Constant Resistance (CR)
Brujo,
Constant Resistance (CR) between partners is what you are really talking about when you talk about a strong frame. The term strong frame is not descriptive of the technique. SF can mean any sundry conditions and does not go directly to the crux of the problem. Teachers invent abstract terms that sound good but only complicate the learning process.
Now I will give you the best exercise, I have come across in over 50 years of teaching, to develop CR when you are dancing. Please keep in mind what this will do for you is give you a solid foundation for CR and when you mentioned, 'my elbow goes limp' that gave me the key to your problem. Let me preface this exercise by admitting I got onto it by observing an Asian American couple giving a lesson at Lance's 'Lindy Groove', I believer his name was Bernie and I'm sorry I can't recall the lady's name, but here is the exercise, and I'll bet you a dollar to a donut someone will negate this exercise by saying it's been around for years and they have better ways to develop CR, but don't be dissuaded, try this for 15 minutes, and if it doesn't work for you I'll give you your money back. Within 15 minutes of this exercise your 'limp elbow' will be history. This is the Magic Pill for your problem. But there's a catch! You do need a partner to practice with.
Magic Pill, Constant Resistance (CR):
1) Get in the Push Position, palms of hands to palms;
2) Test each other by gently pushing and pulling away, Resisting in equilibrium to each others pushes and pulls; the arms always in a bent 'obtuse angle' which is maintained THROUGHOUT this exercise with slightly flexible adjusting: (about a 100 to 120 degrees; NO straight stiff arms)
3) Now slowly go into squats together leaning slightly away from each other and supporting each other to avoid falling backwards;
4) Now rise slowly leaning inward pushing in equilibrium gently toward each other in a balanced posture with slight body tilt inward keeping hips tucked in normal posture;
5) Now go into same squat, but leaning gently but firmly toward each other:
6) Now rise with a slight but firm lean way from each other.
Repeat these six steps without relenting with your constant pressure to or tension from each other BETWEEN rises and squats. There are other techniques of leading and following which I have described in previous Commentaries under the thread, 'Teaching Technique's.
Black Sheep, I'm free but expensive.