Trail Running After 40: A Masters Runner's Training Guide

Trail running after 40: what really changes physiologically, a weekly structure built around slower recovery, and the strength and protein targets that matter.

Trail running after 40 is where the sport gets interesting, and the demographics prove it. Masters runners make up a large share of ultra fields, and the podium at long mountain races frequently includes people in their forties. The physiology does change, but the changes are smaller and more manageable than the received wisdom suggests, and the biggest performance factor is not age at all. It is whether you can keep training consistently. This guide covers what genuinely changes, what does not, and how to build a training week that works with an older body rather than against it.

What actually changes

VO2 max declines, but slowly if you train. In sedentary adults, maximal oxygen uptake falls roughly 10% per decade after 30. In active runners past 40 the rate is closer to 1% per year, about half the sedentary figure, and longitudinal work in masters endurance athletes shows the decline tracking training volume closely rather than age alone (Tanaka & Seals, 2008).

The practical reading: the decline is real, and a large share of it is a training effect rather than an ageing effect.

Running economy barely changes. Among the main determinants of endurance performance, VO2 max is the parameter most affected by age, while economy and lactate threshold decline considerably less. In endurance-trained masters athletes, running economy is largely preserved.

That matters enormously for trail running, where economy, fatigue resistance, and pacing judgement decide long races more than peak aerobic power does.

Peak performance holds longer than expected. Endurance performance remains broadly stable to around 35, then declines modestly through the 50s. Masters athletes have progressively extended what is achievable at these ages (Lepers & Stapley, 2016).

Recovery slows. This is the change you will notice first. Ageing muscle shows anabolic resistance, a blunted response to the usual stimuli of exercise and protein intake, and the repair and inflammatory resolution processes take longer (Doering et al., 2016).

Tissue tolerance changes. Tendons become stiffer and less compliant, which raises the risk of Achilles and patellar problems, particularly with sudden increases in intensity.

Muscle mass declines without resistance training, through both fibre size and fibre number.

Structuring the week

The changes above point to a specific structure. Fewer hard sessions, more recovery between them, and non-negotiable strength work.

A workable week for a masters trail runner:

  • Monday: rest or 30 minutes easy walking
  • Tuesday: quality session, hills or threshold, 60 to 75 minutes total
  • Wednesday: easy 45 to 60 minutes, plus strength
  • Thursday: rest or cross training, 45 minutes cycling or swimming
  • Friday: easy 40 to 50 minutes
  • Saturday: long run, 2 to 4 hours on terrain
  • Sunday: easy 45 minutes, or a second shorter long run in a build, plus strength

The key adjustments:

  1. One or two quality sessions per week, not three. The recovery cost of intensity rises with age, and the third hard session is where masters runners break
  2. Two rest or cross training days. Most 25 year olds do not need these. You do
  3. 72 hours between hard efforts rather than 48
  4. Strength training twice weekly, permanently. This is the single highest-value change

Strength work specifically

Resistance training addresses muscle mass loss and tendon stiffness directly, and it is the intervention masters runners skip most often.

  • Twice weekly, 30 to 40 minutes
  • Load matters. Sets of 5 to 8 repetitions at genuinely challenging weight, not 20 repetitions of bodyweight
  • Key movements: squats, deadlifts or hip hinges, split squats, calf raises, single leg work
  • Add eccentric emphasis for tendon health, particularly slow heel drops
  • Include plyometrics carefully, since power declines faster than endurance and jumping is how you keep it

Our strength training guide for trail runners covers the programme in detail.

Fueling and recovery adjustments

More protein, spread out. Anabolic resistance means older athletes need a higher per-meal protein dose to trigger the same muscle protein synthesis response. Target 1.6 to 2.0 g/kg daily, in four or five servings of 30 to 40 g each. That upper per-meal figure is higher than the 20 to 25 g often quoted for younger athletes.

Protect sleep aggressively. Sleep quality declines with age at exactly the point where your recovery depends on it more. Our sleep and recovery guide covers the practical levers.

Check bloods annually. Ferritin, vitamin D, B12, thyroid, and testosterone or oestradiol as appropriate. Deficiencies that a 25 year old absorbs without noticing show up as flat training in your 40s.

Do not under-eat. Low energy availability accelerates every age-related change on this list, and masters runners chasing a race weight are unusually exposed. Our RED-S guide covers the warning signs.

Trailia's readiness scoring adjusts training load against recovery data rather than a fixed template, which matters more as recovery becomes the binding constraint. The Race Readiness check shows how load and recovery are tracking against each other.

The advantages nobody mentions

Masters trail runners have real edges, particularly at long distances.

Fatigue resistance and pacing judgement. Ultras reward not blowing up, and experience is the best predictor of that.

Years of accumulated aerobic base. Someone with 15 years of consistent running has a foundation that no 12 week block replicates.

Tendon and connective tissue adaptation from long-term loading, provided you have avoided major injury.

Better decision-making on kit, fuelling, and when to back off, which is worth more over 100 km than a 2 point VO2 max difference.

More stable life circumstances for many, which allows the consistency that actually drives performance.

