If you're heading down to the London Marathon this year, chances are you'll be wanting to keep tabs on someone when they're pounding the streets.Whether that's just to make sure that someone is still going and not given up in the sweltering heat (I won't lie - it's starting to frighten me a bit) or just want to know how many times you'll be able to see them, knowing their current whereabouts is crucial.Thankfully, if you've got a smartphone or internet-connected tablet, you'll be able to see where they are in glorious detail, making sure you'll be able to spot them at the crucial time.It's worth noting a couple of things though: most of these will be a little delayed, so don't assume that you'll be able to track people to the exact meter.

With that in mind, always arrive about five minutes early if you're expecting to see them.Also, with over 30,000 runners and many spectators, the networks can get pretty congested quickly so some of the apps suggestions below may splutter and die in the race itself.Just before we get into that - I wanted to share something with you that came across my desk today.

I'm equal parts excited and frightened by this thingThe official London Marathon appThe simplest way to track a buddy is through the official app itself, which now allows you to track 20 runners, rather than 10.All you need is their name or (ideally) their number, fling that in and you can see how everyone is progressing in 5km chunks.This is a great way to monitor people without worry about the network failing, as well as removing the problem if someone doesn't have a phone.You'll also get a map of the course, a charity module for donations, a leaderboard and push notifications of the people you care about. Download it from the Play Store or App Store and get ready for the race ahead of time.Find My FriendsIf your running chum is using an iPhone, you can monitor them during the race using this function of the phone.Simply turn it on in the app that comes pre-loaded on the iPhone (or you can re-download it from the App Store) and then add the people that you want to track you - you're in complete control of who gets to see your location.Remember to revoke access afterwards if you're worried about them knowing where you are at all times otherwise it's carte blanche to pop up when you least expect it.Garmin LiveTrackGiven we've found most people are actually using Garmin watches during the race, it makes sense to use this feature to monitor where they are.One of the key benefits here is that you can see how fast they're going, which means you can predict some times based on speed, pace, elevation in short, most of the things the watch is showing.One of our favourite elements is the fact you can even sync heart rate data across - so your partner can see just how much you're struggling around the course.Simply download the Garmin Connect app and start a LiveTrack session before the race begins and invite people to the web link it generates through Twitter, Facebook or email.It's worth noting that this app has been a bit juddery for us in the past (although it may have improved) and if you're running it's worth putting your battery-saving settings up to help your phone survive to the end of the race.Runkeeper Live TrackRunkeeper's service is very different to that of Garmin's in some ways - namely, it doesn't use a watch to power the information.Instead, you're doing it all from the app.

It's also only available to Runkeeper Go subscribers, so you'll need to fork out to use it.To get going, simply toggle the 'Broadcast live' option in the corner of the run screen, and make sure in the 'Promotions and Privacy' part of the settings you're not keeping your account and profile private.After that, the advice is the same as above: turn your phone's power settings right down, and get runningStrava BeaconThis is something more for the family runners, or those with a close group of friends.If you're a Strava Premium member (this costs extra from the basic service) you can send out a beacon from your phone when running.

This works in a similar way to Find My Friends, and doesn't contain as much information as Garmin or Runkeeper's options, but does show where someone is.The runner will need to manually activate the mode before starting, and once again remember to get saving that battery in the settings (turning down screen brightness really helps)It's only available to three close contacts at one time though, so it's worth making sure you know who really wants to see you during the race.yco5QywDXqsqs8WhjM2T5G.jpg#