The particular product I'm referring to is the Sennheiser MX 70 VC

Firstly, they fall out of the ear if you try to walk never mind do any sport. They are just too bulky. They are not sports earphones, sorry..!

Secondly, I'd like to comment on the sound quality but i can't as they never stay in the ear for long enough. Please be aware that i only use them for sport activities. I have other earphones for passive leisure. Now the Sennheiser MX 70 VC earphones sit on a shelf somewhere in my house gathering dust while i use my iPod earphones.

One last thing, the thick green cord that comes out of the volume control splits within about two weeks of normal usage (walking, jogging around the park, etc). The split exposes the raw copper metal cables inside the wire. After check other blogs I have come to understand that this has happened with other people. In reality this is a very poor product and should be discontinued by the manufacturer.

These earphones are the worst really! I bought them to use in the gym and they fall out before I even  start. I then did some research and found the Soundwise S6 its really well designed for use in the gym.  Conlusion if your doing sport and want a practical, good sounding earphone take a look at the Soundwise S6 if you want a lime green earphone that is completly impractical then pick the Sennheiser. Do admit I like the colour though 

Ive found the Sennheiser CX500 best for the gym (And sound quality) as it has a clip to stop the lead pulling on the phones and to stop the damn things falling out!