I am a qualified exercise teacher and was working with the over 60's when I was diagnosed with PMR.
Below is some information which may help people who are struggling with regaining muscle strength and maintaining or putting on weight.
First thing I would say to you is regarding diet. If you are in good health, that is to say no cardiac problem, stroke risk or diabetic and you wish to put on weight then I would suggest that you increase your protein intake to help build muscles and your fat intake to help maintain your weight. As you probably know fat is the thing your body can lay down as a reserve quickly. Carbs also gets metabolized and stored as fat but they have to use more energy to get converted although they do give you a fast amount of energy if you need an energy boost. Therefore, providing you don't have any preexisting conditions I would recommend adding extra protein (meat, milk, cheese, eggs and fish) into your diet. So perhaps an extra cheesy snack or an extra egg. Also you can enrich your food with fats such as adding olive oil to your salads, eat full fat yoghurts, add cream to your cereal or make creamy pasta sauces with an addition of cheese and cream. Sounds like madness but its what's generally done in order to enrich a diet of an older person who can't maintain weight.
There's a nutritional supplement that's given, which is available on prescription which is a high dose of fat. But its revolting and only used if the person cannot eat in sufficient quantities.
My advice is enjoy your freedom to eat cream and cheese whenever you fancy!
Please don't follow the above advice if you are suffering from other conditions without consulting your GP.
On strength training. All muscle strength training relies on micro-trauma to our muscle fibers. ie we damage our muscles so that the repair themselves stronger. This is a natural process but obviously when you lift heavy weights or do repeated strength exercises more muscle fibers suffer micro trauma.
Therefore as our muscles are affected in pmr we need to be careful as the blood supply is lessened and the micro trauma takes longer to heal.
We need to start slowly and gently and build up gradually giving muscles time to recover in between sessions.
My recommendation for upper body would be short slow Nordic walking as this works the core, upper arms and legs. Start out with a short 5 mins or 10 mins and build up gradually. You can go faster as you get better but speed burns calories and you need to hold on to your calories so slow is good
Pilate's works the muscles by elongating them. Often in Pilate's a rebounder machine is used to offer resistance to build strength. Pilate's is very good for core strength.
My own recommendation would be to have a personal lesson with a Pilates instructor so that your exercises can be tailored to you. Pilates instructors are highly trained and should be able to offer you a tailored session. You can join a group session when you have built up your strength and endurance. Never be afraid to ask the instructor for help.
Swimming can cause repetitive strain on the muscles and joints although the water does support the muscles. I would keep swimming down to a leisure pace and not try to do as many lengths as you can. Swimming doesn't burn so many calories so is a good one for not losing weight unless of course you are an Olympic swimmer. A gentle aqua aerobic class might help but most aerobic classes by their very name are cardio and are usually to lose weight. Try to find a gentle one. I know I have seen some classes described as
aqua splash which is much gentler and does not concentrate on cardio.
Little and often is the key. You can start from your armchair. Bicep curls in your armchair using full tins of beans as weights, start with small tins and progress to big tins or small bottles of water remembering that a small bottle of water is usually 500mls and is the same as a half kilogram weight or roughly one pound. You should start with a small amount of repetitions say 5 curls a time about 4 times a day and building up very gradually until your can do 10 easily. Cheap and in the comfort of your own home
Later as you get stronger you might like to put a few tins in two carrier bags and use those as your weights.
Hope this helps you and anyone else reading. You should always discuss any new exercise program with your gp.
Good luck with your endeavours.