Protein for the Lifting Triathlete: How Much, When, and What Changes After 50

Most triathletes think about carbohydrate first, and for endurance training that's the right priority. But once you start lifting, and especially once you're past 50, protein becomes a more common question. How much do you need? Does it have to be eaten straight after a session? Do older athletes need more?

This article looks at what the research shows for endurance athletes who also do strength training. It covers the largest meta-analysis of protein and resistance training, the research on anabolic resistance in older adults, the position statements, and a small study in masters triathletes. It doesn't give individual intake targets: those depend on your health, diet and training, and a dietitian is the right person to help.

Why protein matters for lifting

Muscle is constantly being broken down and rebuilt. Both resistance exercise and eating protein stimulate muscle protein synthesis, the process of building new muscle protein. The 2017 International Society of Sports Nutrition (ISSN) position stand on protein, led by Ralf Jäger, describes their effects as synergistic when protein is eaten before or after resistance exercise.

For a triathlete, this matters in two ways. First, lifting is one of the few things that can maintain or build muscle with age, as TriForward's "Strength Training After 50" covers. Second, endurance training also causes muscle damage and remodelling, particularly running. Protein supports both.

The 49-trial meta-analysis

The most influential study on how much protein supports resistance training is a 2018 meta-analysis by Robert Morton and colleagues, led by Stuart Phillips at McMaster University, in the British Journal of Sports Medicine. They included 49 randomised controlled trials with 1,863 healthy adults. In every trial, participants did at least 6 weeks of resistance training, with or without protein supplements.

Compared with resistance training alone, protein supplements added:

• 2.49 kg to one-repetition maximum strength (95% CI 0.64 to 4.33).
• 0.30 kg of fat-free mass (95% CI 0.09 to 0.52).
• Larger muscle fibre and thigh cross-sectional area.

Three further findings matter for triathletes:

• A ceiling on total intake. Total protein intakes above about 1.62 g per kg of body weight per day produced no further gain in fat-free mass.
• Age reduced the benefit. The effect of supplementation on fat-free mass gains got smaller with older age.
• Training experience increased it. People with resistance-training experience got a larger benefit from supplements.

The effects are real but modest. Inference: a 2.49 kg improvement in a lift over weeks or months of training is useful but small, and most of the strength gain in these trials came from the training itself. Supplements were simply a way to raise total intake; the authors' finding was about total protein, not about protein powder specifically.

These trials were in healthy adults doing resistance training, not endurance athletes, and the figure of about 1.6 g/kg/day was the point where the average benefit levelled off, not a precise individual requirement.

What the position statements say

The 2017 ISSN position stand concluded that:

• About 1.4 to 2.0 g of protein per kg of body weight per day is sufficient for most exercising people to build and maintain muscle.
• Individual doses of about 0.25 g/kg, or 20 to 40 g, of high-quality protein are a general guide, though this depends on age and recent exercise.
• Protein should ideally be spread evenly across the day, roughly every 3 to 4 hours.
• Timing is likely a matter of individual tolerance, since both pre- and post-workout intake provide benefit, and the anabolic effect of exercise lasts at least 24 hours.
• Whole foods can meet protein needs, with supplements a practical option.
• Endurance athletes should prioritise carbohydrate, with protein helping recovery and offsetting muscle damage.

The ISSN position stand addresses healthy exercising people. It isn't a guide for people with medical conditions.

Anabolic resistance: what changes with age

As we age, muscle becomes less responsive to the same stimulus. This is known as anabolic resistance. A 2015 analysis by Daniel Moore and colleagues in The Journals of Gerontology looked at how much protein, in a single dose, is needed to maximise muscle protein synthesis in older and younger men.

The researchers pooled data from their laboratories on healthy men aged about 71 and about 22, who each consumed between 0 and 40 g of high-quality protein.

• Muscle protein synthesis at rest was similar in older and younger men.
• Older men responded less to small doses.
• The response levelled off at about 0.40 g/kg in older men, compared with 0.24 g/kg in younger men, per kg of body weight. This difference was just short of statistical significance (p = 0.055).
• Per kg of lean body mass, the difference was clearer: about 0.60 g/kg in older men compared with 0.25 g/kg in younger men (p < 0.01).

