Health ArticleEducational review — not personal medical advice

Exercise Before and After Colorectal Cancer Surgery: Does It Reduce Fatigue?

22 min

Summary: In a randomized trial of 518 patients with colorectal cancer, people who were asked to do unsupervised moderate exercise for two weeks before surgery and four weeks afterward reported less fatigue than those who received standard care. The difference at four weeks after surgery was 3.75 points on a 0-100 fatigue scale (95% confidence interval 0.01 to 7.49; p=0.05), and among patients who actually completed the exercise program as intended the difference was slightly larger and lasted as long as 12 months. The exercise program did not change patients' quality of life, pain levels, or their sense of mental recovery.

Table of Contents

Key Points

  • In a randomized trial of 518 colorectal cancer patients, unsupervised moderate exercise before and after surgery was linked to less fatigue at four weeks, but the result was borderline.
  • Among patients who completed the exercise program as intended, the fatigue benefit was slightly larger and remained statistically significant at 12 months.
  • The exercise program did not change quality of life, pain levels, or mental recovery at any time point measured.
  • The authors describe these as exploratory secondary analyses and call for cautious interpretation; further studies are needed to define any role for this exercise approach.
  • Patients considering exercise around surgery should talk to their surgical team first and aim for moderate intensity, such as 30 minutes daily of walking, cycling, swimming, or running.

Background: Why Fatigue After Cancer Surgery Matters

Cancer treatment often causes fatigue — a deep tiredness that does not go away with rest. This is different from simply feeling sleepy after a poor night, and it can persist for months after surgery.

The World Health Organization (WHO) has reported that low levels of physical activity influence the risk of developing cancer, including colorectal cancer (cancer of the colon or rectum). For general health, the WHO recommends 150 to 300 minutes per week of aerobic physical activity at a medium level for adults. That works out to roughly 30 minutes a day, five days a week.

Prehabilitation (pre-treatment rehabilitation, sometimes shortened to "prehab") means getting physically prepared before an operation. It has been tested in several types of abdominal cancer, but a systematic review found that prehabilitation programs differ so much — some include only exercise, others add nutrition or psychological support — that it was impossible to draw a firm overall conclusion.

For patients with colorectal cancer, researchers have hypothesized that prehabilitation before treatment could improve physical strength, recovery, and the risk of postoperative complications. But the evidence is mixed. A recent meta-analysis (a study that pools results from many studies) of single-component high- or moderate-intensity training in colorectal cancer patients produced conflicting results. Randomized trials of multi-component programs in frail patients undergoing major abdominal or colorectal surgery have also reported conflicting findings about complications after surgery.

Previous research has suggested that fatigue and mental health can improve after physical training in patients with cancer. A review of 11 studies with a low risk of bias reported improvement in fatigue after supervised exercise training. And in a breast cancer trial, a program of high-intensity interval training plus resistance training beat usual care for fatigue, pain, and emotional function. The researchers behind the current study wanted to see whether something similar — but simpler and easier to deliver — could help colorectal cancer patients.

What Is the PHYSSURG-C Trial?

PHYSSURG-C was a prospective, randomized, controlled, open-label superiority trial conducted at six Swedish hospitals. "Prospective" means patients were followed forward in time. "Randomized" means patients were assigned to a treatment group by chance rather than by choice. "Open-label" means the patients and their caregivers knew which group they were in. "Superiority" means the study was designed to test whether one approach was better than another. The trial's registration number is NCT02299596.

The main goal of PHYSSURG-C was to see whether extra physical activity before and after surgery improved short-term recovery. The primary outcome was self-reported physical recovery at four weeks after surgery — and that outcome showed no difference between groups. The paper discussed here is a secondary, exploratory analysis looking at fatigue and other outcomes measured along the way.

The original trial had a more complicated history with sample size. It began with a sample size calculation based on the primary outcome of physical recovery. Because researchers had limited knowledge of what effect size to expect, an external group performed a planned interim analysis after the first 100 randomizations and recalculated the sample size, which led to an increase. A further increase followed later, when it became clear that more patients than expected were dropping out. Importantly, no sample size calculation was done for the secondary outcomes analyzed here — fatigue, quality of life, pain, and mental recovery.