The single most important principle from the research is the least glamorous: maintaining a high training stimulus with advancing age is the main means of limiting performance decline. Consistency is the whole game.

Starting trail running after 40

If you are new rather than continuing:

  1. Build a walking and hiking base first, 8 to 12 weeks before running much
  2. Run-walk intervals rather than continuous running for the first two months
  3. Add strength from day one, not once you are fit
  4. Increase volume by no more than 10% per week, and hold steady weeks every fourth week
  5. Give tendons more time than muscles. Cardiovascular fitness improves faster than connective tissue adapts, and that gap is where injuries happen

Our couch to trail running guide covers the full progression.

Key takeaways

  • VO2 max declines around 1% per year in trained runners past 40, roughly half the sedentary rate
  • Running economy and lactate threshold hold up far better than VO2 max
  • Recovery is the binding constraint, so allow 72 hours between hard sessions
  • Strength training twice weekly is the highest-value single addition
  • Target 1.6 to 2.0 g/kg protein daily in four or five servings of 30 to 40 g

Where to go from here

If you take one thing from this, make it the strength work. It addresses muscle mass, tendon stiffness, and power decline simultaneously, and it is the thing masters runners consistently skip in favour of more running they recover from less well.

Trailia builds plans that adapt to your recovery rather than pushing a fixed schedule, which is exactly what training after 40 requires.

Citations

  • Tanaka, H., & Seals, D. R. (2008). Endurance exercise performance in Masters athletes: age-associated changes and underlying physiological mechanisms. The Journal of Physiology, 586(1), 55-63.
  • Lepers, R., & Stapley, P. J. (2016). Master Athletes Are Extending the Limits of Human Endurance. Frontiers in Physiology, 7, 613.
  • Doering, T. M., Reaburn, P. R., Phillips, S. M., & Jenkins, D. G. (2016). Postexercise Dietary Protein Strategies to Maximize Skeletal Muscle Repair and Remodeling in Masters Endurance Athletes: A Review. International Journal of Sport Nutrition and Exercise Metabolism, 26(2), 168-178.
  • Mountjoy, M., Ackerman, K. E., Bailey, D. M., et al. (2023). 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). British Journal of Sports Medicine, 57(17), 1073-1097.

Frequently Asked Questions

How much slower do you get at trail running after 40?

Less than most people expect if you keep training. VO2 max falls around 1% per year in active runners past 40, roughly half the rate seen in sedentary adults, and longitudinal data shows the decline tracking training volume closely. Endurance performance stays broadly stable to around 35 and then declines modestly through the 50s.

What changes most about running as you age?

Recovery speed, more than performance itself. Ageing muscle shows anabolic resistance, meaning a blunted response to exercise and protein, and inflammatory resolution takes longer. Running economy and lactate threshold hold up far better than VO2 max, which is good news for trail running specifically.

How many hard sessions should a masters runner do per week?

One or two, not three. The recovery cost of intensity rises with age, and the third hard session each week is where masters runners typically break down. Allow 72 hours between hard efforts rather than the 48 a younger runner might use.

Is strength training necessary for runners over 40?

It is the highest-value single addition to a masters training week. It addresses muscle mass loss, tendon stiffness, and power decline at the same time, and those three account for most of what feels different after 40. Twice weekly for 30 to 40 minutes, using challenging loads for sets of 5 to 8 repetitions.

How much protein do masters runners need?

Target 1.6 to 2.0 grams per kilogram daily, split into four or five servings of 30 to 40 grams each. That per-meal figure is higher than the 20 to 25 grams often quoted for younger athletes, because anabolic resistance means older muscle needs a larger dose to trigger the same response.

Do masters trail runners have any advantages?

Several, and they matter most at long distances. Fatigue resistance and pacing judgement come from experience, years of accumulated aerobic base cannot be replicated by a 12 week block, and better decisions on kit and fuelling are worth more over 100 km than a small VO2 max difference. Ultra fields are full of runners in their forties for these reasons.

Can you start trail running after 40?

Yes, and plenty do. Build a walking and hiking base for 8 to 12 weeks first, use run-walk intervals rather than continuous running for the first two months, and add strength work from day one. Increase volume by no more than 10% per week.

Why do older runners get more Achilles problems?

Tendons become stiffer and less compliant with age, which raises the risk of Achilles and patellar tendinopathy, especially with sudden increases in intensity. Cardiovascular fitness also improves faster than connective tissue adapts, so a runner can feel ready for work their tendons are not. Eccentric loading such as slow heel drops helps directly.

What blood tests should masters runners get?

Ferritin, vitamin D, B12, thyroid function, and sex hormones as appropriate, at least annually. Deficiencies that a 25 year old absorbs without noticing show up as persistently flat training in your forties. Take your training log to the appointment so the results can be read in context.

Should I lose weight to run better after 40?

Be careful here. Low energy availability accelerates every age-related change on this list, including bone density loss and muscle mass decline, and masters runners chasing a race weight are unusually exposed. Prioritise eating enough and building strength over reducing body mass.