Jump Science: Specific Strength Training

KEY POINTS

Practicing and playing your sport is the ultimate specific training.
If the ultimate specific training is already in place, attempts at specific strength training can only be effective through general means.
Explosive resistance training may make untrained male athletes stronger in the short term, but the stimulus is not strong enough to take most people to a high strength level over time.
Pure strength training like squats offers long term strength progress.
There is a significant gap between squatting and explosive athletic performance. This eventually causes difficulty in getting strength to translate to sports.
Using strength training in a cyclical manner is an effective solution to this problem.
Specific strength training can serve the purpose of strength maintenance, but it should not be needed for specific abilities, because true specific training should never stop.

The remaining 4,500+ words expound on those points. Read if you wish.

Specific Strength Training

Specific strength training is a hot topic in the sports training world. For those who are not familiar, what people call specific training aims to mimic sports movements in an effort to ensure that the training adaptations translate into improved sports performance. An example of jump training that is considered highly specific is jumping with a weight vest. When I was going through college, the general consensus among the people in the field that I knew was that most attempts at specific strength training were worthless, because it altered the movement and slowed it down but wasn't heavy enough to make anyone stronger. However the current trend in the field seems to be in favor of specificity in strength training. And since everyone knows that the athletic development field is constantly pioneering new and effective training methods (rolls eyes), it seems a lot of people are hopping on the bandwagon. Let's talk about whether or not that is a good trend.

It's important to understand that playing your sport is training. It is the most specific training you can do, and there is a set of adaptations that results. The whole point of doing additional training is to get a different stimulus to provoke greater adaptation. For example let's say your sport is jumping as high as possible, and let's consider flexibility for a moment. You practice jumping all the time and have some level of flexibility just from that but could benefit from more. You begin to use daily stretching, which is a more impactful flexibility stimulus, and make improvements in flexibility that translate to improved jumping. In this example, training that is quite different from jumping is used to develop a useful ability to a greater degree than jumping could by itself. And the stretching does not make you specifically more flexible for jumping but more flexible all around. Stretching is not specific training but general.

Now consider resistance training. Again let's assume you already practice jumping all the time. The ultimate specific training is already in place. That means any resistance training cannot possibly further develop specific jumping abilities. Explosiveness? Force production at high contraction velocity? Reflexive response? Jumping coordination? Stiffening the leg at a particular knee angle? These are already trained by jumping. Slowing movement down with any type of resistance cannot possibly train those qualities better. The only way it can be effective is by increasing neuromuscular strength. We're talking about motor unit recruitment, rate coding, and packing more protein filaments into muscle fibers. That is general adaptation. If you already practice jumping, even the most jumping specific resistance training can only be effective through general means. In that situation it really shouldn't even be called specific training. It could be called highly transferable training but not specific, because the only way it works is through general adaptations. Consider the example of jumping with a weight vest. If we are comparing it to not jumping at all, then yes, the weight vest jumping becomes highly valuable. It trains specific components of jumping plus offers a slight strength stimulus. But if an athlete is already getting lots of jump reps, the only potential benefit of the weight vest is increased general strength.

RESEARCH

Much of the research support for specific strength training comes from isolating a stimulus. During the study the subjects only do the research protocol. One group of subjects does some type of explosive resistance training, and another group does something more slow and heavy, and after the training period the two groups show different adaptations. Wow, so enlightening. Here are two examples:

People might look at research like that and say that the adaptations to explosive resistance training are more relevant for sports, so that's the better option for athletes. But what if we have athletes who are already frequently sprinting, jumping, or playing a sport? In this case a superior specific training stimulus is already in place, which means the specific strength training can only offer increased general strength. When we examine more of a real world situation, the specific strength narrative tends to not show up so much. This can be learned through experience, but it's supported by research as well.

Effect of the movement speed of resistance training exercises...

In this study there was a light and fast resistance training group and a heavy and slow group, but all the subjects continued to do sprint training along with the research protocol. That means they already had specific training covered, which means the high velocity component of the light resistance training is just redundant.
After 7 weeks there were no significant differences between the groups. They made similar improvement in strength and speed. The researchers concluded, "...the present results suggest a lack of velocity-specific performance changes in elite concurrently training sprint runners..."
All the subjects made 20m sprint improvements using squats and single joint exercises. These exercises are general strength training, not specific.
The light resistance training increased max strength as much as the heavy. It was effective only through general adaptation. But also it's extremely useful to know that in some situations strength can be increased without lifting heavy.
Neither group made significant improvements in the flying 20m. To me this is expected. In athletes as fast as these subjects, strength training is unlikely to produce immediate increases in max velocity. A break from strength training is typically necessary to see those results show up.

