RunningPhysio review – Ankle Foot MaXimizer

I arrived in our clinic @ThePhysioRooms and there, sat on the desk was a box with “Air Mail” written on it. Air mail? I never get Air Mail and yet here it was, looking fresh despite a long journey from Canada. I was like a child in a sweet shop. A very geeky child in a sweet shop that sells high-tech rehab equipment!

As soon as I’d torn off the tape and opened the box I knew we had a product on our hands. The first thing that greets you is the black AFX carry bag, neatly folded on top. Peel that away and the first sight is a little intimidating – the foot pad, the cables, the handles and pole – and yet I was pleasantly surprised to find it came ready to use, literally straight out of the box. It comes with fool proof instructions and a 30 minute instructional DVD.

In seconds the socks were off and AFX was on. It feels really comfortable on the foot, almost like it gives it a little hug. You can instantly feel the muscles around the foot and ankle working as you use it. But “feel” isn’t enough for me. I wanted something a bit more objective, so I put it through it’s paces with a 3 stage review process….

Stage 1 – EMG Tests

EMG (Electromyography) is an assessment used to determine the electrical activity within a muscle. It is a measure of how well a muscle is activating. In this case the higher the value the better. We used our EMG unit to assess how red, medium level AFX compared with black resistance band ( XX Heavy resistance from Stretchaband) Tables below detail the approximate resistance profiles of each. There are a lot of variables in this assessment and it was only done on 1 subject (me!) so it’s an approximation rather than firm scientific research.

Stretchaband is a latex free resistance band, ranging in strength from yellow to black. Further details can be found here.

Black was chosen as it’s resistance at 100% elongation (double normal length) was similar to the red level on AFX. These can only be approximated as resistance varies hugely depending on elongation, as the chart shows.

AFX comes in 4 levels of resistance from low in yellow to performance in blue.

For this stage we assessed the maximal EMG score achieved when testing a) gastrocnemius (calf) muscle contraction and b) Tibialis Anterior contraction. Best score of 5 attempts was recorded with maximal stretch on the resistance band or AFX.

Picture on the right shows EMG set up to test Tibialis Anterior.

Stage 2 – Fatigue test

We compared numbers of repetitions needed to fatigue the calf muscle using the black band and red AFX with maximal stretch.

Stage 3 – Group Evaluation

I work with a lovely team of experienced physios and they kindly gave up an hour of their time to try out the AFX, compare it to resistance band and discuss their findings. They had 2 main questions to answer;

  1. Does AFX have key advantages to resistance band?
  2. Are there disadvantages to AFX?

The results

Stage 1

AFX scored higher than resistance band for both gastrocnemius and tibialis anterior muscles in our EMG studies;

For the gastrocnemius muscle both AFX and resistance band scored less than a single leg calf raise. This isn’t surprising as this involves resistance of the entire body weight. That said, AFX scored 425 to single calf raise at 460. Had we used a harder AFX level we may well have achieved the same muscle activation.

Stage 2

Guest blogger and fellow Physio Andy took on this challenge (as he has calf muscles of solid steel!). He did AFX first and his calf muscle fatigued at 36 reps. He repeated the test with resistance band after a rest period…he stopped at 70 reps, and still hadn’t fatigued the calf.

Stage 3

At first I think our team were a little sceptical and I faced the question, “isn’t it just posh resistance band?” Their views soon changed once they’d had a chance to use the AFX. After some experimenting they answered the questions

  1. AFX does have key advantages to resistance band. It provides a harder resistance, appears to increase activity in the intrinsic muscles in the foot and proved an easier way of resisting foot and ankle movements. It also can be used for stretching and improving ankle range of movement, I found it especially useful for improving ankle inversion (turning in) which can be a challenging movement to stretch. Because AFX attaches to the toes and metatarsals it allows you to combine movements such as plantarflexion and toe flexion to work multiple areas. The way AFX attaches also prevents slippage that you can get with resistance band and maintains resistance throughout. Because of this it was easier to use than band for eccentric muscle work, especially on Tibialis Posterior.
  2. The only noted disadvantages were cost and portability. It was pointed out that resistance band could fit in a handbag or travelbag when AFX probably couldn’t.

AFX in action;


Overall AFX is an exciting new product that has multiple uses and our testing indicates it’s a more effective way of strengthening the foot and ankle. The AFX certainly “feels” like it works the muscle harder and the EMG results suggest it achieves better muscle contraction than resistance band. Not only this, but it fatigues muscles more efficiently – with resistance band it took double the reps needed with AFX to reach fatigue. Our usual rep range to improve endurance is 15-25 reps. Fatigue was achieved at 36 with the AFX, with 2 harder levels of resistance available it is likely we could work in this range using a harder level. Resistance band needed over 70 reps to reach fatigue with the hardest band available to us, at maximal stretch. It’s unlikely this would improve strength or endurance and this is consistent with what I’ve found with patients – resistance band doesn’t offer enough resistance to improve most people’s calf muscle strength. It is probably adequate for the smaller muscles involved in inversion and eversion but for calf rehab I would definitely choose AFX over resistance band.

This review isn’t just about AFX vs band. AFX stands on its own as a product. In many areas in rehab we have several tools that aim to achieve a similar goal, each with their own benefits. Take wobble boards, rocker boards, balance cushions, BOSU balls etc etc. they all work balance in slightly different ways. Resistance band certainly has a role and this review shows that AFX does too. The only downside is cost. Bought in bulk, bands can be as little as £1 to £2 per metre. Currently AFX is not available in the UK but manufacturers are hoping to introduce it in Autumn/ Winter. In Canada and the US it is available in 2 different packages, standard at $99 and “Pro” at $129.

To put this into perspective though, a BOSU ball in the US cost $109 (at and my running shoes (Gel Kayano 18) around $140. For individuals it may be at the top end of their budget but for a product that could really help rehab foot and ankle problems, which are very common in runners, it could be money well spent. As it’s easy to clean, physiotherapy clinics could invest in an AFX and potentially use it for multiple clients.

Final thoughts: AFX is an exciting and innovative new product in foot and ankle rehab. It shows great potential for strengthening and stretching and has clear advantages over resistance band if you’re happy to pay the extra cost.

For more information on this product check out their website or chat to Matt on @afxonline on Twitter.