Why High-Carb Nutrition Is the Key to Adapting to Summer Heat

Hot-weather training can be brutal, especially before we’ve adapted properly. Our heart rate is abnormally high, we sweat profusely, and our legs feel heavier than normal. Heat acclimation helps, but it doesn’t always guarantee a performance bump. Some athletes even get slower immediately after a heat block due to the heightened stress. What’s the explanation?

​A new study has a potential answer: carbohydrates. Specifically, it asked whether eating more carbs during a heat acclimation protocol can rescue performance right after the heat stress ends. As someone who’s struggled through summer heat training and wondered if more carbs might help, this study immediately piqued my interest.

Researchers divided 14 healthy men into two diet groups during a 6-day high-intensity heat acclimation protocol. The high-carb group consumed 70% of its total calories from carbohydrates, while the control group consumed 35% of its calories from carbohydrates.

Both groups went through the same heat acclimation protocol and then completed a 3.22 km time trial in the heat, both 1 day and 5 days after the protocol.

Both groups successfully acclimated. Lower heart rates, lower core and skin temps, and higher sweat rates showed that the physiological adaptations were there.

But performance diverged. The high-carb group ran significantly faster one day after heat acclimation, experiencing a 7% improvement vs. 0.7% in the control group. They also completed the time trial about 1 minute and 48 seconds faster than the control group at this time point. Five days after heat acclimation, the high-carb group had an 8.4% improvement in performance vs. a 2.8% improvement in the control group.

Interestingly, the difference wasn’t due to heat strain. Both groups had similar heat stress markers and acclimation responses. The carbs seemed to influence performance, not adaptation per se.

What this means for runners

If you're doing short-term heat training to prep for a summer race, don’t skimp on carbs. Even if you feel like your body is adapting (you’re sweating more, your heart rate is dropping), performance can still suffer if your glycogen tanks are low.

Carbs seem to act like a performance insurance policy during heavy heat blocks, likely preserving muscle glycogen, supporting central fatigue resistance, and maybe even helping with recovery from daily heat exposure.

Target 60–70% of your daily calories from carbs during any heat-focused training block lasting 5–7 days. Remember to fuel during workouts in the heat just like you would for a race—don’t treat these sessions as “just training.” This isn’t the time to try to train low.

RELATED ARTICLE: The Best Carbs For Runners: Power Up Your Performance By Fueling Right​

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Fueling Your Comeback: Why Prioritizing Nutrition Is Key After a Running Injury

We talk a lot about rehab protocols, strength training, and cross-training post-injury. But what about the role of protein timing? Micronutrient status? Energy availability? A new review paper puts nutrition squarely at the center of the injury-recovery-immune function triangle—and every endurance athlete should take note.

This wasn’t a traditional intervention study but rather a review and synthesis of current evidence by experts in clinical nutrition and sports immunology.

Here are the key insights:

Injury and poor nutrition lead to a vicious cycle. Injury disrupts normal training and reduces physical activity, lowering the beneficial effects of exercise on immune and metabolic health. If nutritional intake isn’t adjusted, the risk of prolonged recovery and immune dysfunction increases.
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​Energy intake and protein are crucial. Low energy availability is a huge red flag because it impairs wound healing, increases muscle loss, and delays return to sport. Protein intake should be 1.6–2.5 g/kg body mass/day (during injury as well as training), with ~20–30g per meal, evenly spaced throughout the day. Whole-food proteins (like beef or eggs) may outperform supplements for stimulating muscle protein synthesis.

Micronutrients matter too. Vitamin D, iron, zinc, and omega-3s deficiency are common culprits in immune dysfunction and impaired recovery. Supplementation is typically only advised when deficiencies are present, and excessive antioxidant supplementation (like megadoses of vitamin C or E) can blunt training adaptations, so be wary of using these, especially during fitness-building periods.

Our immune system needs fuel too. During illness or recovery, immune cells require more glucose, amino acids, and antioxidants. Proper nutrition not only boosts immune resistance but also enhances tolerance (i.e., reducing excessive inflammation that can damage tissues). So if you feel like you’re coming down with an illness or doing a lot of traveling or mingling, make sure to eat enough.
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What this means for runners

This review is a wake-up call for endurance athletes who pride themselves on pushing through injuries and skimping on calories in pursuit of race weight. If you’re injured or recovering, don’t skimp on nutrition. And even if you’re not injured, regular nutrition assessments—especially in high-load training periods—can prevent issues before they arise.

RELATED ARTICLE: 10 Rules of Marathon Training Nutrition​

Train the Norwegian Way: The Science-Backed System Behind the World’s Fastest Runners

When it comes to endurance performance, Norway punches way above its weight. A small country with a small talent pool, yet they're consistently on the podium in endurance sports, from cross-country skiing to triathlon to distance running. What are they doing differently?

​A new study gives us a rare behind-the-scenes look. Researchers interviewed 21 top Norwegian coaches working with Olympic-level endurance athletes across eight endurance sports (cross-country skiing, biathlon, cycling, orienteering, triathlon, athletics, rowing, and swimming) to understand their approach to training, periodization, and performance development (yes, the Norwegian “double threshold” model makes an appearance).

They distilled 20 best-practice themes across these categories. Here's a breakdown of what they found.

Coaches emphasized long-term development over short-term results. They used detailed performance models to guide both daily training and season planning. Training volumes were high and progressively increased, especially during the athlete’s junior-to-senior transition.

Across all sports, coaches structured training around intensity zones, using zone 1 (low-intensity) for ~80% of training. Threshold training (zone 2) and high-intensity work (zone 3) were prescribed with precision. While the now-famous double threshold model was used in running and cross-country skiing, it wasn’t universally applied.

All coaches incorporated year-round strength training, not just for injury prevention but also for performance. Strength work was sport-specific, periodized, and adapted around competitions.

Coaches actively managed training load, sleep, and life stress, not just workout metrics. Open communication was a cornerstone for adjusting training in real time, and coaches promoted athlete autonomy and self-regulation—many athletes had input into how sessions were executed. Coaching wasn’t just about prescribing sessions, but instead, long-term, trust-based relationships. Several coaches emphasized consistency, patience, and emotional intelligence over novel training fads.

What this means for runners

Even if you’re not chasing Olympic medals, there’s a lot to learn from how elite Norwegian coaches operate: long-term thinking, low-intensity training as a cornerstone, an emphasis on strength training for whole-body development, and (perhaps most importantly), an open relationship with yourself and your coach about how training and racing are going.

RELATED ARTICLE: How To Apply The Norwegian Method Of Endurance Training​

Here's what else you would have received this week if you were a subscriber to the complete, full-text edition of “Run Long, Run Healthy.” SUBSCRIBE HERE.

• Why you’re not burned out—just bored (and how to fix it)

• Could this supplement help your gut and improve your performance?

• Men or Women: Who’s Got Better Endurance?
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​Thanks for reading. As always—Run Long, Run Healthy
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~Brady~