Wednesday, 30 December 2020

DIY Cannonball Grips - How To Make Your Own

Something I always wanted to do was make my own set of cannonball grips to take my pull up and grip training to the next level. One of my local leisure centres had a gym rig that had molded on cannonball grips but obviously these aren't portable.

Looking online for some pre-made cannonball grips and well they aren't cheap especially for something so simple. So eventually I decided to dive in and make my own. This post will share with you how I went about doing it, the costs, and some of the setbacks and remedies I came across.

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Several years ago I saw a video on how to make cannonball grips however I can't remember where at. Luckily the basics of it remained lodged in my memory so I knew what I needed to go for. The equipment needed is incredibly simple and easily attainable:

  • Two baseballs or other kind of hard ball to use as the cannonballs. Whatever you choose ensure they are solid hard balls. See Problems encountered below for why.
  • Two eyebolts at least 4-5 inches long with a good thickness. For mine I choose ones that were 9mm thick.
  • Four nuts and four washers. Two pairs for each eyebolt. This helps keep the ball in place.
  • Two straps for attaching the grips to a pull up station.
  • Two carabiners to attach the eyebolts to the straps.
All the bits needed to make a large and small pair of cannonball grips.

Along with this you only need a few basic items to assemble the grips:

  • Adjustable wrench
  • Drill with a Spade or Spur Point wood drill bit a size down from the bolt. I.e. 8mm for a 9mm bolt.
  • Clamp for holding the ball in place whilst you drill.

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Sourcing the parts

Firstly I went onto Amazon and purchased two Wilson baseballs at £4.49 each. I would strongly recommend not buying these ones. Again see Problems encountered for why.

I also bought a two pack of 6cm diameter Efco wooden balls for £2.70. I bought these so I could try different sized grips to vary my exercises.

Next I ordered a set of Joyhoop Hammock Straps, which came with carabiners for £11.98 (at the time). There are other straps available and for cheaper however I liked the look of these ones and they were also shorter meaning the grips wouldn't end up hanging too low. After receiving them I can currently testify that they are indeed a good job able to support my 79kg body, and the carabiners are good and thick.

I went to the nearest hardware store to look for the eyebolts, however the smallest length they had was 6 inch, which I felt was too long. After driving around a few places I decided to return and just buy them. They cost 90p each slightly more than other places but unlike other places each bolt came with two nuts and two washers attached rather than one. This meant less hassle to find the right sized nut and washer.

I bought five eyebolts, one of which was to be a spare. I intended to glue the balls and nuts into place so needed one eyebolt for each grip. You could if you want use just two eyebolts and swap the grips for a different size for variation however for the cost of the eyebolts why waste the time it'd involve?

As a bit of a DIY enthusiast I already had the equipment needed to assemble the grips so I didn't need to deal with that stuff. So in total (excluding the Efco wooden balls as they are an extra) this cost £22.76. Not too bad, though turns out I could have done it for £19.76. Indeed even less with a cheaper set of straps.

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Making the grips

When it came to making the grips, the process was easier and quicker than sourcing the parts.

Firstly place the ball into a vice clamp. The one I used had a moveable neck allowing me to have it positioned so that I could drill straight down without hitting anything.

The next bit is the hardest bit: trying to drill through the ball so that it goes straight through the north and south poles of the ball. Unless you are using a drill press, which takes the problem away, you will have to depend on human judgement and you will not get it perfect, but you should be able to get it close enough. The drill bit should go through easy enough though there will be some cork dust ejected so do it outdoors or somewhere easy to hoover it up.

Vice, vice, baby! Make sure its tight enough to stop the ball moving whilst drilling.

Once the hole has been drilled through get an eye-bolt (with a nut and washer already on it) and start to screw it through the ball, or vis versa. I found screwing the ball the easiest way of doing it. Keep screwing until you have enough of the bolt protruded through the other side of the ball so that you can place on the other washer and nut. I found the hole a good width and snug fit for the bolt allowing for a tight fit.

After this tighten both nuts with the wrench. For added stiffness to prevent the nuts from possibly unscrewing over time you can apply glue to the bolt at either end of the ball and screw the nuts tight on top of it and then letting it cure.

Give both ends a good tighten with the wrench.

