What the gym can add to a marathon build
Strength training is a common addition to a marathon build, and a contested one, with some runners worried it will add bulk. The most useful single summary of the research for distance runners is a 2018 systematic review by Richard Blagrove, Glyn Howatson and Philip Hayes in Sports Medicine, which brought together 24 controlled studies. Here is what it found, how much and what kind of strength work the studies used, and where in a block it seems to fit.
Some perspective before the detail. For nearly all marathoners, the thing that moves performance most is the running itself, repeated week after week for months and years. Strength work is a second-order support that sits on top of that running. It can make each stride slightly cheaper, and it earns its place once the running is already consistent.
Key takeaways
Of the 20 studies that measured running economy, 14 found a significant improvement of 2–8% at one or more speeds after runners added heavy, explosive or plyometric strength training. Six found no improvement.
Body mass and body composition were essentially unchanged. The review found no negative effect on body composition.
VO2max and blood lactate measures were largely unaffected, so the added work neither helped nor hindered aerobic power.
Most positive studies used two or three sessions a week for at least six weeks, built around multi-joint, free-weight exercises. In a 40-week study, one session a week held the gains through the competitive season.
No included study tested marathon or half marathon performance. Time trials ran from 1,000 m to 10 km.
What the review covered
Blagrove and colleagues searched three databases for studies published up to October 2017. To be included, a study had to involve middle- or long-distance runners with at least six months of running experience, a strength intervention lasting at least four weeks that was heavy, explosive or plyometric, and a control group that only ran. Triathletes and duathletes were allowed.
The 24 studies that qualified included 469 participants, most of them men. Training status ranged from recreational to highly trained, and the events covered went from middle distance to ultra. Most interventions lasted 6–14 weeks, with one running for 24 weeks and one for 40.
In all but three studies, strength work was added on top of normal running, and the authors report that running did not differ between the strength and control groups. That running ranged from 16 to 170 km a week, across three to nine sessions. The studies that replaced some running with strength work found no greater benefit.
Running economy: the main effect
Running economy is the energy cost of running at a given submaximal speed. Tomorrow’s post covers it in depth, so this section sticks to what strength work did to it.
Twenty studies measured it, and 14 found significant improvements of 2–8% at one or more speeds, though six of those had mixed results across the speeds tested. Six found no change. The review notes this is consistent with earlier meta-analyses, which put the average improvement at around 4%.
Two cautions sit alongside those figures. The typical measurement error for running economy is 1–2%, and the authors treat about 2% as the smallest worthwhile change, so results at the bottom of the range are close to measurement noise. No study directly showed that the economy gain caused a performance gain.
Strength, performance and body composition
Maximal strength, measured as a one-repetition maximum, improved by 4–33% in every study that tested it. Of 12 time trials, eight improved significantly compared with controls. Gains were 3–5% for middle-distance events and 2–4% over 5–10 km. In one 10 km study, the improvement came from a faster final 3 km with no change in running economy, which the authors suggest may reflect better resistance to fatigue. Sprint speed also improved, by 1.1–3.4%.
VO2max was largely unchanged across the studies that measured it, and the speed at VO2max improved significantly in only two of nine. Blood lactate measures were largely unaffected.
Body mass was unchanged in 18 studies, with a single study reporting a 2% increase. Fat mass, lean mass, skinfolds and girths were generally unchanged, and one study found a 3% rise in total lean mass. The authors conclude that body composition was not negatively affected.
How much, and what type
Type of work
The studies used three broad kinds of strength training: heavy resistance work (loads above roughly 80% of one-repetition maximum, or fewer than nine reps to fatigue), explosive lifts and plyometrics. All three improved running economy to a similar extent.
Free weights and multi-joint exercises featured in most of the positive studies. The studies that used only machines or single-joint exercises found no effect, though they also trained less often, so the two explanations can’t be separated. Example exercises included squats, deadlifts, step-ups, lunges, isometric calf work, squat jumps, Olympic lift variations, depth jumps from a 20–30 cm box, skipping, hopping and bounding. For plyometrics, ground contact was kept under about 0.2 seconds.
