Can resistance bands improve bone density?

Posted on March 25, 2016


I think space is awesome. I think going to Mars is awesome. I think it’s important to do. I’m not going to make an argument why, but you can see one here.

A problem for human spaceflight is countering the negative impacts of moving in an environment where gravity is less than Earth’s. This is the predominant impetus for some space posts I’ll have, as there is a ton here which can be applied to everyday people on Earth, and vice versa.

Sometimes I’ll hit on current treatments; sometimes I’ll hit on ways things could potentially be improved. Maybe this can be my small way to help the Mars movement.

Finally, I want to stress, even if you’re not interested in space, I think this stuff can be valuable to learn about. For instance, this post will show when how you lift takes a back seat to how much you’re lifting

I hit on the benefits of using bands over weight machines in minimizing mass for human spaceflight (size is money). Long story short, you can get a lot more resistance for a lot less mass. A band which gives 45 pounds of tension can be 44 pounds lighter than a 45 pound free weight. While free weights aren’t feasible in space, the current technology necessitates about one thousand pounds in order to garner 600 pounds of resistance. It’s worse than free weights. Bands again are much, much more efficient. In that post there was also discussion on differences between using bands vs free weights.

Nuances aside, what it comes down to is can bands give similar results? For instance, biking and running can give similar muscular results, but not bone results. Biking is not good for bone density. One way to picture this:

Compared to:

To start out NASA tried some band like equipment. They would add bungees as resistance when the machine wasn’t enough.

iRED heel raise squat set up with bungee circle

From: Results of the International Space Station Interim Resistance Exercise Device Man-in-the-Loop Test

This machine used some canisters -lateral to the red circles above- containing quite the arrangement of elastics:

iRED canister

When studying this set up, the interim resistive exercise device, iRED, compared to free weights:

“For controls, no changes occurred pre- to posttraining. For iRED3 [3 sets each of bench, squat, and deadlift for 3 days per week for 16 weeks], increases in one-repetition maximum (1-RM) strength (Squat 21 +/- 4%, Heel Raise 17 +/- 4%, Deadlift 29 +/- 5%), leg lean mass (3.1 +/- 0.5%) by dual energy x-ray absorptiometry (DXA), and thigh (4.5 +/- 0.9%) and calf (5.9 +/- 0.7%) muscle volume (by magnetic resonance imaging) occurred after training with no changes in Bone Mineral Density (DXA).

For Free Weights, increases in 1-RM strength (Squat 22 +/- 5%, Heel Raise 24 +/- 3%, Deadlift 41 +/- 7%), whole body (3.0 +/- 1.1%) and leg lean mass (5.4 +/- 1.2%), thigh (9.2 +/- 1.3%) and calf (4.2 +/- 1.0%) muscle volumes, and lumbar Bone Mineral Density (4.2 +/- 0.7%) occurred after training. For iRED6 [6 sets of each exercise], all responses were similar to iRED3.”

To clarify that chaos above, bone density did not change with iRED, but did change with free weights.

So far as I’ve been able to see, this study seems to be one primary impetus for the fear NASA has when using bands compared to a free weight analogue. Because of this result, this is where NASA seems to have placed a primary deficiency of the iRED and elastomerics on the differences in the force curve. Namely, when using a band the resistance is not the same throughout the entire rep. At the beginning of the rep it’s easier than at the end.

Looking at a recent competition NASA had for designing an exercise device, they essentially banned elastics from being used for this reason.

Some in the lifting world know how incredibly strong people like Westside Barbell have become (in part) from using bands.

Large human with a lot of weight...using bands.

Large human with a lot of weight…using bands.

What’s going on here?

First, notice in that study there was only one site the free weight group got a benefit in bone mineral density, which was the lower back. It’s not like it was every site on the body. It was one. That’s strange.

With iRED, squatting takes place with a vest / harness.

Single leg squat variation:

Single Leg Squat iRED harness

While I haven’t gotten the full text of this study (it appears to be NASA funded; we shouldn’t need to pay for it twice), it’s safe to assume the free weight group didn’t do this for their squat. Instead putting a barbell on their shoulders.

When using a vest or harness, it’s conceivable the person moved so the weight was more or less directly under them. Directly through their center of mass. Something like this, but with the spine more perpendicular to the floor (will show another example in a second):

squat with harness 2

Notice the line of pull of the resistance goes straight up through the hips.

