I see two ways to look at this problem. You have in mind either some form of hardened suit or exoskeleton, or you're thinking of a lightweight jogging suit-style apparel. I'll discuss both of these for completeness.
Exosuit
First off is the hardened suit/exoskeleton option, which I will simply call the exosuit. The biggest problem I see with this is the weight issue. According to this medical catalog, a heart-lung machine has a shipping weight of 500 lb. (226.8 kg). Even if we supposed we could improve that technology such that the weight is reduced by half, it'd still be unreasonable to attempt to run with it. You may as well make the suit fully mechanized, which also significantly reduces the stresses on the human occupying it and increases performance. 441
With this setup, oxygen infusion happens constantly with minimal maintenance.
Soft Suit
The soft suit, on the other hand, might be more workable. I'd see it coming equipped with a backpack of sorts that contains a power supply, a pair of small pumps, and a reservoir of oxygen-laden microparticles. Probably also a sensor to detect the wearer's blood oxygen level. When the suit detects your oxygen levels getting low, it turns on the two pumps, one to add microparticles and the other to remove excess fluid to offset what is being pumped in (it's not much). With this setup, oxygen infusion lasts only until the reservoir is depleted, at which point you're lugging around an extra 20 lb. (9 kg) of dead weight.
Injection
Adding oxygen to a person's bloodstream via a machine isn't an easy process. The most efficient way would be to inject directly into a major vein, such as the femoral vein. However, doing this is hazardous to health as the femoral artery and vein occupy the same part of the body and severing either is an effective means by which to kill someone. This activity is not conducted outside of clinical settings except in emergencies.
Conclusion
So it can be done, there's existing research to support it, and it would improve oxygen-related performance, but there are significant risks that might make it infeasible.
Additional reading: Popular Mechanics 75