Who Took Part in This Study?

Between January 22, 2015, and May 28, 2020, the trial screened 1,870 people for eligibility. Of those, 1,109 were ineligible for reasons including declining to take part (409), too little time remaining before surgery (399), no physiotherapist available (83), language or cognitive barriers (77), missed patients (55), inability to perform the intervention (36), no research nurse available (34), and other reasons (90).

In total, 761 patients were included and randomized: 379 to the intervention group and 382 to the control group. During follow-up, 62 people in the intervention group were excluded (32 withdrew consent, 30 for other reasons) and 31 in the control group were excluded (13 withdrew consent, 18 for other reasons). A further 30 intervention patients and 22 control patients were lost to follow-up, including 9 and 6 deaths respectively. At 12 months, 287 intervention patients and 329 control patients remained in the trial, and 518 patients returned the 12-month questionnaires: 250 in the intervention group and 268 in the control group. These 518 patients form the analysis population for this study.

The two groups were very similar at the start. The median age was 70 years in both groups. In the intervention group, 39% (about 4 in 10) were women and 61% were men; in the control group, 41% (about 4 in 10) were women and 59% were men. Median body mass index (BMI, a measure of weight relative to height) was 25.4 in the intervention group and 25.3 in the control group.

Educational backgrounds were comparable: about 21% in each group had completed compulsory school only, roughly 41% and 46% had finished upper secondary school, and 38% and 33% had a university education. Most patients were born in Sweden (87% and 88%). Roughly two-thirds were retired (66% and 63%), about 29% and 26% were working, and 5.4% and 10% were on sick leave or unemployed. Most were married or living with a partner (73% and 76%).

Few patients were active smokers (2.5% and 2.7%). Risk-level drinking was reported by 15% of the intervention group and 18% of the control group. At baseline, most patients described themselves as doing some physical activity (68% and 67%), while 15% and 17% were sedentary, 16% and 15% did regular physical activity and training, and fewer than 2% in either group did regular hard physical training.

Comorbidities (other health conditions) were similar between groups: cardiovascular disease affected 40% and 38%, diabetes 13% and 11%, pulmonary (lung) disease 2.8% and 3.4%, neurological disease 2.4% and 1.5%, and mental illness 6.4% and 8.6%. Other diseases were reported by 37% and 41%.

Tumor stages were broadly comparable. Stage I disease affected 30% of both groups, stage II 25% and 31%, stage III 39% and 31%, and stage IV 5.7% and 7.6%. Using the American Society of Anesthesiologists (ASA) classification — a scale of physical fitness for surgery ranging from 1 (healthy) to 4 (severe disease) — most patients were ASA 2 (63% and 62%) or ASA 1 (20% and 18%). Surgery types were colon resection (52% and 45%), anterior resection (28% and 33%), and abdominoperineal excision (20% and 21%).

What Did the Exercise Program Involve?

The intervention was deliberately designed to be practical. Patients in the intervention group met with a physiotherapist (a physical therapist) at the time they joined the study. Together they discussed which physical activities suited the patient, and the physiotherapist gave instructions on inspiratory muscle training — exercises that strengthen the breathing muscles — including how to adjust the resistance on the training device.

The physiotherapist listened to what activities the patient already did and typically recommended walking, running, swimming, or bicycling. The target intensity was "medium," defined as exercise that makes you breathless but still able to talk.

  • Aerobic exercise: 30 minutes per day at relative medium intensity, matching the WHO recommendation for adults
  • Inspiratory muscle training: 30 repetitions twice daily (30 × 2)
  • Timing: Starting 14 days before surgery, then continuing for four weeks after discharge from hospital — but with aerobic exercise only after surgery

The program was unsupervised, meaning patients exercised on their own rather than in a clinic or supervised gym session. To support adherence, patients in the intervention group received two phone calls: one week into the preoperative period (reminding them to change the resistance on the breathing device and encouraging them to keep up the aerobic training) and again three weeks into the postoperative period (encouraging aerobic activity). Patients also recorded their physical activity in a diary during the two weeks before surgery.

Researchers chose this pragmatic model for a reason: if it worked, it would be easier to roll out in routine care than supervised, intensive, multi-component programs.

