I work out four days a week for 40 minutes a time. Is it better to focus on one body part per session or to try to hit everybody part at every session?
Ali Hubbard, via email

Matt Hart answers: There are two schools of thought on this. The first is in favour of hitting every conceivable muscle fibre in a session by splitting the body into segments and concentrating on small areas at a time. This is good for working the muscle hard and stimulating maximal growth but you can do this only once a week, so you may lose some of the gains over this time. You may also suffer severe delayed onset muscle soreness (DOMS).
The second approach views training the body as a whole unit. This is great for achieving constant growth for the entire body because you can hit every muscle up to three times a week. The flipside is that you cannot easily target a single muscle group. One solution is to do whole-body sessions using large exercises such as squats, bench presses and bent-over rows three times per week and include an extra session to target a different muscle group each month.