 An initial screening questionnaire will determine general eligibility. The investigators will screen white young males with low to moderate choline intake 450 mgd for CK response to exercise highlow by having them do intense eccentric exercise 12 elbow flexor contractions of non-dominant arm with dumbbell at 100 maximal lift capacity and then 72 hours 3 days later draw 250 μl capillary blood by finger stick for CK, metabolomic and genetic measurements. 