Why exercise right after a cancer diagnosis is one of the smartest things a patient can do.

Hearing the words “you have cancer” is disorienting. Between appointments, scans, and decisions, there’s often a short, but surprisingly powerful, window between diagnosis and the start of treatment. Using that time to begin or safely ramp up exercise is not just about staying busy: it’s medicine. A growing body of research shows that targeted physical activity started at diagnosis (often called prehabilitation) improves physical resilience, emotional wellbeing, treatment tolerance, and recovery. 1

What the research actually says

Large reviews and clinical trials over the last few decades consistently report benefits of exercise for people with cancer. Exercise during treatment improves cardiorespiratory fitness, strength, fatigue, and quality of life. One major clinical review found consistent, clinically meaningful improvements in patient-reported outcomes when exercise was added to standard care. 2

When it comes to chemotherapy, systematic reviews point to better treatment adherence and fewer dose reductions when patients follow a structured exercise program, likely because exercise helps manage dose-limiting side effects (fatigue, deconditioning, and some toxicities). One review concluded that exercise interventions may improve chemotherapy completion rates by helping patients tolerate and finish prescribed treatment. 3

For surgery, randomized trials of prehabilitation - programs combining exercise, nutrition and stress management - have shown fewer severe post-operative complications, shorter or optimized recovery, and better functional outcomes after operations such as colorectal cancer surgery. The PREHAB randomized clinical trial demonstrated real, measurable improvements in postoperative recovery for patients who did prehabilitation vs. usual care. 4

How exercise helps physically and biologically

Exercise improves cardiovascular fitness, muscle strength, balance, and endurance, all of which matter during chemo, radiation, and surgery. Better fitness reduces surgical risk (less anesthesia complications, better wound healing potential, lower infection rates) and shortens recovery time. Physiologically, exercise improves circulation, insulin sensitivity, and markers of inflammation; these changes can translate into fewer side effects and better tolerance of aggressive therapies. Recent large reviews conclude that exercise can lower postoperative complications and reduce hospitalization. 5

Emotional and cognitive benefits

Beyond the physical, exercise is a potent mood regulator. Physical activity reduces anxiety and depression, improves sleep and cognitive clarity (“chemo brain”), and increases a patient’s sense of agency during a time that otherwise feels out of control. This emotional resilience matters: patients who feel more capable and less overwhelmed are better able to follow difficult regimens, attend appointments, and adhere to lifestyle and medical recommendations.

Real-world Results from trials

• In breast cancer trials that paired supervised exercise with standard chemotherapy and nutrition coaching, women were more likely to complete planned chemo and experienced lower hospitalization. These program-level outcomes reflect improved tolerance and adherence. 6

• In colorectal cancer prehabilitation trials (like PREHAB), patients who completed a multimodal program before surgery had fewer severe postoperative complications and an easier recovery timeline than those who did not engage in structured prehab. Those are concrete, clinically meaningful gains. 7

These aren’t anecdotes; they’re reproducible findings across multiple trials and systematic reviews.

Patient Case Study

Meet Suzanne Porath

When Suzanne Porath was diagnosed with stage 3 breast cancer, the world tilted. Multiple surgeries and 32 rounds of radiation loomed ahead. Instead of retreating, Suzanne decided to fight on her own terms.

“I couldn’t control the diagnosis,” she says, “but I could control how strong I went into treatment.”

Taking Action Early

Before her first surgery, she began walking every morning and incorporated resistance exercises a friend taught her. Her oncologist approved a gentle plan that helped her regain energy between radiation cycles.

“Those walks became my lifeline,” Suzanne says. “They reminded me I was still me - not just a patient.”

Building Strength for Recovery

By the time she faced her deep flap reconstructive surgery, Suzanne’s stamina had transformed. Her surgeon later remarked that her recovery was “remarkably faster” than most patients who’d undergone the same procedure. She was out of bed and walking the halls days ahead of schedule, experiencing less pain and fewer complications.

Healing Inside and Out

Exercise became her therapy—physically and emotionally. It reduced her fatigue, lifted her mood, and helped her body respond better to treatment.

“Because I stayed active from the start,” Suzanne reflects, “my body knew how to heal—and my spirit did, too.”

Practical, safe steps to use the diagnosis-to-treatment window

Ask your care team for clearance. Most oncologists support exercise but will advise limits based on diagnosis, blood counts, fractures, heart issues, or venous access devices.
Start with what you can sustain. Walking, light resistance bands, short strength circuits, breathing and mobility work are effective and safe starting points.
Prioritize function. Focus on legs (walking, step-ups), core, and upper-body strength so you can tolerate IV lines, transfers, and surgical positioning.
Mix aerobic and resistance work. Both have unique benefits, cardio improves endurance; resistance builds the muscle that supports recovery.
Use the window. Even 2–6 weeks of systematic, progressive exercise before chemo or surgery has been shown to make a difference in outcomes. The period from diagnosis to first treatment is time you can intentionally use to build resilience. 8

How programs can help, and where personalized support fits

There is strong data that proves that patients do better with structured support: tailored programs, coaching, and clinical integration that align exercise with treatment schedules and medical needs. Platforms and clinical partners that provide live coaching, bespoke plans, and coordination with oncology teams can raise adherence and safety, turning the diagnosis-to-treatment period into proactive healthcare rather than idle worry. Complement 1 is evidence-based, personalized coaching that integrates with routine cancer care to help patients adopt high-adherence lifestyle habits during treatment and survivorship.

Bottom line: use the time from diagnosis to treatment well

A cancer diagnosis is scary, but it’s also a pivot point. Small, consistent exercise begun with medical oversight at diagnosis helps patients physically brace for treatment, cope emotionally, and in many studies, improves treatment completion and recovery after surgery. If your oncologist gives the go-ahead, consider a supervised, personalized program (or even simple daily walking plus strength work) and use that window to gain strength. It’s not a cure on its own but it’s proven, practical medicine that helps people get through treatment and get back to life.

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