The final thing to do was to simply attach the eye part of the eye-bolt to the carabiner, which itself was attached to the eyes of the strap, and voila! A cannonball grip.

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Problems encountered - 1

Everything seemed to go great. I had done the baseball grips first and thought they looked great. I had orignally screwed the balls to the top of the eyebolts and intended to get the bottom of the bolt grinded off. However after hanging them there was no need for them to be screwed so high considering the height of my pull up bar. A bigger problem with them however was that they felt like if I hung my entire bodyweight off them then the baseballs would tear through the nuts at the bottom.

Checking online it turns out proper baseballs are made out of a combination of cork, rubber and wound string inside a leather skin. Some are simply pure cork. The ones I had purchased whilst feeling quite firm on the outside consisted of nothing but sponge. They bounced well but that was it. At least I can fun with my daughter throwing them about.

Looking around online for a pair of proper baseballs I couldn't find a good cheap ball or trust they had a good amount of cork in them. You could get full cork bodied ones yet I found them hard to find. I also wouldn't be able to tell if they were truly solid until delievered. They all seemed to be over £6-7 each. For something that goes for a couple of bucks in the states, it appears not for the UK. Had I not already wasted £10 on those soft baseballs I may have went for two of these other ones.

A day later I had to go Sports Direct to get my daughter a new pair of trainers and thought I'd chance my arm in seeing if they had any baseballs. I didn't hold much hope but lo and behold they did, and thankfully these Slazenger ones had a solid cork core and for only £2.99 each discounted from £5.99! I would caution that they do also sell a soft ball version, which should be avoided.

Arriving back home I went straight away to drill holes in the two balls and found it a better process than for the sponge core ones. When it came to putting the eyebolts through them it took a good steady screwing action to do so and it was a nice tight fit. After tightening the nuts I gave them a test and bingo they fitted the bill perfectly.

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Problems encountered - 2

Another issue I had was with the Efco wooden balls. It turns out it was next to impossible to screw the 9mm eyebolt through 8mm holes. I tried to find a 9mm flat-wood/spade wood drill bit (external link) of any kind in my local hardware shops however couldn't find anything but even numbered sizes over 12mm. So I had to use my 10mm Spur Point wood drill bit (external link) instead. It didn't matter in the end as tightening the bolts enough ensured the ball didn't twirl around.

Unfortunately the 10mm Spur Point drill bit wouldn't drill through the "pilot" 8mm hole without getting stuck so I decided to drill a new hole through it (intersecting the original hole track). Maybe a Spade wood drill bit wouldn't have had this sticking problem?

Filling in the gaps with some good ol' wood filler.

The gaps and damage to the ball from the original hole I filled in with wood filler. Unfortunately it was white coloured whereas the balls are a natural wooden colour, however I may end up painting the balls anyways. They are untreated wood so would benefit from a coat of something if I use them in poor weather.

After it sets give it a nice sand.

Thankfully the second ball hadn't been drilled through yet so I didn't have the same problems.

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The end product

The finished cannonball grips.
Don't let them dangle too low :-)

Wednesday, 7 October 2020

Low Back and Hamstrings Flexibility by Yoga With Adriene

Picture from

When it comes to yoga, one of the most popular and recommended YouTube channels is that of Yoga With Adriene, who currently has 8.42 million followers on the site. They also have a LOT of videos, so many

Friday, 11 September 2020

Triceps Dips

The full triceps dip is an advanced exercise that when performed correctly is one of the best exercises for the triceps muscle especially in calisthenics. It also hits the front of the shoulders and chest muscles making a great compound movement.

Unlike triceps bench dips, which require your feet to be supported, unaided dips utilise the full effect of gravity on your body to create the resistance, which can be increased with weight added such as with a dipping belt or weighted vest.

Wednesday, 3 June 2020

When opposites contract - muscle partners

For every movement your body makes, a combination of muscle contractions occur. For each of these contractions there is a relaxation in the opposite muscle. Welcome to the world of muscle pairs.

Virtually all muscles have an opposite. When a muscle is contracting it is known as the agonist. When it contracts, it causes its opposite muscle, the antagonist, to relax. For example if you flex your biceps, its opposite the triceps relaxes. If you flex your triceps the biceps relaxes. This is something called reciprocal inhibition

Agonist and antagonist muscle pairings
The basics of agonist/antagonist muscle action. Picture from

So why should you care about this? Read on...

