Or imbalances in your abs/back muscles.
totally. it's the only time i ever do crunchy situps. as many as you can til you hurt too much. do it for 3 days and if your back is no better i'll give you your money back.
@mrsblucher started
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totally. it's the only time i ever do crunchy situps. as many as you can til you hurt too much. do it for 3 days and if your back is no better i'll give you your money back.