Progressive overload

What it is

The 2026 ACSM position stand on resistance training calls progressive overload a concept considered fundamental to programming¹. In the stand’s words, the stimulus placed on the muscle needs to rise throughout a training programme¹.

The stand also gives the usual reasoning: progressive overload is often put forward as essential to continued progress in any kind of exercise training¹. The argument is that the body’s systems adapt in ways that reduce the stress of the exercise¹.

The routes overload can take

Sources name several variables that can carry the increase¹:

• The 2026 ACSM stand lists load, volume, training frequency, exercise selection and duration¹.
• A 2004 review lists exercise choice and order, rest between sets, repetitions, sets and intensity as the variables of a workout⁵.
• A 2022 trial report notes that progressive overload typically relies on increasing load, and that adding repetitions has received little attention⁶.

The 2004 review states that for progression these variables must be varied over time⁵. The 2026 stand notes that the increase may be slight as muscle continues to adapt¹.

Variation and periodisation

The 2026 stand defines variation as the systematic modification of training variables over time to help adaptation continue¹. It describes periodisation as among the most common forms that variation takes¹. Periodisation means intentionally modifying variables such as load, volume and frequency through a programme¹. In the stand’s terms, a non-periodised programme is one whose prescription is not manipulated during the programme¹.

Model	How the 2026 ACSM stand defines it
Linear (traditional)	Load rises and volume falls during the programme1.
Undulating (non-linear)	The prescription is changed daily or weekly1.
Block	The programme is split into multiweek blocks with distinct training goals1.

A non-periodised programme can still progress. A 2015 review describes one such model, linear progressive training, in which intensity progressively increases while volume stays the same or rises⁷.

How it is measured

The 2026 ACSM stand notes that load has typically been quantified in two ways¹. One is a percentage of the one-repetition maximum (1RM), the heaviest load a person can lift once¹. The other is a repetition maximum, the heaviest load a person can lift a set number of times¹.

The stand notes that raising the percentage of 1RM can support progressive overload¹. The percentage can also stay the same while absolute load rises with strength gains¹. That applies when strength is tested regularly or perceived exertion scales (scores for how hard effort feels) are used¹.

Rules used to raise load

• The 2009 ACSM stand’s rule raises load by 2 to 10% once a person can do one or two repetitions more than the target number⁸. The 2026 stand states that it updates the 2009 stand¹.
• A 2015 review notes that programmes for sedentary people often use sets of 8 to 12 repetitions, adding resistance once more than 12 are possible⁷.

What goes unreported

The 2026 stand defines weekly volume load as the total load lifted in a week of training¹. It notes that the reviews it included rarely considered this measure¹.

A 2021 systematic review covered 52 randomised controlled trials of resistance training in lower limb tendinopathies⁹. A systematic review searches for all the research on a question and sums it up. A randomised controlled trial assigns people to groups by chance, and tendinopathy is local pain in a tendon that comes with loading it. Of those trials, 92% considered the principle of progression⁹. Of the 52, 19 (37%) appropriately described how the progression in resistance was achieved⁹.

What studies found

Progressing against holding steady

One trial compared rising load with constant load within the same people². Each arm of 55 untrained young women was randomly assigned to progressive overload, the same load throughout, or no exercise². After 8 weeks of elbow extension training, the triceps had thickened in both trained conditions². The progressively loaded arms grew about twice as much, about 23% against 12%². The authors concluded that training without progression was still enough to produce growth in these women².

A second trial progressed sets. For 12 weeks, 31 resistance-trained men were randomly allocated to a constant set volume or to adding lower-limb sets every 2 weeks¹⁰. Squat 1RM rose most in the six-set progression group, then the four-set group, then the constant group¹⁰. Muscle cross-sectional area (the size of a slice cut straight across the muscle) and thickness showed no between-group differences¹⁰. The authors reported a possible small benefit of the higher volumes for growth and urged caution over the limited certainty¹⁰.

The 2026 stand’s authors state that progression is not necessary for benefit, and that a rising stimulus is likely required just for continued longer-term progress¹. They add that in some populations loads are necessarily low, and progression is then a requirement for meaningful benefit¹.

