PMID 34389552

Research
All papers

Cardiorespiratory fitness in breast cancer survivors: a randomised controlled trial of home-based smartphone supported high intensity interval training

Ochi E, Tsuji K, Narisawa T, Shimizu Y, Kuchiba A, Suto A, Jimbo K, Takayama S, Ueno T, Sakurai N, Matsuoka Y

Question

Does the 12-week home-based smartphone-supported habit-B HIIT program improve cardiorespiratory fitness in sedentary early-stage breast cancer survivors compared with control?

Summary

This single-center randomized trial tested a 12-week home-based, smartphone-supported HIIT program using bodyweight exercise in sedentary Japanese women who had survived early-stage breast cancer. Compared with smartwatch-only usual control, the habit-B program improved peak oxygen uptake and leg press strength, had 86% adherence, and reported no serious grade 3 or higher adverse events. The exact exercise menu and work-rest structure were not included in the article text, but the study is important because it supports feasible, remotely supported HIIT in a clinical survivor population.

Methodology

  • Sedentary women aged 20-59 years with stage I-IIa breast cancer after completion of initial treatment except hormone therapy.
  • 50 participants.
  • Bodyweight exercises at home.
  • Intensity: Maximum RPE target 18 +/- 2; monitored with RPE and smartwatch heart rate.
  • 3 times per week.
  • 12 weeks.
  • Single-center, 12-week, parallel-group, single-blind randomized controlled trial.
  • Peak oxygen uptake, Leg press strength, 6-minute walk test, and Fatigue were tracked.

Outcomes

VO2peak

VO2peak changed by +0.9 (1.7) mL/kg/min in habit-B and -0.8 (1.6) in control; between-group difference 1.7 (95% CI 0.7 to 2.7), ES 1.06.

p<0.01

Improved

VO2peak in L/min

VO2peak changed by +0.06 (0.11) L/min in habit-B and -0.03 (0.09) in control; between-group difference 0.10 (95% CI 0.03 to 0.16), ES 0.95.

p<0.01

Improved

Leg press 1RM

Leg press 1RM changed by +13.0 (15.9) kg in habit-B and -0.5 (18.1) kg in control; between-group difference 13.5 kg (95% CI 2.9 to 24.1), ES 0.79.

p=0.01

Improved

Other physical function, activity, and quality of life outcomes

No significant intervention effects were found for 6MWT, grip strength, chair stand test, physical activity, body composition, or QOL.

6MWT p=0.93, grip strength p=0.53, chair stand p=0.50; other p values not reported in main text.

No clear change

Adherence and serious adverse events

Adherence was 86% (range 19%-100%), and no serious grade 3 or higher adverse events occurred.

Mixed

Insights

  • For selected sedentary breast cancer survivors, home-based bodyweight HIIT can improve CRF when supported by app guidance, reminders, HR monitoring, RPE targets, and remote safety channels.
  • Three sessions per week over 12 weeks is a clinically plausible dose for remote HIIT in this population.
  • RPE-based intensity targets and staged progression are important when exact external workload cannot be prescribed at home.

Limitations

  • Exact work/rest structure and exercise menu were not reported in this article.
  • Small single-center trial.
  • Findings may not generalize to all breast cancer survivors.
  • COVID-19 disrupted and postponed face-to-face outcome measurements.
  • No long-term maintenance follow-up reported.

Safety

  • No serious grade 3 or higher adverse events occurred.
  • Safety was assessed through emails, phone calls, and app input.
  • Exercise adherence was monitored by app input and smartwatch heart rate.