The physiological and ergogenic effects of exercise training
with low carbohydrate availability: a review

Abstract

Due to the importance of glycogen for energy production, research has traditionally recommended sufficient carbohydrate (CHO) availability to maximise exerciseperformance. However, recent evidence has suggested that undertaking some training sessions with low CHO availability may bring about greater physiological adaptations. This strategy has commonly been termed as 'train low'. Although desirable adaptations in gene expression related to mitochondrial biogenesis and the activity of enzymes related to aerobic metabolism have been observed, research is conflicted towards the ergogenic impact this technique has on exercise performance. Additionally, this strategy may produce maladaptations such as reduced training intensity, immunosuppression, protein oxidation and reduced pyruvate dehydrogenase (PDH) activity. Therefore, if athletes are to adopt this strategy, it is suggested that they periodise 'train low' to solely low-intensity sessions which won't be impaired by a drop in work rate, but otherwise maintaining sufficient daily CHO intake. Also, athletes could negate potential maladaptations by using caffeine and/or CHO mouth rinse to maintain exercise intensity, and increasing protein ingestion to counteract increased protein oxidation. Future research should directly compare the effect of 'train low' between use in all sessions and solely low-intensity sessions within one comprehensive study to better understand the mechanisms behind the apparent superiority of the latter strategy.