From the Guidelines
Marathon runners do not require an increase in dietary protein consumption beyond the general recommendation of 1.2 to 1.7 grams of protein per kilogram of body weight daily. The current evidence suggests that the laboratory techniques used to justify increasing the protein RDA for athletes have numerous experimental limitations and therefore its accuracy is difficult to ensure 1. The 'black-box' nature of the balance model does not allow for the assessment of those metabolic adaptations and dietary efficiencies that accrue with chronic training 1.
Key Considerations
- The recommendation to increase protein intake, as determined from N balance, has had serious methodological problems on both the input and output sides of the equation 1.
- Increases in daily energy intakes will reduce the need for protein to maintain N balance, and 30% of the variance in N balance can be accounted for by energy intakes 1.
- There are sex differences in the contribution of protein and amino acids to whole-body energy needs, and these have not been included in the protein RDA recommendations for the habitually active 1.
Protein Intake Recommendations
- A 70 kg (154 lb) runner would require 84-119 grams of protein per day, based on the general recommendation of 1.2 to 1.7 grams of protein per kilogram of body weight daily.
- Protein needs should be distributed throughout the day, with particular attention to post-run recovery when consuming 20-25 grams of protein within 30-45 minutes after finishing can optimize muscle repair.
- Good protein sources include lean meats, fish, eggs, dairy, legumes, and plant-based options like tofu.
- Individual needs may vary based on training intensity, body composition goals, and overall caloric intake, so some runners may need to adjust their intake accordingly.
From the Research
Protein Requirements for Marathon Runners
- The recommended protein intake for marathon runners is not explicitly stated in all studies, but some provide guidelines for optimal health outcomes and athletic performance 2, 3.
- A study published in 2016 suggests that protein intakes in the range of at least 1.2 to 1.6 g/(kg·day) of high-quality protein is a more ideal target for achieving optimal health outcomes in adults 2.
- Another study from 2021 found that master marathon runners who consumed higher protein intakes experienced lower changes in body composition and metabolic blood indices after the race 3.
- The importance of protein intake for marathon runners is also highlighted in a 2021 study, which found that protein metabolism and related body function are crucial for maintaining body composition and functions 4.
Grams of Protein per Day
- Based on the study published in 2016, a marathon runner weighing 70 kg would require at least 84 grams of protein per day (1.2 g/(kg·day) x 70 kg) to achieve optimal health outcomes 2.
- For a runner weighing 80 kg, the recommended protein intake would be at least 96 grams per day (1.2 g/(kg·day) x 80 kg) 2.
Protein Intake and Marathon Performance
- A study from 2021 found that protein intake during the tapering period and the race was related to marathon performance, body composition, and acute race-induced changes in master runners 3.
- The study suggests that consuming adequate amounts of protein can help improve marathon performance and reduce muscle damage and metabolic stress 3.