How is it physically possible to continue breaking sporting records?

The long-running series in which readers answer other readers questions on subjects ranging from trivial flights of fancy to profound scientific and philosophical conceptsRead this weeks replies: What do you wish you could buy in vending machines?Obviously, progressions in sports clothing technology must make a small difference to the abilities of an athlete - but how on earth is it physically possible that we continue to break world records, year-on-year? Are humans really faster or stronger th...