Readers reply: 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 concepts

This week’s question: Is it inevitable that consumerism will literally fill up the planet?

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 than they were decades ago? Jennifer Michaelson, Newlyn

Send new questions to nq@theguardian.com.