For half a century, runners have been told that lifting weights twice a week makes them faster, but the proof has tended to come from fresh-leg laboratory tests that bear little resemblance to the back end of a marathon. A new randomised control trial published in the official journal of the American College of Sports Medicine and run out of Loughborough University tries to close that gap, and the answer it returns is unusually clean: ten weeks of supplementary strength and plyometric work does not just improve running economy, it preserves it under fatigue and dramatically extends time-to-exhaustion at the end of a long, hard run.
The trial enrolled 28 well-trained male runners and split them into two groups for ten weeks. The control arm continued their normal endurance programme; the intervention arm added two short sessions per week of maximal strength work, half-squats and hip thrusts at heavy loads, paired with low-volume plyometric drills such as drop jumps and bounding. Both groups completed identical running schedules. At the end of the block, the researchers tested running economy at the start and at the 90-minute mark of a steady run at heavy intensity, and finished each test with a high-intensity time-to-exhaustion trial. The standard fresh-leg economy test favoured the strength group only modestly, but at the 90-minute mark the gap widened to a 2.1 per cent improvement for the strength runners against a 0.6 per cent decline in the controls.
The really striking number sits in the time-to-exhaustion data. After 90 minutes of running, the strength-trained group could hold their high-intensity test pace for 35 per cent longer than at baseline. The control group, on identical mileage and identical sessions, lost 8 per cent of their late-race endurance over the same ten-week window. In practical terms, that is the difference between holding marathon pace through 32 kilometres and watching it bleed away at 26 kilometres on a course like London or Berlin. It is also the most direct evidence yet that the well-known concept of 'durability' first popularised by Iñigo Mujika is trainable, and that lifting weights twice a week is one of the most reliable ways to train it.
What the trial does not yet do is settle the long-running argument over which kinds of strength sessions matter most. The Loughborough block combined heavy-load slow lifting with explosive plyometrics, and the design does not let the data tease apart how much each component contributed. Earlier meta-analyses from the same group have suggested that the plyometric portion is responsible for the bulk of the fresh-leg economy gains, while the heavy lifting drives the late-race resilience by recruiting fast-twitch fibres that an endurance-only programme leaves under-stimulated. Most coaches reading the new paper are likely to land on the same conclusion they already favoured, which is that runners need both, not one or the other.
The applied takeaway for amateur marathoners is simple enough to fit on a fridge magnet: book in two short, hard strength sessions a week, treat them as non-negotiable through the build, and reduce volume rather than skip them entirely in the final taper. The harder takeaway, the one this study is most likely to nudge into the mainstream, is that the value of those sessions only fully shows up after 90 minutes of running, by which point most runners have already decided whether their training plan is working. Lifting hard, the Loughborough data suggests, is precisely the work that pays off when the rest of the field is starting to slow down.