My clients often complain of pins and needles in their feet when using the elliptical machine for 10 minutes or more. I assumed it may be due to some kind of impingement in the hip area. Do you have an explanation for this and suggestions for preventing it in the future?
Your guess on hip impingement may be correct. However, the elliptical machine can cause a great deal of lower back hyperextension in some people. If this is occurring with your clients, then any lumbar-sacral problems that exist may exacerbate any nerve impingement issues.
You may also want to look at the lower leg for any compartmental syndrome that may occur. This entrapment of blood and lymph fluid can place pressure on the nerves leading to the feet and cause the pain. Neuralgia in the feet is a common syndrome for a few disorders. One disorder is diabetes. Diabetes or pre- insulin resistance types usually complain of pain in their feet. The “pins and needles” you speak of are common with diabetes. You should advise your client with this complaint to see his or her health care professional for a glucose tolerance test and a glycosylated hemoglobin test, just to be safe.
The last possibility is that the elliptical is just not built for them. If you watch your clients' feet when they are using the machine, they stay in contact all the time. This means constant pressure. Other aerobic apparatus has a phase when the foot gets a slight pressure break and relief (i.e., the swing phase when walking or running).
If your clients cannot live without the elliptical, then give it to them in smaller durations: a five minute phase, then lift, then five minutes and lift, etc. You can set up a semi-circuit training system.
I hope this gives you some alternative ideas on helping your clients.