Ultra running after 40: how training has to change, and what does not

Maximal oxygen uptake falls with age because maximal heart rate, cardiac output and oxygen delivery all drift down. Muscle mass, strength and power get harder to hold, and the body's response to training and to protein becomes less efficient.

The part most people miss: a large share of the decline in masters athletes is explained by a drop in training volume and intensity, not by age itself. Runners who keep their volume and keep some hard running hold their aerobic capacity far better than those who let everything become slow. Lactate threshold and running economy are preserved better than maximal capacity in well-trained older runners.

Chronological age is a poor programming variable. A 52 year old with 25 years of consistent running can absorb far more than a 42 year old who started two years ago. Training age, recent consistency, injury history, sleep, work stress and menopause status all matter more than the number on your birth certificate.

There is no established masters mileage. Weekly load should grow from your current sustainable load, not backwards from a pro's training log. The bands below are planning heuristics, not biological thresholds.

Most training should stay below the first threshold, where you can hold a conversation. Elite endurance athletes spend the large majority of their time there. The exact split matters less than the principle: easy days easy enough to repeat.

Keep one truly demanding session a week during high-volume race blocks. Two can work in lower-volume development periods. The long run becomes a quality session on its own when it carries a lot of climbing, descending or late-run effort.

The common masters mistake is medium-hard running almost every day. Nothing is easy enough to recover from and nothing is hard enough to adapt to.

The old rule of increasing weekly mileage by no more than 10% has weak evidence. Studies of new runners never found an injury boundary at 10%, and week-to-week mileage ratios do not predict injury the way most plans assume.

What does predict injury is a single session that jumps well beyond your recent history. In a 2025 study of 5,205 runners, average age about 46, with more than half a million recorded sessions, one run 10 to 30% longer than your longest run of the previous 30 days carried a substantially higher risk of overuse injury. Bigger jumps carried more risk again.

So the guardrail Durability uses is: the planned longest run stays at or under about 110% of the longest run you completed in the last 30 days. Not a magic number, but the best translation of the strongest recent evidence.

Long runs do several jobs at once: durability, fuel practice, foot conditioning, climbing and descending tolerance, kit testing, and hours on your feet. Prescribe them by time and terrain, not an arbitrary distance.

There is no reason to under-fuel long runs to chase fat adaptation. Chronic low carbohydrate availability lowers training quality and, combined with low energy intake, causes real health problems.

Back-to-back long runs are a specific tool, not a weekly habit: every two or three weeks, with the second day smaller than the first. For 100 mile races they are often more useful than one enormous run.

Strength training is the most defensible addition to a masters endurance programme. Across sport, strength work substantially reduces overuse injury. In runners, heavy and plyometric strength improves running economy, and a study in masters runners found maximal strength work improved economy at marathon pace.

The goal is not size. It is maximal force, then rate of force development, tendon capacity, single-leg control, calf and soleus capacity, and resilience under fatigue. Two sessions a week: squat or trap-bar deadlift, split squats, calf raises, a hinge, a pull, trunk work, and low-volume hops only once you have a base of strength and pain-free impact tolerance.

Progress load only with good technique. In Durability's plans the two strength days are fixed in the week and sit next to the harder running so the easy days stay easy.

Carbohydrate should track the training day: roughly 3 to 5 g per kg on rest days, 5 to 7 g on moderate days, 6 to 10 g on heavy 1 to 3 hour days, and potentially 8 to 12 g during exceptional ultra or stage-race load. Low-carbohydrate diets raise fat oxidation but show no consistent endurance advantage.

Protein matters more with age because endurance training raises protein turnover and older muscle responds less to a given dose. A useful default is 1.6 to 1.8 g per kg per day, rising towards 2.0 g in high-volume, low-energy or rehab periods, spread across the day at about 0.35 to 0.45 g per kg per meal every three to four hours.

In races over three hours, 60 to 90 g of carbohydrate an hour is the evidence-based range. Intakes above 90 g are an advanced experiment after extensive gut training, not a requirement. Start where your gut is: 40 to 60 g if you are new or sensitive, 60 to 75 g when trained, 75 to 90 g when well practised. Rehearse it on long runs until it is boring.

Hydration: the dangerous mistake in ultras is usually overdrinking, not modest dehydration. Drink to thirst, informed by rehearsal and conditions, and never force fluid to hold your starting weight. Sodium does not make overdrinking safe.

The order is sleep, then food and carbohydrate and protein, then load management, then stress management, then active recovery, then optional modalities. Sleep loss measurably hurts endurance performance, and the longer the event, the more it hurts.

After a 100 mile race, soreness returns to normal around day five while performance is still clearly impaired. Legs that do not hurt are not the same as legs that have recovered.

Ice baths, compression and massage can help how you feel. None has a consistent effect on recovery across the research. An active recovery session that itself needs recovering from has defeated its purpose.

Taper is one of the clearer areas of endurance science. Reduce volume by roughly 40 to 60% over two, and for long ultras or heavily fatigued masters runners up to three, weeks, while keeping run frequency and short pieces of intensity.

Do not compensate for nerves by adding fitness work. New fitness cannot be built in the final fortnight. Fatigue can.

Combine how you feel, session effort, performance trends, symptoms and recent training exposure. Heart rate variability is useful as a trend under standardised conditions, not as an oracle. Never cancel a key session because one morning's readiness score is orange, and never ignore persistent exhaustion because the watch is green.

Wrist heart rate is reasonably accurate for easy running. Use a chest strap for threshold and interval work where precision matters.

In a 100 km World Masters Championship analysis, the best performers ran more conservatively early and held speed late. Across multi-day ultras, greater pacing variability goes with worse results.

Three ceilings govern the early race: effort that feels conspicuously sustainable, most running below threshold, and descents controlled before the legs are damaged. Then four stages: protect, settle, assess, compete. Compete only late, and only if you can still make decisions rather than survive them.

Durability is an adaptive coaching system for runners 40+. It starts from your race, your training history and what you can sustain now, not from a template. It proposes each fortnight from the training you actually completed, holds the long run inside the 30-day guardrail above, keeps two strength days in the week, and reads heart-rate discipline, long-run drift, training load and recovery as context. Every change is approved by the coach before you see it.

When there is not enough data, it starts conservatively and says so.