The Science of Wearable Resistance for Sports Performance

Weighted vests and other garments are not new, but recently there has been an increase in interesting science. In the past, most of the research was on weight vests and how they helped athletes get faster and jump higher, but now a lot has evolved in both the equipment industry and the sports training progression. Before this, wearable external loads were a matter of adding a near arbitrary weight to the body and just having the athletes train with the device. Now the science and practice are far more sophisticated, and even more confusing.

In this blog, expect a dramatic change from most of my other science reviews because I combine both the research and some speculation on the findings. With no pun intended, I weigh-in on how coaches should view the science and ask the tough questions that will improve training design.

The New Definition of Wearable Resistance

Just to make sure we are on the same page, in this article “wearable resistance” is an external gravitational load worn by an athlete. Some products have internal resistance qualities such as elastic bands that make it more difficult to move limbs, or have actual load embedded in them. Most weighted garments are heavy vests, but a lot of ankle and wrist products exist because of the fitness market. Some thigh and head items make the rounds from time to time, but weight vests for athletes are the primary option of choice.

Wearable resistance shares the same challenges with quantifying the load and demand as sled training, but the modality has some unique differences. If wearable resistance was just how much weight was on a vest and that was it, this section would be a short paragraph. However, wearable resistance is tricky because the load is distributed differently when the weight is placed on different parts of the body. Most coaches just assume that loading the center of mass with a weight vest that places the lead shots near the ribs is good enough for training, but what about when the load is near the distal part of the extremities? For the sake of future research and better articles on the subject, the distribution of load and specifics on location must be extremely clear.

Wearable resistance is tricky because the distribution of the load depends on its body placement. Click To Tweet

A weight vest of 20 pounds on a 200-pound athlete is far different than thigh and ankle weights of the same weight on the legs of a sprinting athlete. The weight is the same, but the demand is far different. To get the most out of wearable resistance, you need to know all of the details on the training level of the athlete and how the load is placed on the body. Usually, weighted vest training and other modes are done early in the development program, making it a possible problem if you are dealing with a lot of “unknown unknowns” with athletes. Even the mode of training makes loading unique, as slideboard training and swimming workouts have radically different interactions with a gravity-based wearable load.

Mechanical stress changes, so it’s important to distinguish from the system weight of external load to something closer to a combined term such as wearable resistance. For example, if an athlete bench presses a heavy load, it’s still not a large system weight because only their arms are moving. A jump squat with heavy additional load and bodyweight represents an exercise with a lot of system weight, so wearable loading is not just adding weight to your body mass. Therefore, with all of the considerations of wearable resistance, it’s important to know the details of terminology to plan training and communicate the concepts of wearable resistance.

The Physics of Weighted Vests and Wearable Loads

Building on the information from the terminology section, the next step is understanding how a wearable load interacts with a human body, mainly from a simple physics perspective. Sure, metabolically an external load changes the physiology of a session, but most of the performance coaches just want to know the essentials of something as simple as a weighted vest for power. A wearable resistance product like a vest isn’t very complex: Anyone can put a weighted vest on, it’s just the programming of it is obviously more sophisticated.

Most of the value of wearable loads comes from making a basic sporting action more demanding. Click To Tweet

Most of the value from weighted vests and wearable loads comes from making a basic sporting action more demanding, such as sprinting and jumping. A small load transforms a routine exercise into something more, without much extra work or coaching responsibility. The simplest form of progressive overload is adding more external weight to an exercise using wearable resistance.

The truth, though, is that the process becomes more and more difficult to manage as load moves around the body, because the forces through muscles and tendons are not neat incremental steps based on adding weight. With the majority of products focusing on central loading of the torso, think of an athlete gaining body fat, thus decreasing their strength to weight ratio. A few extra pounds do make a difference, but the physics isn’t as simple when the load becomes much higher or when the weight moves away from the center of mass.

In order to keep things easy for coaches, think about the three simple factors that are relevant to wearable resistance. The main factor is total load compared to body weight and an athlete’s power. The second consideration is where the load is placed on the body, anatomically. Lastly, think of what activities the athlete does and how the load can provide possible enhancement later. A cheap jacket vest with heavy load in the front of the chest can cause fatigue to the erectors of the spine, but a better-constructed system may distribute load more uniformly. Ergonomics matter with large loads, so it’s important to be cognizant of the subtle differences.

Ergonomics matter with large loads, so it’s important to be aware of the load distribution. Click To Tweet

Common Equipment Design and Market Options

Design variables build off the physics section in this article and you should review them carefully before investing in wearable resistance. It may sound boring, but I don’t like most options because they are hard to clean and uncomfortable to wear. The heavier the garment, the harder it is to design due to the limitation of adding lead shot or other incremental weights. If you are a coach and work with groups, cleaning a sweaty weight vest isn’t a fun experience, as you must take the weights out to launder it and that’s a big chore.

I believe that wearable resistance is for advanced athletes, not from the training practice, but because of the administrative burden of using it. Don’t be scared away from buying a wearable resistance tool—it’s just a design feature you need to consider like any wearable technology. How easy is it to wash and clean, and will the stitching survive constant use? If it’s a personal vest for fitness, that factors as a different experience than working with large teams.

