weigh 150 lbs. You obviously want to be able to move your bodyweight (150 lbs) as fast as possible. In this situation just moving your bodyweight represents a fairly high percentage of your max strength (75%). So you could try to work on developing your rate of force development and speed-strength. Let’s say you decide to train speed-strength by doing jump squats with 30% of your max. So you’d load up the bar with 60 lbs and try to increase the height you can jump with the load on your back. You might have some success but the gains from that would be very quick and brief.

It would likely be much easier to just increase your squat. If you increase your squat to 300 lbs then your bodyweight represents only 50% of your max strength and the 60 lb jump squats now only represent 20% of your max squat instead of 30%. All things being equal you can move loads of 50% and 20% faster then loads of 75% and 30%.

Anytime you increase max strength anything below that represents a lower % of your max force output and should be easier to move. There will come a time though when further relative strength increases won’t lead to increases in speed-strength and in fact can detract from it, but that point is variable for everyone.


Your post is well stated.

Kelly, I agree with CoachMdd, excellent points.

However, in referencing Siff’s definition of relative strength and speed strength:

Speed-Strength Characterizes the ability to quickly execute an unloaded movement or a movement against a relatively small external resistance

Relative Strength Amount of force produced per kilogram of bodymass or sports apparatus

I fail to see, nor have I observed, how any increase in relative strength would inhibit the development or expression of speed strength-so long as viable training methods are employed which serve to concurrently develop the two motor qualities.



I fail to see, nor have I observed, how any increase in relative strength would inhibit the development or expression of speed strength-so long as viable training methods are employed which serve to concurrently develop the two motor qualities.

Think of the difference between a tractor and a funny car of equal size. The tractor can pull a heck of a lot of weight, but it can’t pull a light weight much if any faster then it can pull a heavy weight. The funny car can move fast but can’t pull a lot of weight period. The tractor has that low gear and the funny car has that high gear. What we want is the strength of the tractor with the speed of the funny car. Gaining very large amounts of relative strength over time can cause us to function like the tractor. We get that low gear which gives us bigger strength increases but in order to do that we must sacrifice speed. When we gain relative strength yet can’t move a given load any faster or with any more power then before then the additional relative strength is by itself useless and steps must be taken to focus on speed-strength.

Eventually further strength increases can lead to a decrease in speed-strength or relative power because of the programming. This point will vary for everyone though. I periodically train with a couple of 160 lb powerlifters who deadlift 550+ lbs and squat ~450 and they would be lucky to run a 5.5 fourty yard dash and vertical jump 18 inches on their best day. They became like a tractor long ago and in order to change things they’d need to change a lot and probably have to sacrifice some relative strength for an improvement in speed strength/relative power. In contrast Fred Hatfield squatted 1014 lbs in less than 2 seconds from start to finish and had a 40 inch vertical leap. He obviously was very efficeint at converting relative strength into relative power which is the hallmark of a great athlete. For everyone else it’s a bit more complicated.


Wouldn’t this “worry” be irrelevent for sprinters who work speed strength and relative strength “conjugately” at least sprinters following CFTS do this. It seems to me it would be.

Same for OLifters.

Also, wouldn’t this be irrelevent for Westside or similar powerlifters. They include at least strength-speed and relative strength at the same time. I doubt many of them have really poor verts may be forty’s but let 'em lose some weight.

Reference Fred Hatfield, it is no surprise that he acheived the 40" vert and the 2 second squat. He coined the term Compensatory Acceleration and he also trained speed strength/strength speed as well as relative strength at the same time. It seems genetics aside, that is why he was good at both.

So if we train both won’t we be a tractor and a funny car?

Ir1400, has stated my point.

Kelly, I see your perspective. However, what I originally stated, and what Ir1400 eluded to, is that the two motor qualites may be developed concurrently. Your depiction of the Hatfield squat is an example of this.

The WSB method does exactly this, by addressing limit strength and strength speed on ME days and speed strength, reactive strength on DE day.

Zatsiorsky stated that 2-3 motor qualities may be developed concurrently. Thus relative strength and speed strength may be developed concurrently.

I believe your point of view is pointing out the defficiency associated with the linear development of speed strength followed by relative strength, which over time, would obviously lead to a detraining effect on speed strength.


Perhaps this will help to explain my thoughts.

Zatsiorsky’s explosive strength deficit

As the resistance decreases and the motion time becomes shorter, the
difference between Fm (the maximal force reached in a given condition) and
Fmm (the highest among the maximal forces attained in the whole range of the
tested conditions) increases.

The difference between Fmm and Fm is termed the explosive strength deficit

ESD = 100 * (Fmm - Fm )/Fmm

ESD shows the percentage of an athlete’s strength potential that was not used
in a given attempt.
In movements such as takeoffs and delivery phases in
throwing, ESD is about 50%. For instance, among the best shotputters during
throws of 21.0 m, the peak force Fm applied to the shot is in the range of 50
to 60 kg. The best results for these athletes in an arm extension exercise
(Fmm, bench press) are typically about 220 to 240 kg, or 110 to 120 kg for
each am. Thus, in throwing, they can only use about 50% of Fmm.