Adding load or adding repetitions

Two trials compared these routes^3,6. In a randomised trial, 43 people with at least 1 year of lower-body training experience progressed load or repetitions for 8 weeks⁶. The groups showed similar changes, with differences of questionable practical significance⁶. Strength slightly favoured load⁶. Growth of the rectus femoris (a quadriceps muscle) modestly favoured repetitions⁶.

The second trial was in 39 previously untrained young men and women³. Each person’s legs were randomised to add load or add repetitions for 10 weeks³. Both legs gained 1RM strength and muscle cross-sectional area, with no difference between the two routes³.

Which variables changed the outcome

The overview found that few prescription variables affected the primary adaptations¹. Its comparisons between prescriptions reported the following¹:

• Strength was positively affected by session frequency, load, range of motion (how far a joint moves), volume and exercise order¹.
• Strength was not affected by time under tension (how long a muscle works during a repetition or set) or rest between sets¹.
• Muscle growth was enhanced by higher volume, 10 or more sets per muscle group per week¹.
• Muscle growth was not influenced by fast (0.5 second) versus slow (8 second) repetitions, or by periodisation¹.

Separate reviews looked at single variables. A 2025 meta-analysis of 14 studies in healthy adults concluded that tempo’s overall effect on muscle growth appears minimal, with possible differences under specific conditions¹¹.

A 2021 meta-analysis found significantly greater lower-limb muscle growth with full than with partial range of motion, effect size 0.88¹². An effect size is a standard measure of how large a difference between groups is. The 2026 overview found insufficient data to determine whether range of motion influenced muscle growth¹.

Periodised against non-periodised training

Five pooled analyses compared periodised with non-periodised training, or two periodised models with each other^{4,13,14,15,16}.

Review	What it found
2004 statistical review	An overall effect size of 0.84 favoured periodised strength and power programmes; 0.25 was specific to variation, with volume, frequency and intensity controlled13.
2017 meta-analysis, 18 studies	1RM strength improved more after periodised training, effect size 0.4314.
2022 meta-analysis, 35 studies	With volume equated, 1RM strength favoured periodised training, effect size 0.31; muscle growth did not differ4.
2015 meta-analysis, 17 studies	Linear and undulating models showed no differences in upper-body or lower-body strength in 510 participants15.
2017 meta-analysis, 13 studies	Linear and daily undulating models were likely to have similar effects on muscle growth16.

The 2022 analysis also found an overall 1RM effect favouring undulating over linear models, effect size 0.31⁴. In trained participants the effect was 0.61, with a confidence interval (a range showing a result’s precision) from 0.00 to 1.22⁴. Untrained participants showed no difference in 1RM changes⁴.

One 12-week trial randomly divided 33 untrained men into non-periodised, traditional periodisation, daily undulating and control groups¹⁷. The three training groups had similar gains in squat 1RM, at 19.5%, 17.9% and 20.4%¹⁷. Between weeks 6 and 12, the traditionally periodised group was the one group to raise squat 1RM¹⁷.

The 2026 ACSM stand concluded from its overview that the impact of periodisation on strength could not be determined¹. A 2024 umbrella review (a review that sums up other systematic reviews) of 44 systematic reviews found insufficient evidence that periodisation influenced muscle adaptations¹⁸.

What is disputed

Whether progression is needed

Sources disagree. An anatomy textbook states that lifting the same weight without increasing it does not increase muscle size¹⁹. The 2009 ACSM stand states that progressive protocols are necessary to stimulate further adaptation toward specific goals⁸. The 2026 stand notes that the 2009 stand was criticised for lacking evidence-based rigour¹. Its own authors state that progression is not necessary for beneficial outcomes, but is likely required for continued longer-term progress¹.

The direct trials cited on this page lasted 8 to 12 weeks^2,10. The authors of the constant-load trial call it an open question whether constant-load training keeps working over longer periods². The authors of the 8-week load-or-repetition trial called it the first designed to compare the two directly⁶. They limit their conclusion to the short to medium term⁶.