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Supersets and alt-sets

Knowing your prime antagonist helps in the creation of effective supersetting or alt-setting if you goals are not hypertrophy or endurance. Supersetting is were you perform two exercises back to back. If you are seeking hypertrophy or looking to exhaust a particular muscle, then agonist supersets such as bench press followed by chest flyes, is the way to go. Alt-setting is where you are doing two exercises alternatingly, not necessarly as a supeset, but as a way to save time.

If you are not going for bodybuilding or the like, then agonist-antagonist supersetting or alt-setting provides the benefit of the second exercise (focusing on the antagonist muscle to the first exercise) causing reciprocal inhibition, meaning your prime agonist muscle from the first exercise relaxes and stretches, helping improve its recovery between sets.

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Antagonist-stretching is an effective form of muscle stretching whether it is done actively or passively.

An example of actively stretching your hamstrings is by raising your knee up and extending your leg at the knee. This contracts your quadriceps causing your hamstrings to relax and stretch. This kind of active movement is believed to be better for increasing range of motion and flexibility in the stretched muscle.

You could also do this passively, by flexing the antagonist muscle if possible whilst stretching.

Clenching your quadriceps whilst stretching your hamstrings, can allow you to go deeper into the stretch. Picture from Sports Injury Clinic

Interestingly you can mix it up with a form of strectching that seems contrary to the point of reciprocal inhibition. It is antagonist static stretching. An example is if you are doing biceps curls, then you would stretch your triceps between sets. Research shows that this form of stretch can cause an increase of repetitions and agonist activiation during the exercise.

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Split routines

Knowing your muscle pairs helps in the devising of more effective split routines. If you train chest and triceps primarily on what you might call a "push" day, then the next session you train upper back and biceps on a "pull" day. This allows you to avoid overloading the previously worked out muscles whilst given them a stretch through reciprocal inhibition.

Devise more effective and efficient split routines. Picture from The Fitness Bible

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Muscle pairs

It can be quite confusing matching up each specific muscle to its opposite especially when certain actions call different muscles or parts of a muscle into action or relaxation. Thus I'll try to keep this as simple as possible by basing it on the primary motions, common exercises for those motions and the primary muscles. Keeping it simple also helps for devising agonist-antagonist muscle pairings for supersets or split sessions amongst other things.





Spinal flexion

Sit-ups, hollow holds

Rectus abdominus

Erector spinae

Spinal extension

Back extensions, good mornings

Erector spinae

Rectus abdominus

Horizontal flexion

Press-ups, bench-press

Pectoralis major

Rhomboids, trapezius (mid)

Horizontal extension

Cable rows, seated rows

Rhomboids, trapezius (mid)

Pectoralis major

Elbow flexion

Bicep curls, chin-ups



Elbow extension

Dips, triceps extensions



Shoulder flexion

Pull-ups, pull-downs

Latissimus dorsi


Shoulder extension

Shoulder press


Latissimus dorsi

Knee flexion

Hamstring curls



Knee extension

Leg extensions



Hip flexion

Bent-knee leg raise, hanging-knee raise


Gluteus maximus

Hip extension

Hip thrusters

Gluteus maximus


Ankle flexion

Banded foot pulls


Gastrocnemius, soleus

Ankle extension
(Plantar flexion)


Gastrocnemius, soleus


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Lombard's paradox

Now whilst we know how muscles are meant to work and the effect they have on their opposite muscle, there is a interesting circumstance known as Lombard's paradox where this goes out the window. Lombard's paradox is where both the agonist and antagonist activate at the same time, this is commonly seen when standing up from a seated or squatting position.

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Knowing the antagonist muscle to that which you are working out allows you to fine tune your training in various ways. Whether it be more effective alternating sets, stretches, or split routines. Whilst the musculoskeletal system is highly complex and there are a multitude of different muscles and muscle heads activating in any given movement, each with their own antagonist, exercises can be broken down into their prime agonist and the primary antagonist.

If you have any questions then feel free to ask away in the comments or send me some feedback!

Saturday, 16 May 2020

Should you RICE RICE baby?