The authors concluded that older men need a greater relative protein intake in a single meal to maximise the muscle-building response. Important limits: this was a retrospective analysis of laboratory data, only men were included, the older participants were around 70, and the measure was a short-term laboratory response rather than long-term muscle gain.

Masters endurance athletes

Do active older people still show anabolic resistance? A 2016 review by Thomas Doering and colleagues in the International Journal of Sport Nutrition and Exercise Metabolism looked at masters endurance athletes, including long-distance triathletes and runners. They concluded that:

• Masters athletes recover more slowly than younger athletes after muscle-damaging exercise, such as downhill or long running, but not after exercise that doesn't damage muscle.
• Training may reduce anabolic resistance but doesn't eliminate it.
• Masters athletes were generally advised to have the same post-exercise protein as younger athletes, about 20 g or 0.25 g/kg.
• They suggested masters athletes might benefit from more, with attention to leucine content, but didn't give a specific figure.

A study in masters triathletes

The same research group then tested the idea. In a 2017 study, also in the International Journal of Sport Nutrition and Exercise Metabolism, 8 masters triathletes aged about 52 completed a 30-minute downhill run designed to cause muscle damage. The abstract doesn't give a sex split.

In a randomised, double-blind crossover design, they received either:

• A moderate protein intake: 0.3 g/kg per feeding.
• A high protein intake: 0.6 g/kg per feeding.

Each was given three times, every 2 hours, starting immediately after the run. Eight hours later, they completed a cycling time trial.

• Recovery didn't differ significantly between the two conditions.
• The time trial was almost identical: 2,395 seconds after high protein and 2,369 seconds after moderate protein (effect size 0.09).
• Leg strength in the afternoon had fallen by 3.6% after high protein and by 8.6% after moderate protein, and perceived fatigue was lower after high protein. The researchers reported these as effects within each condition; the differences between conditions weren't statistically significant.

Inference: in this small study, doubling protein after a hard run didn't measurably improve performance the same day. There may be small effects on fatigue and strength loss, but 8 participants is too few to say. It also didn't test longer-term strength gains from lifting.

Recommendations for older adults

The 2013 PROT-AGE position paper, led by Jürgen Bauer, set out protein recommendations for people over 65 in the Journal of the American Medical Directors Association:

• At least 1.0 to 1.2 g/kg/day for healthy older people.
• At least 1.2 g/kg/day for those who exercise or are otherwise active.
• 1.2 to 1.5 g/kg/day for older people with acute or chronic disease.
• An exception for severe kidney disease (estimated glomerular filtration rate below 30) in people not on dialysis, who may need to limit protein.

These recommendations were written for the general older population, not athletes. Inference: they're broadly consistent with the ranges in the ISSN position stand and the Morton meta-analysis, which suggests that older athletes are unlikely to need radically different total amounts from younger ones. The main difference may be in how protein is distributed across meals.

Why the endurance side complicates things

Almost all of the protein research above comes from people doing resistance training alone. Triathletes do something different: two or three lifting sessions a week on top of many hours of swimming, cycling and running. That changes the question in a few ways, all of which are inference rather than tested findings:

• Energy and carbohydrate come first. A triathlete's protein needs sit inside a much larger total energy requirement. If overall intake is too low, extra protein is unlikely to make up for it, and the ISSN's advice that endurance athletes prioritise carbohydrate reflects this.
• Running causes more muscle damage than cycling or swimming. The Doering review found that masters athletes' slower recovery showed up after muscle-damaging exercise in particular. A week with long or hilly runs may be when spreading protein evenly matters most.
• Lifting and endurance sessions often fall on the same day. Because the ISSN found that the anabolic effect of exercise lasts at least 24 hours, there's no strong reason to fit protein around one particular session. Regular meals across the day cover both.
• Appetite can be blunted after long or hard sessions, especially in the heat. Meals and snacks that are easy to eat, such as milk-based drinks or yoghurt, may help some athletes meet their needs without forcing large meals.