What the periodisation trials can show

• The comparison group. A 2019 review found that none of the 21 studies in two meta-analyses compared periodised programmes with varied, non-periodised ones²⁰. It argues that the comparisons therefore support variation, not periodised variation²⁰. Its authors state that this is not a criticism of the concept of periodisation²⁰.
• Length. A 2019 mini-review notes that most studies in a 2017 meta-analysis lasted less than 16 weeks, whereas periodisation is designed as a long-term approach²¹.
• Who was studied. In a 2017 review of linear against daily undulating models, most studies were in untrained people¹⁶. A 2015 review noted that few studies had examined adolescent or athletic populations¹⁵.
• Testing. A 2024 umbrella review notes a suggestion that periodised groups gain more strength because they lift heavier loads in the last weeks before testing¹⁸. None of its reviews controlled for this¹⁸. The specificity page covers that principle.
• Definitions. The 2026 ACSM stand notes that definitions of periodisation vary, and that periodisation and programming are often conflated¹.

Connections

The 2026 ACSM overview concerns resistance training and its effects on strength, muscle size and power¹. A 2017 review notes that adult muscle size can change after 3 to 4 weeks of heavy resistance training²². It found no reports of such rapid changes in tendon structure²². A 1998 review proposed that bone cells get used to routine loading and respond less to it²³.

Neighbouring principle pages meet this one¹:

• Training volume is one of the routes the 2026 ACSM stand lists¹.
• Rest covers rest between sets, which a 2004 review counts among the variables of a workout⁵.
• Listening to your body covers perceived exertion scales, which the 2026 stand names as one way to raise absolute load¹.
• Overtraining and detraining are the pages on recovery falling short and on training stopping. The reasoning the stand reports is that the body’s systems adapt in ways that reduce the stress of exercise¹.