After cleaning, now comes the main benefit of good design: comfort. Good engineering of wearable resistance reflects an understanding and appreciation of comfort, and measuring this subjective quality isn’t easy when prototyping products. When buying a vest, the equipment must feel connected to the body, as stopping and starting in sprinting feels like a punch when the weights are not tied down properly.

Good engineering of wearable resistance reflects an understanding and appreciation of comfort. Click To Tweet

Usually, the cheaper the product, the less comfortable it is, as manufacturers are just trying to find ways to inexpensively hide lead in small pockets. There’s not much innovation with wearable resistance, but a few products have moved past the typical designs of the past. Neoprene and other materials are common in the more comfortable products, but keep in mind that durability and comfort are sometimes compromised when a company provides a better solution. Wear patterns usually form along the oscillation location of the load, and you should ask around to find coaches who have had a system for a few years before buying one.

Durability and aesthetics are sometimes a tradeoff, as the best-looking equipment is often not the one that lasts year after year. Inspect the product, looking at its stitching and how the material was cut. Nearly every company spends its time finding a way to manufacture more cheaply, so look to those products that don’t compromise on design. I treat each wearable resistance product like work boots: They should be replaced every few years, but should never last less than a year, even with heavy use.

I do care that the product looks good, as visual appeal usually demonstrates a dedication to design. Often, we separate aesthetics from science and function, but compression-style products that have wearable resistance improve the application of science, thus making it useful in the real world. Many of the best weighted garments look good and function just as well as they appear.

What the Sport Science Tells Us Today

Now comes the heavy part of the article—the science of wearable resistance. Simply put, most of the research that was done in the past was a little primitive, but some timeless investigations were performed years ago. I want to be crystal clear here: I am not worshiping the “old stuff,” but many of the researchers who believe they are cutting-edge now are simply adding a twist to what was done earlier. For example, the advancement in resisted sprints has been very useful for coaches, but it’s still early before we know the difference in results between training systems chronically and isolated variables. So, instead of just listing summaries of the research, I added another section on why the science still isn’t conclusive, with a coaching perspective immediately after.

Wearable resistance isn’t just adding loads to different body party; it’s subtracting it as well. Click To Tweet

Perhaps the best review on the wearable resistance subject comes from AUT in New Zealand, and it is a great synopsis for coaches who want to know as much as possible. My recommendation is to start there, and attack the separate articles immediately afterward. Don’t get lazy and just skip to the conclusions or read the abstract and make assumptions—do your homework, as I have found a lot of limitations to meta-analysis as Cliff’s Notes for coaches. Also, keep in mind that wearable resistance is not just adding loads to different parts of the body; it’s subtracting it as well, since several studies have made efforts to reduce the weight of sports equipment over the years through creative experiments.

Here is a list of common activities that have been studied by scientists on wearable resistance. Most of the studies are on the training effects of trunk loading, but there are also some studies on limb-mounted resistance. Generally, the results are in output changes such as heart rate, speed, jump power, and physiology. Kinetic and kinematic differences have been evaluated with variable resistance, mainly to see how they interfere with, or improve, athletic movements that coaches want enhanced.

Sprinting Speed

So far, most of the research is on wearing weight vests and other garments such as thigh, shank, ankle, and wrist devices. Even some novel studies on forearm loading and how they decrease speed acutely after early acceleration are provocative. Chronically, the results of training with a weight vest for 4-8 weeks or even longer isn’t exciting, but new studies with light loads are very promising.

Agility, while a component of speed, does have some merit, but there’s not much research on change of direction compared to linear speed. We do know the kinematic differences between sleds and vests are real, but we don’t have many intervention studies besides the one by Clark. His study on lacrosse athletes (sleds and vests) was thought-provoking and surprising, but it just leads to the point of population-specific responses dictating the strength of an intervention. Generally, horizontal resistance for speed is far more effective for developing linear speed, but acceleration tends to benefit most.

So far, I haven’t seen a solid research study on maximal velocity and wearable resistance, but I would conclude that it’s likely to have very little impact, if any, due to the difficulty of changing such a quality in general. More electromyography and force analysis needs to be done on wearable resistance, especially with equipment that doesn’t load the trunk. A recent study on repeated speed with weight vests showed the same pattern as earlier research, making wearable resistance more of a GPP strength option for speed and power athletes based on the findings.

Leg Power

A current and fascinating study redistributed the total system weight from the bar to the body with a heavy weighted vest (12% of BM) and found it to be a superior way to develop leg power as compared to the conventional approach. The New Zealand study mentioned above, as well as several jump training investigations, shows that adding weight vests works in training. Many of the studies simply found that adding a load, ranging from 3-30%, really doesn’t make a big difference, but they were mainly jump testing. Unfortunately, the leg power research was either oversimplified vertical jump training in a constrained design, or studies of the elderly walking up stairs or similar.

Based on the outcomes of the jump training studies, it looks like it’s best to view weighted vests as a way to help overload exercises already performed, but the expectations need to be toned down. Finally, a warm-up that utilizes a weighted vest was found to be helpful in horizontal leg power, and that was with an athletic female population. A similar study using a weighted vest with box jumps was found not to have much influence, but that was more vertical than horizontal.

