Hands-on – Runkeeper Pro’s HRM support (via Wahoo Fitness Fisica key)

This post covers the Wahoo Fitness Fisica key and its integration with the Runkeeper Pro app. Applicable photos to be added later today.

Until recently, the only way to record HRM data against Runkeeper activities was to:

  • record the average HR
  • import the HR data from a compatible Polar or Garmin device

However, several days ago, Runkeeper launched v2.4 of their Pro app which almost silently included support for Wahoo Fitness’ Fisica Key which is a dongle that attaches to the bottom of your iPhone.

Firstly, many have asked why the iPhone (and Runkeeper) won’t support Bluetooth HRM chest straps. The reason is that Apple currently prevent this type of device interacting with the iPhone. Some BT profiles are compatible with the iPhone. The profile used by HRM straps isn’t. It’s unclear whether they will in the future but let’s hope so.

So, if you want integrated HRM on your iPhone, the only sensible option is to use the Wahoo Fisica Key and an application that’s compatible. Wahoo provide an API for app developers to integrate to the key. The key uses ANT+ to collect or read data from a compatible HRM chest strap and the app developer use the API to collect data from the key.

It is currently only possible to purchase the WFK from the Wahoo Fitness website (http://www.wahoofitness.com). If you live in the UK, you can expect delivery to take only 3 – 4 working days. This is pretty impressive! The product is shipped by USPS and then Parcelforce. Tracking is only possible for the USPS part of its journey. The tracking information is sent via email once the product has been dispatched.

Upon delivery of the WFK and, if you have a compatible HRM strap, you are ready to try out the HRM feature within Runkeeper Pro.

The WFK plugs into the socket at the bottom of the iPhone. The key is small, although ideally I’d like it smaller. Once plugged in, the key’s dimensions are 27mm x 17mm x 7mm.

When plugged in, the WFK seems pretty secure. More about this later.

Some users are concerned that they may not be able to use the WFK with their current armband. It really depends if the armband has a suitable hole/slot at the bottom. If you can plug a USB charger cable into the bottom of your iPhone whilst in your armband, plugging in the WFK will be fine. If you can’t, it’s time to invest in a new armband. The tuneband armband (http://grantwoodstore.com/Tuneband-for-iPhone-4-Fits-both/M/B003ZZKL6U.htm) works fine.

Wahoo have a couple of apps in the iPhone app store. These are the Wahoo Fisica Utility and Fisica Fitness. The former app is useful in checking that your HRM strap is compatible. The latter app is odd as if you choose to run, it seems to prevent you using it unless you have a stride sensor.

In terms of compatibility between the WFK and HRM straps, any ANT+ strap will be fine. I have a Garmin Premium Soft HRM Strap which is ANT+ compatible.

It is recommended that you download and install Wahoo Fisica Utility to initially pair the WFK with your HRM strap. The app provides quite a lot of informational content about the Wahoo Fisica solution. In addition, it allows the user to connect to and test each of the sensors (the Fisica key supports HRM, bike speed/cadence sensors, bike power sensors, stride sensors, weight scales and blood pressure sensors. Please note that the Runkeeper app only integrates HRM data at the time of writing).

Once you have the app installed, simply connect the WFK to your iPhone, start up the app, choose Sensors, select Heart Rate and then click Connect. Within a couple of seconds, the HR will be presented on screen along with the signal efficiency and serial number of your key.

In terms of allowable distance between the HRM strap and your iPhone (with key plugged in), Wahoo state 5 feet. My Garmin HRM strap states 3 metres. However, I’ve got at least 15 feet away and still had a very good signal.

Once you’ve tested the WFK and got it to connect using the Fisica Utility, it’s time to start tracking activities with HR data via Runkeeper.

With the WFK plugged in and an activity started, the only indication that HRM being captured is the heart symbol and the current HR being presented under the activity stats panel on the Current Activity page. As you proceed through your activity, this is updated about once per second.

Runkeeper Pro Current Activity Screen showing current HR

During the activity, the WFK seemed to remain securely attached to my iPhone. I was concerned that it may drop out as I ran but this (fortunately) didn’t happen. I was also concerned that if the armband moved around my arm that there could be a possibility of stress on the connector for the WFK. To allay this fear, periodically during my run, I moved the armband to a position such that this couldn’t happen.

At the end of the activity and once the data had uploaded to Runkeeper, the HRM data is presented in the pace/elevation/speed chart as a new data series as shown below.

Runkeeper HRM graph

The Wahoo Fitness Fisica key solution isn’t cheap (about £60) and with an ANT+ HRM strap is likely to cost about £100 in total. However, this is cheaper than the cheapest GPS/HRM sports watch and Runkeeper is much more powerful than watches in the class.

I decided to go ahead and buy the Wahoo solution based on the following:

  • I had a ANT+ compatible strap already (£35-40 in the UK)
  • Wahoo and ANT+ support a number of other sensors (bike speed/cadence, bike power, stride sensors) which may be supported by Runkeeper in the future. Potentially good for cadence tracking while running or for cycling
  • Apple don’t currently support Bluetooth HRM straps and there’s no proof that they ever will (although it would make sense for them to do so)
  • Apple don’t currently support ANT+ devices directly. Maybe the next generation of iPhone will include ANT+ support but this is likely to be several months away at the earliest
  • Investing in an ANT+ solution gives me future compatibility with Garmin sports watches and maybe the newly announced Nike/TomTom watch should I ever decide to purchase one.

In terms of the HRM integration with Runkeeper Pro, the first phase is basic (presentation of current HR on activity screen) and then download of HRM data as part of activity. However, I think there’s a lot of scope to make HR data much more useful for training workouts through the inclusion of HR zones for workout intervals.

In fact, here’s some feedback I provided re HRM data to the Runkeeper team:


(a) it looks like the presentation of the HR was an afterthought. Would be good if the HR could be integrated more into the ‘activity metrics’ at the top of the screen. Maybe allow the user to choose whether to display calories or HR.

(b) I’d like to see the HR being presented per interval in the splits/intervals display

(c) It would be useful if current HR (averaged over a period of time) were announced. For some, this is more important/useful than pace. The same with the ‘last interval’ HR.

(d) It would be good to be able to view the ‘average’ HR per minute by selecting the bars in the chart


(i) In the splits display, it would be useful to present the average HR for the split/interval

(ii) when scrolling over the pace/elevation/HR chart, the choice of information presented in the metrics popup appears sporadic. For example, when choosing pace, HR is not presented in the ‘popup’ and time disappears at some points during the scrolling. When ‘tracking’ the HR line, pace isn’t presented and time sporadically disappears from the popup

(iii) HR data is not currently exported as part of the .GPX export. This should be added.

6 thoughts on “Hands-on – Runkeeper Pro’s HRM support (via Wahoo Fitness Fisica key)

  1. Great article thanks. I’m probably going to go this route too since there doesn’t seem to be any other option for an iPhone 4.

    Just wondering if there is any sort of calorie read out?

  2. What a great hand-on piece. This gives everything I needed to know and in a non-geeky way that’s understandable – thanks.

  3. I purchased this and was interested in your feedback with the dongle being secure. Have you encountered any issues with the sensor falling off or did you breakdown and by the armband?

    • Although the sensor looks insecure, I have had no trouble with it. I use an arm band if the weather is good and/or put it in the pocket of my jacket, if not.

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