Saturday 29 June 2013

Holux M1000C inaccuracy

This table shows comparative features of GPS loggers and notes that the Holux is low resolution. Could that explain the disappointing log data?

I've collated this example of performance to illustrate my concern. The lack of alignment of the Holux is not due to the Google photo as I've overlayed the GPX on both OS and OSM mapping on different platforms with the same result.

Three GPS logging devices and their respective tracks along a suburban track near home. Mapping is OSM, Google Earth and OS 1:25000 respectively. Software was Garmin Connect, GPS Visualizer and Android Viewranger. 

Holux binary logs record latitude and longitude as 4 byte,  32 bit floats. This should allow 7 to 9 significant figures of a decimal number which is plenty for real world logging.  It is also worth seeing this illustration of truncation errors.
5 minutes of capturing NMEA sentences followed by logging. Plotted as divergence in degrees from the average position indicted from each recording.
I have compared the standard NMEA data against the float32 capture data; the quantization of the latter is very evident. However note that the errors of both fall within 0.0001 degree for nearly all of the time.

A 0.0001 degree ring around a point in the outdoor swimming pool at Hathersage. Most points would be well within this margin.

This Google Map shows that this variation is little more than the width of a road and so the 'theoretical resolution problem' does not account for the real-world logging errors seen.

Tuesday 25 June 2013

Out of the woods?

Yesterday I saw the physio again and she thought I could try a 'long run' today. The pain has become little more than discomfort and isn't really knee-related anymore. Just generally in my both legs! Anyway, I managed 9.2km which meant that I had run far enough to leave Ecclesall woods for the first time in a month.

A check of the Holux record showed it to be quite a long way off course again despite making an effort to leave the box exposed at the top of a bag with the battery on the lower surface. It's something to do with the location as the east of the woods has recorded more accurately than the west on 2 occasions now.

Saturday 22 June 2013

Knee recovering

The physio thought that this week would be a key test for how well I was recovering. Well so far it looks pretty good. I've run 1.8km, 3.8km, 7.0km on alternate days with no problems. Today I did feel a bit of tightness in my left hamstrings and that is a bit of an issue as it seems to upset The Knee.  Let's be glad of the success though.

On a down side, today was my first run with the Holux, comparing it with the Garmin 110. It was a damp day and the Holux was in a bag in a pocket and there was tree cover. It lost its signal quite badly resulting in some false recording of position and which increased distance covered and speed.

In this image the pink shows alignment of the routes, turquoise is Garmin and yellow is Holux. From the mapping data it is clear that the Garmin route is the most realistic. Perhaps this isn't the device but position, a wrist is far more open to the sky than a wet pocket. I'll have to test this. On the plus side, it has run for 15 hours on a single charge with Bluetooth enabled, and the low battery indicator is still off, so that's pretty good.

Thursday 20 June 2013

Holux M1000C on Android and OSX

Although the Garmin Forerunner 110 is a great training aid it's not reliable to log ultra runs as its battery life is only 5 to 6 hours in GPS mode. Ok, one doesn't do longer runs very often (indeed ones body can't cope with it) but it would be a shame not to log them. Additionally,  some events don't permit GPS aids, but you might still want to log the route. The answer is a display-free logger, such as the Holux M1000C, and similar devices.
The 'user interface' is very simple, an ON-OFF slide and 3 LEDs, amber, blue and a red/green one. This makes its use pretty foolproof and no one can accuse you of getting assistance from it! In the UK these retail for around £40 from online shops but they do seem cheaper (and dearer) elsewhere. One of the great things is that it has a removable mobile phone type battery so very long use times can be achieved without a socket.

It is supplied without software although some for Windows can be downloaded. However, despite what the manufacturers say, the loggeer will work well on OSX, Linux and Android as the chipset is commonplace and developers have made software to download the data and convert it to GPX files. I've been using Androidmtk so I can read the data via my Nexus 7 and upload from there.

It's worth mentioning that presently the programme muddles the <ele> and <speed> tags in the file as the Holux M1000C swaps the data in it binary file compared to other MTK-based devices. However this isn't a problem as most online GPS mapping services use an altitude map to define height rather than the (usually rather poor) GPS-derived altitude.

Also, the BT747 software on OSX seems good too as it will control the features of the Holux rather than just downloading. I had a bit of trouble getting the USB 'serial' port to be recognised and I ended up using the Silicon Labs USB to UART driver with a recent (ie non default version) of BT747 as there's some issue with the version of a module incorporated into the program:

On my computer (Snow Leopard on 64bit Intel) the correct 'USB' serial port to use is /dev/cu.usbmodem24310 but it could be different for you. My old iMac doesn't have Bluetooth, but that might be an easier route to go. I can't get any version of the software to work on a 6 year old 32bit Core Duo Snow Leopard MacBook with either USB or Bluetooth.

Thursday 13 June 2013


As 2.5 km was fine on Tuesday I tried 3.7 km today. Not good, The knee became an irritation.

The physio mentioned this little muscle on Monday and here's a little summary. It seems like the history, presentation and causes fit. I've had tight hamstrings for as long as I can remember and this is given as a predisposing factor. Notably I gave them a good stretch before setting off on Tuesday but didn't today; historically I've not been a supporter of pre-exercise stretching. This little video is quite useful.

