With the rise in popularity of High Intensity Interval Training (HIIT), it’s no surprise that people are wanting to know how they can go about doing it right! As a specific training methodology and fat loss tool, HIIT training seems to surpass regular steady state endurance training for fast fat loss goals. However, sustaining these high intensity training techniques can prove difficult without adequate fuelling, so I intend to provide a few key areas where you can amend your diet so that you can sustain your HIIT.
What is HIIT?
High Intensity Interval Training (HIIT) is pretty self-explanatory, it requires the athlete to perform bouts (intervals) of exercise that is of a high intensity i.e. short periods of intense activity with slightly longer periods of low intensity activity. HIIT training improves the metabolic functions of our muscles which enhances the delivery of the energy substrate glucose. It does this because HIIT training has the capacity to really tap into your two main energy systems that are the anaerobic and aerobic pathways. The improved metabolic functions enables you to train harder for longer, and a useful and desirable side effect of HIIT training is the increased fat oxidation rate, enabling your body to burn more fat for energy than it ordinarily would. HIIT training can last anything between 4-30mins, which implies the metabolic benefits of HIIT can be seen via multiple, short burst intervals, or more prolonged intervals too (Talanian, Galloway, Heigenhauser, et al. 2007).
Your energy levels during HIIT
The intense nature of interval training means energy levels are used up quite rapidly, so sustained HIIT training is difficult. Perhaps some of the best proponents of HIIT type activity are football players who have been documented performing 150- 250 brief intense sprints over 10-15 metres, which totalled 10-15 kilometres during a match (Gibala, 2011). This level of HIIT training is rare, certainly in recreational athletes, however it is relative to the individual and will take its toll on any body’s energy systems. This type of activity recruits both the aerobic (energy in the presence of oxygen) and anaerobic (energy in the absence of oxygen) energy pathways. Both of these pathways require glucose, and in particular the stored form of glucose, glycogen. Going back to the football player example, almost half of the muscle fibres analysed after an average football match were nearly, or completely depleted of glycogen. Researchers suggest that this alone is the main reason for reduced sprint capacity during the second half of the football match, which places a large emphasis on food and drink provisions that deliver glucose and thus glycogen.
Nutrition for HIIT
So what can an athlete do to optimise their ability to perform HIIT? Well, there is a fine line with dietary recommendations for athletes such as footballers who may need higher carb intakes to sustain energy for performance, and for those people adopting HIIT for fat loss. A footballer for example will benefit from a high carbohydrate diet, so a carb, protein and fat ratio of approx. 60: 20: 20 may be useful. A good guide would be approx. 6-12g carbs per kg bodyweight per day as this will maximise glycogen stores and meet energy demands of training. Conversely, a person wanting to burn fat may wish to keep their carbs regular i.e. hit a carb, protein and fat ratio of approx. 40: 30: 30 respectively. This person may wish to shoot for 4-6g carbs per kg bodyweight per day in order to fuel shorter bouts of HIIT, whilst not provide an energy surplus to requirements and thus weight maintenance, or worse still weight gain!
‘Train low’ principle
With all this talk of performing HIIT whilst carb stores are high, there is in fact a theory that performing HIIT in the presence of low carb stores may be beneficial to promoting muscle adaptations. Morton et al. performed a study that found those men who performed HIIT training in a carb depleted state had a better muscle adaptation compared to those training with a carb drink. However, this was only seen in those training in a depleted state no more frequently than 1-2 times a week.
Last but by no means least is the potential role that supplements play when performing HIIT. There is some evidence that the supplement powerhouse Beta- alanine can help to buffer the hydrogen ions deposited during HIIT, in turn enabling you to training harder for longer and thus maximising your training adaptations and fat burning potential. Sodium bicarbonate might also exert the same buffering potential as Beta- alanine, so this too may help prolong one’s ability to perform HIIT.
Gibala, M, J. (2011). Nutritional strategies to support adaptation to high-intensity interval training in team sports. Retrieved 8th September, 2014, from discount supplements
Talanian, J L., Galloway, S, D., Heigenhauser, G, J., Bonen, A, & Spriet L, L. (2007). Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. J Appl Physiol. 102: 1439-1447