The machine works the gluteus medius as well as floor exercisesEmerging evidence
In 11 men doing ten maximal reps of each, gluteus medius activity was the same on the machine, in clamshells and in side-lying abduction. The front-of-hip muscle worked harder in side-lying abduction, so the machine gave the medius the biggest share of the work.
Source 1
An elastic band drew more gluteus medius activityEmerging evidence
In 16 untrained women, abduction against an elastic band drew more gluteus medius activity than the seated machine, while the inner thigh muscles worked alike on the band and the adduction machine. We read this study as an abstract, which doesn't say how the band exercise was done.
Source 2
Several exercises work the gluteus medius hardEmerging evidence
Across 56 studies of muscle activity, the hip hitch, resisted standing abduction, the single-leg bridge, side-lying abduction with the hip turned in, the lateral step-up and resisted side-stepping drew high activity in the gluteus medius. The machine is one good option among several.
Source 13
Side-hip training grew the upper and side glutesEmerging evidence
17 young adults trained one leg with cable hip abduction and the other with cable hip extension, about 10 sets a week over 2 sessions, for 10 weeks. Abduction grew the upper gluteus maximus 10%, its middle 4% and lower part 1%, and the gluteus medius and minimus 4%; extension grew the gluteus maximus more overall (9% against 5%), mostly its lower part. It's one small trial, with cables rather than the seated machine, and we read it as an abstract.
Source 5
Squats and hip thrusts barely grew the side glutesEmerging evidence
In 34 untrained young adults, 9 weeks of squats or hip thrusts grew the gluteus maximus about equally, but the gluteus medius and minimus showed little to no growth with either.
Source 6
Training one area doesn't take the fat off itStrong evidence
A meta-analysis of 13 studies of 1,158 people aged 14 to 71 found no extra fat loss in a trained limb. When 11 young adults trained one leg for 12 weeks, fat fell 10.2% in the arms and 6.9% in the trunk, but not in the trained leg.
Sources 7, 8
Where you store fat is strongly influenced by genesEmerging evidence
When 12 pairs of identical twins were overfed by 1,000 kcal a day for 84 days, the weight they gained ranged from 4.3 to 13.3 kg, and each pair matched closely in where they stored fat.
Source 14
Hip strengthening helps kneecap painStrong evidence
Across 14 trials of 673 people, hip and knee strengthening eased pain and improved activity more than knee strengthening alone, and the benefit lasted after treatment. Other reviews agree, though many trials were small. The trials used a range of hip exercises, not specifically this machine.
Sources 9, 15, 16
Knee osteoarthritisEmerging evidence
In 89 people with osteoarthritis on the inner side of the knee, 12 weeks of hip abductor and adductor strengthening improved pain, function and strength but didn't change the load on the knee.
Source 17
The certainty is lower for other conditionsMixed evidence
A review of hip strengthening across trunk and leg conditions, including back pain, rated the certainty of its effects very low to uncertain.
Source 18
Outer hip tendon painStrong evidence
In 204 people aged 35 to 70 with tendon pain on the outside of the hip, 14 sessions of education plus exercise over 8 weeks succeeded for 51 of 66, against 38 of 65 after a steroid injection and 20 of 68 with wait and see; education plus exercise still led at a year.
Source 10
After a hip replacementEmerging evidence
In 7 people with sensor-fitted hip replacements, about 17 months after surgery, leg press, leg curl, leg extension and standing cable exercises loaded the hip no more than walking. The seated abduction machine wasn't tested.
Source 19
Adductor strength and groin problemsStrong evidence
In 652 semi-professional footballers, an adductor programme built on the Copenhagen exercise cut groin problems by 41%. That's evidence for the Copenhagen plank, not the adduction machine.
Source 20