A few weeks ago I was on vacation and apparently strained a groin muscle running what amounted to 100-yard dashes on the beach with our 9 month old puppy. I did manage four easy runs of 3 to 6 miles on vacation too and have been able to continue running, but I still get pain inside my upper thigh and especially across my lower abdomen when I sit up or turn. It felt good enough yesterday that I ran a few intervals on the track, which might have been a mistake as on the last interval my thigh muscle really started hurting. I have a 5K in two weeks so I don't want to stop training completely but I'm worried about whether I'll be able to do any more speed work.
What is the best way to get this to heal fast? I'm taking ibuprofen and a rice/heat pad.
Healing time for an injury is hard to predict without a firm diagnosis, so I will not be able to tell you if you can race tomorrow or in 6-12 weeks. The likely diagnoses are injury to the muscle-tendon-bone units, the classic groin pull or strain; or a disruption of your normal mechanics. The groin and abdominal strain will take 12 weeks, on average, to heal to 100 percent of strength barring re-injury. The mechanical disruption of your normal kinetic chain motion can be resolved, in some cases, in a day in the hands of a skilled manual therapist.
Sprinting in sand on a beach that likely slopes toward the water is a set up for both injuries. Many people choose to run barefoot on the beach when they are not conditioned or transitioned for barefoot running in soft sand. The slope of the beach sets up an apparent leg length discrepancy and forces the muscles to work in unaccustomed ways setting you up for a groin and rectus (lower abdomen) strain. The slant also puts abnormal stresses on the ankles, knees, hips, pelvis, abdomen, and low back forcing the muscles to contract to different lengths than during usual running, and sometimes causing the pelvis to rotate or the lumbar spine articulations to “lock up” (for lack of a better descriptor). Finally, if you switched to 100 yard sprints from your usual workouts, you may have overloaded the muscle-tendon junctions and caused the strain.
Training errors cause many injuries and this may be the case for you. The muscles will heal with time. Heat, gentle stretching, eccentric strengthening and a gradual return to running should do the trick, unless you mechanics are out of line (think of the alignment in your car). Then you will need to be evaluated for kinetic chain dysfunction and may require the services of a sports minded DO, PT, or chiropractor for manual therapy.
I hope this helps.