None of this has been tested directly in triathletes who lift, which is one of the clearest gaps in the evidence.

Putting it into practice

The following are general principles drawn from the research above, not individual targets. A registered or sports dietitian can help you apply them:

1. Prioritise carbohydrate for endurance training. The ISSN position stand says this explicitly for endurance athletes.
2. Focus on total daily protein rather than precise timing. The Morton meta-analysis found the benefit plateaued with total intake.
3. Spread protein across the day. Including a protein source in each meal and snack is a simple way to do this.
4. Older athletes may benefit from more protein per meal, particularly in meals that are typically low in protein, such as breakfast. This is inference from laboratory work in older men.
5. Use whole foods first. Dairy, eggs, fish, meat, legumes, tofu and soy foods are good sources. Supplements are a convenience, not a requirement.
6. Don't expect protein to replace training. The strength gains in the trials came mainly from the lifting.

A triathlon scenario

The following example is illustrative, not drawn from a study. A 56-year-old woman training for a half-Ironman starts lifting twice a week. She eats a light breakfast of toast and fruit, a sandwich at lunch and a good evening meal, and she's read that she needs a protein shake within 30 minutes of every session.

Based on the evidence, she might:

• Not worry about the 30-minute window. The ISSN position stand found timing largely a matter of preference.
• Add protein to breakfast and lunch, such as yoghurt, eggs, beans or fish, to spread intake more evenly across the day.
• Keep carbohydrate as the priority around her key endurance sessions.
• Talk to a dietitian if she's unsure whether her overall intake is adequate, or if she has any kidney or other health concerns.

TriForward's "Creatine for Endurance Athletes" covers the other supplement most often discussed alongside protein for masters athletes.

Common mistakes

• Cutting carbohydrate to make room for protein. For endurance athletes, this can compromise training quality.
• Obsessing over timing while total intake is low or uneven.
• Assuming more is always better. In the meta-analysis, the benefit levelled off above about 1.6 g/kg/day.
• Relying on supplements rather than food.
• Ignoring kidney health. People with kidney disease may need to limit protein and should get medical advice.
• Using protein targets to restrict food. Protein is part of fuelling, not a substitute for it.

What we don't know

• How much protein masters triathletes need for long-term strength gains, since no trial has tested it.
• Whether women show the same anabolic resistance as the men in the laboratory analysis.
• Whether higher protein after endurance sessions improves recovery over weeks, not just hours.
• How endurance and strength training together change protein needs compared with lifting alone.
• Whether the per-meal findings translate into long-term muscle and strength, since the laboratory work measured a response over a few hours, not over months of training.
• How the picture changes for plant-based athletes. The ISSN notes that sources with all essential amino acids and adequate leucine are most effective, but the laboratory work on older adults used doses of high-quality protein, and plant-based diets weren't tested.

References

• Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, Aragon AA, Devries MC, Banfield L, Krieger JW, Phillips SM. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 2018;52(6):376–384. doi:10.1136/bjsports-2017-097608
• Moore DR, Churchward-Venne TA, Witard O, Breen L, Burd NA, Tipton KD, Phillips SM. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. The Journals of Gerontology: Series A, 2015;70(1):57–62. doi:10.1093/gerona/glu103
• Jäger R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 2017;14:20. doi:10.1186/s12970-017-0177-8
• Bauer J, Biolo G, Cederholm T, Cesari M, Cruz-Jentoft AJ, Morley JE, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association, 2013;14(8):542–559. doi:10.1016/j.jamda.2013.05.021
• Doering TM, Reaburn PR, Phillips SM, Jenkins DG. 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, 2016;26(2):168–178. doi:10.1123/ijsnem.2015-0102
• Doering TM, Reaburn PR, Borges NR, Cox GR, Jenkins DG. The effect of higher than recommended protein feedings post-exercise on recovery following downhill running in masters triathletes. International Journal of Sport Nutrition and Exercise Metabolism, 2017;27(1):76–82. doi:10.1123/ijsnem.2016-0079