As the muscle is involved in medial rotation of the knee (lateral rotation is the key to breaststroke) perhaps swimming is not ideal as there must be side-to-side loading. I've been doing 50:50 breaststroke and crawl, perhaps I need to adjust that.

Tuesday 11 June 2013

Road shoes worn too?

Today I did a gentle 2.5km to test the relaxed legs. A quick examination of my road shoes revealed an issue there. I have 2 pairs of Saucony Grid shoes whose age is unknown, perhaps 10 years? A notable feature is that 1 pair, which I suspect to be the newer, show considerable effects of pronation.

I decided to go out in the apparently less-worn shoes even though the EVA might be harder. I think it's time to try to load my knees consistently. 
This was a slow, gentle jog with mild ascent and descent but went well with no knee pain. A very small twinge from the insertion of quadriceps but that's a step forwards, if you'll pardon the pun!

It's coming up roses?

Monday 10 June 2013

No serious damage

That was the general opinion of the physiotherapist. The movement of pain is apparently quite common and tends to show compensation between muscle groups and ligaments as they each try to help each other out. The main issue seemed to be marked tension extending from my lower back all the way to the sole of my left foot. This is putting my pelvis out of balance and so every step requires a twist of my leg through The knee.

Forty minutes of massage and it seems I'm a little more balanced and I can feel a reduction in tension through my calf muscles.

The original cause is unclear; probably a gradual fatigue and spasm with a 'final straw' after the bank holiday marathon and the new-shoe-run. The good news is that as there is hopefully no underlying injury I might well be fit in a month or so, Until then, I need to try short runs and see what happens, and of course, keep up the stretches.

Another interesting point was raised, "What about your walking?". On average I walk 30 miles a week just through commuting and more if I go on a hike. As I've done this since I was 18 it doesn't feel like training. However, this is wrong, it makes great base training and whilst I'm doing little running it is still wear on the legs. I probably should log this mileage and consider it part of my training plan, especially on weeks where I do a longer than usual walk.

Swimming is allowed too, so now I have to work on not bobbing my head side to side since my arms are getting tidier.

Saturday 8 June 2013

Gentle Parkrun

As The Knee survived thursday's trip around the block I decided to do the 5km Parkrun gently, rather than attempt the usual 10km plus uphill struggle. I'm pleased that I did as The Knee did pull on the second lap although it wasn't too unpleasant. This time the pain seemed to come mostly from the origins of gastrocnemius and not laterally. It was fine on the uphill walk home and now there's a very slight ache from deep to the patella. How odd that it's moving around all the time. I've got a physio appointment next week and quite nervous about hearing a diagnosis, and moreover, an opinion of healing time.

For what it's worth, my 5km took seconds more than 31minutes.

Thursday 6 June 2013

Baby steps

I've not run for 8 days due to ill defined pain around my left knee; my guess now is  that it's not ITBS as the discomfort is rather diffuse and tends to move around! I've been stretching, icing and merely walking into work to allow some healing of whatever the problem is. In an attempt to maintain aerobic fitness I have been swimming a couple of times but I can't do that for a 2 hour spell so not very good for endurance training.

Anyway, after a day sat on a train and in a meeting I needed a bit of fresh air. My knee also felt to be improving over the last few days and so I decided, rather hesitantly, to do a run around the block. 1.5km later it was still OK and so I called it a day and did stretches.

Hopefully this marks the beginning of the road to recovery.

Sunday 2 June 2013


A few years ago I struggled with lateral knee pain on my right leg after cycling for 20 minutes or so. A local physiotherapist diagnosed iliotibial band syndrome (ITBS) and prescribed some exercises. I have to say that I haven't cycled since. I think the precipitating factor was doing a long ride whilst under-trained. The bad news is that I now think I've started it in my left leg; I woke up this morning with a bit of an ache and I'm well aware of it after a stroll around Yorkshire Sculpture Park.

I suppose I had always done more of the stretches on the right and neglected the  left and perhaps that has come back to haunt me. It's the classic presentation, novice runner 2 months before event who increases distance. Anyway, I've paid good money for an event this summer so I'll have to work hard on the recovery programme:

  • relative rest - probably means more swimming?
  • ITBS stretches
  • gluteus medius strengthening
  • ice
I suspect that the long run and then a short run with new shoes were a trigger, but the old shoes and lack of stretching on the left had probably set things in motion already.

Saturday 1 June 2013

Bifocal sunglasses

On Tuesday I had my annual eye test and asked the optician about various options for mapreading whilst running with or without sun. I'd read online about using 1 contact lens for close work but he said that only 1 in 3 can adapt to that. He didn't offer a trial of that or anything. Not so helpful. Anyway, more online searching came up with bifocal safety sunglasses. Might be useful in summer, although not good in winter rain!

Elvex Atom glasses with +2 diopter reading area

The reading element is quite low and smaller than that in my normal glasses so it doesn't restrict the main view much. Nonetheless there is a distinct reading area that seems to work quite well. They were just under £9 from here so can't complain if they're not useful in the longer term.