How Researchers Measured Fatigue, Quality of Life, Pain, and Mental Recovery

Patients completed questionnaires at three time points: at baseline (before surgery), 4 weeks after surgery, and 12 months after surgery. All questions were framed to cover the situation during the past 4 weeks.

Fatigue was measured using the vitality domain of the RAND-36 instrument, a widely used health survey. "Vitality" here works as the mirror image of fatigue: the scale runs from 0 to 100, where low scores mean feeling worn out and high scores mean feeling full of energy. The domain is based on 4 questions. The Swedish translation of RAND-36 has been shown to be equivalent in content to the original, with internal consistency reliability (a measure of how consistently the questions measure the same thing) above 0.8.

Quality of life was measured with the vertical visual analogue scale (VAS) of the EQ-5D-3L questionnaire, which asks patients to rate their health from 0 (worst imaginable health) to 100 (best imaginable health).

Pain was measured using the Brief Pain Inventory, Short Form (BPI-SF), a tool developed specifically for cancer patients. The researchers used the "interference" dimension — that is, how much pain interfered with patients' daily life — based on seven questions. The score was calculated as the average of the interference items when at least four of the seven questions were answered. The BPI-SF has demonstrated high internal consistency across cancer populations in several countries, with reliability scores ranging from 0.77 to 0.91 overall and 0.89 to 0.92 for the pain interference items.

Mental recovery was measured with a single question developed by the research group: "To what extent do you feel mentally recovered after the operation?" Patients chose from five answers ranging from "Not relevant, I do not feel recovered" through 25%, 50%, and 75% recovered, up to "I feel fully recovered."

Clinical data — tumor details, ASA classification, how radical the surgery was, surgical technique, and pathology reports — came from hospital records and the Swedish ColoRectal Cancer Register (SCRCR), a national database with high validity for the variables used.

How the Data Were Analyzed

The main analyses followed the intention-to-treat principle. This means every patient was analyzed in the group they were randomly assigned to, whether or not they followed the program. Intention-to-treat gives the most honest picture of what happens when a treatment is offered in the real world.

The researchers also ran per protocol analyses for exploratory purposes. These look at what happened among patients who actually did the intervention as intended. In this study, a patient counted as "per protocol" if they were randomized to the intervention group and their exercise diary showed preoperative exercise — inspiratory muscle training, aerobic exercise, or both — on at least eight days. Patients randomized to the intervention who did not return diaries, or whose diaries did not meet that threshold, were excluded from the per protocol analysis. Everyone randomized to the control group was analyzed as control.

Linear mixed models were used to compare fatigue, quality of life, and pain at 4 weeks and 12 months. Results are reported as mean differences with 95% confidence intervals (CI) and p-values. Ordinal regression models were used for mental recovery. The models were adjusted for baseline values, time point (4 weeks or 12 months), the interaction between time and treatment, and the factors used to balance randomization: tumor site (colon or rectum), neoadjuvant therapy (none, radiotherapy, or chemoradiotherapy), and surgery type (open or laparoscopic).

Missing values were handled by listwise deletion, meaning a patient was excluded from a given analysis if they were missing the data required for it. Because these were exploratory analyses of secondary outcomes, no correction for multiple testing was performed — a technical point that matters for interpretation, and one the authors flag themselves. Analyses were run in R, version 4.3.2.

Key Finding 1: Fatigue Was Lower in the Exercise Group

This was the headline result. Looking at raw median scores, the intervention group started with slightly lower vitality than the control group at baseline (65 vs 70 on the 0-100 scale), but reported higher vitality — meaning less fatigue — at 4 weeks after surgery (60 vs 55) and at 12 months (75 vs 70).

In the intention-to-treat analysis, the mean difference in fatigue at 4 weeks after surgery was 3.75 points in favor of the intervention group (95% CI 0.01 to 7.49; p = 0.05). At 12 months, the mean difference was 2.63 points (95% CI −0.97 to 6.22; p = 0.15), which was not statistically significant.