In other words, the person would be able to remain more upright. Opposed to having a barbell on the shoulders, where the torso ends up significantly leaning forward 1) the barbell is pushing you that way 2) otherwise you’d fall backward. With a harness, you can be more upright as it will pull you forward some.

Notice on the harness the bungee connection is on the front of the person’s shoulders.

iRED squat harness 2

Cable attachments are in front of her arms.

Squat iRED harness bungee close up

This would be analogous to a front squat. In a front squat, one can maintain much more of a vertical back angle. (Again, harder to fall backward being upright when the weight is on the front of your shoulders, pulling you forward.) Meaning the lower back isn’t getting as much work compared to a back squat. Those who know what they’re doing, who exercise people with a lower back history, know a front squat will be better tolerated than a back squat.

I believe the original credit for this goes to Mark Rippetoe.

The spine leans more forward when the bar is on the back. (I believe the original credit for this goes to Mark Rippetoe.)

My hunch is this is was the primary difference between the groups. The free weight group significantly worked their lower back more than the non-free weight group. Hence more bone density there. The free weight group squatted like the middle or right picture above; the non-free weight group squatted like the picture on the left.

-> Sometimes iRED users will use a harness for deadlifting too. I can’t speak with any confidence as to whether a bar or harness was used for deadlifting though. (For squatting, NASA documents, like this one, state only the harness is used.) If the harness was used at all though, the same thought process may apply. Where when using the harness the lower back was perhaps not as worked, and then the free weight group would have worked their lower backs even more, relative to the iRED group. (Without seeing video of the form used, it’s tough to know.)

Overall, we’re attempting to compare similar variables for not completely similar exercises. With one of those variables, bone density, incredibly sensitive to the angles in which it’s loaded.

Another noteworthy aspect of that study is the deadlift improved significantly more in the free weight group compared to the non. 41% compared to 29%. Ignoring the vest and such above, this brings up another handicap of iRED:

iRED lift capabilities

We have a max load of 300lbs. When accounting for how extended the cords are though, this maximum gets significantly lessened. NASA documents appear to make little reference to this cord length limitation. Based on the chart above, one would think for large range of motion movements, like squatting, the load limitation gets significantly reduced below 300 pounds. To maybe ~200lbs, as a squat is going to approximate two feet or so of range of motion.

I’m not sure how this study handled this discrepancy- a 300 pound max isn’t going to be enough in the squat and deadlift for decently strong males to get stronger. If the iRED group never squatted or deadlifted more than 200 to 300 pounds, but the free weight group did, we’d expect them to get stronger. (If volume was equalized between the two, then we’re back to examining technique.)

Regardless, we know this was a significant limitation because the new version of iRED, the ARED, goes up to 600 pounds. The reason for 600 pounds is in space, without your bodyweight being a factor, you need to make up for that. If you weigh 200 pounds and squat 400 pounds on Earth, you need 600 pounds of resistance in microgravity for things to be equal. (The iRED was really inadequate in this regard.) With this new load, the bone density issues have become much less of a concern for astronauts. Thing is, ARED isn’t elastic based. So, we can’t say the benefits in bone have come from extra loading, or transitioning to a free weight analogue, which ARED is.

Luckily, other research has beautifully looked at this, though not with the intent.

Site-specific response of bone to exercise in premenopausal women

This research group previously found lower body exercise, even impact (jumping) oriented, benefitted hip bone mineral density, but not spine. (Lower body exercise here did not include barbell training, but weighted vests. Sounds like what we just talked about!) So,

“To also study the response of the spine to specific training, we added upper body exercise to the lower body program in order to provide a targeted stimulus to improve spine bone mineral density. We hypothesized that women who performed both upper and lower body exercise would increase bone mineral density at both the spine and the hip whereas women who performed lower body exercise only would demonstrate an increase in bone mineral density at the hip but not the spine.”

The researchers figured they’d divide things up to see if exercise which hit musculature around the spine, like the lats, impacted bone mineral density.

And amazingly, for our purposes, the upper body training consisted of only using elastic bands. The resistance of the bands was progressively changed, in a strength oriented rep and volume range, over the course of a year. Perfect!

