Detraining

What it is

A 2000 review defines detraining as losing, in part or in full, the adaptations that training produced, because the training stimulus is insufficient¹. This page covers what studies found was lost, how fast, what reduced training kept, and what happened on retraining. Short planned breaks are covered under rest.

The same two-part review splits detraining by length¹. Short term means under 4 weeks in which the training stimulus is insufficient, and long term means more than 4 weeks¹.

A systematic review (a checkable search of the research on a question) of detraining in athletes separates two forms³. In complete cessation, training is fully interrupted apart from daily physical activity³. In partial cessation, some exercise at a certain intensity continues each week³.

How it is measured

Studies use two reference points^7,8. One is the trained level: a study of seven endurance-trained subjects reported VO2max as a percentage below the trained value⁷. The other is the starting level. A meta-analysis of 86 randomised controlled trials compared values before the programme with values after detraining⁸. A randomised controlled trial assigns people to groups by chance, then compares the groups.

Its 5,670 participants were aged about 8 to 84 and included healthy adults and clinical groups, such as cancer survivors⁸. The pooled exercise ranged from aerobic and resistance training to stretching, yoga and Pilates⁸.

A meta-analysis of resistance training cessation (103 studies) reported submaximal (below maximum) strength, maximal force and maximal power separately². It expressed each change as a standardised mean difference, a gap put on a common scale so studies can be compared². One study of 9 men and 10 women took muscle biopsies (small tissue samples) to count myonuclei and measure fibre size⁵. It used ultrasound for muscle thickness and a one-repetition maximum, the heaviest load lifted once, for strength⁵.

What studies found

Strength after stopping

A meta-analysis of 103 studies found a detrimental effect of stopping resistance training on every component of muscular performance it examined². The standardised mean differences were -0.62 for submaximal strength, -0.46 for maximal force and -0.20 for maximal power². It identified a dose-response relationship (how a result changes as an amount changes) between how long training had stopped and the size of the fall². The effect was larger in people over 65 years old². For maximal force and maximal power, it was larger in inactive people than in recreational athletes².

One study followed 18 young (20 to 30 years) and 23 older (65 to 75 years) men and women¹⁰. After 9 weeks of one-leg training and 31 weeks off, one-repetition maximum strength was down 8% in the young and 14% in the older group¹⁰. Most of the loss came between weeks 12 and 31¹⁰. In a trial of 70 young and old adults, strength gained over 16 weeks was largely retained through 32 weeks of detraining¹¹. There was a slight drop at the last measurement¹¹.

A 2000 review of long-term detraining states that force production declines slowly and usually stays above control values for very long periods¹².

Muscle size after stopping

A 2000 review of short-term detraining states that training-induced changes in muscle fibre cross-sectional area are reversed, while declines in strength performance are limited¹. Cross-sectional area is the size of a slice cut straight across a structure. Two small studies reported a similar split over breaks of 1 month and 20 weeks^4,5:

• Eight subjects did 3 months of isometric knee extension (straightening the knee) training, in which the muscle works but the joint does not move⁴. Muscle cross-sectional area was back at its pre-training level after 1 month off, while strength did not change⁴.
• Nine men and 10 women strength-trained one leg for 10 weeks⁵. Muscle thickness and fibre cross-sectional area returned to baseline during 20 weeks off, while strength stayed elevated⁵.

A meta-analysis of 6 studies in adults aged 65 or over found that muscle size decreased significantly after training stopped¹³. The decrease was not significant after 12 to 24 weeks off but was significant after 31 to 52 weeks¹³. In the 86-trial meta-analysis of several exercise types in healthy and clinical groups, muscle mass did not change significantly during the programmes⁸. Its authors state that this was a lack of initial response to the exercise, not a loss of training efficacy⁸.

Endurance after stopping

A 2000 review states that in highly trained athletes, short-term detraining brings a rapid decline in VO2max and blood volume, with impaired endurance performance¹. The changes are more moderate in people trained recently¹. Over the long term, it states, the VO2max of athletes declines markedly but stays above control values, whereas recently acquired gains are completely lost¹².

A systematic review and meta-analysis of 21 studies in athletes found significant falls in VO2max after short-term and long-term training cessation³. The effect was larger after long-term cessation³. The table sets the average falls it reported beside those of one study of seven endurance-trained subjects^3,7.

