PMID 41418486

Research
All papers

Feasibility and efficacy of peak-velocity interval training vs. moderate-intensity walking training in people with multiple sclerosis with severe fatigue and walking impairment: A pilot randomized controlled trial

Cleland BT, Jeng B, Brown N, Motl RW, Madhavan S

Question

Is peak-velocity interval walking training feasible and initially efficacious compared with moderate-intensity continuous walking training for people with multiple sclerosis who have elevated fatigue and walking dysfunction?

Summary

This pilot randomized controlled trial tested peak-velocity interval treadmill walking, a HIIT-style walking protocol, against moderate continuous walking in 12 people with multiple sclerosis, elevated fatigue, and walking impairment. Participants completed 12 sessions over about 5.5 weeks with 100% retention, high adherence, 100% intensity compliance, and no adverse events. PVIT achieved higher relative heart rates and greater relative walking velocity than MICT and improved VO2 peak more, but other walking, fatigue, and cognitive outcomes did not differ between groups.

Methodology

  • Twelve people with multiple sclerosis, elevated fatigue, and walking dysfunction randomized to PVIT or MICT.
  • 12 participants.
  • Treadmill walking.
  • Work intervals: For each interval, speed ramped over 2 minutes to safe/tolerable peak velocity, then peak velocity held for 10 seconds.
  • Recovery: Walk at warm-up recovery velocity until HR was within 5 bpm of warm-up; if not recovered within 4 minutes, treadmill stopped and participant stood until HR recovered.
  • Intensity: Peak safe/tolerable walking velocity; achieved 82.6 (7.8)% HRR across intervals/segments and 92% of intervals in vigorous HR range.
  • Up to 40 minutes prescribed including pauses; observed walking time excluding rests/early stoppage 30.4 (10.0) minutes.
  • 2-3 sessions per week.
  • 12 sessions.
  • Single-center, parallel-groups pilot randomized controlled trial.
  • Peak oxygen consumption, Walking performance, Fatigue severity, and Cognition were tracked.

Outcomes

Feasibility

All enrolled participants were randomized and completed all testing and allocated training sessions; retention was 100%, overall adherence 86.1%, and intensity compliance 100%.

PVIT adherence 84.5 (24.3)%, MICT 88.3 (9.5)%; retention 100% in both groups.

Improved

Safety

No adverse events occurred in either group.

Improved

Exercise intensity fidelity

PVIT achieved higher relative HR and peak velocity relative to maximal overground velocity than MICT; 92% of PVIT intervals achieved vigorous HRs.

PVIT HRR 82.6 (7.8)% vs MICT 55.5 (14.1)%, p=0.002; peak velocity relative to maximal overground velocity 95 (41)% vs 70 (12)%, p<0.001.

Improved

VO2 peak

VO2 peak improved more in PVIT than MICT: PVIT increased 2.3 mL/kg/min (13.8%) compared with MICT 0.4 mL/kg/min (1.0%).

t(10)=2.2, p=0.05; Cohen's d 0.47 for PVIT and 0.10 for MICT.

Improved

Walking, fatigue, and cognition

Between-group changes did not differ for comfortable or maximal 10MWT, 6MWT, FSS, SDMT, or CVLT-II.

Other outcomes t<=1.9, p>=0.09; Z<=1.9, p>=0.07.

No clear change

Session duration and distance

PVIT had shorter walking duration, more pause/rest duration, and less distance covered than MICT.

Session duration 30.4 (10.0) vs 37.1 (5.6) min, p<0.001; pause/rest 3.6 (3.7) vs 1.1 (1.8) min, p<0.001; distance 1285 (780) vs 2167 (1085) m, p<0.001.

Mixed

Insights

  • In a supervised clinical setting, individualized peak-velocity walking intervals can be feasible for people with MS who have fatigue and walking impairment.
  • Clinical HIIT may need flexible scheduling, HR recovery-based rests, and safety regressions rather than rigid session timing.
  • Higher intensity may improve aerobic fitness even with less total walking time and distance, but walking, fatigue, and cognitive benefits remain uncertain.

Limitations

  • Pilot sample of 12 participants.
  • Planned sample was 20, but study stopped after interim analysis.
  • No long-term follow-up.
  • Trainers and participants could not be fully blinded.
  • Duration compliance was 60%, and PVIT had less walking time than MICT.
  • Flexible weekly dose improved real-world practicality but limited methodological rigor.
  • Requires supervised treadmill safety setup.

Safety

  • No adverse events occurred.
  • Participants wore a harness without body-weight support and could hold handrails.
  • Participants had to pass a graded exercise stress test.
  • PVIT included HR recovery criteria and treadmill stopping if HR did not recover within 4 minutes.