Metabolic Conditioning

It is no mystery why I love weighted vests and walking for health and restoration. Due to compressed schedules from either life or sport, a brisk walk with a weighted vest is obviously more metabolically demanding. I don’t do any running with a weight vest myself, and based on the research, it does appear to have value in challenging the body.

Bosco and Rusko performed experiments in the 1980s, similar to ’60s and ’70s work with added load, and they should be credited with the term “hypergravity” and many of their training concepts. What has not been researched is the use of slideboard training and pool work, as most progressive coaches like the low-impact benefits of both modalities. Generally, the addition of low loads to conventional training, mainly in the fitness arena, is used to help accelerate fat loss due to the increase in output.

Athletic Movement and Training

This is not a perfect category, but I’m placing the rest of the research that I felt wasn’t running in a straight line or jumping here, so bear with me. It’s hard to really put agility into a category, but a few studies show small loads added to an athlete may result in favorable adaptations to raw change-of-direction abilities. Most studies look at time performance with change of direction; we need more research to look at both the kinetics and kinematics of small loads and incrementally heavier loads.

A very recent study on jump landings with a weight vest identified different movement strategies, showing that coaches need to be aware of the subtle differences between athletes when training with weighted vests. I could have placed the warm-up study on leg stiffness in another category for this section, but enhancing stiffness could be a benefit that helps with athletic development. Alone, the process may not be enough to be seen as a complete intervention.

Coaches gravitate to wearable resistance because it’s familiar, so it’s unlikely we’ll see radical research designs in the future, but I don’t bet against something novel down the road. A good working philosophy can be created with the above summaries, and as a coach or athlete, I recommend you decide whether and how you plan to use wearable resistance in your training routine.

Overall, the research has not brought about anything game-changing, and this is not shocking. Wearable resistance is an adjustment to conventional training, it’s not a new training modality.

Wearable resistance is an adjustment to conventional training, not a new training modality. Click To Tweet

In closing, I want to make sure we start thinking about the general teaching points of adding small loads or slowing things down slightly as a positive opportunity, provided the outcomes show long-term value. Resistance is not just a training benefit—it’s also a possible biofeedback tool that can teach athletes the consequences or advantages of changing a movement strategy. For athletes who have been injured or show deficits from added external load, the use of wearable resistance is not only a teaching option, it’s a way to monitor progress.

Counterpoints to the Research We Need to Know

The second part of the science is now the reason I think the findings may be skewed too much or not enough. I do not disagree with the research; I just want to make sure coaches can think about the studies’ conclusions and rethink the magnitude of the results. Often, the research can’t be replicated with coaching programs that have multiple variables that overlap the benefits of a single intervention (weighted vests or similar), so we need to have realistic expectations. Conversely, coaches who may work with an athlete for years and who constantly use a modality over and over again may see different outcomes than the peer-reviewed studies. One example is a coach using weighted vests with plyos who may see very nice benefits with maximal speed years from now, yet a short eight-week study found no change.

Most sport science research is designed to give an intervention a chance to succeed, as researchers usually compare the intervention to a control or nothing, making it hard for a program that typically does other activities with their athletes. My favorite example is weighted sleds, where a control simply sprints with lighter sleds or does free sprinting instead of using the extra energy to go harder on the weights or save the effort left for plyometrics. If you really want to test the value of an intervention, you need to see it in your program and other coach’s programs over years, and look at the research.

The most common arguments against adding wearable resistance to the extremities is slowing down the movement or overloading the muscle groups artificially. I have heard a good point that athletes will sometimes discover a movement strategy to “find a way” to achieve performance and those motor skills could transfer later, so it’s still fuzzy now. Some coaches (rightly so, by the way) worry that a muscle that may be prone to injury could be exposed to a strange overload and become injured. Unfortunately, we don’t have any real research on the injury rates and rehabilitation benefits of wearable resistance to draw conclusions. A volleyball study with elite players did look at ground reaction forces, though.

My own conclusion is that the value of wearable resistance is using it as a way to add a small incremental strain to familiar movements that are fast and ballistic. It’s popular to use very heavy weighted vests to load athletes up for single leg exercises, but in team settings it’s not practical and not unique. When utilizing any modality, the key is not to see it as just a specific tool in the toolbox, but a better analogy is to see it as the right medium in art. I love the craftsmanship of coaches who can teach and program athletes, and I do conclude that wearable resistance is a tool.

Some Final Thoughts on Wearable Resistance

Even my own article on weight vest training is dated and way too oversimplified to get answers for how hypergravity can help athletes. I like a combined approach to training and I rarely find a magic bullet, but if you want to make a difference with athletes, using weighted garments is a good idea if the training is properly designed.

Using weighted garments is a good idea if your training is properly designed. Click To Tweet

As a solution in sport, think about the big three: testing, training, and, of course, teaching. Whatever your situation, I would focus on selectively using wearable resistance as a way to create small variability with ballistic activities. Have fun and be smart with wearable resistance—there are quite a lot of options, so be thorough with your experimentation.

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