Here's an example with plyometrics, which are not resistance training but are considered to be more specific power training. Short-term effects of strength and plyometric training...

In this study the subjects were professional athletes and were doing frequent soccer training.
In this situation the addition of plyometrics, the more specific training, made no difference. The subjects that did strength training, with and without plyometrics, made significant improvements in everything...
Except the counter-movement jump. This probably occurred because soccer players are not practiced jumpers. They are lacking the best specific jump training.
The strength training group did make larger improvements in the speed measures than the control group, but they were not statistically significant. Just like in the last study, with some proper periodization I would expect to see the increased strength translate to greater speed improvements down the road.

Here's a study done with young shot throwers. Effects of strength vs. ballistic-power training on throwing performance.

In this case the subjects stopped their throws training during the study but they did have a minimum of six months of throwing experience.
Both the strength and ballistic training groups made significant improvements in throwing performance. The strength training produced greater results although not to a statistically significant degree. So even with no throws practice or explosive training, the strength training produced positive results. If they continued throwing practice and did the study for longer than six weeks I would expect the strength group to separate much further from the ballistic group.
The study also measured counter-movement jump, loaded jump, and loaded throw performance. The ballistic training group made far greater improvements in these tests, because they practiced the tests and did drop jumps in their training. The strength group did no jumping or anything explosive, and these subjects were not experienced jumpers, so they had no specific training for those tests and made no improvements. The need for specific training is obvious. The best specific training would have been the tests themselves.
In the case of their shot throwing performance, they already had a history of throws practice, so no additional specific stimulus was needed to produce excellent results in the short term. But we can assume that over time those throwers would have to start throwing again to keep making progress.

To be clear, specific training is completely necessary for successful athletic development. But the best specific training for a sport is the sport itself. If you want to jump higher, practice jumping. If you want to sprint faster, practice sprinting. If you want to be quicker in basketball, play basketball. Get your specific adaptation from the most specific source. If you do that, the only means by which any type of strength or power training can make you better is by making you generally stronger. So don't worry about trying to recreate your sport in your resistance training. Don't seek out quasi-specificity. Just do what it takes to get stronger. Now we do need to keep in mind the transferability of strength training to sport performance, but it is every bit as important to consider the potency of the training. Ask the simple question, "Will this make me stronger?"

TRANSFERABILITY AND POTENCY

Let's examine some different types of strength training. Again say the sport is jumping as high as possible, and let's assume jumping is practiced regularly. An example of an exercise with high potency would be something like a heavy machine leg curl. In this case, the stress placed on the hamstring is far greater than the stress of jumping, so there should certainly be adaptation. But transference is in serious question. We could theorize that because the hamstrings are used in jumping, simply making them stronger should improve jumping. But realistically we have serious doubts, because, unlike jumping, leg curls isolate a muscle group, are slow and heavy, and train knee flexion. I have to admit I have never attempted to increase anyone's vertical using just leg curls. But it would not surprise me if some low level, untrained athlete experienced some positive short term jumping results by doing them. They should stimulate increased force production in the hamstrings. In the right person in the right situation, some of that increased force is likely to translate to more powerful hip extension and a higher jump. It's simple. Now let's say we add in some other isolation exercises, machine knee extensions and calf raises, which at least train the correct joint movements for jumping. With those added in, I'd be quite confident that some untrained athletes would see good short term jumping results, assuming they are also getting jump reps. However in the long term or with any trained athlete, isolation exercises do not seem to work well. The massive difference in coordination between these and more global movements severely limits neurological transfer. Any training lacking that component is likely to be ineffective. Many athletes, coaches, and researchers have learned this, which is why isolation exercises are widely regarded as minimally useful for athletic development. But we still need to acknowledge that these exercises do offer a very strong stimulus on the target muscles, and in the right situation the adaptations can transfer to jumping ability in spite of the lack of similarity or specificity.

We can do better than isolation exercises by using training that is more similar in coordination to jumping. If it closely mimics the sport, we can be confident that adaptations will transfer well. An example of highly transferable resistance training is simply jumping while wearing a 15-lb weight vest. In this case training transfer should not be an issue. The question is, "Will there be any adaptation?" Is the addition of 15 pounds to some jumps enough to stimulate improvement in force production? For an untrained athlete who has never been exposed to a stronger stimulus than jumping with body weight, it is possible that the addition of 15 lbs to some jumps could be enough to increase strength in the short term. In that case the jumping results will probably be great, but short lived. This is not training that is going to take an athlete to a high level of strength over time. Even among untrained athletes, many will not see results, and certainly any athlete who has a history of strength training is not going to get stronger from lightly weighted jumps. The stimulus is not potent enough.

