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HMB for Endurance, Rehydration for Endurance Athletes and Intermittent Fasting’s Impact on Strength

Welcome to our weekly summary of the latest research from the worlds of sports science and sports nutrition.

In this week’s summary:


The Effects of HMB on Endurance Performance and VO2 Max

Two trail runners resting at the top of a trail looking our over the forest and mountains

This study investigated the impact of HMB (β-hydroxy-β-methylbutyrate) on the endurance performance of healthy individuals. Although HMB is popular among athletes, its effects on endurance activities were not clearly understood. The researchers reviewed and analyzed data from 11 studies with 279 participants and found that taking 3 grams of HMB daily for 2 to 12 weeks significantly improved endurance performance and maximum oxygen consumption (VO2 max). This suggests that HMB could be a beneficial supplement for enhancing endurance in physically active people.

Our thoughts: This is a solid meta-analysis of the research on HMB and its ability to improve endurance performance. If you’re taking HMB to improve your training, just make sure your supplement provides 3g of HMB per day (like HMB Sport) to realize its full effects.


Recommendations for Rehydration During Endurance Exercise 

Man filling a bottle with water and Blonyx Hydra+ at a sink

This review article examines the challenges of rehydration during endurance exercise, such as maintaining the right balance of fluids and electrolytes to prevent dehydration and overhydration. Dehydration occurs when water and sodium are lost but not adequately replaced, while overhydration involves excessive fluid consumption and retention. Both conditions can impair performance and cause health issues like exertional hyponatremia, or EHN (low sodium levels). The article discusses research findings and expert consensus on hydration and provides nine recommendations for rehydration during endurance activities:

  1. Measure body weight before and after exercise to estimate water gain or loss.
  2. Avoid weight gain during exercise to reduce the risk of fluid retention and EHN.
  3. Limit fluid intake to less than 700 mL/h to prevent EHN.
  4. Reduce fluid intake if experiencing stomach fullness, bloating, or vomiting.
  5. Aim for modest dehydration levels of up to 2–3% of body weight, which are generally well-tolerated.
  6. Seek medical consultation if weight loss exceeds 4% of body mass.
  7. Monitor for white salt deposits on clothing, indicating high sweat rate and sodium loss, and adjust sodium intake accordingly.
  8. Be aware that sodium consumption has a minor impact on serum Na+ and may not prevent EHN during prolonged exercise.
  9. Experiment with different rehydration strategies during training to find what works best for competition.

These guidelines aim to help athletes achieve optimal hydration, improve performance, and reduce the risk of illness.

Our thoughts: What stood out to us was that the researchers concluded that taking in salt (in drinks, tablets, foods, etc.) during endurance training had very little impact on body sodium levels. This is why we don’t add much salt to Hydra+. We add enough to speed water’s movement into the body, but don’t claim it’s there to replenish sodium during training.


How Intermittent Fasting Impacts Resistance Training Performance

Man in a blue Blonyx shirt taking a break during a CrossFit workout

This study investigates how intermittent fasting affects strength, power, and hunger in resistance-trained young men. The participants underwent resistance training sessions after fasting for 12 or 16 hours or in a fed state. The researchers measured maximum voluntary isometric contraction (the greatest amount of force a muscle can exert without moving), countermovement jump (a vertical jump starting from an upright standing position) performance, maximum number of repetitions, and total volume load (total weight lifted in session) in exercises like the back squat and leg press. They also assessed hunger using a visual analogue scale. The results showed that fasting for 12 or 16 hours did not significantly impact strength and power performance. However, hunger and the desire to eat were significantly higher after 16 hours of fasting compared to 12 hours of fasting and being in a fed state. This suggests that while intermittent fasting might not affect resistance training performance, it does increase feelings of hunger, especially with longer fasting durations.

Our thoughts: In short, intermittent fasting won’t improve your strength during resistance training (or necessarily reduce your strength), but it’ll certainly make you feel more hungry!

That’s all for this week. We hope you learned something new that you can incorporate into your training!

— Train hard!


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