Who was studied	Detraining period	Fall in VO2max (%)
Trained individuals (meta-analysis)	Short-term detraining	3.933
Trained individuals (meta-analysis)	Long-term detraining	9.433
Seven endurance-trained subjects	First 21 days	77
Seven endurance-trained subjects	From 56 days, when it levelled off	167

After 84 days, those seven subjects still had a higher VO2max than eight sedentary controls who had never trained⁷. Sedentary means doing little or no regular physical activity. The meta-analysis in athletes found no significant difference in the fall between 30 to 90 days and more than 90 days of detraining³.

The meta-analysis of 86 trials pooled healthy and clinical groups aged about 8 to 84, across several exercise types⁸. VO2max remained significantly above the pre-exercise baseline in its three detraining subgroups: 2 months or less, 2 to 6 months, and over 6 months⁸. The standardised mean differences ranged from 0.29 to 0.62⁸. The authors describe the 2 to 6 month result, from 5 studies, as of borderline significance and call for cautious interpretation⁸.

Tendon and bone

Two small studies measured tendon stiffness, how much force it takes to stretch something by a given amount^4,14. In nine men aged 21 to 27, 3 months of isometric plantar flexion (pointing the foot down) training raised Achilles tendon stiffness by 50.3%¹⁴. After 1 month of detraining, stiffness had already fallen back to its pre-training level¹⁴. In 8 subjects doing isometric knee extension training, tendon stiffness did not rise until after 2 months of training⁴. It was back at its pre-training level after 2 months off⁴.

For bone, the studies cited here measured bone mineral density or bone mineral content^15,16. Density is how much mineral is packed into a given amount of bone. Content is the amount of mineral in a bone or a section of bone.

• In 29 premenopausal (before menopause) women, bone mineral density decreased significantly toward baseline in the 6 months after a 12-month jump and resistance programme ended¹⁵.
• Of 43 adolescent ice hockey players, the 21 who ended their career lost significantly more hip bone mineral density than the 22 still active¹⁷. The authors conclude that the loss follows within 3 years of reduced activity¹⁷.
• In 64 adult female tennis and squash players followed for 5 years, the playing arm’s extra bone mineral content was well maintained despite reduced training¹⁶. The authors call for controlled studies to confirm this¹⁶.
• A systematic review of 3 studies in postmenopausal (after menopause) women reported that benefits declined gradually within a few months of stopping exercise¹⁸.

What reduced training kept

A 2000 review of long-term detraining states that reduced training can avoid or limit its negative effects¹². Its conditions are that intensity is maintained and frequency is reduced only moderately, while volume can be markedly reduced¹². The studies in the table cut training back and followed what happened^19,20:

Who was studied	What was cut	What was found
Twelve subjects, average age 23	Training days, from 6 a week to 4 or 2	VO2max stayed essentially at the trained level in both groups over 15 weeks19
Thirteen subjects	Session length, from 40 minutes to 26 or 13	VO2max was maintained; long-term endurance fell by 10% in the 13-minute group21
Twelve subjects	Work rate, by one-third or two-thirds	VO2max was not maintained with the one-third cut and fell further with the two-thirds cut9
70 adults, aged 20 to 35 or 60 to 75	Training dose, to one-third or one-ninth	Both reduced doses preserved muscle growth in the young but not the old over 32 weeks11
Ten older men, about 70 years	Knee extensor (knee-straightening muscle) training, from 3 days a week to 1, or stopped	The five training weekly kept strength and size for 6 months; the five who stopped lost 11% of strength20

In the athlete meta-analysis, exercise during long-term detraining can lessen the harm to VO2max compared with no exercise³. Partial cessation had no buffering effect during short-term detraining, which the authors suggest may reflect low exercise intensity in those studies³.

A brief narrative review, a summary written without a set, checkable search method, looked for the minimal dose of exercise that maintains performance²². Its conclusions are given here as that review’s reading of the studies, not as a programme²²:

• It concluded that general populations can keep endurance performance for up to 15 weeks on as few as 2 weekly sessions, if intensity is maintained²².
• It concluded that younger populations, at least, can hold strength and muscle size for up to 32 weeks on as little as 1 weekly session²². Its conditions were 1 set per exercise and a maintained relative load²².
• Older populations, it concluded, may need up to 2 weekly sessions and 2 to 3 sets per exercise to maintain muscle size, with intensity maintained²².