What about plyometrics? That word encompasses a lot of different exercises, so let's be clear what we're talking about. Some plyometrics utilize minimal knee and hip flexion, short ground contact time, and high impact forces. When compared to jumping practice, this type of exercise potentially could give an athlete faster force production and a stronger reflexive response, but it's not really strength training (except maybe for the lower leg). Other plyometrics that utilize greater knee and hip flexion and longer contact time offer more of a strength stimulus. For some untrained athletes this type of training can be enough to increase strength. And since the transferability is high, the jumping results are great. People typically think of plyometrics as explosive training, but in truth when young athletes make fast gains in jumping ability by doing plyometrics, it happens largely because they are getting stronger. But of course the success is short term. A young male athlete may add six inches to his vertical in two months and then never make any improvement from plyometrics again.

What if we add more load and do jumps with a barbell, dumbbells, or a hexbar? The stimulus is more intense, so it should be effective for a greater percentage of the population and take people to a higher level of strength than plyometrics or lighter resistance. But again it is unlikely to produce long term progress and unlikely to provoke much of any change in an athlete with a history of jumping and strength training. Let's go heavier. What about olympic lifts? It's the same story. Let me tell you that I love olympic lifts. I fell in love with them in college and have used them in my training for a decade now. They are just not strong enough of a stimulus to make trained athletes stronger. I'll use myself as a quick example. I can snatch or clean or jerk several times per week for months, and none of those lifts will go up. But if I then do a couple good squat sessions, those explosive lifts increase right away, because squats are a stimulus that can actually change me. That is where this discussion has been leading.

Large scale strength movements like full squats offer a combination of potency and transferability. Squats train knee and hip extension strength as well as torso rigidity in a much more intense fashion than jumping. They should certainly provoke significant adaptation. What about transfer? Squats are like jumping in that they train full body extension, but they are unlike jumping in that they are slow and heavy and use greater range of motion. From a purely theoretical standpoint, the transfer is hard to predict. What happens in practice? We have already covered a few research studies that support the use of squats. Let me tell you there are mountains and mountains of more supporting evidence. Fundamental strength exercises are often referred to as general strength training, and that's an appropriate term. The deep squat is the king of generality. What people typically find is that making squat strength gains turns you into a generally more forceful person. Other lifts like deadlift and lunges get stronger. Power on clean, snatch, and jump squat goes up. You likely accelerate and stop faster, jump higher, and throw stuff farther. People can't push you around any more. It really is an awesome experience. This happens because force production is to some degree a general ability. All movements are driven by nerve signals stimulating muscle contraction. If an exercise makes the neuromuscular system better at doing that on a large scale, the results show up in a lot of different movements. This is what quality squatting does.

If that can be achieved using something lighter or faster, that's a great situation. If you can get stronger through explosive training and not have to worry about strength training reducing explosiveness, that's ideal. But I'm telling you right now that scenario is nearly impossible to sustain. All these exercises that exist in between jumping and squatting, (jump squats, med ball and shot throws, band resisted jumps, olympic lifts and their derivatives, etc) are potentially effective for some people in some situations. But in the long term the vast majority of people need to use pure strength training to get stronger. Squat, hip hinge, and lunge variations are really where the money is at. These feature enough similarity in coordination to transfer to sports movements while also offering a strong enough stimulus to change people over time. "More specific" strength training just does not get the job done.

RESEARCH

I make that claim based largely on my experience, which honestly is not always consistent with research. For example the shot throwers increased leg press max strength by an average of 21% after just six weeks using explosive weight training, not even pure strength training. I look at that and think, "Did they conduct this research in some kind of sports training fantasy world?" Published research results can be deceiving for several reasons.

Researchers often aim to experiment on a population that is likely to respond dramatically to training. Typically that means young, minimally trained males.
Some studies isolate a stimulus. A group of subjects performs one type of training for the research and does no other exercise. This is not a real world scenario.
Research usually examines short term results. We may see jump squats be effective over the course of six weeks. What about a year? Or several years?
Research shows the immediate results of the training but disregards the periods before and after the study.
Studies where the training method doesn't work typically don't get published. "Basketball players who spend 10+ hours per week on the court do a plyometric training program, and none of them show any results." Is that getting published? "Football players who spent the entire spring doing speed, agility, and strength training add jump squats to their summer regimen, and it accomplishes absolutely nothing." Is that showing up in the JSCR?

