Comparison between moderate-load and high-load exercises in the rehabilitation of runners with Achilles tendinopathy: Protocol for a blind randomized controlled trial.

The trial will enroll 60 amateur runners randomly allocated to either a high-load exercise group (HLG) or moderate-load exercise group (MLG).

• Participants are amateur runners with Achilles tendinopathy.
• Random allocation will be used to assign participants to one of two groups.
• The study is designed as a blind randomized controlled trial.
• Registration number: RBR-4vwy5xj.

The high-load exercise group will progressively increase exercise load from 55% to 90% of 1 repetition maximum over 12 weeks.

• HLG starts treatment with calf exercises at 55% of 1RM.
• Load is progressively increased over 12 weeks to reach 90% 1RM.
• The 1RM load will be reassessed every 2 weeks.
• Intervention duration is 12 weeks total.

The moderate-load exercise group will perform calf exercises consistently at 55% of 1RM throughout the entire 12-week intervention.

• MLG maintains 55% 1RM load for the full 12 weeks without progression.
• The 1RM load will also be reassessed every 2 weeks in this group.
• Total training volume (total repetitions and tendon time under tension per week) will be the same in both groups.
• This equal-volume design is described as a key distinguishing feature of the trial.

Both groups will perform additional strengthening exercises for quadriceps and gluteal muscles as part of the intervention.

• Quadriceps strengthening exercises are included for both HLG and MLG.
• Gluteal muscle strengthening exercises are included for both groups.
• This component is in addition to the primary calf exercise protocol.

The primary outcome measure is symptom severity assessed using the Victorian Institute of Sport Assessment-Achilles (VISA-A) questionnaire.

• VISA-A will be evaluated at baseline, week 6, week 12 (end of intervention), and 6 months after the intervention.
• Pain will be evaluated using the visual analogue scale (VAS) at the same time points.
• Secondary outcomes include peak isometric strength of ankle, knee, and hip muscles; plantar flexor muscle function; quality of life; and perception of improvement.

Statistical analysis will be conducted under the intention-to-treat principle using generalized estimating equations (GEE) with Bonferroni-adjusted post hoc tests.

• Intention-to-treat principle will be applied to all results.
• Generalized estimating equations (GEE) will be the primary analytical method.
• Bonferroni-adjusted post hoc tests will be used for multiple comparisons.

This trial is described as the first randomized controlled trial comparing high-load versus moderate-load exercises in individuals with Achilles tendinopathy with equal training volume applied between groups.

• The authors state: 'This will be the first randomized controlled trial comparing high-load exercises versus moderate-load exercises in individuals with Achilles tendinopathy applying equal training volume.'
• Exercise-based interventions are identified as the main treatment options for Achilles tendinopathy.
• The ideal exercise dosage for Achilles tendinopathy is described as currently unknown.
• Achilles tendinopathy is described as 'one of the most frequent conditions affecting runners.'