I eat mostly a plant-based diet with very little animal products (one to two servings of dairy per week and fish usually once a week). I also exercise a lot. My current schedule includes yoga three times a week, softball twice a week, one personal training session per week (weights and circuit training), as well as hiking, biking and running. I use to eat chicken and veggies or cottage cheese and fruit after working out, as well as drink a shaker of protein powder with a scoop of L-glutamine. I didn't use to get sore after working out, but now my muscles ache somewhat regularly. I would prefer to avoid synthetic protein, but am worried I might be developing a deficiency. How do you know if you have a protein deficiency?