Sets, reps and loads
Heavy work typically used 2–6 sets of 3–10 reps above 70% of one-repetition maximum, with two to three minutes of rest between sets. Plyometric sessions used 30–228 foot contacts, building from 30–60 in the first week to 110–228 by weeks six to nine. Most programmes started at one or two sets and progressed to three to six. Near-maximal loads of three to five reps were no better than moderate loads of 60–80%, and training to failure was unnecessary for strength gains.
These ranges are averages from research groups, a reasonable starting point for the gym. The running around them can be set far more precisely. kaizen is hyper-personalised: it sets your training target for the week from the overall intensity of the running you actually do, measured by pace and elevation, and recalculates as you run.
How often, and for how long
Most positive studies used two or three sessions a week. One session a week of explosive or plyometric work for eight weeks still produced moderate gains, and across 311 runners the link between session frequency and economy improvement was weak, which led the authors to judge two sessions a week as likely sufficient.
Six weeks was long enough to see gains, and four weeks was enough in some studies. Longer interventions produced larger effects: six-week studies improved time trials by 2.4–2.7%, while 8–11-week studies improved them by 3.1–5.5%. Unsupervised programmes produced no strength gains, and the authors consider qualified supervision important.
Where it fits in a block
Most studies didn’t report the phase of the season, so the trials alone can’t settle timing. Two findings help. Stopping strength work led to detraining back to baseline within six weeks. In the 40-week study, two sessions a week with a heavy emphasis during the preparation phase, reduced to one explosive and plyometric session a week in-season, maintained the gains.
The authors recommend two to three sessions a week in preparation phases and one a week during the competitive season, with mixed types of work periodised over time and heavy lifting prioritised first. On spacing, they suggest leaving more than three hours after high-intensity running before lifting, and at least 24 hours between a strength session and an intensive running session. In one study, lifting straight after running brought no added benefit, which was attributed to fatigue.
For a marathon build, our reading is that the base and early build weeks correspond to the preparation phase, and the final weeks before the race to the competitive phase. A fixed rule like “two sessions a week” still has to fit around the running you have actually done. In kaizen you choose the sessions that meet your weekly target, so you can keep the days around a gym session easy and the hard running well clear of it.
Limits worth knowing
No marathon outcomes. Time trials ranged from 1,000 m to 10 km, plus 5-minute and 40-minute tests. Applying the findings to the marathon is an extrapolation.
Small, short studies. Samples were small, most interventions lasted 14 weeks or less, conclusions rested mostly on p-values, and study quality scores were moderate, with points lost for lack of blinding.
Running was rarely controlled. Only three studies properly controlled running volume and intensity in both groups.
Narrow participant pool. Few studies included women or masters runners, and participants’ history of strength training was often unclear.
Economy and performance. The link from economy gains to race performance was not directly shown.
Sources and how sure we can be
All figures come from the full open-access text of Blagrove, Howatson and Hayes (2018), Sports Medicine, which covers studies published up to October 2017. This post does not attempt to cover later trials. The mapping of preparation and competitive phases onto a marathon build is our interpretation, since none of the included studies tested marathon performance. The review’s evidence for economy, strength and body composition is reasonably consistent. The evidence on timing and frequency is thinner.
Strength work around consistent running
The review makes a reasonable case that two well-chosen strength sessions a week can make a distance runner a little more economical without adding weight, and that one a week can hold those gains through a racing season. For almost every marathoner, the larger and more dependable gains still come from running more, consistently, across many months. Strength work is a second-order addition worth making once that running is ramped up and steady.
See your fitness in kaizen
Adding strength work to a marathon build takes commitment, and it pays off most when the running around it is consistent. kaizen calculates your fitness from your recent training and past races, then sets the weekly training target your goal requires. Every run counts by its pace and elevation, the target recalculates as the week goes, and you choose the sessions that fill it, so the gym days fit where they suit you. Get kaizen on iOS or Android and see where your fitness stands.