In the per protocol analysis — among patients who actually did the exercise as intended — the picture was stronger:

  • At 4 weeks after surgery: mean difference 4.04 points (95% CI 0.14 to 7.93; p = 0.04)
  • At 12 months after surgery: mean difference 4.29 points (95% CI 0.44 to 8.14; p = 0.03)

In plain language, the p-value of 0.05 means there is about a 5% chance — roughly 1 in 20 — that a difference this large would appear purely by chance if the intervention truly had no effect. A p-value of 0.04 or 0.03 means that chance is about 1 in 25 or 1 in 33. These are borderline results, right at the edge of conventional statistical significance, not overwhelming ones.

Key Finding 2: Quality of Life Did Not Change

Quality of life scores were similar between groups at every time point. Median scores on the 0-100 EQ-5D scale were 74 (intervention) vs 75 (control) at baseline, 75 vs 70 at 4 weeks, and 80 vs 80 at 12 months.

In the statistical models, no differences were found:

  • At 4 weeks: mean difference 1.38 points (95% CI −2.17 to 4.92; p = 0.45)
  • At 12 months: mean difference 0.14 points (95% CI −3.25 to 3.54; p = 0.93)
  • Per protocol at 4 weeks: mean difference 1.25 points (95% CI −2.49 to 4.99; p = 0.51)
  • Per protocol at 12 months: mean difference 2.09 points (95% CI −1.57 to 5.75; p = 0.26)

Because each confidence interval crosses zero, these results are consistent with no real difference at all.

Key Finding 3: Pain Did Not Change

Pain interference scores were almost identical between groups throughout. Median scores (on the BPI-SF interference scale) were 3 (intervention) vs 3 (control) at baseline, 3 vs 3 at 4 weeks, and 3 vs 3 at 12 months.

Statistically, the difference at 4 weeks was −0.18 points (95% CI −0.83 to 0.48; p = 0.59), and at 12 months it was −0.07 points (95% CI −0.72 to 0.58; p = 0.84). The per protocol analyses also showed no differences in pain or quality of life.

It is worth noting that the pain questionnaire had a large amount of missing data: 145 intervention patients and 152 control patients were missing baseline pain data, and similar numbers were missing at follow-up. This makes the pain results less certain than the fatigue results.

Key Finding 4: Mental Recovery Did Not Differ

Both groups felt more mentally recovered over time, but there was no significant difference between them at either time point.

At 4 weeks after surgery, patients reporting full mental recovery were 42% in the intervention group (about 4 in 10) and 45% in the control group. Those reporting they did not feel recovered were 3% and 6%. The full breakdown at 4 weeks:

  • Not recovered: 7 patients (3%) intervention vs 14 (6%) control
  • 25% recovered: 18 (9%) vs 19 (8%)
  • 50% recovered: 34 (16%) vs 27 (11%)
  • 75% recovered: 64 (30%) vs 75 (30%)
  • Fully recovered: 89 (42%) vs 112 (45%)

By 12 months, most patients had recovered mentally — but again, similarly in both groups:

  • Not recovered: 3 patients (1%) vs 4 (2%)
  • 25% recovered: 6 (3%) vs 5 (2%)
  • 50% recovered: 12 (5%) vs 19 (7%)
  • 75% recovered: 75 (31%) vs 82 (31%)
  • Fully recovered: 147 (60%) vs 151 (58%)

Are These Differences Big Enough for Patients to Notice?

This is the question patients care about most, and the answer is genuinely uncertain.

For the RAND-36 vitality scale, researchers generally consider a change of 3 to 5 points to be the smallest difference a patient would actually feel — what is called a clinically meaningful difference. The main result of 3.75 points falls inside that range. That sounds encouraging.

But there is a catch. The authors point out that the lower end of the confidence interval (0.01 points) sits well below the clinically meaningful range. That means the true effect could be essentially zero. So while the average result looks like it could matter, the study cannot rule out that there is no real benefit at all.

For quality of life measured with the EQ-5D, the clinically meaningful difference is usually described as 7 to 10 points on the 0-100 scale. The differences observed here — 1.38 points and 0.14 points — are far smaller than that, which supports the conclusion that quality of life genuinely did not change.

One strength the authors highlight: using the vitality scale from a validated instrument (RAND-36) rather than an informal feeling-of-tiredness question reduces the risk that the result was driven by patients' subjective expectations.

How These Results Compare With Other Studies

The authors place their findings in the context of earlier work.