In principle, there are two ways to increase the force output in explosive
motions - to increase Fmm or decrease ESD. The first method brings good
results at the beginning of sport preparation. If a young shot-putter
improves achievement in, say, bench press from 50 to 150 kg and also pays
proper attention to the development of other muscle groups, this athlete has
a very strong basis for better sport performance in shotputting.

This is not necessarily valid, however, for a bench press gain from 200 to
300 kg. In spite of efforts devoted to making such a tremendous increase, the
shot-putting result may not improve. The reason for this is the very short
duration of the delivery phase. The athlete simply has no time to develop
maximal force (Fmm). In such a situation, the second factor, explosive
strength, not the athlete’s maximal strength (Fmm), is the critical factor.
By definition, explosive strength is the ability to exert maximal forces in
minimal time.

Let’s compare two athletes, A and B, with different force-time histories (Fig
2.9). If the time of motion is short (i.e., in the time deficit zone), then A
is stronger than B. The situation is exactly opposite if the time of the
movement is long enough to develop maximal muscular force. Training of
maximal strength cannot help athlete B improve performance if the motion is
in the time deficit

When sport performance improves, the time of motion turns out to be shorter.
The better an athlete’s qualifications, the greater the role of the rate of
force development in the achievement of high-level performance.

Neural (central) factors include intramuscular and intermuscular
coordination. Neural the level of intramuscular coordination, three main
option, are used by the CNS for varying muscle force production: recruitment
of MUs, rate coding, and synchronization of MUs (motor units). These can be
observed in well trained athletes during maximal efforts. The orderly
recruitment of MUs is controlled by the size of motoneurons (Hennemann’s size
principle): Small motoneurons are recruited first and requirements for higher
forces are met by the activation of the large motoneurons that in innervate
fast MUs. It seems that the involvement of slow twitch MUs is forced,
regardless of the magnitude of muscle force and velocity being developed. The
firing rate of the MUs rises with increased force production (rate coding).
The maximal force is achieved when (a) a maximal number of MUs is recruited,
(b) rate coding is optimal and © MUs are activated synchronously over the
short period of maximal effort.

The primary importance of intermuscular coordination for generating maximal
muscular force is substantiated by many investigations. Thus, the entire
movement pattern rather than the strength of individual muscles or single
joint movements should be the primary training objective. Explosive strength
(or rate of force development) and the force exerted in stretch-shortening
(reversible) muscle actions are independent components of motor function.

Time (and Rate of Force Development)

Because of the explosive strength deficit (ESD), maximal force F cannot be
attained in the time deficit zone. If the training objective is to increase
maximal force production (Fmm), there is no reason to use exercises in the
time deficit zone where Fmm cannot be developed. Furthermore, heavy
resistance exercises are not very useful for enhancing the rate of force
development in qualified athletes (Fig 6.3).

If the general objective of training is to increase force production in
explosive types of movement, in principle this can be done in one of two
ways. One option is to increase maximal force Fmm. This strategy, however,
brings good results only when the ESD is substantially less than 50%.

As an example, imagine two athletes who put a shot with a force of 500 N. The
first athlete can bench press a 120 kg barbell (roughly 600 N per arm). The

ESD for this athlete is [(600 - 500)/600] - 100 = 16.6%. This is an extremely
low value for shot-putting. The athlete has a great potential to improve
performance by increasing Fmm. Lifting a 200-kg barbell in the bench press
will surely lead to improvement in this individual’s performance. For the
other athlete, 1RM in the bench press is 250 kg. The ESD is (1250 -

500)/1250] - 100 = 60%. Further improvement of this athlete’s maximal bench
press, say to 300 kg, will not result in improvement in shot-putting

The second option for training to enhance force production is to increase the
rate of force development. Heavy resistance exercises are not the best choice
in this instance, especially for elite athletes. Special exercises and
training methods are a better alternative…

Kelly, I am in complete understanding of your perspective, and also an owner and desciple of Science and Practice of Strength Training, however, it appears as if we may not share the same perception of the discussion.

Given the fact that increases in Fmm, in an elite athlete, may not aid in developments in speed strength, RFD, or decreases in ESD, it must also be noted that he who possess a higher Fmm and a lesser ESD is more capable of expressing greater power, specifically upon greater loads.

Your example is an illustration of Timmerman’s improvement upon Beyer’s throw distance, despite the fact that Beyer possessed greater limit strength.