We can see examples of this in the research presented in this article. Two of the studies in this article showed significant increase in strength and power through ballistic power training. The subjects were "novice male shot throwers" and "relatively weak men," and the studies lasted six and ten weeks. These results are not indicative of the norm or what can be accomplished in the long term. We can't conclude that we can all just ride jump squats to elite athleticism. In addition, the power training in both studies produced similar explosive performance gains, but the strength training produced much larger increases in maximum strength. We don't get to see the future benefits of that higher strength level.

In reality making long term improvements in athleticism through strength and power development is far more difficult than some research might lead us to believe. Whatever early success people may have with plyometrics or the vertimax or jump squats or whatever, everyone ends up needing to get on the squat grind to keep getting better. And even then the process can be slow and frustrating. It's not easy to find research where a training method just does nothing, but truth be told unsuccessful training is far more common than successful.

Here is a study that gives more of a realistic view: Training Strategies to Improve Muscle Power: Is Olympic-style Weightlifting Relevant?

In this case the subjects were badminton, volleyball, and hockey players (10 females, 29 males). They were 17-23 years old and had experience with strength and power training, including olympic weightlifting. During the study they continued regular off-season sport training.
The results indicated that olympic weightlifting was ineffective for improving speed and jumping ability. The other two interventions, squatting for strength and power with free weights, and doing isokinetic/isotonic squats in a smith machine produced superior results. But even those results were modest. This is more in line with reality. Power training did not accomplish much of anything. Strength training was required to make changes.
Also note that the subjects in this study could have used some specific training for the tests. Volleyball, badminton, and hockey players are probably not experienced straight line sprinters. They likely would have seen better results in the 30m sprint if they had practiced sprinting during the study. The badminton and hockey players are probably not experienced jumpers. They likely would have made larger jumping improvements if they practiced jumping.

Another factor to consider is injury prevention. While plyometrics, jump squats, olympic lifts, etc may be able to increase strength and power in some cases, they cannot establish structural integrity and sound mechanics the way that fundamental strength training can. Adding power to athletic movements without (1) strengthening tissues to handle higher forces and (2) addressing the quality of the movement increases risk of injury. Fundamental movements like squats, lunges, and hip hinges develop a structural strength buffer against injury, and proper performance of these exercises is the best way to establish sound general mechanics throughout all movements. So even in situations where power gains might be made through more explosive resistance training, it may not be the best choice for the safety of the athlete.

PRACTICAL APPLICATION

What I'm advocating is the use of the best specific training, which is practicing and playing your sport, and the use of the most effective general training, which is squatting and other strength exercises. There may be situations where less potent training is effective, but in order to sustain athletic improvements over time people need to train pure strength.

Of course this process is not without its challenges. We do have to acknowledge the difference between general strength training and explosive athletic performance. Early in an athlete's training career, it can be surprising how much benefit can come from just a little deep squatting. The stimulus is so strong that it can change people fast. I've seen athletes get decisively more athletic from one workout. And in some athletes seeing improvement within two weeks is expected. But eventually we run into a big problem with strength training. It's slow. Over time it slows down force production, so while people may continue to get stronger, gains in athleticism stop or even go backwards. It's a battle between max force production and fast force production, strength and speed.

How do we solve this problem?

Fortunately another benefit of using such a potent strength stimulus is the long lasting nature of the adaptations. Often times after consistent squatting for a few months, an athlete can take an extended break from heavy lifting, get fresh and explosive, maintain power, then begin squatting again and return to the previous strength level within a couple weeks. This means long term strength gains can be made while also taking periods off strength training to regain explosiveness. I have plenty of content on this already. If you are not familiar with it, check out the following pages:

Using strength training in a cyclical manner is a solution to the strength vs speed problem. In this approach explosive training never stops, and strength training is used on and off. Explosive lifting can fit into this model as well. I am not trying to discourage anyone from doing olympic lifts or jump squats. Personally I like to measure power with this type of exercise to aid decision making throughout the training process. Power exercises can definitely serve a purpose, but understand that by themselves they are typically not strong enough of a stimulus to change a trained athlete. Positive changes come from pure strength training, sprinting, jumping, and specific sport practice.

Conclusion

If you need to figure out where you're at in this process, ask the question, "Am I as athletic as I can be at my current strength level?" To answer this accurately consider your genetics, body type, athletic background, and training history, particularly what the impact of strength training has been on your athleticism. If the answer is yes, then you have to get stronger to get more athletic. I would say that you need to get generally stronger. If the answer is no, you may be due for a break from general strength and a focus on speed. Part of your training in this scenario could be some more specific strength training used to maintain strength.

Pages

Specific Strength Training

KEY POINTS

Specific Strength Training

RESEARCH

TRANSFERABILITY AND POTENCY

RESEARCH

PRACTICAL APPLICATION

How do we solve this problem?

Other solutions?

Conclusion