In a randomized trial of exercise training for patients receiving adjuvant chemotherapy (post-surgery chemotherapy) after breast cancer surgery, the reduction in fatigue was larger than in this study, and pain levels remained stable. That trial's program was 16 weeks of supervised high-intensity training — much more intensive, much longer, and supervised by professionals. By contrast, PHYSSURG-C tested unsupervised, medium-intensity exercise for a shorter period: 2 weeks before surgery plus 4 weeks afterward.

The rationale for testing medium-intensity activity also came from earlier work. A previous study found that a habit of light-to-medium physical activity decreased the risk of postoperative complications after colorectal cancer treatment compared with no physical activity at all. And in an international cohort of patients operated for rectal cancer with curative intent, the same research group had previously found that fatigue and pain were predictors of overall quality of life. That link — between fatigue and how good life feels — is part of why these results matter.

The authors also note a practical reality in Sweden: only a minority of patients diagnosed with colorectal cancer exercise at the level tested in this trial.

What This Means for Patients

The most honest reading of this study is that it offers a suggestion of benefit, not proof. The authors describe it that way themselves: "This exploratory study found a suggestion of less postoperative fatigue in the intervention group."

Three things stand out for patients considering exercise around colorectal cancer surgery:

  1. Exercise may help with tiredness, but probably not with everything. Fatigue trended in a favorable direction; quality of life, pain, and mental recovery did not change at all.
  2. Doing the exercise matters. Among patients who actually did the program, the fatigue benefit was slightly larger at 4 weeks and remained statistically significant at 12 months. The per protocol analysis, though, is subject to selection bias (people who complete an exercise program may be different from those who do not), so the authors label it hypothesis-generating rather than definitive.
  3. The exercise tested was moderate and manageable. Thirty minutes a day of walking, swimming, running, or cycling at a "breathless but able to talk" intensity, plus brief breathing-muscle training, is a realistic goal for many people preparing for surgery.

It is also worth noting that in the original PHYSSURG-C trial, the primary outcome — self-reported physical recovery at four weeks — showed no significant difference between groups. The authors state they have not explored whether "physical recovery" and "fatigue" are related to each other, which leaves an open question about how these two results fit together.

Limitations: What This Study Could Not Prove

The authors are candid about the weaknesses of this analysis. Keeping these in mind is essential when reading the results.

  • These were secondary, exploratory analyses. The trial was designed and powered to answer a different question (physical recovery), not fatigue. Sample size was never calculated for any of the outcomes studied here.
  • No correction for multiple testing was made. When a study tests many outcomes, the chance of finding at least one "significant" result by luck increases. The p-values of 0.05, 0.04, and 0.03 must be interpreted with this in mind.
  • Wide confidence intervals and borderline p-values prompted the authors to call for "cautious interpretation of the results."
  • The per protocol subgroup may be biased. Because the intervention was individualized, patients who completed it were not necessarily "fitter" at baseline — but selection bias cannot be ruled out, so the authors describe this finding as hypothesis-generating.
  • Only 518 of 761 randomized patients were analyzed. The analysis population consisted of everyone who returned questionnaires at the 12-month follow-up, which raises the possibility that patients who felt worse (or better) dropped out disproportionately.
  • Large amounts of missing data for pain make the pain findings less reliable than the fatigue findings.
  • The trial ran for more than five years (January 2015 to May 2020), and cancer care changed during that time.

The authors conclude plainly: further studies are needed to define the role, if any, of unsupervised moderate exercise before and after surgery in relation to postoperative fatigue in patients with colorectal cancer.

Practical Recommendations for Patients

Based on this study and the wider research it references, here is what patients might reasonably take away — while remembering that no single study settles a question.

