PMID 35597974

Research
All papers

Feasibility and acceptability of high-intensity interval training and moderate-intensity continuous training in kidney transplant recipients: the PACE-KD study

Billany RE, Smith AC, Hutchinson GM, Graham-Brown MPM, Nixon DGD, Bishop NC

Question

Are two cycling HIIT protocols and a moderate continuous cycling protocol feasible, acceptable, and safe for kidney transplant recipients, and what outcomes might inform a larger trial?

Summary

In kidney transplant recipients, 24 supervised cycling sessions of either HIIT or moderate continuous training were generally safe and well attended, with no major adverse events reported. The main feasibility problem was intensity: only 40% achieved the required power-output intensity, although 75% met a secondary heart-rate intensity criterion. Participants completed 92% of sessions, reported the programs as enjoyable and beneficial, and VO2peak and peak power tended to improve, but this pilot was not powered to test efficacy.

Methodology

  • Stable adult kidney transplant recipients.
  • 24 participants.
  • Stationary cycling.
  • Work intervals: HIIT A: 4-, 2-, and 1-min intervals; HIIT B: 4 x 4-min intervals.
  • Recovery: HIIT A: 2 min active rest; HIIT B: 3 min active rest plus final active stage.
  • Intensity: 80-90% watts at VO2peak, aiming for 85-95% HRpeak.
  • About 45 min including warm-up/cool-down.
  • About 3 sessions/week.
  • 24 sessions.
  • Randomized three-arm pilot and feasibility trial.
  • Feasibility, VO2peak, and Safety were tracked.

Outcomes

Session adherence

Participants who completed the intervention attended 92% of sessions.

Mean 22/24 sessions; average 10 +/- 3 weeks to complete.

Improved

Intensity feasibility

Power-output intensity targets were difficult, especially for HIIT A, but heart-rate targets were more often achieved.

Required power achieved by 8/20 completers; secondary HRpeak criteria achieved by 15/20.

Mixed

Safety

No major adverse events were reported.

Improved

VO2peak and peak power

VO2peak and peak power increased descriptively in all groups.

VO2peak mL/kg/min pre/post: HIIT A 24.28 to 27.06; HIIT B 24.65 to 27.48; MICT 29.33 to 33.05.

Improved

Insights

  • Supervised cycle HIIT can be acceptable to stable kidney transplant recipients but should use achievable intensity targets.
  • A familiarization period and shorter hard intervals may improve feasibility.
  • Flexible scheduling or partial home-based delivery may improve recruitment and retention.

Limitations

  • Pilot sample size and not powered for efficacy.
  • Baseline heterogeneity.
  • Intensity target based on watts may not have matched participants' ability to repeat intervals.
  • Variable time to complete 24 sessions.
  • Follow-up attrition.

Safety

  • No major adverse events were reported.
  • One abdominal pain session stop was clinically reviewed and considered unrelated to exercise.
  • One session stop was due to urinary tract infection pain under clinical treatment.
  • Cold/flu symptoms led to many cancelled and rescheduled sessions.