Children, and function in older adults

In a cluster-randomised study, which assigns whole groups by chance, 20 children aged 7 did muscular fitness training and 19 were controls²³. After 8 weeks without it, the exercise group kept its gains in curl-ups and single-leg hop, while long jump and balance regressed²³.

A meta-analysis of 15 randomised controlled trials covered 787 participants aged 60 or over²⁴. Measured against control groups, exercise programmes significantly preserved functional capacity after 4 to 36 weeks without training²⁴. Greater age was associated with smaller residual effects²⁴.

Retraining after a break

In a randomised trial of healthy untrained adults, 20 completed periodic training with a 10-week break and 22 completed continuous training²⁵. Strength, muscle size and jump height fell during the break and were regained rapidly on retraining²⁵. The two groups ended with similar adaptations²⁵. In that trial, biceps brachii cross-sectional area grew faster in the first 5 weeks of retraining than in the continuous group²⁵.

What is disputed

Whether muscle “remembers” earlier growth

A 2016 review proposes a cellular model of muscle memory²⁶. In it, a fibre that was once large regains lost mass faster than one that was never large²⁶. The reason given is that myonuclei gained earlier are retained through atrophy (shrinking)²⁶. A 2020 review states that this idea has mainly been based on rodent data⁶. It concluded that current evidence provides no consensus on whether such memory exists in animal or human muscle⁶.

Human findings point in different directions^27,28:

• In twelve untrained men and women, myonuclei added by 10 weeks of one-arm training were maintained through 16 weeks off²⁷.
• In those twelve, the change in type 2 (fast-contracting) fibre size during retraining did not differ between the previously trained and the untrained arm²⁷.
• In 9 men and 10 women, a trained leg rested for 20 weeks⁵. On retraining it gained muscle thickness and strength to a similar degree as the untrained leg⁵. The authors note this was not a rigorous test of muscle memory⁵.
• A meta-analysis of human and rodent studies found that extra myonuclei from muscle growth were retained with atrophy in rodents but not humans²⁸.

The meta-analysis authors list as a limitation that the evidence for muscle memory rests on few studies, five in animals and four in humans²⁸. They suggest that other mechanisms may matter more for muscle memory²⁸.

How little training keeps muscle size in older adults

The studies disagree^11,20. Five older men training once a week kept their muscle size for 6 months²⁰. In the trial of 70 adults, neither reduced dose preserved muscle growth in the old¹¹. In a third study, previously sedentary older women who cut from two sessions a week to one lost their earlier gain in quadriceps cross-sectional area²⁹.

Sources also differ on frequency^12,19. The 2000 review states that frequency can be reduced only moderately¹². In the study of twelve subjects, VO2max stayed essentially at the trained level after a cut from 6 days a week to 2¹⁹.

Whether recent endurance gains are fully lost

The 2000 review states that recently acquired VO2max gains are completely lost during detraining of more than 4 weeks¹². The meta-analysis of 86 trials followed programmes of 2 to 24 weeks⁸. It found VO2max still significantly above the pre-exercise baseline after more than 6 months of detraining⁸.

Where the evidence is thin

• Tendon. The two stiffness studies above had 9 and 8 people^4,14. A systematic literature review of tendon detraining found four clinical studies, and its authors state that the findings need confirmation³⁰.
• Bone. The one systematic review cited here included 3 studies, in postmenopausal women¹⁸.
• Muscle size. The pooled result by age group cited here is in adults aged 65 or over¹³. The single studies cited above for muscle size after a full stop had 8, 19 and 42 people^4,5,25. One pointed the other way: in six women who stopped leg strength training for 30 to 32 weeks, fibre cross-sectional area changed relatively little³¹.
• Children. The one study cited here had 39 children²³.
• Retraining. The one trial cited here had 42 completers²⁵.
• Women. The athlete meta-analysis of VO2max had two studies of female athletes³.
• Athletes’ maintenance dose. The narrative review found too few data to recommend anything specific for athletes or military personnel²².

Connections

The pooled strength evidence here follows resistance training². The tissues measured are muscle, tendon and bone^4,18. The tendon data come from the Achilles tendon and the knee extensors^4,14.

Neighbouring principles meet this one where training is cut back, not stopped. The narrative review concluded that intensity seems to matter most for maintaining performance, despite relatively large cuts in frequency and volume²². Those variables are covered under training volume and progressive overload. Planned breaks are under rest, and how adaptations match what was trained is under specificity.

