Isometric versus isotonic exercise for greater trochanteric pain syndrome: a randomised controlled pilot study

Key points

1. 01No significant difference between isometric and isotonic exercise at 4 or 12 weeks on any outcome
2. 02VISA-G scores improved by roughly 10 points in both groups by week 12
3. 0355% of isometric and 58% of isotonic participants achieved a clinically meaningful pain reduction (at least 2 points on NPRS) by week 12
4. 0464% of isometric and 75% of isotonic participants reported meaningful overall improvement on the Global Rating of Change Scale at 12 weeks
5. 05Over 35% of participants in both groups did not improve, highlighting that a substantial minority do not respond to loading programmes

How it was conducted

Design

Randomised controlled pilot trial

Participants

30 adults with GTPS (lateral hip pain for more than 3 months) recruited from NHS physiotherapy waiting lists

Groups

Isometric exercise (n=15) versus isotonic exercise (n=15), both daily progressive home programmes for 12 weeks with 8 supervised physiotherapy sessions

Primary outcome

Victorian Institute of Sport Assessment-Gluteal (VISA-G) questionnaire (0-100, higher = better)

Secondary outcomes

Numeric Pain Rating Scale (0-10), Global Rating of Change Scale (11-point), Pain Catastrophising Scale, HOOS, EQ-5D-5L, IPAQ-SF

Follow-up

Baseline, 4 weeks, and 12 weeks

What they found

• VISA-G isometric group: baseline 54.6 (SD 23.1), week 4 59.2 (SD 21.0), week 12 65.0 (SD 22.6)
• VISA-G isotonic group: baseline 61.9 (SD 16.1), week 4 60.8 (SD 12.8), week 12 72.4 (SD 13.3)
• Between-group difference on VISA-G at week 4: 5.5 points (95% CI -3.5 to 14.4); at week 12: -0.1 points (95% CI -13.8 to 13.5)
• Cohen's d effect size at week 12: d=0.45 (isometric), d=0.71 (isotonic)
• NPRS MCID (at least 2-point pain reduction) achieved by week 12: 6/11 (55%) isometric versus 7/12 (58%) isotonic
• GROC MCID (at least 2-point improvement) at week 12: 7/11 (64%) isometric versus 9/12 (75%) isotonic
• VISA-G scores worse or unchanged at week 12: 4/11 (36%) isometric, 5/12 (42%) isotonic
• HOOS pain domain improved significantly within isotonic group at 12 weeks (p=0.042); no significant between-group differences on any secondary measure
• Exercise adherence: 70% of isometric completers and 58% of isotonic completers achieved at least 80% of daily sessions
• 23 of 30 participants completed the trial (7 dropouts, at least 20% per group)

Limitations

• Small pilot sample (n=30, only 23 completers) is underpowered to detect between-group differences
• No control group, so it is unclear how much improvement reflects natural history or the education component rather than the exercise type
• Diagnosis was clinical only without MRI or ultrasound confirmation, so participants with partial gluteal tendon tears or other pathology may have been included
• Outcome assessor and supervising physiotherapist were the same person and not blinded, introducing potential assessment and performance bias

Why it matters

For patients

Both exercise approaches appear to reduce hip pain similarly, so patients can work with their physiotherapist to choose whichever type is more comfortable or practical for them.

For clinicians

Isometric hip abduction holds are a viable alternative to isotonic exercises for GTPS, which may be useful when patients have concurrent hip osteoarthritis or difficulty with range-of-motion movements; muscle contraction type appears less important than consistent progressive loading.

For readers

This is the first head-to-head RCT of isometric versus isotonic exercise in GTPS; results are preliminary and a fully powered trial is needed before firm clinical guidelines can be drawn.