Picture from

A staple of injury healing, the RICE methodology has been around since Sportsmedicine Book was released in 1978. It is an acronym for Rest Ice Compress and Elevate and is the go to response when someone suffers an injury.

We've all either used it ourselves or been told by a doctor or physio to. Yet over the years it has come under ever more scrutiny with even the doctor who first came up with the RICE method, Dr. Gabe Mirkin, decades later changing his view on the Rest and Ice parts of it as they can actually delay your recovery.

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Movement over rest

Resting your injury makes a lot of sense. With more rest then it will heal better, right? Well, depending on the type of injury and your stage of recovery no it turns out.

If the injury is not a fracture, spinal or a catastrophic injury, then movement is necessary in the recovery process. In fact too much rest can be detrimental.

In 1996, doctors Jim and Phil Wharton released The Wharton's Stretch Book, which argued that movement rather than rest should be performed on an injury. The key reasons being that:

  • Rest causes the muscle to be inactive, thus shutting down and restricting blood flow.
  • Immobilisation of a muscle caused it and everything around it such as tendons and ligaments to atrophy (get smaller).
  • Muscular-imbalances due to compensations the body needs to make to get around an injured atrophied area.
  • That movement at a muscle or joint encouraged "blood flow to oxygenate the area and flush out metabolic waste from the injury".
  • Any careful and gentle movement no matter how small was good for helping improve range of motion after an injury.
Restricting movement could lead to delayed recovery. Picture from Industrial Health & Hygiene News

On the reverse side however too much movement, such as continuing on as normal or trying too much too soon, can exacerbate the injury and increase inflammation. This itself can lead to the injury being stuck in a chronic inflammation phase preventing recovery resulting in tissue atrophy etc. If it hurts or feels strenuous then you're doing too much too soon.

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Warmth over ice

The Wharton's despite their recommendation to substitute movement for rest, still agreed with icing the injured area. Other's however have come out against this part of the RICE protocol including its inventor.

On Dr. Mirkin's website is his article Why Ice Delays Recovery, first published in 2015. A highlight of the key points include:

  • Ice treatment causes blood vessels to constrict and close. These took many hours to reopen deceasing blood flow.
  • This could cause nerve damage and even tissue death.
  • Ice and cold packs reduced inflammation, which also delays healing.
  • Icing for more than 5 minutes reduces a person's strength, speed, endurance and coordination.

According to Muscle Injuries: Biology and Treatment, published in American Journal of Sports Medicine (vol. 33, no. 5, pp. 745-764, 2005), no randomised clinical trials have proven the effectiveness of icing an injury to aid recovery. This was backed up by a meta-analysis in the British Journal of Sports Medicine of 22 separate studies on the effects of ice on acute muscle strains.

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Alternative to RICE?

There is one alternative to RICE that seems to be gaining traction - MEAT. This acronym stands for:

  • Movement - Gentle movement to help encourage blood flow, improve range of motion, as well to ensure scar tissue forms in proper alignment. Helps prevent atrophy.
  • Exercise - Controlled and specifically prescribed to progressively improve range of motion and strength.
  • Analgesics - For pain relief, however not NSAIDs. Natural pain relief has been suggested as more beneficial.
  • Treatment - A long term solution, such as physiotherapy, to aid in successfully recovering from the injury.
RIC or MEAT injury recovery protocol
Would you like a side of meat or rice with your injury, sir?

Of course this applies to non-acute injuries. The RICE protocol still has merit when it comes to helping reduce swelling and pain in serious injuries such as fractures, torn ligaments etc. though once the injury has settled MEAT comes into play.

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If the injury is not a serious one then resting it can be detrimental to the injured area and prolong your recovery. It can lead to atrophy of the affected area and a loss of strength as well as imbalances.

In regards to icing, it is good for pain relief and reducing inflammation, especially in the immediate aftermath of an injury, however it also delays the recovery process and can actually cause tissue death and nerve damage.

MEAT on the other hand helps encourage the healing process whilst maintaining tissue health, yet RICE does have its place for helping with acute injuries. Thus after four decades RICE would seem to have had its day in certain aspects with MEAT appearing to be the way to go... unless of course you're a vegetarian or vegan.