Sources

1. Mujika I, Padilla S (2000). Detraining: loss of training-induced physiological and performance adaptations. Part I. Sports medicine (Auckland, N.Z.). doi:10.2165/00007256-200030020-00002 PMID 10966148
2. Bosquet L, Berryman N, Dupuy O, Mekary S, Arvisais D, Bherer L, Mujika I (2013). Effect of training cessation on muscular performance: a meta-analysis.. Scandinavian journal of medicine & science in sports. doi:10.1111/sms.12047 PMID 23347054
3. Zheng J, Pan T, Jiang Y, Shen Y (2022). Effects of Short- and Long-Term Detraining on Maximal Oxygen Uptake in Athletes: A Systematic Review and Meta-Analysis.. BioMed research international. doi:10.1155/2022/2130993 PMID 36017396
4. Kubo K, Ikebukuro T, Yata H, Tsunoda N, Kanehisa H (2010). Time course of changes in muscle and tendon properties during strength training and detraining.. Journal of strength and conditioning research. doi:10.1519/JSC.0b013e3181c865e2 PMID 19996769
5. Psilander N, Eftestøl E, Cumming KT, Juvkam I, Ekblom MM, Sunding K, Wernbom M, Holmberg HC, Ekblom B, Bruusgaard JC, Raastad T, Gundersen K (2019). Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle.. Journal of applied physiology (Bethesda, Md. : 1985). doi:10.1152/japplphysiol.00917.2018 PMID 30991013
6. Snijders T, Aussieker T, Holwerda A, Parise G, van Loon LJC, Verdijk LB (2020). The concept of skeletal muscle memory: Evidence from animal and human studies.. Acta physiologica (Oxford, England). doi:10.1111/apha.13465 PMID 32175681
7. Coyle EF, Martin WH, Sinacore DR, Joyner MJ, Hagberg JM, Holloszy JO (1984). Time course of loss of adaptations after stopping prolonged intense endurance training.. Journal of applied physiology: respiratory, environmental and exercise physiology. doi:10.1152/jappl.1984.57.6.1857 PMID 6511559
8. Zhang H, Zhu Y, Zhao Z, Tan D (2026). The effects of detraining on body composition and cardiometabolic health: a systematic review and meta-analysis of randomized controlled trials.. Frontiers in physiology. doi:10.3389/fphys.2026.1891899 PMID 42558561
9. Hickson RC, Foster C, Pollock ML, Galassi TM, Rich S (1985). Reduced training intensities and loss of aerobic power, endurance, and cardiac growth.. Journal of applied physiology (Bethesda, Md. : 1985). doi:10.1152/jappl.1985.58.2.492 PMID 3156841
10. Lemmer JT, Hurlbut DE, Martel GF, Tracy BL, Ivey FM, Metter EJ, Fozard JL, Fleg JL, Hurley BF (2000). Age and gender responses to strength training and detraining.. Medicine and science in sports and exercise. doi:10.1097/00005768-200008000-00021 PMID 10949019
11. Bickel CS, Cross JM, Bamman MM (2011). Exercise dosing to retain resistance training adaptations in young and older adults.. Medicine and science in sports and exercise. doi:10.1249/MSS.0b013e318207c15d PMID 21131862
12. Mujika I, Padilla S (2000). Detraining: loss of training-induced physiological and performance adaptations. Part II. Sports medicine (Auckland, N.Z.). doi:10.2165/00007256-200030030-00001 PMID 10999420
13. Grgic J (2022). Use It or Lose It? A Meta-Analysis on the Effects of Resistance Training Cessation (Detraining) on Muscle Size in Older Adults.. International Journal of Environmental Research and Public Health. doi:10.3390/ijerph192114048 PMID 36360927
14. Kubo K, Ikebukuro T, Maki A, Yata H, Tsunoda N (2012). Time course of changes in the human Achilles tendon properties and metabolism during training and detraining in vivo.. European journal of applied physiology. doi:10.1007/s00421-011-2248-x PMID 22105708
15. Winters KM, Snow CM (2000). Detraining reverses positive effects of exercise on the musculoskeletal system in premenopausal women.. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. doi:10.1359/jbmr.2000.15.12.2495 PMID 11127215
16. Kontulainen S, Kannus P, Haapasalo H, Sievänen H, Pasanen M, Heinonen A, Oja P, Vuori I (2001). Good maintenance of exercise-induced bone gain with decreased training of female tennis and squash players: a prospective 5-year follow-up study of young and old starters and controls.. Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. doi:10.1359/jbmr.2001.16.2.195 PMID 11204418
