Masters runners who hold their training volume close to its previous level lose about 5% to 6.5% of their maximal aerobic capacity per decade, according to a review of studies on aging endurance athletes. Those who cut volume by more than 20%, or drift toward inactivity, lose between 15% and 46% per decade. Changes in training volume explain 54% of the variation in that decline among men and 39% among women. A half marathon block after 40 is therefore a question of staying in training for the full block, and that depends on eating enough to finish each session and recovering well enough to start the next one.
Fat and Carbohydrate Use at Different Paces
Trained masters athletes burn fat efficiently. Their peak fat oxidation occurs at roughly 59% to 64% of maximal aerobic capacity, compared with 47% to 52% in the general population. Easy mileage draws heavily on that supply.
Tempo runs, intervals and the final miles of a long run are different. As pace rises, the body uses a larger share of carbohydrate, and stored carbohydrate in muscle and liver is limited. A runner can feel fine for 40 minutes at an easy effort and then fade during a threshold segment because the fuel that segment needs was never eaten.
Carbohydrate Intake on Training Days
A consensus paper by Louise Burke and colleagues in the Journal of Sports Sciences set daily carbohydrate targets by training load. Moderate training of about an hour a day calls for 5 to 7 g per kilogram of body weight. Endurance programs of 1 to 3 hours a day call for 6 to 10 g/kg. At 70 kg, the low end of the moderate range is 350 g of carbohydrate in a day.
Older athletes often eat less than this. Researchers who used 24-hour dietary recall at the World Masters Athletics Championships found average carbohydrate intake below the recommended range for endurance athletes, and protein intake was short in most groups as well. Adding a starch to each meal on days with a quality session makes up much of that shortfall, along with a carbohydrate-based meal or snack 1 to 4 hours before the run.
Fuel During Runs Longer Than an Hour
Long runs pass the 60-minute mark by the middle weeks of most half marathon plans, and race day lasts longer for most people in this age group. An Outside analysis of about 1 million 2024 results put the median half marathon time at 2:03:53 for men aged 40 to 49 and 2:24:15 for women in the same bracket. At those durations, food taken during the run affects the result.
The American College of Sports Medicine recommends 30 to 60 g of carbohydrate per hour for exercise lasting longer than an hour. More recent work suggests 60 to 90 g per hour can help in a half marathon if the stomach tolerates it. Long runs are the place to test those amounts, since race morning is a poor time to learn what the gut rejects.
Gels and sports drinks are the usual choices, though solid food works too. Some runners buy energy waffles for a chewier option, and others pack dates or a banana. Each packaged option lists grams of carbohydrate on the label, so an hourly plan can be worked out before leaving the house.
Protein Timing for Muscle Repair
Older muscle has a blunted response to the same dose of protein, which researchers call anabolic resistance. In a pooled analysis of healthy men, muscle protein synthesis after a protein meal was 16% lower in men around 75 than in men around 22. One retrospective analysis estimated that older adults need about 68% more protein per meal than younger adults to maximally stimulate muscle protein synthesis, which comes to roughly 0.4 g per kilogram of body weight. Those figures came from untrained adults over 65. A 2021 Sports Medicine review argued that trained people over 35 keep muscle and protein metabolism close to that of younger athletes, while a 2025 review in Nutrients cited limited evidence of a blunted post-exercise response even in lifelong-trained older athletes. With the evidence split, the higher dose is a safety margin for a runner in steady training.
Reviews of masters athletes suggest 0.3 to 0.4 g/kg at each meal and about 0.5 g/kg in the meal after endurance training. A 60 kg runner would aim for about 24 g of protein at a regular meal and 30 g after a long run. Spreading protein across breakfast, lunch and dinner meets these per-meal figures more reliably than one large evening serving.
Downhill sessions call for extra attention, because downhill running damages muscle more than flat running. In a crossover study, eight masters triathletes with an average age of 52 ran downhill for 30 minutes and then took 0.3 or 0.6 g/kg of protein in three feedings over 8 hours. The difference between doses fell short of statistical significance. Within each trial, the higher dose limited the afternoon loss of knee strength to 3.6%, compared with 8.6% on the moderate dose, and the athletes reported less fatigue.
Protein can share the recovery window with carbohydrate. A 2023 trial in the Journal of the International Society of Sports Nutrition gave 22 male masters endurance athletes, average age 49, one of three drinks during a 2-hour recovery window. One drink had 1.2 g/kg of carbohydrate, one had 0.8 g/kg of carbohydrate plus 0.4 g/kg of protein, and one was a placebo. Both fuel drinks increased time to exhaustion in the follow-up effort, so trading part of the carbohydrate for protein kept the performance benefit intact.
Rest Days Between Hard Sessions
Masters athletes recover from muscle-damaging running more slowly than younger training partners, even though their recovery from non-damaging work such as cycling is similar across ages. Coaches of older runners commonly extend the gap between hard sessions from about 24 to 36 hours to 48 to 72 hours, with weeks built as hard, easy, easy, hard. A tempo run that feels flat often comes two days after an interval session the body has not yet recovered from.
Fueling Concerns for Women in Perimenopause
Low energy availability means too little food remains, after training costs are met, to support normal body functions. The International Olympic Committee's 2023 consensus statement on Relative Energy Deficiency in Sport defines the resulting syndrome as impaired physical or psychological function in female and male athletes caused by prolonged or severe low energy availability. A study of 70 female runners from London running clubs found the condition across age groups, and a low fat-free mass index was common among participants aged 35 and older.
Many perimenopause symptoms overlap with the signs of energy deficiency, which makes the two hard to separate in a woman who feels flat through a training block. Matching food intake to training load first removes one possible cause, and a doctor can assess the other.
Race-Week Carbohydrate Loading
Burke's guidelines reserve carbohydrate loading for events of more than 90 minutes, which includes most finishers over 40. The recommendation is 10 to 12 g/kg per day for the 36 to 48 hours before the race, a large jump from normal eating. Practicing that intake once before a long run in the final month is a safe test of how the stomach copes with the volume.
One Long-Run Week on Paper
Record every meal and snack for 7 days in a week that includes a run of 90 minutes or longer. Add the carbohydrate grams for the long-run day and the day before it and compare each total with 5 to 7 g/kg. Then compare the grams taken during the run with 30 to 60 per hour, and mark any meal that fell short of about 0.4 g/kg of protein. If the second half of a training block feels heavy, one of those numbers is usually low, and the week of notes points to the one to raise first.
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