Should you change your diet when exercising at altitude?
Intuitively, we all know that exercising at altitude is typically more challenging than exercising at sea level. Theoretically, due to this increased demand, it is likely that we are required to eat and drink more calories because we are working harder, right? Nutritional advice is always a constantly trending ‘hot’ topic, with most evidence supporting different claims – it could be suggested that adding altitude into this already complicated area will fuel more debate. However, a recently published review article regarding this area has provided some reliable and valid insights into how best to fuel your body for the challenge of exercising at altitude.
To begin with, short-term responses to altitude training include slight reductions in total body mass, whereas, long-term adaptions include loss of body mass and protein stores, muscle atrophy and total fat decreases. Hydration status is also negatively impacted, with males losing around a total of 1.9L per day, and females 0.5L. Finally, energy expenditure was around 2.5-3 times greater at altitude than at sea level. Therefore, continuing a habitual diet that we implement at sea level is possibly a recipe for disaster! Although, it is worth remembering that this research was based on training at an altitude camp, rather than successive visits to an altitude chamber.
The solution the authors recommended was what we expected, eat more! Well… relatively more. Around 60% of one’s daily calorie intake should be from carbohydrate sources and spread out evenly through the day; pre-, during and post- exercise. A greater reliance on slow-releasing carbohydrates should be employed pre- and during exercise, whereas post-exercise, fast-releasing intake is key! In addition to carbohydrate, the authors pay particular attention to antioxidants through consumption of fruit and vegetables as an important factor to maintaining performance at altitude.
Overall, it is important to remember that altitude training is more metabolically challenging than sea-level training. To reduce the potential of fatigue, starvation or even dehydration, those exercising at altitude should look to increase their calorie intake to match their physical challenge and periodise carbohydrate around exercise. However, these findings are based upon altitude training camps where constant exposure is maintained for a number of days up to weeks. Whereas, training in an altitude chamber will not yield the same degree of responses, but nonetheless, consideration of diet adaption should be made!
Michalczyk et al. (2016). Dietary recommendations for cyclists during altitude training. Nutrients, 8(377), doi:10.3390/nu8060377.