BlogNovember 1, 20268 min read

Does adding dairy to home strength training make older adults stronger?

Pedro RodriguesFounder of Actus
Bruna GüntherFounder of Actus

Adding about 10 to 15 g of dairy protein a day to home resistance training did not make older adults stronger than training alone in a 12-week randomized trial of 54 Japanese adults aged 65 and over (Miyazaki et al. 2026). Both groups got a little stronger. Only people who ate little dairy at baseline showed a hint of extra gain, an exploratory finding. If you already eat dairy daily, more is not the lever.

What did the study do?

Researchers at Shimane University, Japan, ran a 12-week, open-label, pragmatic randomized controlled trial (Miyazaki et al. 2026, BMC Geriatrics). They recruited 54 adults aged 65 and over living at home (13 men, 41 women, mean age 78.5 years) and randomized them 1:1 to dairy plus training or training alone, stratified by baseline dairy intake and muscle mass.

Item	Detail
Participants	54 enrolled, 51 completed (94.4% retention); about half pre-frail
Training (both groups)	Four home exercises with no equipment: towel grip, towel shoulder raises, seated knee extensions, lunges. Two sets of 5 to 15 reps, at least three days a week, effort 5 to 7 on the 0 to 10 OMNI-RES scale
Dairy (one group only)	About 10 to 15 g a day of extra dairy protein from milk, yogurt, cheese or a 3.8 g protein supplement stick, inside normal meals
Primary outcome	Functional strength: the 30-second arm curl test and the 30-second chair-stand test
Secondary outcomes	Handgrip strength, gait speed over 5 m, body fat and skeletal muscle index by bioimpedance

The training-only group received no dietary advice. The three dropouts were all in the dairy group (two with leg pain, one with constipation), leaving 24 versus 27 for analysis.

What did it find?

Adherence was high: the milk supplement went down a median 7.00 times a week, and both groups trained about three times a week (3.13 versus 3.25 sessions, p = 0.940).
No outcome favored the dairy group: no group-by-time interaction was significant for strength, gait or body composition. In the authors' words: "Adding modest dairy product intake to home-based resistance training did not provide additional overall benefits compared to exercise alone."
Both groups got a little stronger. Arm curls went from 18.8 to 20.1 reps with dairy (p = 0.033) and from 16.9 to 18.0 without it (p = 0.084). Chair stands went from 15.8 to 16.4 reps with dairy (p = 0.090) and from 14.6 to 15.6 without it (p = 0.025). Time mattered, group did not.
Handgrip did not improve: it fell slightly with dairy, from 26.9 to 26.0 kg (p = 0.022), and stayed flat without it (24.3 to 24.2 kg).
Body weight rose in the dairy group, from 55.2 to 56.1 kg (interaction p = 0.006), as did body fat, from 30.8% to 32.7% (p = 0.006). Skeletal muscle index fell and normal gait speed slowed from 1.3 to 1.2 m/s in both groups; the authors say the design cannot show whether dairy caused any of it.
The exploratory subgroup is the headline. Among people drinking less than 1 cup of dairy a day at baseline, arm curls rose from 17.7 to 19.9 reps with dairy (effect size d = 0.98, p = 0.006) but only from 18.5 to 18.8 without it (d = 0.08). Chair stands rose from 15.7 to 16.5 reps with dairy (d = 0.59, p = 0.064). The fine print: the direct comparison of changes between those subgroups was not significant (p = 0.223 for arm curls, p = 0.654 for chair stands), with 12 and 14 people per cell.

How does this compare with earlier evidence?

No meta-analysis specific to dairy in older adults was available, so the comparison rests on protein and training research.

The largest review of protein with resistance training, Morton et al. 2017, pooled 49 studies and 1863 participants. Protein supplementation added to training gains on average: 2.49 kg more on a one-repetition maximum and 0.30 kg more fat-free mass. Two details fit the new null result: the fat-free mass benefit shrank with increasing age, and above about 1.6 g/kg/day of total protein, extra protein added nothing. A 10 to 15 g top-up in well-nourished people in their late seventies is where that review predicts little.

The training stimulus matters too. Schoenfeld et al. 2017 found across 21 studies that muscle growth is similar with light or heavy loads when sets go to failure, while maximal strength favors loads above 60% of 1RM. The home program used towels and body weight at an effort of 5 to 7 out of 10, not to failure. Pelland et al. 2025, a meta-regression of 67 studies and 2058 mostly young participants, found that strength and size gains rise with weekly set volume, with diminishing returns. Two sets per exercise is a low dose by that standard, so the extra protein had little adaptation to feed.

The authors read it the same way. They cite Verdijk et al., who found no extra muscle or strength from protein in older men already eating enough, Campbell and Leidy, who saw gains mainly below 0.8 g/kg/day of habitual protein, and Churchward-Venne et al., who suggest around 40 g/day may be needed with training. The low-dairy subgroup fits that pattern without proving it.

What are the limits?

Small and short: 54 enrolled, 51 analyzed, 12 weeks. The sample size was powered for muscle mass, not for the strength tests used as the primary outcome.
Open-label, with self-reported logs: dairy was tracked by frequency, not grams, through an unvalidated questionnaire, so habitual intake may be misclassified.
A healthy, health-conscious sample: frailty prevalence was 5.6% against 8.7% in older Japanese adults, dietary variety scored 8.3 and 8.4 out of 10, and about half already met the 1 cup a day mark, leaving little room for a top-up to show.
The subgroup analyses were exploratory, with 12 to 14 people per cell, and the between-group tests inside them were not significant.
Funding and materials: the grants listed on PubMed include the Japan Dairy Association (J-MILK), and part of the supplements came from Morinaga Milk Industry Co., per the competing interests statement.

What should you do with it?

Over 65 and already eating dairy daily: this trial gives no reason to add more for strength. The training produced the gains, so protect the habit of at least three sessions a week.
Over 65 and eating little dairy, under 1 cup a day: adding roughly 10 to 15 g of dairy protein a day is cheap and is where the only hint of extra benefit appeared. A reasonable bet, not a proven effect.
Training at home with body weight: the dose here was light, two sets of four exercises. Prior evidence (Schoenfeld et al. 2017, Pelland et al. 2025) favors heavier effort and more weekly sets before you adjust protein.
Experienced lifters under 65: this trial is not about you. Morton et al. 2017 found protein helps more in trained and younger people, with no further gains above about 1.6 g/kg/day.

Does milk protein build muscle in older adults?

Not reliably, on this evidence. Skeletal muscle index fell in both groups over 12 weeks. Morton et al. 2017 found protein adds a modest 0.30 kg of fat-free mass on top of training in healthy adults, an effect that shrinks with age. Older adults who eat little protein have the most to gain.

How much protein should an older adult eat per meal?

The paper cites guidance of about 25 to 30 g of high-quality protein per meal for older adults, and notes that around 80% of them do not reach it. The trial's extra 10 to 15 g a day is a small step toward that target, one reason its effect may have been hard to detect.

Was the home workout real resistance training?

Yes, a light version: two sets of 5 to 15 reps of four towel and body-weight exercises at an effort of 5 to 7 out of 10, at least three days a week, which the authors put at roughly 50% to 75% of a one-repetition maximum. It still improved arm curls and chair stands over 12 weeks in people with a mean age of 78.2 years.

Sources

This brief was drafted with AI from the sources listed above and passed automated source checks before publishing. Pedro Rodrigues, founder of Actus, is the responsible author.

Educational content, not medical advice. Training and diet changes carry risk; stop if you feel pain and talk to a physician before changing your program.