17. Nordström A, Olsson T, Nordström P (2005). Bone gained from physical activity and lost through detraining: a longitudinal study in young males.. Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA. doi:10.1007/s00198-004-1749-4 PMID 15517188
18. Gombarčíková T, Svobodová L, Svobodová A, Gimunová M (2025). The effect of physical activity intervention and detraining on postmenopausal osteopenia and osteoporosis: a systematic review.. Frontiers in sports and active living. doi:10.3389/fspor.2025.1655404 PMID 41059215
19. Hickson RC, Rosenkoetter MA (1981). Reduced training frequencies and maintenance of increased aerobic power.. Medicine and science in sports and exercise. PMID 7219129
20. Trappe S, Williamson D, Godard M (2002). Maintenance of whole muscle strength and size following resistance training in older men.. The journals of gerontology. Series A, Biological sciences and medical sciences. doi:10.1093/gerona/57.4.b138 PMID 11909878
21. Hickson RC, Kanakis C, Davis JR, Moore AM, Rich S (1982). Reduced training duration effects on aerobic power, endurance, and cardiac growth.. Journal of applied physiology: respiratory, environmental and exercise physiology. doi:10.1152/jappl.1982.53.1.225 PMID 6214534
22. Spiering BA, Mujika I, Sharp MA, Foulis SA (2021). Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time.. Journal of strength and conditioning research. doi:10.1519/JSC.0000000000003964 PMID 33629972
23. Faigenbaum AD, Farrell AC, Fabiano M, Radler TA, Naclerio F, Ratamess NA, Kang J, Myer GD (2013). Effects of detraining on fitness performance in 7-year-old children.. Journal of strength and conditioning research. doi:10.1519/JSC.0b013e31827e135b PMID 23222078
24. Buendía-Romero Á, Vetrovsky T, Hernández-Belmonte A, Izquierdo M, Courel-Ibáñez J (2025). Residual Effects of Physical Exercise After Periods of Training Cessation in Older Adults: A Systematic Review With Meta-Analysis and Meta-Regression.. Scandinavian journal of medicine & science in sports. doi:10.1111/sms.70010 PMID 39764712
25. Halonen EJ, Gabriel I, Kelahaara MM, Ahtiainen JP, Hulmi JJ (2024). Does Taking a Break Matter-Adaptations in Muscle Strength and Size Between Continuous and Periodic Resistance Training.. Scandinavian journal of medicine & science in sports. doi:10.1111/sms.14739 PMID 39364857
26. Gundersen K (2016). Muscle memory and a new cellular model for muscle atrophy and hypertrophy.. The Journal of experimental biology. doi:10.1242/jeb.124495 PMID 26792335
27. Cumming KT, Reitzner SM, Hanslien M, Skilnand K, Seynnes OR, Horwath O, Psilander N, Sundberg CJ, Raastad T (2024). Muscle memory in humans: evidence for myonuclear permanence and long-term transcriptional regulation after strength training.. The Journal of physiology. doi:10.1113/JP285675 PMID 39159314
28. Rahmati M, McCarthy JJ, Malakoutinia F (2022). Myonuclear permanence in skeletal muscle memory: a systematic review and meta-analysis of human and animal studies.. Journal of cachexia, sarcopenia and muscle. doi:10.1002/jcsm.13043 PMID 35961635
29. Walker S, Serrano J, Van Roie E (2018). Maximum Dynamic Lower-Limb Strength Was Maintained During 24-Week Reduced Training Frequency in Previously Sedentary Older Women.. Journal of strength and conditioning research. doi:10.1519/JSC.0000000000001930 PMID 29570597
30. Frizziero A, Salamanna F, Della Bella E, Vittadini F, Gasparre G, Nicoli Aldini N, Masiero S, Fini M (2016). The Role of Detraining in Tendon Mechanobiology.. Frontiers in aging neuroscience. doi:10.3389/fnagi.2016.00043 PMID 26973517
31. Staron RS, Leonardi MJ, Karapondo DL, Malicky ES, Falkel JE, Hagerman FC, Hikida RS (1991). Strength and skeletal muscle adaptations in heavy-resistance-trained women after detraining and retraining.. Journal of applied physiology (Bethesda, Md. : 1985). doi:10.1152/jappl.1991.70.2.631 PMID 1827108

Every source the library cites

Changes

• October 6, 2026 First published.