The researchers give plenty of citations illustrating bands get the job done strength wise. So muscularly we know they’re sufficient. Bone is what we’re most interested in.

upper body band training for bone mineral density

Looking at the far right, we can see the upper body group got a direct bone density benefit at the spine. Coinciding with a (albeit small and not statistically significant) benefit for whole body bone density:

Bone density comparisons with bands

Bone density was still improving at month 12. It’s possible more time was needed to hit statistical significance.

Again, this was from only using bands as resistance training for the upper body.

The force curve of bands, or tubing, is not something to worry about. This statement from NASA researchers,

“Use of the bungee augmentation is helpful but is not an optimal solution, particularly for the squat exercise, which involves a large range of motion because, at the beginning of the range of motion, the bungee cords are slack and do not provide additional force.”

That statement doesn’t follow.

1) You can make the bands tight enough that there *is* tension at the bottom of a rep:

exrx bands squatting

-> If a lack of tension at the bottom of the squat or deadlift happened in the iRED compared to free weights study, this further exemplifies differences between the groups. Particularly because the bottom of a squat or deadlift can be when the lower back has to work the hardest. You’re more likely to hurt your back at the bottom of a deadlift than at the top. Given equal resistance then, you would expect the free weight group to get more from the exercises. With the band group, you’d need to give them more resistance to fully equal things out.

2) Relative to other stages, the terminal range of motion of many exercises, like a squat and bench press, involves little force. Nobody gets stuck during a squat the last six inches. Once past the sticking point, the latter portion of the range of motion is never maximally worked. You can quarter squat more than you can half squat. If we’re going to criticize bands for what they lack in providing at the bottom of a rep, we need to concurrently criticize free weights for what they lack in providing at the top of a rep. (And no one has trouble getting strong muscles and bones from free weights!)

->If your max squat is 200 pounds, that’s probably because you get stuck towards the bottom of the rep at 201lbs. Therefore, bands which can provide 200 pounds of resistance are not sufficient. Because at the bottom of the squat, with the bands, you won’t have 200 pounds of resistance. You’ll have that 200 pounds at the top of the squat, but at the top you can lift more than 200 pounds. You might need bands which give 250 pounds of resistance (at the top) to get a similar effect at the bottom of a squat as 200 pounds of free weights.

In that case, you’d then get a greater benefit at the top of the squat, because you’d also be working at your max in that range! With bands, you can get more of a complete rep with your maximal tension throughout the entire rep. A band may actually be able to vary its tension in accordance with your lifting capability. You can’t get this weight free weights, as the resistance is always whatever the weight is, for the entire rep, and that doesn’t match the force curve of most people’s muscles, in most exercises.

There are many ways to get around this stuff anyways. Rack pulls involve manipulating the height of a deadlift to only work a certain range of motion. If we felt a full deadlift with bands was insufficient in only working say the top two thirds of the rep, we could manipulate the exercise to only work say, the first third of the rep.

Rack Pull exercise working the top of the rep. Pins prevent bar from going below the top phase. Place the bar under the pins, and now we prevent the person from going *to* the top phase. We could also just tell the person to do this!

Board pressing does the same for bench pressing.

Rather than work the top part of the rep like in the above photo, we could switch it around and only work the bottom part of the rep.

We could use one band for a certain range of motion then a different band for another range of motion. (There will be another article on this for clarity.)

Perhaps most importantly, as the above photos suggest, an incredible amount of people have gotten very strong, very jacked, using partial range of motion exercises. Westside Barbell does things like rack pulls and board presses because they only work part of the range of motion. There is even a group of people who have specifically tested this, over generations. We call them “most bodybuilders.” Some of the biggest bodybuilders are actually afraid to use full range of motion, because they don’t like having their joints anywhere but the mid range.

The force curve of bands is not a problem with resistance training. (Nor is it with free weights for that matter.) Whether worried about muscles or bones. Bizarrely, NASA should already know this, as they funded the bone density study I’ve been referencing! (I had an email exchange with the study’s author and they didn’t have an explanation.) What may be a concern is getting enough overall resistance. At least the way bands are commonly used, and particularly for males, where a routinely used theraband or commoditized tube won’t get the job done, for even a moderately strong man. But places like EliteFTS makes bands strong enough for anyone…Or we can double the bands…Or we can just use more bands period…

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