However, we must also agree that the sport goal is of ultimate importance when discussing such matters. Thus, in reference to the shot put event, it has been made clear that there comes a point where the development of maximal strength( Fmm),on its own, will not yield optimal performences. However, with respect to my Beyer-Timmerman comparison, the question must be asked; to what extent did Beyer develop his speed strength and was that development hindered by his max strength. Not to mention all of the other potential variables in comparing the two throwers (eg biomechanics, skill, etc)

Furthermore, with respect to sport, although shot putters possess tremendous strength speed, their sport is ultimately a function of speed strength. Theirin lies the fact that maximal strength, strength speed, determine to a large extent, ones success in speed strength sports.

Additionally, when referencing contact sports (football, rugby, hockey, MMA, etc) we must acknowledge the high resistance posed by opponents. Now the importance, without question, is the development of max strength and strength speed.

So what we may conclude is that the importance or magnitude of the ESD is ultimately relative to the sport in question. My view of the matter is that most strength/power development athletes (specifically non-Olympic athletes) are so far from developing their Fmm to a point which would hinder the ESD, that it would be in their best interests to seek to become stronger and faster concurrently and only consider limiting the development of Fmm when they near a point in their strength/athletic development where their performance suggests so.

Great discussion


So what we may conclude is that the importance or magnitude of the ESD is ultimately relative to the sport in question. My view of the matter is that most strength/power development athletes (specifically non-Olympic athletes) are so far from developing their Fmm to a point which would hinder the ESD, that it would be in their best interests to seek to become stronger and faster concurrently and only consider limiting the development of Fmm when they near a point in their strength/athletic development where their performance suggests so.

Yes I definitely agree with this James.

SO I gather from all of this that a sprinter doesnt need to to any specific speed strength work like Olifts if they are increasing relative strength and doing speed work.

Agree with Kellyb and jman for most of us it does not matter we aren’t close to topping out Fmm. For Ben Johnson, increasing his squat anymore past '88 numbers probably wouldn’t have helped him. It most certainly helped between '84 and '88. If memory serves me correct he increased it dramatically during that time period.

I don’t think it would’ve detracted if he had increased it past '88 numbers. I think when most say more relative strength will impact speed strength neagtively maybe they really mean more time should be spent on other qualities once realtive strength is “sufficient”. And thus if focusing on relative strength you may indirectly suffer because you need to be training something else not because more relative strength per se will force performance to suffer.

It is true, that sprinters are best served by developing RFD on the track, and leaving the work in the weight room to develop limit strength, strength speed.

However, for non ‘sprinters’ per se, but for sports where explosive strength, acceleration strength are required (eg football players, rugby, hockey, etc) many increases in speed may be seen from utilizing speed strength methods as well as limit strength methods, in the weight room. The advantages to developing certain components of speed in the weight room lie in the fact that, for many sports, practice and competition alone, amount to a high stress on the CNS, therefore, any additional sprint work would contribute too high a volume of CNS strain. Thus, speed strength lifts may be performed in the weight room, which will serve to develop explosive strength, starting strength, reactive strength, acceleration strength, etc., and at a lesser cost to the CNS than sprinting itself.


  1. What about low volume plyo’s? For example how many do sprints, plyo’s, then weightroom, why not do plyo’s, then weight room, using GPP idea’s on low intensity days to develop fitness?(this is assuming that practice is being performed, otherwise a mode of conditioning the proper energy systems for the sport). But for example. 3-4xplyo push up, 3-4xhigh box jumps? And the plyo exercise could be switched every 4 weeks(after the unloading week)?

  2. And I know this is probably a stupid question, but I have been thinking, swimming is non impactful on joints and musculature, would short swimming sprints(25 or 50yard) develop RFD as do sprints without the effect on the joints and musculature?

  3. Could relative strength not be improved with general fitness(ie on the low intensity days the push ups and pull ups?)?

  4. And it was my impression that developments at the more extreme ends renders best results. For example when I did only sprinting and limit strength training my lifts kept getting fast even towards the heavier range and my sprints faster. Surely improvements in both strength speed and speed strength were made for the lifts to go up faster at near relative maximum?

Numba, could you rephrase this segment. I am confused by your statement/question.

The only instance in which I would recommend swimming, for a non swimmer, would be if the athlete in question was recovering/rehabing from some sort of lower extremity injury that prevented him/her from performing any type ground based work.

Only to a degree, without eventually adding resistance. There comes a point with pushups/pullups/dips/handstand pushups, etc. where weight must eventually be added in order to further induce increases in relative strength. Once an athlete becomes proficient in (bodyweight only) exercises, the only gains they have to look forward to are gains in strength endurance.

Generally, I would agree. However, one must not forget the various components of both the force end and the rate end of the curve (and all in between), and that the development of any on part of the curve serves to develop the whole. Furthermore, if weaknesses exist in between the expression of limit strength and speed strength, then there is an instance in which the specific development of that quality is appropriate.

For example: in elite OL lifters, we know that increases in limit strength (alone), past a certain degree, will not yield further increases in the classical lifts. Correspondingly the use of sub-maximal weights must be used in order that the lifter may further perfect technique and develop the various manifestations of muscular strength which exist to the right of limit strength.