Sources

1. Currier BS, D'Souza AC, Singh MAF, Lowisz CV, Rawson ES, Schoenfeld BJ, Smith-Ryan AE, et al (2026). American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews.. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000003897 PMID 41843416
2. Kassiano W, Santos-Melo V, Manske I, Lisboa F, Miguel A, Gomes F, Prado A, et al (2026). Progressive Overload Affects the Magnitude of Muscle Hypertrophy.. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000003968 PMID 41718594
3. Chaves TS, Scarpelli MC, Bergamasco JGA, Silva DGD, Medalha Junior RA, Dias NF, Bittencourt D, et al (2024). Effects of Resistance Training Overload Progression Protocols on Strength and Muscle Mass.. International journal of sports medicine. doi:10.1055/a-2256-5857 PMID 38286426
4. Moesgaard L, Beck MM, Christiansen L, Aagaard P, Lundbye-Jensen J (2022). Effects of Periodization on Strength and Muscle Hypertrophy in Volume-Equated Resistance Training Programs: A Systematic Review and Meta-analysis.. Sports medicine (Auckland, N.Z.). doi:10.1007/s40279-021-01636-1 PMID 35044672
5. Kraemer WJ, Ratamess NA (2004). Fundamentals of resistance training: progression and exercise prescription.. Medicine and science in sports and exercise. doi:10.1249/01.mss.0000121945.36635.61 PMID 15064596
6. Plotkin D, Coleman M, Van Every D, Maldonado J, Oberlin D, Israetel M, et al (2022). Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations.. PeerJ. doi:10.7717/peerj.14142 PMID 36199287
7. Strohacker K, Fazzino D, Breslin WL, Xu X (2015). The use of periodization in exercise prescriptions for inactive adults: A systematic review.. Preventive medicine reports. doi:10.1016/j.pmedr.2015.04.023 PMID 26844095
8. American College of Sports Medicine (2009). Progression Models in Resistance Training for Healthy Adults. Medicine and science in sports and exercise. doi:10.1249/mss.0b013e3181915670 PMID 19204579
9. Burton I, McCormack A (2021). The implementation of resistance training principles in exercise interventions for lower limb tendinopathy: A systematic review.. Physical therapy in sport : official journal of the Association of Chartered Physiotherapists in Sports Medicine. doi:10.1016/j.ptsp.2021.04.008 PMID 33965702
10. Enes A, DE Souza EO, Souza-Junior TP (2024). Effects of Different Weekly Set Progressions on Muscular Adaptations in Trained Males: Is There a Dose-Response Effect?. Medicine and science in sports and exercise. doi:10.1249/MSS.0000000000003317 PMID 37796222
11. Enes A, Piñero A, Hermann T, Zamanzadeh A, Hennessy T, Montenegro D, Parnell C, et al (2025). How Slow Should You Go? A Systematic Review With Meta-Analysis of the Effect of Resistance Training Repetition Tempo on Muscle Hypertrophy.. Journal of strength and conditioning research. doi:10.1519/JSC.0000000000005302 PMID 42709703
12. Pallarés JG, Hernández-Belmonte A, Martínez-Cava A, Vetrovsky T, Steffl M, Courel-Ibáñez J (2021). Effects of range of motion on resistance training adaptations: A systematic review and meta-analysis.. Scandinavian Journal of Medicine & Science in Sports. doi:10.1111/sms.14006 PMID 34170576
13. Rhea MR, Alderman BL (2004). A meta-analysis of periodized versus nonperiodized strength and power training programs.. Research quarterly for exercise and sport. doi:10.1080/02701367.2004.10609174 PMID 15673040
14. Williams TD, Tolusso DV, Fedewa MV, Esco MR (2017). Comparison of Periodized and Non-Periodized Resistance Training on Maximal Strength: A Meta-Analysis.. Sports medicine (Auckland, N.Z.). doi:10.1007/s40279-017-0734-y PMID 28497285
15. Harries SK, Lubans DR, Callister R (2015). Systematic review and meta-analysis of linear and undulating periodized resistance training programs on muscular strength.. Journal of strength and conditioning research. doi:10.1519/JSC.0000000000000712 PMID 25268290
16. Grgic J, Mikulic P, Podnar H, Pedisic Z (2017). Effects of linear and daily undulating periodized resistance training programs on measures of muscle hypertrophy: a systematic review and meta-analysis.. PeerJ. doi:10.7717/peerj.3695 PMID 28848690
17. De Souza EO, Tricoli V, Rauch J, Alvarez MR, Laurentino G, Aihara AY, Cardoso FN, et al (2018). Different Patterns in Muscular Strength and Hypertrophy Adaptations in Untrained Individuals Undergoing Nonperiodized and Periodized Strength Regimens.. Journal of strength and conditioning research. doi:10.1519/JSC.0000000000002482 PMID 29683914
18. Mcleod JC, Currier BS, Lowisz CV, Phillips SM (2024). The influence of resistance exercise training prescription variables on skeletal muscle mass, strength, and physical function in healthy adults: An umbrella review.. Journal of sport and health science. doi:10.1016/j.jshs.2023.06.005 PMID 37385345
19. Betts JG, Young KA, Wise JA, Johnson E, Poe B, Kruse DH, Korol O, Johnson JE, Womble M, DeSaix P (2022). Anatomy and Physiology 2e. OpenStax. Link
20. Afonso J, Rocha T, Nikolaidis PT, Clemente FM, Rosemann T, Knechtle B (2019). A Systematic Review of Meta-Analyses Comparing Periodized and Non-periodized Exercise Programs: Why We Should Go Back to Original Research.. Frontiers in physiology. doi:10.3389/fphys.2019.01023 PMID 31440169
21. Evans JW (2019). Periodized Resistance Training for Enhancing Skeletal Muscle Hypertrophy and Strength: A Mini-Review.. Frontiers in physiology. doi:10.3389/fphys.2019.00013 PMID 30728780
22. Mersmann F, Bohm S, Arampatzis A (2017). Imbalances in the Development of Muscle and Tendon as Risk Factor for Tendinopathies in Youth Athletes: A Review of Current Evidence and Concepts of Prevention.. Frontiers in Physiology. doi:10.3389/fphys.2017.00987 PMID 29249987
23. Turner CH (1998). Three rules for bone adaptation to mechanical stimuli.. Bone. doi:10.1016/s8756-3282(98)00118-5 PMID 9823445

Every source the library cites

Changes

• October 6, 2026 First published.