  1. Talk to your surgical team before starting an exercise plan. In PHYSSURG-C, every intervention patient met with a physiotherapist before beginning. Personalized guidance matters, especially if you have heart or lung conditions.
  2. Aim for moderate intensity. The target used here was exercise that leaves you breathless but still able to hold a conversation — 30 minutes a day of walking, cycling, swimming, or running.
  3. Consider starting before surgery if there's time. The preoperative window in this trial was only 14 days. If your team offers prehabilitation, that window may be worth using.
  4. Keep moving after discharge. The postoperative phase lasted four weeks and involved aerobic exercise only (no breathing-muscle training).
  5. Track your activity. Patients in this trial kept diaries, and diary data determined who counted as completing the program. Self-monitoring is also a well-established way to stay on track.
  6. Set realistic expectations. Exercise in this trial did not improve quality of life, pain, or mental recovery. If fatigue is your main concern, this is where the possible benefit lies — and it is a modest possibility, not a certainty.
  7. Report persistent fatigue to your care team. Fatigue after cancer surgery is common and should be discussed, not simply endured.

Frequently Asked Questions

What did the exercise program involve?

It was unsupervised moderate exercise: 30 minutes daily of walking, running, swimming, or bicycling at an intensity that leaves you breathless but still able to talk, plus breathing-muscle training (30 repetitions twice daily). It started 14 days before surgery and continued four weeks after discharge, with aerobic exercise only after surgery. Patients received two supportive phone calls and kept activity diaries.

Did exercise reduce fatigue after colorectal cancer surgery?

In a randomized trial of 518 patients, those asked to exercise reported less fatigue at four weeks after surgery, with a mean difference of 3.75 points on a 0-100 scale. This was borderline statistically significant. Among patients who completed the program as intended, the difference was slightly larger and remained significant at 12 months. The authors call this a suggestion of benefit, not proof.

Did exercise improve quality of life, pain, or mental recovery?

No. Quality of life scores were similar between groups at every time point, with differences far smaller than the 7-10 points usually considered noticeable. Pain interference scores were almost identical throughout. Mental recovery also did not differ: at four weeks, 42% of the exercise group and 45% of the control group reported feeling fully recovered. The authors conclude exercise did not change these outcomes.

What does a p-value of 0.05 mean?

A p-value of 0.05 means there is about a 5% chance—roughly 1 in 20—that a difference this large would appear purely by chance if the exercise truly had no effect. The fatigue result at four weeks had a p-value of 0.05, and the per-protocol results had p-values of 0.04 and 0.03. These are borderline, not overwhelming, results.

What are the limitations of this study?

These were secondary, exploratory analyses of a trial designed to test physical recovery, not fatigue. No sample size was calculated for fatigue, quality of life, pain, or mental recovery, and no correction was made for multiple testing. Only 518 of 761 randomized patients were analyzed, and pain data had large amounts missing. The authors call for cautious interpretation and say further studies are needed.

What should patients considering exercise around surgery know?

Talk to your surgical team before starting an exercise plan, especially if you have heart or lung conditions. The program tested was moderate and manageable: 30 minutes daily at a breathless-but-able-to-talk intensity, starting before surgery if time allows and continuing after discharge. Track your activity. Exercise may help with tiredness, but it did not improve quality of life, pain, or mental recovery in this trial.

When should a patient with colorectal cancer considering exercise before and after surgery seek a second opinion?

A second opinion can be useful when the role of exercise around colorectal cancer surgery is unclear for your situation. In a randomized trial of 518 patients, unsupervised moderate exercise for two weeks before surgery and four weeks afterward was linked to less fatigue at four weeks, but quality of life, pain, and mental recovery did not change, and the authors call for cautious interpretation and further studies. An independent review can help you weigh whether prehabilitation fits your health, surgical plan, and timing. Diagnostic Detectives Network provides independent expert second opinions.

Source Information

Original article title: Effects of Prehabilitation by Physical Activity on Fatigue After Surgery for Colorectal Cancer. Results From Secondary Analyses in the Randomized Controlled Trial PHYSSURG-C.

Authors: Afshari K, Onerup A, Li Y, Angenete E, Ehrencrona C, Wedin A, Haglind E.

Journal: Cancer Medicine, 2026; 15:e72142. Published open access under a Creative Commons Attribution License.

Publication timeline: Received 19 December 2025; revised 23 June 2026; accepted 18 July 2026.

Trial registration: ClinicalTrials.gov identifier NCT02299596.

Corresponding author: Eva Haglind (eva.haglind@gu.se).

This patient-friendly article is based on peer-reviewed research. It summarizes the findings of a single exploratory analysis and should not replace personalized medical advice from your own treatment team.